tag:theconversation.com,2011:/nz/topics/geoscience-5940/articlesGeoscience – The Conversation2024-02-23T13:48:54Ztag:theconversation.com,2011:article/2232752024-02-23T13:48:54Z2024-02-23T13:48:54ZWar in Ukraine at 2 years: Destruction seen from space – via radar<figure><img src="https://images.theconversation.com/files/577463/original/file-20240222-27-6vdacx.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C742%2C589&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Satellite radar data shows the complete destruction of the Ukrainian city of Bakhmut.</span> <span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/pii/S2666592124000064">Xu et al. (2024)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>As soldiers and citizens provide information from the front lines and affected areas of the war in Ukraine – two years old as of Feb. 24, 2024 – in quasi-real time, an active <a href="https://www.wired.com/story/open-source-intelligence-war-russia-ukraine/">open-source intelligence community</a> has formed to keep track of troop activity, destruction and other aspects of the war. </p>
<p>Remote sensing complements this approach, offering a safe means to study inaccessible or dangerous areas. For example, seismologists have documented the high pace of <a href="https://doi.org/10.1038/s41586-023-06416-7">bombardments and firing of artillery</a> around Kyiv during the first few months of the war. </p>
<p>Previously, <a href="https://scholar.google.com/citations?hl=en&user=-Yl3IoQAAAAJ&view_op=list_works&sortby=pubdate">Teng Wang</a>, a professor at the Peking University in China, and <a href="https://scholar.google.com/citations?hl=en&user=1vR8GGoAAAAJ&view_op=list_works&sortby=pubdate">I</a> – both Earth scientists – studied <a href="https://www.science.org/doi/10.1126/science.aar7230">illegal nuclear tests in North Korea</a> with satellite data. </p>
<p>Putting our skills to good use once again, we, with graduate student <a href="https://www.researchgate.net/profile/Xu-Hang-3">Hang Xu</a>, have <a href="https://doi.org/10.1016/j.nhres.2024.01.006">analyzed the development of the war from space</a>. We exclusively used open-source, freely accessible data to ensure that all our findings could be reproduced, guaranteeing transparency and neutrality. </p>
<h2>View from above</h2>
<p>Sensors on satellites record electromagnetic waves radiated or reflected from Earth’s surface with wavelengths ranging from hundreds of nanometers to tens of centimeters, enabling semi-continuous <a href="https://earth.jaxa.jp/en/eo-knowledge/eosatellite-type/index.html">monitoring on a global scale</a>, unimpeded by political boundaries and natural obstacles. </p>
<p>Optical images, the equivalent of photographs taken from space, help governments, researchers and journalists monitor troop movements on the front and the destruction of equipment and facilities. Although optical images are easily interpreted, they suffer from cloud cover and operate only during daylight. </p>
<p>To counter these issues, we used radars onboard satellites. Space-borne radar systems beam long-wavelength electromagnetic waves toward the Earth and then record the returning echos. These waves – about 0.4 to 4 inches (1 to 10 centimeters) – can penetrate clouds and smoke. <a href="https://nisar.jpl.nasa.gov/mission/get-to-know-sar/interferometry/">Radar interferometry</a> has already proved to be an invaluable tool to monitor widespread damage caused by <a href="http://dx.doi.org/10.26443/seismica.v2i3.502">natural disasters</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a pair of satellite views showing the same section of a city, one with intact buildings and green space and the other damaged or destroyed buildings and charred earth" src="https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=757&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=757&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=757&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=952&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=952&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577455/original/file-20240222-26-fyycrl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=952&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Satellite photography like these ‘before’ and ‘after’ images can provide a visceral sense of the destruction in the war in Ukraine.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/maxar-satellite-imagery-comparing-the-before-after-news-photo/1255499859">Satellite image (c) 2023 Maxar Technologies via Getty Images</a></span>
</figcaption>
</figure>
<h2>Radar from space</h2>
<p>Free and publicly available radar data for civilian applications is rare – the United States is scheduled to launch its <a href="https://nisar.jpl.nasa.gov/mission/quick-facts/">first one</a> in March 2024 – but the European Space Agency has made such data available since the early 1990s. Data from the European Space Agency’s <a href="https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-1/data-products">Sentinel-1</a> satellite radar is freely accessible via their data hub. </p>
<p>Two radar images formed over the same area can be used to detect changes to structures and other surfaces. Interferometry measures <a href="https://nisar.jpl.nasa.gov/mission/get-to-know-sar/interferometry/">the difference in travel time between two radar signals</a>, which is a measure of change in the shape or position of surfaces. Another measure of surface change is the coherence of the reflected signals – that is, the degree of similarity between two different images when comparing neighboring pixels at the same position in the two images. A large coherence implies little change and thus the preservation of a building or other structure. On the other hand, a loss of coherence in the context of a battlefield implies damage or destruction of a building or structure. </p>
<p>Sentinel-1 radar’s spatial resolution of 66 feet (20 meters) over a swath of 255 miles (410 kilometers) combined with 12-day updates makes its radar data ideal for monitoring urban warfare. Previous research efforts have used satellite radar data to assess damage in <a href="https://doi.org/10.3390/rs14246239">Kyiv</a> and <a href="https://doi.org/10.3390/rs15123096">Mariupol</a>. We used the data to analyze the evolution of damage to cities over time during several lengthy battles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="four maps of a city with increasing amounts of the buidlings marked in red" src="https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=487&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=487&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=487&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=612&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=612&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577471/original/file-20240222-24-cgcs3i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=612&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Changes in radar data during the battle of Bahkmut show increasing amounts of destruction. Red pixels imply damaged or destroyed buildings.</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/pii/S2666592124000064">Xu et al. (2024)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Measure of destruction</h2>
<p>We flagged highly damaged areas by comparing radar coherence before and after the war, within the areas classified as artificial surfaces by the European Space Agency’s <a href="https://worldcover2021.esa.int/">WorldCover 2021 dataset</a>. Using this approach, we first analyzed the <a href="https://www.usnews.com/news/world/articles/2023-05-20/key-moments-in-the-battle-of-bakhmut-in-ukraines-east">battle of Bakhmut</a>, one of the longest and bloodiest of the war, which began on Oct. 8, 2022, and ended with a Russian victory on May 20, 2023. </p>
<p>When Hang Xu showed Teng Wang and me the data he had processed, we were puzzled. We saw a checkerboard pattern all over the city. We quickly realized the horror of the situation. The only thing that survived after the yearlong battle was the network of roads in the city. All buildings had partially or completely collapsed due to the continuous bombardment.</p>
<p>We then took a look at the battles of Rubizhne, Sievierodonetsk and Lysychansk that started in April 2022 and ended with a Russian victory on July 2, 2022. The comparatively lower destruction of Lysychansk is explained by the rapid encirclement of the city from the south instead of continued frontal assaults, as was the case in Bakhmut. The radar data reveals destruction away from the front line within cities, showing the whole extent of the devastation. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="four maps of a set of three cities with increasing amounts of the buidlings marked in red" src="https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=488&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=488&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=488&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=613&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=613&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577472/original/file-20240222-18-3rco59.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=613&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Changes in radar data during the battles of Rubizhne, Sievierodonetsk and Lysychansk show increasing amounts of destruction. Urban areas are shown in gray with damage in red.</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/pii/S2666592124000064">Xu et al. (2024)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Devastation in focus</h2>
<p>Remote sensing images offer the means to safely monitor the impact of armed conflicts, particularly as <a href="https://thedocs.worldbank.org/en/doc/8bc2ffd2ca0d2f174fee8315ad4c385b-0090082021/original/Classification-of-Fragility-and-Conflict-Situations-web-FY22.pdf">high-intensity wars</a> in <a href="https://www.nytimes.com/interactive/2024/02/01/world/middleeast/Israel-gaza-war-demolish.html">urban environments proliferate</a>. Open-access satellite instruments complement other forms of open-source intelligence by offering unimpeded access to high-resolution, unbiased information, which can help people grasp the true impact of war on the ground. </p>
<p>The picture is clear: The real story of war is <a href="https://www.rferl.org/a/bakhmut-ukraine-satellite-images-maxar-destruction/32416025.html">destruction</a>.</p><img src="https://counter.theconversation.com/content/223275/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sylvain Barbot receives funding from the National Science Foundation. </span></em></p>Satellite photography of the Ukrainian city of Bakhmut shows block after block of destroyed buildings. Satellite radar provides a different view – a systematic look at the destruction of the whole city.Sylvain Barbot, Associate Professor of Earth Sciences, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2167012023-12-04T13:27:46Z2023-12-04T13:27:46ZNew England stone walls lie at the intersection of history, archaeology, ecology and geoscience, and deserve a science of their own<figure><img src="https://images.theconversation.com/files/562785/original/file-20231130-25-3xzmdr.jpeg?ixlib=rb-1.1.0&rect=16%2C0%2C1800%2C1191&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A typical New England stone wall in Hebron, Conn.</span> <span class="attribution"><span class="source">Robert M. Thorson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>The abandoned fieldstone walls of New England are every bit as <a href="https://www.smithsonianmag.com/travel/how-stone-walls-became-a-signature-landform-of-new-england-180983250/">iconic to the region</a> as lobster pots, town greens, sap buckets and fall foliage. They seem to be everywhere – a latticework of dry, lichen-crusted stone ridges separating a patchwork of otherwise moist soils.</p>
<p>Stone walls can be found here and there in other states, but only in New England are they nearly ubiquitous. That’s due to a regionally unique combination of hard crystalline bedrock, glacial soils and farms with patchworks of small land parcels. </p>
<p>Nearly all were built by European settlers and their draft animals, who scuttled glacial stones from agricultural fields and pastures outward to fencelines and boundaries, then tossed or stacked them as lines. Though the <a href="https://books.google.com/books/about/A_Long_Deep_Furrow.html?id=Hn-5AAAAIAAJ">oldest walls</a> date to 1607, most were built in the agrarian century between the American Revolution and the cultural shift toward cities and industry after the Civil War. </p>
<p>The mass of stone that farmers moved in that century staggers the mind – an estimated <a href="https://wwnorton.com/books/Sermons-in-Stone/null">240,000 miles (400,000 kilometers)</a> of barricades, most stacked thigh-high and similarly wide. That’s long enough to wrap our planet 10 times at the equator, or to reach the Moon on its closest approach to Earth.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/BwPUy6kjISv/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Natural scientists have been working to quantify this phenomenon, which is larger in volume than the Great Wall of China, Hadrian’s Wall in Britain and the Egyptian pyramids at Giza combined. This work began in 1870 and generated the U.S. government’s 1872 <a href="https://www.primaryresearch.org/stonewalls/fencesurvey.pdf">Census of Fences</a>. Today, scientists are using <a href="https://stonewall.uconn.edu/wp-content/uploads/sites/534/2014/03/Johnson-and-Ouimet-2014-Rediscovering-the-lost-archaeological-landscape-of-southern-New-England-using-airborne-LiDAR.pdf">a technique called LiDAR</a>, or light detection and ranging, to <a href="https://granit.unh.edu/pages/nh-stone-walls">measure and map</a> stone walls across New England.</p>
<p>Being <a href="https://scholar.google.com/citations?user=ElExWMsAAAAJ&hl=en">a geologist</a>, I’m interested in walls as landforms that are distinctive to the region, created during the lead-up to the <a href="https://www.npr.org/2023/07/11/1187125012/anthropocene-crawford-lake-canada-beginning">Anthropocene</a> epoch – a time when human agency dominates all others. I’ve written about the <a href="https://www.bloomsbury.com/us/stone-by-stone-9780802776877/">history of stone walls</a> and how to <a href="https://stonewall.uconn.edu/books-2/exploring-stone-walls/">interpret them in the field</a>, and developed the <a href="https://stonewall.uconn.edu/about-swi/mission-and-purpose/">Stone Wall Initiative</a> to draw public attention to their importance in New England. Now, I’m working with students and colleagues to develop a formal interdisciplinary science of stone walls that will help researchers understand and preserve them.</p>
<h2>Dens and pathways</h2>
<p>My brother-in-law enjoys his backyard wall in Lee, New Hampshire, mainly for its aesthetic, historic and literary ambiance. The wild things living in his neighborhood depend on it as unique habitat. </p>
<p>To lichens and moss, the wall’s dry stones are surfaces where plants can’t compete. For plants, such walls are edges that separate patches of ground into zones that are sunny or shady, windward or leeward, uphill or downhill, wetter or drier. Stone walls offer small mammals porous volumes in which to live their furtive lives. Predators use the walls as hunting blinds and travel corridors.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CdEgCxhvYBv/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Just for fun, my brother-in-law installed a motion-activated, infrared video camera on his backyard wall to see who was using the wall and how. On June 21, 2023, the summer solstice, he <a href="https://stonewall.uconn.edu/author/rmt02003/">filmed a bobcat (<em>Lynx rufus</em>)</a> hiding behind it and then using it as an elevated pathway.</p>
<p>The more we researchers learn about New England’s abandoned stone walls, the more we realize that they transcend and obliterate the narrow treatments of our scholarly disciplines. These archaeological artifacts are so ubiquitous that they have become a geological landform that in turn creates a novel ecological habitat. These walls also are literary icons, historic sites and spiritual oracles, as Robert Frost recognized when he penned “<a href="https://www.poetryfoundation.org/poems/44266/mending-wall">Mending Wall</a>,” on an <a href="https://www.robertfrostfarm.org/">old farm</a> in Derry, New Hampshire. </p>
<p>But despite their importance, never have the stone walls of New England been technically defined, classified and given a common terminology in a peer-reviewed journal. They fell, it seems, through disciplinary cracks. </p>
<p>My initial step toward changing this situation was writing a mini-monograph in 2023 for the journal Historical Archaeology on the “<a href="https://doi.org/10.1007/s41636-023-00432-0">Taxonomy and Nomenclature for the Stone Domain in New England</a>.” Its goal is to coalesce the study of these stone walls into an interdisciplinary science by following the precedents of other disciplines – most notably, the 18th-century <a href="https://www.britannica.com/science/taxonomy">Linnaean taxonomy</a> that biologists still use today. Here’s how that approach works:</p>
<h2>Defining and classifying</h2>
<p>Understanding the stone walls of greater New England scientifically requires starting with a technical definition that is based on field criteria rather than tradition or inference. There are many kinds of historical stone features – waste piles, cairns, scatters, lines, kilns, gravestones, cobbles, patios and more. The goal is to isolate walls as a set of objects within this larger domain. </p>
<p>For example, a definition can require that each wall be composed of stone; composed of particles, rather than one enormous slab; continuous; elongated; and sufficiently high. Without such explicit criteria, one person’s wall is another’s elongated pile, and one person’s waste heap is another’s <a href="https://www.arcadiapublishing.com/products/9781634990493">sacred site</a>.</p>
<p>It’s nice when descriptions and classifications can be loose and flexible, as with genres of music, styles of fashion, and disciplines within academia. These are typologies, bins, pigeonholes. But to make scientific sense of the world, researchers need to convert descriptions into precise definitions and use them in binary, rule-driven classifications. <a href="https://www.britannica.com/search?query=taxonomy">These are taxonomies</a>.</p>
<p>Every field of science requires its own language. Chemists group <a href="https://sciencenotes.org/periodic-table-groups-and-periods/">elements with similar properties</a>, like halogens and noble gases. Biologists divide life forms into <a href="https://kids.britannica.com/students/article/biological-classification/611149">domains, kingdoms, phyla and smaller groups</a> with shared characteristics. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chart showing biological classification of domestic dogs and the larger biological groups to which they belong." src="https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=605&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=605&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=605&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=761&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=761&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562817/original/file-20231130-23-c9e5wt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=761&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This graphic shows how biologists use taxonomy to name, describe and classify one subspecies, domesticated dogs (<em>Canis lupus familiaris</em>), and relate that subspecies to larger groups such as carnivores, mammals and animals.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/7/75/Figure_20_01_05.png">CNX Open Stax/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Terms in stone wall science involve the size, shape, composition, source and arrangement of stones; the vertical and horizontal structures of tiers, courses and terminations; and their topographic settings on the landscape. </p>
<p>Stone wall classification begins with the stone domain – the entire constellation of historical stone objects. From there, we carve out a distinct class of stone walls that’s separate from other rock assemblies, like concentrations and lines, as well as notable individual stones, like <a href="https://seeplymouth.com/listing/plymouth-rock/">Plymouth Rock</a>. Then, using diagnostic criteria, we divide the class walls into five families – free-standing, flanking, supporting, enclosing and blocking – and break them down further into types, subtypes and variants within <a href="https://doi.org/10.1007/s41636-023-00432-0">a new taxonomy</a>. </p>
<h2>What stone walls can tell us</h2>
<p>At this stage, my students, colleagues and I are just beginning to pair stone wall science with LiDAR techniques at the scale of villages. Tantalizing spatial patterns are emerging. </p>
<p>Different types of walls occur in predictable arrangements. For example, we commonly find well-built double walls near cellar holes, with simpler single walls at further distance and waste piles beyond those. Such patterns provide an independent source of primary documentary evidence that researchers can use to interpret past cultural behaviors, above and beyond the written documents of history and the <a href="https://en.wikipedia.org/wiki/In_Small_Things_Forgotten">much smaller artifacts</a> of excavation-based archaeology. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/4YAIq-Whttg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Many of New England’s forests stand on land that used to be family farms. Stone walls in these forests mark former boundaries.</span></figcaption>
</figure>
<p>Such spatial patterns can also be used for ecological interpretations. For example, a bobcat is more likely to hunt along a normal single wall than other subtypes because it has the required stability and height to support the cat and sufficient void space for prey to live in. </p>
<p>These structures – these elevated drylands – are in some ways analogous to the region’s wetlands, which also are landforms that farmers created or <a href="https://pubs.geoscienceworld.org/gsa/books/book/751/chapter-abstract/3902909/Colonial-impacts-to-wetlands-in-Lebanon?redirectedFrom=fulltext">significantly modified</a> as they settled the land in the 18th and 19th centuries. However, since the 1990s, wetlands have earned a <a href="https://nap.nationalacademies.org/catalog/4766/wetlands-characteristics-and-boundaries">robust science</a>, a solid <a href="https://www.epa.gov/wetlands">legal framework</a> and excellent <a href="https://www.nawm.org/">management protocols</a>. </p>
<p>In my view, the time has come to do the same for New England’s stone walls. These dryland structures are so ubiquitous, massive and unique relative to other habitats that it’s high time for natural scientists to give them the respect they deserve.</p><img src="https://counter.theconversation.com/content/216701/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert M. Thorson created and coordinates the Stone Wall Initiative, an online resource on the historic stone walls of New England. He is an advocate for their conservation and management, and a frequent public speaker on this topic for land trusts, historical societies, environmental non-profits, public libraries, and “friends of…” organizations. </span></em></p>New England has thousands of miles of stone walls. A geoscientist explains why analyzing them scientifically is a solid step toward preserving themRobert M. Thorson, Professor of Earth Science, University of ConnecticutLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2132022023-11-20T13:15:30Z2023-11-20T13:15:30ZHow do crystals form?<figure><img src="https://images.theconversation.com/files/557894/original/file-20231106-25-rk3zxx.jpg?ixlib=rb-1.1.0&rect=33%2C0%2C5595%2C3713&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Two crystalline materials together: kyanite (blue) embedded in quartz (white).</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/bladed-crystals-of-kyanite-in-quartz-from-brazil-news-photo/869774444">Photo 12/Universal Images Group via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>How do crystals form? – Alyssa Marie, age 5, New Mexico</strong></p>
</blockquote>
<hr>
<p>Scientifically speaking, the term “crystal” refers to any solid that has an <a href="https://theconversation.com/why-does-nature-create-patterns-a-physicist-explains-the-molecular-level-processes-behind-crystals-stripes-and-basalt-columns-186433">ordered chemical structure</a>. This means that its parts are arranged in a precisely ordered pattern, like bricks in a wall. The “bricks” can be <a href="https://australian.museum/learn/minerals/what-are-minerals/crystal-shapes/">cubes or more complex shapes</a>.</p>
<p>I’m <a href="https://scholar.google.com/citations?user=EqUjQbwAAAAJ&hl=en">an Earth scientist and a teacher</a>, so I spend a lot of time thinking about minerals. These are solid substances that <a href="https://www.britannica.com/science/mineral-chemical-compound">are found naturally in the ground</a> and can’t be broken down further into different materials other than <a href="https://www.youtube.com/watch?v=wzTRPlG1L0o">their constituent atoms</a>. Rocks are mixtures of different minerals. <a href="https://www.geologyin.com/2016/03/what-is-difference-between-minerals-and.html">All minerals are crystals</a>, but not all crystals are minerals. </p>
<p>Most rock shops sell mineral crystals that occur in nature. One is <a href="https://theconversation.com/not-so-foolish-after-all-fools-gold-contains-a-newly-discovered-type-of-real-gold-161819">pyrite, which is known as fool’s gold</a> because it looks like real gold. Some shops also feature showy, human-made crystals such as <a href="https://www.zmescience.com/feature-post/natural-sciences/geology-and-paleontology/rocks-and-minerals/the-bismuth-crystal-why-it-looks-so-amazingly-trippy-and-why-its-actually-a-big-deal-for-science/">bismuth</a>, a natural element that forms crystals when it is melted and cooled. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark gray rock with a large concentration of shiny yellow material covering part of its surface." src="https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=453&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=453&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=453&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=569&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=569&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557895/original/file-20231106-267473-4zr8g4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=569&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pyrite in black shale rock from a quarry in Indianapolis, Ind.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/uJq9jj">James St. John/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Why and how crystals form</h2>
<p>Crystals grow when molecules that are alike get close to each other and stick together, forming chemical bonds that act like Velcro between atoms. Mineral crystals cannot just start forming spontaneously – they need special conditions and a <a href="https://www.thoughtco.com/definition-of-nucleation-605425">nucleation site</a> to grow on. A nucleation site can be a rough edge of rock or a speck of dust that a molecule bumps into and sticks to, starting the crystallization chain reaction.</p>
<p>At or near the Earth’s surface, many molecules are dissolved in water that flows through or over the ground. If there are enough molecules in the water that are alike, they will separate from the water as solids – a process called precipitation. If they have a nucleation site, they will stick to it and start to form crystals. </p>
<p>Rock salt, which is actually <a href="https://www.britannica.com/science/halite">a mineral called halite</a>, grows this way. So does <a href="https://www.britannica.com/science/travertine">another mineral called travertine</a>, which sometimes forms flat ledges in caves and around hot springs, where water causes chemical reactions between the rock and the air. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="White rock terraces around a vent in the earth's surface releasing steam." src="https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557876/original/file-20231106-23-phmp31.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Travertine ledges at Mammoth Hot Springs in Yellowstone National Park in Wyoming. Terraced pools form due to deposition of travertine from the hot spring fluids as they cool and release carbon dioxide.</span>
<span class="attribution"><a class="source" href="https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/thumbnails/image/P7190038.JPG">USGS</a></span>
</figcaption>
</figure>
<p>You can make “<a href="http://www.sciencekidsathome.com/science_experiments/growing_stalactites.html">salt stalactites</a>” at home by growing salt crystals on a string. In this experiment, the string is the nucleation site. When you dissolve Epsom salts in water and lower a string into it, then leave it for several days, the water will slowly evaporate and leave the Epsom salts behind. As that happens, salt crystals precipitate out of the water and grow crystals on the string.</p>
<p>Many places in the Earth’s crust are hot enough for <a href="https://www.britannica.com/science/magma-rock">rocks to melt into magma</a>. As that magma cools down, mineral crystals grow from it, just like water freezing into ice cubes. These mineral crystals form at much higher temperatures than salt or travertine precipitating out of water. </p>
<h2>What crystals can tell scientists</h2>
<p>Earth scientists can learn a lot from different types of crystals. For example, the presence of certain mineral crystals in rocks can reveal the rocks’ age. This dating method is called <a href="https://www.britannica.com/science/geochronology">geochronology</a> – literally, measuring the age of materials from the Earth. </p>
<p>One of the most valued mineral crystals for geochronologists is <a href="https://geology.com/minerals/zircon.shtml">zircon</a>, which is so durable that it quite literally stands the test of time. The <a href="https://www.si.edu/newsdesk/releases/earths-oldest-minerals-date-onset-plate-tectonics-36-billion-years-ago">oldest zircons ever found</a> come from Australia and are about 4.3 billion years old – almost as <a href="https://www.amnh.org/exhibitions/darwin/the-world-before-darwin/how-old-is-earth">old as our planet itself</a>. Scientists use the chemical changes recorded within zircons as they grew as a reliable “clock” to <a href="https://knowablemagazine.org/article/physical-world/2021/keeping-time-zircons">figure out how old the rocks containing them are</a>.</p>
<p>Some crystals, including zircons, have growth rings, like the <a href="https://naturalsciences.org/calendar/news/science-at-home-tree-rings/">rings of a tree</a>, that form when layers of molecules accumulate as the mineral grows. These rings can tell scientists all kinds of things about <a href="https://theconversation.com/1-000-year-old-stalagmites-from-a-cave-in-india-show-the-monsoon-isnt-so-reliable-their-rings-reveal-a-history-of-long-deadly-droughts-189222">the environment in which they grew</a>. For example, changes in pressure, temperature and magma composition can all result in growth rings.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="White rectangular feldspar crystals with faintly visible growth rings are prominent against grey granodiorite rock." src="https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=530&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=530&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=530&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=666&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=666&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559134/original/file-20231113-25-cx8jko.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=666&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Feldspar crystals with growth rings in granodiorite rock near Squamish, British Columbia.</span>
<span class="attribution"><span class="source">Natalie Bursztyn</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Sometimes mineral crystals grow as high pressure and temperatures within the Earth’s crust change rocks from one type to another in a process called <a href="https://www.amnh.org/exhibitions/permanent/planet-earth/how-do-we-read-the-rocks/three-types/metamorphic">metamorphism</a>. This process causes the elements and chemical bonds in the rock to rearrange themselves into new crystal structures. Lots of spectacular crystals grow in this way, including <a href="https://geology.com/minerals/garnet.shtml">garnet</a>, <a href="https://geology.com/minerals/kyanite.shtml">kyanite</a> and <a href="https://geology.com/minerals/staurolite.shtml">staurolite</a>.</p>
<h2>Amazing forms</h2>
<p>When a mineral precipitates from water or crystallizes from magma, the more space it has to grow, the bigger it can become. There is a <a href="https://cen.acs.org/physical-chemistry/geochemistry/Naicas-crystal-cave-captivates-chemists/97/i6">cave in Mexico full of giant gypsum crystals</a>, some of which are 40 feet (12 meters) long – the size of telephone poles.</p>
<p>Especially showy mineral crystals are also valuable as gemstones for jewelry once they are cut into new shapes and polished. The highest price ever paid for a gemstone was $71.2 million for the <a href="https://www.npr.org/sections/thetwo-way/2017/04/05/522739361/pink-star-diamond-sells-for-71-million-smashing-auction-record">CTF Pink Star diamond</a>, which went up for auction in 2017 and sold in less than five minutes.</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/213202/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natalie Bursztyn does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>There are a lot of myths about crystals − for example, that they are magical rocks with healing powers. An earth scientist explains some of their amazing true science.Natalie Bursztyn, Lecturer in Geosciences, University of MontanaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2120082023-08-29T01:30:16Z2023-08-29T01:30:16ZNatural hazards, a warming climate and new resource laws – why NZ needs geoscientists more than ever<p>Earth scientists and technical staff are in scope for potential job losses at New Zealand universities as part of a wider cost-cutting exercise. As a geologist, I find these mooted redundancies stupefying.</p>
<p>New Zealand faces multiple natural hazards, the geotechnical industry is already struggling to recruit graduates, and the demand can only grow as we tackle multifaceted global problems such as climate change and reliable energy supplies. </p>
<p>We need geoscientists more than ever, and here are three big reasons why.</p>
<h2>Construction demand</h2>
<p>Most of the land in New Zealand is “greenfield” and undeveloped. We are either building new houses and infrastructure or rebuilding damaged houses and infrastructure following natural hazard events. </p>
<p>New Zealand is yet to develop serious public transport infrastructure (intercity rail, tunnels) and has only relatively recently embarked on <a href="https://www.nzta.govt.nz/resources/national-land-transport-programme-nltp/2009-12/roads-of-national-significance/">major roading projects</a>, including the <a href="https://www.nzta.govt.nz/projects/waikato-expressway/">Waikato expressway</a> and <a href="https://www.nzta.govt.nz/projects/wellington-northern-corridor/peka-peka-to-otaki-expressway/">Kāpiti expressway</a>.</p>
<p>Rail to Auckland’s North Shore, and rail and vehicle harbour tunnels, are only now being <a href="https://www.beehive.govt.nz/release/phased-tunnels-second-harbour-crossing">seriously considered</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/slow-train-coming-only-a-genuine-shift-to-rail-will-put-nz-on-track-to-reduce-emissions-211662">Slow train coming: only a genuine shift to rail will put NZ on track to reduce emissions</a>
</strong>
</em>
</p>
<hr>
<p>A prerequisite for any new construction is a ground investigation to understand the subsurface. This is to identify any potential ground hazards – subsidence, flooding, groundwater, slips, weak soils and rocks – and to mitigate any geotechnical “ground risks” through sound land-use planning and zoning, and appropriate building design. </p>
<p>Even the building of a single-storey house requires a geologist to drill a shallow borehole into the soil and to undertake <a href="https://www.building.govt.nz/building-code-compliance/b-stability/b1-structure/module-1-overview-guidelines/">shear-strength and penetration-resistance tests</a>.</p>
<h2>Geohazards and climate</h2>
<p>New Zealand straddles a convergent plate boundary and is surrounded by mid-latitude oceans creating a humid climate. We are in the gun barrel of several <a href="https://www.rnz.co.nz/news/national/493893/heavy-rain-events-reveal-landslide-problems-on-puhoi-to-warkworth-highway">natural hazards</a>. In a warming world, New Zealand will also experience more extreme weather events. </p>
<p>When a construction site, house, road, rail line or water pipeline is affected by natural hazards, we need geologists to respond. They advise on mitigation so that temporary works can occur, and they provide information to inform longer-term engineering design solutions. </p>
<p>Demand is high and rising for <a href="https://www.careers.govt.nz/jobs-database/science/science/geologist/">earth science</a> and <a href="https://www.careers.govt.nz/jobs-database/engineering/engineering/civil-engineer/">civil engineering graduates</a> to deal with these large-scale environmental management issues. Graduates at my department all receive multiple job offers, including from overseas, and universities are struggling to supply domestic needs. </p>
<h2>Critical minerals</h2>
<p>In addition to the above roles, geoscientists are also in demand in the minerals and energy sectors, both vital industries to mitigate climate change and provide us with technology. In New Zealand, we tend to conveniently ignore the minerals that facilitate our everyday existence. </p>
<p>Take the <a href="https://www.geolsoc.org.uk/%7E/media/shared/documents/education%20and%20careers/Resources/Posters/Minerals%20in%20a%20smartphone%20poster.pdf?la=en">14 different minerals</a> (at least) used in a typical smartphone. The tantalite that provides the tantalum used in smartphone capacitor anodes comes from the Democratic Republic of Congo and is recognised as a <a href="https://policy.trade.ec.europa.eu/development-and-sustainability/conflict-minerals-regulation/regulation-explained_en">conflict mineral</a>. </p>
<p>The beryllium used to make the battery contacts either comes from Mozambique, China or the US. Cassiterite is mined for the tin used to solder components together and likely comes from a mine in Myanmar or Indonesia.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/critical-minerals-are-vital-for-renewable-energy-we-must-learn-to-mine-them-responsibly-131547">Critical minerals are vital for renewable energy. We must learn to mine them responsibly</a>
</strong>
</em>
</p>
<hr>
<p>Brushing your teeth tonight? That’s flourite, diatomite, calcite, quartz, barite and rutile in your toothpaste. If your toothbrush handle is made of plastics, it likely originated in a Middle East oil field.</p>
<p>Some of these minerals exist in New Zealand’s rocks in sufficient concentrations to make mining viable, but we shift environmental and social impacts to other countries. This allows New Zealand to claim a “clean and green” image, but reflects badly on us as global citizens. </p>
<p>The extraction of some of our own minerals with targeted precision mining is surely more appropriate, especially given the uncertainty of global supply chains. </p>
<h2>Environmental management legislation</h2>
<p>An additional demand for geoscience graduates will emerge with the reform of the Resource Management Act 1991 (<a href="https://www.legislation.govt.nz/act/public/1991/0069/latest/DLM230265.html">RMA</a>), the main law that determines how people interact with New Zealand’s natural resources. It sets out the <a href="https://www.parliament.nz/en/pb/sc/select-committee-news-archive/rma-reform-at-select-committee-stage/">rules</a> about air, soil, freshwater and coastal and marine areas, as well as regulating land use and the allocation of scarce resources. </p>
<p>The RMA is being replaced by three bills. The Natural and Built Environment Bill and the Spatial Planning Bill have both passed their <a href="https://www.rnz.co.nz/news/political/495939/rma-replacement-bills-pass-third-readings-in-parliament">third readings in parliament</a> this month. A third bill focuses on climate adaptation. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1691722163685065159"}"></div></p>
<p>All three new laws will create new compliance requirements that will need to be negotiated. Geoscientists, including those with geospatial skills, are fundamental to that process.</p>
<p>Much of the above creates domestic demands for geoscience graduates in environmental management and geotechnical sectors. This is irrespective of additional demands by Australian mining companies. </p>
<p>If we were to get serious about geoscience, it would be prudent for the government to develop an updated National Geospatial Strategy (<a href="https://www.civildefence.govt.nz/assets/Uploads/CDEM-Resilience-Fund/2019-20/2019-03-GIS-Investigation-Final-Report.pdf">NGS</a>). As the Norwegian NGS <a href="https://www.regjeringen.no/en/dokumenter/national-geospatial-strategy-towards-2025/id2617560/?ch=4">states</a>:</p>
<blockquote>
<p>Good quality geospatial information is a core part of the knowledge base for many processes in society. </p>
</blockquote>
<p>The New Zealand NGS was developed in 2006. It has been superseded by a range of technological advances in software, computing and satellite sensor platforms. It’s no longer fit for purpose.</p>
<p>Apart from an updated strategy, a national geotechnical engineering office should take overall responsibility for the range of geotechnical activities related to the safe and economic use and development of land in New Zealand. It could be modelled on <a href="https://www.cedd.gov.hk/eng/about-us/organisation/geo/index.html">Hong Kong’s geotechnical engineering office</a>. </p>
<p>At present we have Auckland Council and EQC funding the nationwide New Zealand <a href="https://landslides.nz/nz-landslides-database/">landslides database</a>. Surely, a national body should be overseeing this as well as other geological hazard data sets and mitigation initiatives, under one umbrella.</p>
<p>Notwithstanding all of the above, if the work of geoscientists is to be effective, we also <a href="https://theconversation.com/a-changing-world-needs-arts-and-social-science-graduates-more-than-ever-just-ask-business-leaders-210194">need social scientists</a>, many of whom are also facing redundancies, to consult with communities, with the necessary skills in cultural awareness and diversity of thought.</p><img src="https://counter.theconversation.com/content/212008/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Brook is a Chartered Geologist and receives funding from the Ministry of Business, Employment and Innovation (MBIE), Toka Tū Ake EQC, and the Royal Society Te Apārangi. </span></em></p>Some New Zealand universities have proposed staff and course cuts in earth sciences. This could leave the country ill prepared to deal with natural hazards and extreme weather.Martin Brook, Associate Professor of Applied Geology, University of Auckland, Waipapa Taumata RauLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2090182023-07-20T18:00:01Z2023-07-20T18:00:01ZWhen Greenland was green: Ancient soil from beneath a mile of ice offers warnings for the future<figure><img src="https://images.theconversation.com/files/537577/original/file-20230715-21-gwfd9c.jpg?ixlib=rb-1.1.0&rect=0%2C352%2C4733%2C3053&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Water and sediment pour off the melting margin of the Greenland ice sheet.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/qinnguata-kuussua-river-russell-glacier-greenland-royalty-free-image/604573407">Jason Edwards/Photodisc via Getty Images</a></span></figcaption></figure><p>About 400,000 years ago, large parts of Greenland were ice-free. Scrubby tundra basked in the Sun’s rays on the island’s northwest highlands. Evidence suggests that a <a href="https://www.science.org/doi/10.1126/science.1141758">forest of spruce</a> trees, buzzing with insects, covered the southern part of Greenland. Global sea level was much higher then, between 20 and 40 feet <a href="https://www.science.org/doi/10.1126/science.aaa4019">above today’s levels</a>. Around the world, land that today is home to hundreds of millions of people was under water.</p>
<p>Scientists have known for awhile that the Greenland ice sheet had mostly disappeared at some point in the <a href="https://www.nature.com/articles/nature20146">past million years</a>, but not precisely when. </p>
<p>In a new study in the <a href="http://www.science.org/doi/10.1126/science.ade4248">journal Science</a>,
we determined the date, using frozen soil <a href="https://www.campcentury.org/learning/podcasts">extracted during the Cold War</a> from beneath a nearly mile-thick section of the Greenland ice sheet. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/CYfSphNHOm8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A brief look at the evidence beneath Greenland’s ice sheet and the lessons its holds.</span></figcaption>
</figure>
<p>The timing – about 416,000 years ago, with largely ice-free conditions lasting for as much as 14,000 years – is important. At that time, Earth and its <a href="https://www.smithsonianmag.com/science-nature/how-drastic-ecological-change-led-leap-forward-behavior-weapons-and-tools-180976101/">early humans</a> were going through one of the longest interglacial periods since ice sheets first covered the high latitudes 2.5 million years ago. </p>
<p>The length, magnitude and effects of that natural warming can help us understand the Earth that modern humans are now creating for the future.</p>
<h2>A world preserved under the ice</h2>
<p>In July 1966, American scientists and U.S. Army engineers completed a six-year effort to <a href="https://blogs.egu.eu/divisions/cr/2022/01/28/camp-century-bottom-ice/">drill through the Greenland ice sheet</a>. The drilling took place at <a href="https://www.popsci.com/environment/us-army-arctic-city/">Camp Century</a>, one of the military’s most unusual bases – it was <a href="https://theconversation.com/the-us-army-tried-portable-nuclear-power-at-remote-bases-60-years-ago-it-didnt-go-well-164138">nuclear powered</a> and made up of a series of tunnels dug into the Greenland ice sheet.</p>
<p>The drill site in northwest Greenland was 138 miles from the coast and underlain <a href="https://icedrill.org/sites/default/files/Langway_2008_Early_polar_ice_cores.pdf">by 4,560 feet of ice</a>. Once they reached the bottom of the ice, the team kept drilling 12 more feet into the frozen, rocky soil below.</p>
<figure class="align-center ">
<img alt="A man in a fur-lined coat removes a long ice core about as wide as his hand" src="https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=487&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=487&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=487&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=612&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=612&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537578/original/file-20230715-16554-hkfcq9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=612&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">George Linkletter, working for the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory, examines a piece of ice core in the science trench at Camp Century. The base was shut down in 1967.</span>
<span class="attribution"><span class="source">U.S. Army Photograph</span></span>
</figcaption>
</figure>
<p>In 1969, geophysicist Willi Dansgaard’s analysis of the ice core from Camp Century revealed for the first time the details of how Earth’s climate had <a href="https://www.science.org/doi/10.1126/science.166.3903.377">changed dramatically</a> over the last 125,000 years. Extended cold glacial periods when the ice expanded quickly gave way to warm interglacial periods when the ice melted and sea level rose, flooding coastal areas around the world.</p>
<p>For nearly 30 years, scientists paid little attention to the 12 feet of frozen soil from Camp Century. One study <a href="https://www.cambridge.org/core/journals/journal-of-glaciology/article/evidence-of-the-bedrock-beneath-the-greenland-ice-sheet-near-camp-century-greenland/6F87EC12C84FAFB5BEE3E4A044B52618">analyzed the pebbles</a> to understand the bedrock beneath the ice sheet. Another suggested intriguingly that the frozen soil <a href="https://www.jstor.org/stable/40511026">preserved evidence</a> of a time warmer than today. But with no way to date the material, few people paid attention to these studies. By the 1990s, the frozen soil core had vanished.</p>
<p>Several years ago, our Danish colleagues found the lost soil buried deep in a Copenhagen freezer, and we formed an <a href="https://www.campcentury.org/home">international team</a> to analyze this unique frozen climate archive. </p>
<p>In the uppermost sample, we found perfectly preserved <a href="https://theconversation.com/ancient-leaves-preserved-under-a-mile-of-greenlands-ice-and-lost-in-a-freezer-for-years-hold-lessons-about-climate-change-157105">fossil plants</a> – proof positive that the land far below Camp Century had been ice-free some time in the past – but when?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two microscope images show tiny plant fossils. One a moss stem and the other a sedge seed." src="https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=272&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=272&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=272&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=342&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=342&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537531/original/file-20230714-23018-ycstss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=342&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Exquisitely preserved fossils of more than 400,000-year-old moss, on the left, and a sedge seed on the right, found in the soil core from beneath the Greenland ice sheet, help tell the story of what lived there when the ice was gone.</span>
<span class="attribution"><a class="source" href="https://www.campcentury.org/press/photos">Halley Mastro/University of Vermont</a></span>
</figcaption>
</figure>
<h2>Dating ancient rock, twigs and dirt</h2>
<p>Using samples cut from the center of the sediment core and prepared and analyzed in the dark so that the material retained an accurate memory of its last exposure to sunlight, we now know that the ice sheet covering northwest Greenland – nearly a mile thick today – <a href="http://www.science.org/doi/10.1126/science.ade4248">vanished during the extended natural warm period</a> known to climate scientists as <a href="https://www.sciencedirect.com/science/article/pii/S027737912200124X">MIS 11</a>, between 424,000 and 374,000 years ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A composite photograph of the sediment core showing the luminescence sample used to determine when Greenland was last ice-free beneath Camp Century." src="https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537528/original/file-20230714-15-dx61m2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The uppermost sample of the Camp Century sub-ice sediment core tells a story of vanished ice and tundra life in Greenland 416,000 years ago.</span>
<span class="attribution"><a class="source" href="https://www.campcentury.org/press/photos">Andrew Christ/University of Vermont</a></span>
</figcaption>
</figure>
<p>To determine more precisely when the ice sheet melted away, one of us, <a href="https://www.usu.edu/geo/osl/">Tammy Rittenour</a>, used a technique known as luminescence dating.</p>
<p>Over time, minerals accumulate energy as radioactive elements like uranium, thorium, and potassium decay and release radiation. The longer the sediment is buried, the more radiation accumulates as trapped electrons. </p>
<p>In the lab, specialized instruments measure tiny bits of energy, released as light from those minerals. That signal can be used to calculate how long the grains were buried, since the last exposure to sunlight would have released the trapped energy.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/TpZVa7O863A?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How optically stimulated luminescence works.</span></figcaption>
</figure>
<p><a href="https://www.uvm.edu/cosmolab/">Paul Bierman’s laboratory</a> at the University of Vermont dated the sample’s last time near the surface in a different way, using rare radioactive isotopes of aluminum and beryllium.</p>
<p>These isotopes form when cosmic rays, originating far from our solar system, slam into the rocks on Earth. Each isotope has a different half-life, meaning it decays at a different rate when buried. </p>
<p>By measuring both isotopes in the same sample, glacial geologist <a href="https://andrewjchrist.wixsite.com/website">Drew Christ</a> was able to determine that melting ice had exposed the sediment at the land surface for less than 14,000 years. </p>
<p>Ice sheet models run by <a href="https://ig.utexas.edu/staff/benjamin-keisling/">Benjamin Keisling</a>, now incorporating our new knowledge that Camp Century was ice-free 416,000 years ago, show that Greenland’s ice sheet must have shrunk significantly then. </p>
<p>At minimum, the edge of the ice retreated tens to hundreds of miles around much of the island during that period. Water from that melting ice raised global sea level at least 5 feet and perhaps as much as 20 feet compared to today.</p>
<h2>Warnings for the future</h2>
<p>The ancient frozen soil from beneath Greenland’s ice sheet warns of trouble ahead.</p>
<p>During the MIS 11 interglacial, Earth was warm and ice sheets were restricted to the high latitudes, a lot like today. <a href="https://www.sciencedirect.com/science/article/pii/S027737912200124X">Carbon dioxide levels</a> in the atmosphere remained between 265 and 280 parts per million for about 30,000 years. MIS 11 lasted longer than most interglacials because of the impact of the shape of Earth’s orbit around the sun on solar radiation reaching the Arctic. Over these 30 millennia, that level of carbon dioxide triggered enough warming to melt much of the Greenland’s ice.</p>
<p>Today, our atmosphere contains 1.5 times more carbon dioxide than it did at MIS 11, around <a href="https://keelingcurve.ucsd.edu/">420 parts per million</a>, a concentration that has risen each year. Carbon dioxide traps heat, warming the planet. Too much of it in the atmosphere raises the global temperature, as the world is seeing now.</p>
<p>Over the past decade, as greenhouse gas emissions continued to rise, humans experienced the eight warmest years on record. July 2023 saw the <a href="https://public.wmo.int/en/media/news/preliminary-data-shows-hottest-week-record-unprecedented-sea-surface-temperatures-and">hottest week on record</a>, based on preliminary data. Such heat <a href="https://theconversation.com/whats-going-on-with-the-greenland-ice-sheet-its-losing-ice-faster-than-forecast-and-now-irreversibly-committed-to-at-least-10-inches-of-sea-level-rise-185590">melts ice sheets</a>, and the loss of ice further warms the planet as dark rock soaks up sunlight that bright white ice and snow once reflected.</p>
<figure class="align-center ">
<img alt="Meltwater pours over the Greenland ice sheet in a meandering channel." src="https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537579/original/file-20230715-24-4qk8ya.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">At midnight in July, meltwater pours over the Greenland ice sheet in a meandering channel.</span>
<span class="attribution"><span class="source">Paul Bierman</span></span>
</figcaption>
</figure>
<p>Even if everyone stopped burning fossil fuels tomorrow, carbon dioxide levels in the atmosphere would <a href="https://www.nature.com/articles/nclimate2923">remain elevated</a> for thousands to tens of thousands of years. That’s because it takes a long time for carbon dioxide to move into soils, plants, the ocean and rocks. We are creating conditions conducive to a very long period of warmth, just like MIS 11.</p>
<p>Unless people dramatically lower the concentration of carbon dioxide in the atmosphere, evidence we found of Greenland’s past suggests a largely ice-free future for the island. </p>
<p>Everything we can do to reduce carbon emissions and <a href="https://theconversation.com/the-earth-needs-multiple-methods-for-removing-co2-from-the-air-to-avert-worst-of-climate-change-121479">sequester carbon</a> that is already in the atmosphere will increase the chances that more of Greenland’s ice survives.</p>
<p>The alternative is a world that could look a lot like MIS 11 – or even more extreme: a warm Earth, shrinking ice sheets, rising sea level, and waves rolling over Miami, Mumbai, India and Venice, Italy.</p><img src="https://counter.theconversation.com/content/209018/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Bierman receives funding from the US National Science Foundation.</span></em></p><p class="fine-print"><em><span>Tammy Rittenour receives funding from the US National Science Foundation.. </span></em></p>The soil was extracted during the Cold War from beneath one of the U.S military’s most unusual bases, then forgotten for decades.Paul Bierman, Fellow of the Gund Institute for Environment, Professor of Natural Resources and Environmental Science, University of VermontTammy Rittenour, Professor of Geosciences and Director of Luminescence Lab, Utah State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2098692023-07-18T20:02:02Z2023-07-18T20:02:02ZDid the Anthropocene start in 1950 – or much earlier? Here’s why debate over our world-changing impact matters<figure><img src="https://images.theconversation.com/files/537960/original/file-20230718-29-f4vh8k.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3853%2C2549&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>It made world news last week when a small lake in Canada was chosen as the “<a href="https://www.vox.com/future-perfect/2023/7/11/23791629/anthropocene-climate-epoch-canada-lake-crawford">Golden Spike</a>” – the location where the emergence of the Anthropocene is most clear. The Anthropocene is the proposed new geological epoch defined by humanity’s impact on the planet. </p>
<p>It took 14 years of scouring the world before the geoscientists in the <a href="http://quaternary.stratigraphy.org/working-groups/anthropocene">Anthropocene Working Group</a> chose Lake Crawford – the still, deep waters of which are exceptionally good at <a href="https://www.nytimes.com/2023/07/11/climate/anthropocene-epoch-crawford-lake.html">preserving history</a> in the form of sediment layers. Core samples from the lake give us an unusually good record of geological change, including, some scientists believe, the moment we began to change everything. For this group, that date is around 1950. </p>
<p>But what didn’t get reported was the resignation of a key member, global ecosystem expert Professor Erle Ellis, who left the working group and published an <a href="https://anthroecology.org/why-i-resigned-from-the-anthropocene-working-group">open letter</a> about his concerns. In short, Ellis believes pinning the start of our sizeable impact on the planet to 1950 is an error, given we’ve been changing the face of the planet for much longer. </p>
<p>The other working group scientists argue 1950 is well chosen, as it’s when humans started to really make their presence felt through surging populations, fossil fuel use and deforestation, amongst other things. This phenomenon has been dubbed the <a href="http://www.igbp.net/news/pressreleases/pressreleases/planetarydashboardshowsgreataccelerationinhumanactivitysince1950.5.950c2fa1495db7081eb42.html#:%7E:text=We%20can%20say%20that%20around,to%20the%20global%20economic%20system.">Great Acceleration</a>.</p>
<p>The disagreement speaks to something vital to science – the ability to accommodate dissent through debate. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="lake crawford" src="https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537958/original/file-20230718-19-afp9e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Canada’s Lake Crawford was chosen because it’s a rare meromictic lake, meaning different layers of water don’t intermix. That, in turn, makes it better at laying down sediment.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What’s the debate about?</h2>
<p>Would the public embrace the idea that our actions are making the world almost wholly unnatural? The answer, of course, depends on the quality of the science. Since most people aren’t scientists, we rely on the scientific community to hash out debate and present the best explanations for the data.</p>
<p>That’s why Ellis’s departure is so interesting. His resignation letter is explosive: </p>
<blockquote>
<p>It’s […] [im]possible to avoid the reality that narrowly defining the Anthropocene […] has become more than a scholarly concern. The AWG’s choice to systematically ignore overwhelming evidence of Earth’s long-term anthropogenic transformation is not just bad science, it’s bad for public understanding and action on global change. </p>
</blockquote>
<p>It’s not that Ellis thinks the way we live is problem-free. The central issue, in his view, is that there’s powerful evidence of much earlier global-scale impacts caused by pre- and proto-capitalist societies. </p>
<p>For instance, as Earth systems experts Simon Lewis and Mark Maslin <a href="https://theconversation.com/why-the-anthropocene-began-with-european-colonisation-mass-slavery-and-the-great-dying-of-the-16th-century-140661">have shown</a>, the violent Portuguese and Spanish colonisation of Central and South America indirectly lowered atmospheric carbon dioxide levels. How? By killing millions of indigenous people and destroying local empires. With the people gone, the trees regrew during the 17th century and covered the <a href="https://www.discovermagazine.com/planet-earth/lost-society-found-in-amazon-rainforest">villages and cities</a>, expanding the Amazon rainforest. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537963/original/file-20230718-17-5eworn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Villages and towns dotted many parts of the Amazon before colonisation. This image shows what’s left of a village.</span>
<span class="attribution"><span class="source">University of Exeter</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Why we should welcome honest disagreement in science</h2>
<p>Scientists have been debating in recent years over whether the Anthropocene should be deemed an “epoch” with a specific start date, or else an historically extended “event” caused by different human practices in different places, such as early agriculture, European colonisation and the spread of European and North American capitalism worldwide. </p>
<p>Ellis’ resignation stems from this debate. He’s not alone – other group members and experts have also <a href="https://onlinelibrary.wiley.com/doi/10.1002/jqs.3416">worked to refute</a> the epoch idea. </p>
<p>As philosopher of science Karl Popper and others have argued, productive scientific debate can only occur if there’s space for dissent and alternative perspectives. Ellis clearly believes the Anthropocene group has gone from debate to group think, which, if true, would challenge the free exchange at the heart of science. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-canadian-lake-holds-the-key-to-the-beginning-of-the-anthropocene-a-new-geological-epoch-209576">A Canadian lake holds the key to the beginning of the Anthropocene, a new geological epoch</a>
</strong>
</em>
</p>
<hr>
<p>Longer term, a compromise may well be reached. If the Anthropocene group were to shift tack and label the start of the epoch a multi-century event (a “long Anthropocene”), we’d still benefit from having labels for periods such as our current one where the human impact ramped-up significantly. </p>
<p>One issue with such tensions is what happens when they hit the media. Consider Climategate, the 2009 incident in which an attacker stole emails from a key climate research centre in the United Kingdom. Bad faith actors seized on perceived issues in the emails and <a href="https://www.theguardian.com/theobserver/2019/nov/09/climategate-10-years-on-what-lessons-have-we-learned">used them</a> to claim anthropogenic climate change was fabricated. The scientists at the heart of the controversy were cleared of wrongdoing, but the whole affair helped seed doubt and slow our transition away from fossil fuels. </p>
<p>The risk here is that if the public gets only a glancing, oversimplified view of these debates, they may come to doubt the abundant proof of our impact on Earth. It falls to journalists and science communicators to convey this accurately. </p>
<p>As for our trust in science, the case for declaring the Anthropocene will be subject to very close scrutiny and may not be ratified by the International Commission on Stratigraphy, the <a href="https://stratigraphy.org/">body responsible</a> for separating out <a href="https://theconversation.com/all-things-will-outlast-us-how-the-indigenous-concept-of-deep-time-helps-us-understand-environmental-destruction-132201">deep time</a> into specific epochs. </p>
<p>Stratigraphers such as Lucy Edwards <a href="https://rock.geosociety.org/net/gsatoday/archive/26/3/abstract/i1052-5173-26-3-4.htm">have argued</a> that an emerging epoch isn’t a fit subject for stratigraphy at all because all the evidence cannot, by definition, be in. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="hutton unconformit" src="https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=496&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=496&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537959/original/file-20230718-23-3qk1b4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=496&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This unassuming rock formation in Scotland is the site of a famous geological discovery, where James Hutton first realised the boundary between two types of rock separated geological epochs.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What does this tension mean for the Anthropocene?</h2>
<p>The epoch versus event debate doesn’t mean we’re off the hook in terms of our impact on the planet. It is abundantly clear we have become the first species in Earth’s long history to alter the functioning of the atmosphere, cryosphere, hydrosphere, biosphere and pedosphere (the soil layer) all at once and very quickly. Species such as cyanobacteria or blue-green algae had <a href="https://asm.org/Articles/2022/February/The-Great-Oxidation-Event-How-Cyanobacteria-Change">huge impact</a> by adding oxygen to the atmosphere, but they did not affect all spheres with the speed and severity we have.</p>
<p>While we did not set out to alter the planet, its implications are profound. Humans are not only altering the climate but the entirety of the irreplaceable envelope sustaining life on the only planet known to have life. This is a complex story and we should not expect science to simplify it for political or other reasons.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-the-anthropocene-began-with-european-colonisation-mass-slavery-and-the-great-dying-of-the-16th-century-140661">Why the Anthropocene began with European colonisation, mass slavery and the 'great dying' of the 16th century</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/209869/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Noel Castree does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Our activities now affect the entire planet. But there’s a vital debate over when we started disrupting these systems. Was it 1950 – or hundreds and thousands of years earlier?Noel Castree, Professor of Society & Environment, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2058662023-06-04T07:47:14Z2023-06-04T07:47:14ZWhat are meteorites? I visit and study the craters they’ve left across our planet<figure><img src="https://images.theconversation.com/files/528816/original/file-20230529-17-32pv8c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Impact cratering, caused by meteorites colliding with planetary surfaces, is one of the most fundamental cosmic processes.</span> <span class="attribution"><span class="source">Eshma/Shutterstock</span></span></figcaption></figure><p>Tens of thousands of <a href="https://spaceplace.nasa.gov/asteroid/en/">asteroids</a> – that we know of – are roaming our solar system. These are building blocks made up of metal, silicates, and ice left over from the beginning of time when the <a href="https://theconversation.com/curious-kids-how-are-planets-created-200454">planets</a> (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) and their moons were assembling. </p>
<p>For the most part, the asteroids quietly orbit the Sun – but sometimes they collide with each other or the planets and their moons. An asteroid hitting a planetary surface is called a meteorite. When a meteorite moves at a hyper-speed, between 10km and 70km per second, the collision releases an enormous wave of energy and leaves something in its place on the planetary surface.</p>
<p>These meteorite or impact craters appear as scars. Some planets are more pockmarked with craters than others: <a href="https://www.google.com/maps/space/moon/@-17.1912213,44.6295626,11521099m/data=!3m1!1e3?entry=ttu">the Moon is covered</a> with thousands but the Earth has <a href="https://www.sciencedirect.com/science/article/pii/S0012825222001969">only 200 confirmed meteorite craters</a>. There are several reasons for this. First, meteorites slow down or even burn out in our atmosphere before they can reach the surface. Second, 70% of Earth is covered with water – we can only see craters on land. Earth also has <a href="https://theconversation.com/plate-tectonics-new-findings-fill-out-the-50-year-old-theory-that-explains-earths-landmasses-55424">tectonic plates</a>, which shift and constantly renew the surface.</p>
<p>I am a geoscientist who studies impact craters. I have visited 10 of Earth’s confirmed crater sites, in places as diverse as the Amazon jungle, the Arctic polar circle, central Europe, and South Africa. I’ve even studied lunar samples collected by the Apollo missions.</p>
<p>Impact cratering is one of the most fundamental cosmic processes. It is responsible for the growth of planetary bodies through accretion (the accumulation of mass). For example, the Moon was created as a result of a collision between the young Earth and a smaller planet, Theia. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/p5E_esHiA5Q?wmode=transparent&start=24" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The moon started with a literal ‘bang’</span></figcaption>
</figure>
<p>It has been proven that the <a href="https://theconversation.com/how-the-dinosaurs-went-extinct-asteroid-collision-triggered-potentially-deadly-volcanic-eruptions-112134">extinction of dinosaurs</a> was caused by a massive impact event. Thus, studying impact craters can broaden our understanding of the Earth’s evolution and life, as well its possible future.</p>
<h2>Studying impactites</h2>
<p>I moved to the Free State province in South Africa after defending my doctoral thesis at Austria’s University of Vienna. The closest, most interesting geological site was the Vredefort impact crater. It is <a href="https://earthobservatory.nasa.gov/images/92689/vredefort-crater">the world’s oldest and largest known impact structure</a>, dating back some 2 billion years and spanning between 180km and 300km in diameter.</p>
<p>With fellow researchers, I visited Vredefort several times a year to collect a variety of data. <a href="https://scholar.google.com/citations?hl=ru&user=KIoAMa0AAAAJ&view_op=list_works&sortby=pubdate">Impact cratering research</a> helps me to combine two of my big passions - metamorphic petrology (how rocks can be transformed from one type into another) and the deformation of minerals (how they change their shape and structure under stress). </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-a-moroccan-crater-reveals-about-a-rare-double-whammy-from-the-skies-61406">What a Moroccan crater reveals about a rare double whammy from the skies</a>
</strong>
</em>
</p>
<hr>
<p>So, what happens when an impact crater is formed? A combination of intense heat (reaching thousands of degrees Celsius) and pressure (millions of <a href="https://education.nationalgeographic.org/resource/atmospheric-pressure/">atmospheres</a>) at the moment the meteorite hits the planetary surface. The meteorite is destroyed and part of the target evaporates. </p>
<p>That spot of collision is what’s known as an impact crater; the ground around and below it is full of rocks called <a href="https://www.lpi.usra.edu/publications/books/CB-954/chapter5.pdf">impactites</a>. These cannot be found anywhere else: impactites are not formed by any natural processes, only by meteorite impacts. Unique deformation features form in the minerals that were already on the planet’s surface. </p>
<figure class="align-center ">
<img alt="An aerial view of a rugged, rocky landscape interspersed with patches of green" src="https://images.theconversation.com/files/528822/original/file-20230529-9150-asis0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528822/original/file-20230529-9150-asis0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528822/original/file-20230529-9150-asis0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528822/original/file-20230529-9150-asis0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528822/original/file-20230529-9150-asis0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528822/original/file-20230529-9150-asis0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528822/original/file-20230529-9150-asis0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A satellite image of the Vredefort impact crater in South Africa’s Free State province.</span>
<span class="attribution"><span class="source">Planet Observer/Universal Images Group via Getty Images</span></span>
</figcaption>
</figure>
<p>Sometimes, new minerals are found – examples include <a href="https://link.springer.com/referenceworkentry/10.1007/0-387-30720-6_25">coesite and stishovite</a>, which are high-pressure modifications of quartz, and <a href="https://pubchem.ncbi.nlm.nih.gov/compound/Reidite">reidite</a> - a high-pressure modification of zircon. Another one is impact diamond, called <a href="https://www.nature.com/articles/ncomms6447">lonsdaleite</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/glass-beads-in-lunar-soil-reveal-ancient-asteroid-bombardments-on-the-moon-and-earth-191342">Glass beads in lunar soil reveal ancient asteroid bombardments on the Moon and Earth</a>
</strong>
</em>
</p>
<hr>
<h2>Cutting-edge technology</h2>
<p>Studying impactites isn’t, of course, as easy as looking at them with the naked eye or even putting them under a conventional microscope. A technology called <a href="https://www.sciencedirect.com/topics/physics-and-astronomy/transmission-electron-microscopy">transmission electron microscopy</a> (TEM) is driving the latest research in this field. It has been used for a few decades but, in recent years, there have been big improvements in its quality and precision.</p>
<p>TEM is a way to observe the micro- and nano-structures of impactites at an unbelievably high resolution. Using thin, specially prepared samples, features as small as a few nanometers in size – that’s about 1/10,000th of the diameter of a human hair – can be characterised in terms of their composition, shape, crystalline structure and relationship with the surroundings. Individual molecules and their patterns in crystals can be recognised and imaged. We can even identify what mineral we are looking at by analysing the arrangement of molecules.</p>
<p>This technology is opening the door to an entirely new world of impactite study. Our small-scale analyses will reveal ever more of the Universe’s huge secrets.</p><img src="https://counter.theconversation.com/content/205866/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizaveta Kovaleva receives funding from the National Research Foundation of South Africa, the Alexander Von Humboldt Foundation of Germany, and in the past received funding from the Russian Science Foundation. </span></em></p>Studying impact craters can broaden our understanding of the Earth’s evolution and life, as well as its possible future.Elizaveta Kovaleva, Lecturer, University of the Western CapeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2065892023-05-29T02:58:07Z2023-05-29T02:58:07ZMelbourne earthquake 2023: are they becoming more common? A seismology expert explains<figure><img src="https://images.theconversation.com/files/528747/original/file-20230529-21-rgyd8k.png?ixlib=rb-1.1.0&rect=51%2C75%2C1407%2C1038&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Report locations from people who felt the Sunbury earthquake on May 28.</span> <span class="attribution"><a class="source" href="https://earthquakes.ga.gov.au/event/ga2023kkwzpi">Geoscience Australia</a></span></figcaption></figure><p>Last night at 11:41pm local time, the greater Melbourne region was shaken by a magnitude 4.0 earthquake – as <a href="https://www.src.com.au/earthquakes/">calculated by the Seismology Research Centre</a> – centred near Sunbury, approximately 30km north of the CBD.</p>
<p>Geoscience Australia have <a href="https://earthquakes.ga.gov.au/event/ga2023kkwzpi">so far received more than 25,000 reports</a> from people who felt this earthquake, some as far as Hobart, which is 620km away from the epicentre.</p>
<p>In the Melbourne region, the earthquake reportedly produced shaking which lasted roughly 10–20 seconds, according to witness reports on social media. It was followed two minutes later by a magnitude 2.8 aftershock, which was reported by some people in the epicentral region between Sunbury and Cragieburn.</p>
<h2>Are earthquakes becoming more common in Melbourne?</h2>
<p>In September 2021, a magnitude 5.8 earthquake <a href="https://theconversation.com/melbourne-earthquake-what-exactly-happened-and-whats-the-best-way-to-stay-safe-from-aftershocks-168467">rattled Melbourne</a>, its epicentre being <a href="https://earthresources.vic.gov.au/about-us/news/unpacking-victorias-earthquake-22-september-2021">at Woods Point</a> to the east of the city. This earthquake was felt as far away as Brisbane and Adelaide.</p>
<p>Last night’s earthquake follows a <a href="https://earthquakes.ga.gov.au/event/ga2023jnxntd">magnitude 2.5 earthquake</a> near Ferntree Gully, to the east of Melbourne, two weeks ago on May 16. Another one with a magnitude of 2.0 was felt by about 1,300 people <a href="https://earthquakes.ga.gov.au/event/ga2023jznciz">in roughly the same region on May 22</a>, according to Geoscience Australia.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A screencap of a phone message stating an earthquake was reported with safety info and a link to updates" src="https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1083&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1083&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1083&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1361&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1361&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528748/original/file-20230529-19-3a60es.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1361&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some Android phone users in the area received an earthquake warning message on their smartphones.</span>
<span class="attribution"><span class="source">The Conversation</span></span>
</figcaption>
</figure>
<p>Although this means some Melbournians have experienced two or even three earthquakes in the last two weeks, earthquakes are not becoming more common in Melbourne. It is not unexpected for there to be 10–12 felt earthquakes a year somewhere in the greater Melbourne region – these need not occur at regular intervals. </p>
<p>Earthquakes in Australia occur as a result of stresses at our surrounding tectonic plate boundaries – where different plates collide, grind past one another, or are being forced apart. These stresses make their way towards the middle of the plate, too. </p>
<p>In southeast Australia, the forces <a href="https://www.eastcoastlab.org.nz/discover/learn/east-coast-and-hikurangi-plate-boundary/">at the Pacific-Australian plate boundary</a> to the east of us – the same plate boundary which passes through Aotearoa New Zealand – produce a buildup of strain. This is eventually released in the form of earthquake ruptures at weak zones or “faults” in the crust.</p>
<p>As a result of all this, earthquakes occur in the greater Melbourne region about once a month. Many of these – typically more than three quarters – are too small to be felt.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/nobody-can-predict-earthquakes-but-we-can-forecast-them-heres-how-199757">Nobody can predict earthquakes, but we can forecast them. Here's how</a>
</strong>
</em>
</p>
<hr>
<h2>What determines if you feel an earthquake?</h2>
<p>Generally speaking, a larger magnitude earthquake is more likely to be felt than those of smaller magnitudes. But other factors play a part, too.</p>
<p>Earthquake depth affects how strong the associated ground shaking is – the shallower the earthquake, the stronger the shaking. Last night’s magnitude 4.0 near Sunbury was a relatively shallow earthquake at just 3km depth. Because shallow earthquakes produce stronger ground-shaking, they’re also more likely to cause damage. Minor damage, such as <a href="https://twitter.com/PivaLasVegas/status/1662991379180720129">cracked plaster</a> and <a href="https://twitter.com/natashamitchell/status/1662818213238046720">fallen pictures</a>, were reported as a result of last night’s earthquake.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-are-shallow-earthquakes-more-destructive-the-disaster-in-java-is-a-devastating-example-195110">Why are shallow earthquakes more destructive? The disaster in Java is a devastating example</a>
</strong>
</em>
</p>
<hr>
<p>The closer you are to the earthquake epicentre, the more likely you are to feel it. You’re also more likely to experience an earthquake if you’re stationary, rather than jogging or riding a bike or driving. Some people reportedly slept through last night’s earthquake.</p>
<p>The earthquakes reported as felt by those near the epicentre are mostly ones above a magnitude 2.0–2.5, although smaller events can be felt especially at shallow depths, and in populated areas. If an earthquake happens in a remote region, there are often no people to report having felt it. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1662956470043025408"}"></div></p>
<h2>Booms and aftershocks</h2>
<p>Very small, shallow earthquakes sometimes do not produce any shaking closest to the epicentre, but instead produce a sound akin to an explosion – a short, sharp, loud “boom”. This occurs when the seismic waves reach the surface and transform into sound waves.</p>
<p>This is different to the rumbling sound which is more commonly heard, and is often described as a train approaching. It’s the result of the shaking of the built environment as the seismic wave passes through.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1662835995795148800"}"></div></p>
<p>In addition to the magnitude 2.8 aftershock from last night’s earthquake, there have been additional aftershocks less than magnitude 1.0. These are still being examined by seismologists. There may still be aftershocks large enough to be felt in the coming days, weeks, and months, though the likelihood of these diminishes with time.</p>
<p>Occasionally, a larger earthquake may occur, in which case the magnitude 4.0 will be considered a foreshock.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-earthquake-that-rattled-melbourne-was-among-australias-biggest-in-half-a-century-but-rock-records-reveal-far-mightier-ones-168471">The earthquake that rattled Melbourne was among Australia's biggest in half a century, but rock records reveal far mightier ones</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/206589/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dee Ninis works for the Seismology Research Centre. She is affiliated with the School of Earth, Atmosphere and Environment at Monash University, and is Vice President of the Australian Earthquake Engineering Society.</span></em></p>Some people were woken up near midnight by a powerful ground-shake. But did you know earthquakes occur in the greater Melbourne region about once a month – even though we can’t always feel them?Dee Ninis, Earthquake Geologist, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1731982022-12-19T13:34:59Z2022-12-19T13:34:59ZWhat are mud volcanoes?<figure><img src="https://images.theconversation.com/files/501578/original/file-20221216-13-gh4rg0.jpg?ixlib=rb-1.1.0&rect=119%2C3%2C2309%2C1493&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Engineers have tried to corral a mud volcano in Indonesia that has covered more than 1,700 acres with mud.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/this-aerial-picture-taken-10-march-2007-shows-mud-that-news-photo/73549446?phrase=Eka%20Dharma&adppopup=true">Eka Dharma/AFP via Getty Images</a></span></figcaption></figure><p>Rice farmers living in Sidoarjo Regency, Indonesia, awoke to a strange sight on May 29, 2006. The ground had <a href="http://www.hsf.humanitus.net/media/6412/HSF_Social_Impact_Report_Eng.pdf">ruptured overnight and was spewing out steam</a>.</p>
<p>In the following weeks, water, boiling-hot mud and natural gas were added to the mixture. When the eruption intensified, <a href="https://doi.org/10.1130/GSAT01702A.1">mud started to spread over the fields</a>. Alarmed residents evacuated, hoping to wait out the eruption safely.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Houses are submerged in mud, while gas billows from mud volcano in background." src="https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501645/original/file-20221216-7450-29fumn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The mud onslaught forced tens of thousands of people to relocate from their homes.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/houses-are-submerged-in-mud-as-gas-billows-from-the-mud-news-photo/169621197">Mochammad Risyal Hidayat/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p><a href="https://youtu.be/vJ0PwYamqNE">Except that it didn’t stop</a>. Weeks passed, and the spreading mud engulfed entire villages. In a frantic race against time, the Indonesian government began to build levees to contain the mud and stop the spread. When the mud overtopped these levees, they built new ones behind the first set. The government eventually succeeded in stopping the mud’s advance, but not before the flows had wiped out a dozen villages and <a href="https://news.agu.org/press-release/scientists-determine-source-of-worlds-largest-mud-eruption">forced 60,000 people to relocate</a>. </p>
<p>Why would the Earth suddenly start vomiting forth huge quantities of mud like this?</p>
<h2>Introducing mud volcanoes</h2>
<p>The Lusi structure – a contraction of Lumpur Sidoarjo, meaning “Sidoarjo mud” – is an example of a geological feature <a href="https://www.youtube.com/watch?v=t7UohP-YBc0">known as a mud volcano</a>. They form when a combination of mud, fluids and gases erupt at the Earth’s surface. The term “volcano” is borrowed from the much better known world of igneous volcanoes, where molten rock comes to the surface. <a href="https://scholar.google.com/citations?user=ZQkFbhUAAAAJ&hl=en">I’ve been studying</a> these fascinating structures on subsurface seismic data for the past five years, but nothing compares to seeing one actively erupting.</p>
<p>For mud volcanoes, in many cases the mud bubbles up to the surface rather quietly. But sometimes the eruptions are quite violent. Furthermore, most of the gas coming out of a mud volcano is methane, which is highly flammable. This gas can ignite, creating spectacular fiery eruptions.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/FjzYUdlSs5w?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Gases erupting along with mud can ignite.</span></figcaption>
</figure>
<p>Mud volcanoes are little known in North America, but much more common in other parts of the world, including not only Indonesia but also Azerbaijan, Trinidad, Italy and Japan. </p>
<p>They form when fluids and gases that have built up under pressure inside the Earth find an escape route to the surface via a network of fractures. The fluids move up these cracks, carrying mud with them, creating the mud volcano as they escape.</p>
<p>The idea is similar to a car tire containing compressed air. As long as the tire is intact, the air stays safely inside. Once the air has a pathway out, however, it begins to escape. Sometimes the air escapes as a slow leak – in other cases there is a blowout. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="aerial view of landscape with round holes filled with liquid and mud" src="https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501584/original/file-20221216-26-odcz4g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A series of mud volcanoes on the Nahlin Plateau, British Columbia.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Mud_Volcanos.jpg">Hkeyser/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Overpressure within the Earth builds up when underground fluids are unable to escape from beneath the weight of overlying sediments. Some of this fluid was <a href="https://doi.org/10.1306/522B49C9-1727-11D7-8645000102C1865D">trapped within the sediment</a> when it was deposited. Other fluids may <a href="https://www.researchgate.net/publication/286291175_Mud_volcano_systems">migrate in from deeper sediments</a>, while still others may be <a href="https://doi.org/10.1016/j.earscirev.2021.103746">generated in place by chemical reactions</a> in the sediments. One important type of chemical reaction generates oil and natural gas. Finally, fluids may become overpressured if they are <a href="https://doi.org/10.1038/s41598-021-02868-x">squeezed by tectonic forces during mountain building</a>. </p>
<p>Overpressures are commonly encountered during drilling for oil and gas and are typically planned for. A primary way of dealing with overpressures is to fill the wellbore with dense drilling mud, which has sufficient weight to contain the overpressures.</p>
<p>If the well is drilled with insufficient mud weight, any overpressured fluids can rush up the wellbore to explode out at the surface, leading to a spectacular blowout. Famous examples of blowouts include the 1901 <a href="https://en.wikipedia.org/wiki/Spindletop">Spindletop gusher</a> in Texas and the more recent 2010 <a href="https://doi.org/10.2118/167970-MS">Deepwater Horizon disaster</a> in the Gulf of Mexico. In those cases it was oil, not mud, that burst out of the wells. </p>
<p>In addition to being fascinating in their own right, mud volcanoes are also useful to scientists as windows into <a href="https://doi.org/10.1007/s00531-003-0326-y">conditions deep inside the Earth</a>. Mud volcanoes can involve materials from as deep as 6 miles (10 kilometers) below the Earth’s surface, so their chemistry and temperature can provide useful insights into deep-Earth processes that can’t be obtained in any other way.</p>
<p>For example, analysis of the mud erupting from Lusi has revealed that the water was <a href="https://doi.org/10.1016/j.epsl.2011.11.016">heated by an underground magma chamber</a> associated with the nearby <a href="https://volcano.si.edu/volcano.cfm?vn=263290">Arjuno-Welirang volcanic complex</a>. Every mud volcano reveals details about what’s happening underground, allowing scientists to build a more comprehensive 3D view of what’s going on inside the planet.</p>
<h2>Lusi’s mud is still erupting</h2>
<p>Today, more than 16 years after the eruption began, the Lusi structure in Indonesia continues to erupt, but at a much slower rate. Its mud <a href="https://www.scientificamerican.com/article/scientists-unearth-revealing-details-about-the-worlds-biggest-mud-volcano1">covers a total area of roughly 2.7 square miles</a> (7 square km), more than 1,300 football fields, and is contained behind a series of levees that have been built up to a height of 100 feet (30 meters). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man kneels on cracking dry mud points thermometer at a flowing stream" src="https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501646/original/file-20221216-27-6uanrf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An officer of the Sidoarjo Mud Prevention Agency checks the water temperature of mud near the Lusi mud volcano in 2011.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-officer-of-indonesian-agency-sidoarjo-mud-prevention-news-photo/114923592">Ulet Ifansasti/Getty Images</a></span>
</figcaption>
</figure>
<p>Almost as interesting as the efforts to stop the mud have been the legal battles aimed at assigning blame for the disaster. The initial rupture occurred about <a href="https://doi.org/10.1016/j.marpetgeo.2017.12.031">330 feet (100 meters) from an actively drilling gas exploration well</a>, leading to <a href="https://www.nytimes.com/2015/09/22/science/9-years-of-muck-mud-and-debate-in-java.html">widely publicized</a> <a href="https://doi.org/10.1038/news060828-1">accusations that the</a> <a href="https://doi.org/10.1130/GSAT01702A.1">oil company responsible for the well was at fault</a>. The operator of the well, Lapindo Brantas, countered that the eruption was natural, triggered by an earthquake that had occurred several days earlier.</p>
<p>Those who believe the <a href="https://doi.org/10.1038/ngeo2472">gas well triggered the eruption</a> argue that the well experienced a <a href="https://doi.org/10.1016/j.epsl.2008.05.029">blowout due to insufficient mud weight</a>, but that the blowout did not come all the way up the wellbore to the surface. Instead, the fluids came only partway up the wellbore before injecting sideways into fractures and erupting at the surface about one hundred meters away. As evidence, these proponents point to <a href="https://doi.org/10.1016/j.marpetgeo.2017.12.031">measurements made in the well during drilling</a>. Furthermore, they suggest the earthquake was too far away from the well to have had any effect.</p>
<p>By contrast, proponents of the earthquake trigger believe that the Lusi eruption was caused by an <a href="https://doi.org/10.1016/j.marpetgeo.2017.06.019">active hydrothermal system in the subsurface</a>, somewhat akin to Old Faithful in Yellowstone National Park. They argue that such systems have a long history of being affected by very distant earthquakes, so the argument that Lusi was too far away from the earthquake is invalid.</p>
<p>Furthermore, they suggest that a pressure test in the well conducted after the eruption started showed that the wellbore was intact, not breached by fractures and leaking fluid. Consistent with this interpretation, there is no evidence that any of the drilling mud ever came out of the Lusi eruptions. </p>
<p>In 2009, the Indonesian supreme court <a href="https://en.antaranews.com/news/82478/debate-over-lapindo-mud-disaster-continues">dismissed a lawsuit</a> charging the company with negligence. The same year, police <a href="https://www.thejakartapost.com/news/2009/08/08/police-drop-criminal-probe-lapindo-over-mudflow.html">dropped criminal investigations</a> against Lapindo Brantas and several of its employees, citing a lack of evidence. Although the lawsuits have been settled, the debate continues, with international research groups lining up on both sides of the dispute.</p>
<p><em>This article has been updated to correct the distance between the initial Lusi eruption and drilled wells.</em></p><img src="https://counter.theconversation.com/content/173198/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael R. Hudec receives funding from the Applied Geodynamics Laboratory, an oil-industry funded research consortium supported by more than 20 companies. </span></em></p>When mud, fluids and gases erupt at the Earth’s surface, they hint at what’s happening underground, allowing scientists to build a more comprehensive 3D view of what’s going on inside our planet.Michael R. Hudec, Senior Research Scientist at Bureau of Economic Geology, The University of Texas at AustinLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1891252022-09-08T01:06:11Z2022-09-08T01:06:11ZA giant ‘bullseye’ on the Nullarbor Plain was created by ancient sea life<figure><img src="https://images.theconversation.com/files/483141/original/file-20220907-11-mlo6ss.jpg?ixlib=rb-1.1.0&rect=39%2C12%2C1115%2C640&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Lipar et al.</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Environments across the planet are changing dramatically in response to human population growth and climate change. Some scientists even say human activity has pushed Earth into a new geological epoch: the <a href="https://theconversation.com/an-official-welcome-to-the-anthropocene-epoch-but-who-gets-to-decide-its-here-57113">Anthropocene</a>.</p>
<p>Amid this rapid transformation some special places, protected by fortuitous geography and geology, change so slowly they preserve evidence of Earth’s past over unfathomable timescales. </p>
<p>One such place is the flat, dry expanse of the Nullarbor Plain in southern Australia, where traces still remain of events millions of years in the past. Using high-resolution satellite imaging we have begun to map out some of these traces. </p>
<p>In <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/esp.5459">new research</a> published today in Earth Surface Processes and Landforms, we report the discovery of an enigmatic “bullseye” structure more than a kilometre across. We believe it is the remains of an ancient reef, created by microbes some 14 million years ago when the Nullarbor was at the bottom of the ocean.</p>
<h2>No trees, no water, but not boring</h2>
<p>Named the Nullarbor Plain (meaning “treeless”) during colonisation, and Oondiri (meaning “waterless”) by some of the First Nations people of the area, the region is notoriously dry, flat and barren. The exceptional overall flatness of the plain (the average slope is much, much less than 1°) is one of the first indicators of the region’s stability.</p>
<p>The rocks beneath the Nullarbor Plain are made of limestone that originally formed in shallow marine <a href="https://theconversation.com/meet-the-worlds-largest-plant-a-single-seagrass-clone-stretching-180-km-in-western-australias-shark-bay-184056">seagrass</a> meadows. Such rocks can dissolve in weakly acidic rain and groundwater.</p>
<figure class="align-center ">
<img alt="Man abseils into a cave opening in a flat plain" src="https://images.theconversation.com/files/480406/original/file-20220822-64444-bgk5lv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480406/original/file-20220822-64444-bgk5lv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480406/original/file-20220822-64444-bgk5lv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480406/original/file-20220822-64444-bgk5lv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480406/original/file-20220822-64444-bgk5lv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480406/original/file-20220822-64444-bgk5lv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480406/original/file-20220822-64444-bgk5lv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Abseiling into Murra-El-Elevyn cave, Nullarbor Plain, Western Australia. Photo courtesy of Mateja Ferk.</span>
</figcaption>
</figure>
<p>Due in part to its dryness, the region has not been intensively dissolved, or eroded by rivers or glaciers in the millions of years since it emerged from the ocean. This is in stark contrast to the classic ruggedness of much younger tropical landscapes (such as the volcanic Hawaiian islands), which are far wetter and more geologically active.</p>
<p>The plain covers some 200,000 km² and, like the curvature of the Earth, landscape features on the Nullarbor Plain are almost imperceptible to the human eye. Despite this subtlety, the area is not as featureless as you might think.</p>
<p>Careful scientific study and high-resolution satellite data are increasingly revealing the secrets of the Nullarbor Plain’s past.</p>
<h2>Mummified marsupials and ancient dunes</h2>
<p>Isolated caves do punctuate the Nullarbor Plain. Within their dry chambers, remarkably preserved fossils yield glimpses of <a href="https://theconversation.com/the-worlds-biggest-cuckoos-once-roamed-the-nullarbor-plain-54050">Australia’s extinct animals</a> that would rival the most wondrous zoo menagerie. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing a mummified Tasmanian tiger lying in sediment." src="https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480411/original/file-20220822-53919-8nn9s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A mummified thylacine (Tasmanian tiger) preserved in Thylacine Hole cave on the Nullarbor Plain, Western Australia.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/spelio/49540863313/in/photolist-kPAwy-2itKSFK-2itPzCc-2itPzq3">David C Lowry via Spelio / Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Mummified thylacine (Tasmanian tiger) remains and complete thylacoleo (marsupial lion) skeletons from thousands of years ago capture striking snapshots of changing ecosystems.</p>
<p>Older still are gentle linear ridges that cross the Nullarbor Plain. Recently, we showed these ridges are relics of a <a href="https://www.sciencedirect.com/science/article/pii/S0031018220303564">long-vanished landscape</a>. Ancient sand dunes controlled the gentle dissolution of the underlying limestone to leave a subtle imprint of windblown patterns from millions of years ago.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Coloured map showing a digital model of the landscape preserving linear dune features." src="https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=291&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=291&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=291&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=366&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=366&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481040/original/file-20220825-18-a0mxcz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=366&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A digital model of the landscape showing the imprinted relic of ancient, vanished dunes on the Nullarbor Plain.</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/abs/pii/S0031018220303564">Burnett et al.</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The bullseye</h2>
<p>For our most recent work, we used landscape data from the <a href="https://data.europa.eu/data/datasets/5eecdf4c-de57-4624-99e9-60086b032aea?locale=en">TanDEM-X Digital Elevation Model</a> produced by the German Aerospace Centre, which has a resolution of around 12 metres. </p>
<p>Studying these images of the Nullarbor revealed a previously unnoticed “bullseye” feature: a ring-shaped hill with a central dome, just over a kilometre wide and only a few metres high.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Coloured map showing bullseye structure." src="https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=387&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=387&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480415/original/file-20220822-70261-9xcj09.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=387&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Digital elevation model of the newly discovered bullseye remnant structure.</span>
<span class="attribution"><span class="source">Lipar et al.</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Initially, we thought we had found the first meteorite impact crater to be discovered on the Nullarbor Plain. The area is <a href="https://museum.wa.gov.au/research/collections/earth-and-planetary-sciences/meteorite-collection/meteorites-nullarbor-region">famous for meteorites</a> that can help us understand the <a href="https://theconversation.com/where-do-meteorites-come-from-we-tracked-hundreds-of-fireballs-streaking-through-the-sky-to-find-out-160096">history of our solar system</a>, but to date no definitive craters caused by meteorites have been found. </p>
<p>However, when we took a closer look at the bullseye we saw none of the chemical or high-pressure indicators of an impact. </p>
<p>We uncovered the real explanation for the bullseye after cutting and polishing samples of rock thin enough to let light shine through, and inspecting them under a microscope. Unlike the limestone seen at hundreds of other sites across the plain, here we saw evidence for tiny microbial organisms holding the sediment together. </p>
<p>Supported by similar <a href="https://www.abc.net.au/news/science/2021-03-02/great-barrier-reef-halimeda-bioherms-biodiversity-donut/13196754">“doughnut” structures formed by algae on the Great Barrier Reef</a>, we interpreted the bullseye as an ancient isolated “reef”. This biogenic mound formed on the seabed long ago but degraded so slowly after the land was lifted above the waves that it is still recognisable roughly 14 million years later.</p>
<h2>How understanding the past can help the future</h2>
<p>Our findings add to increasing recognition of the region as an exceptional archive of environmental change that <a href="https://pursuit.unimelb.edu.au/articles/it-s-time-the-nullarbor-caves-had-world-heritage-status">we must better understand and protect</a>.</p>
<p>The emergence of the Nullarbor Plain has been an important driver of the evolution of plants and animals. Ancient fossils and even DNA preserved due to the <a href="https://www.theage.com.au/national/lost-world-yields-ancient-treasures-20020730-gdug04.html">stable conditions</a> will help us more accurately reconstruct its vanished ecosystems. </p>
<p><a href="https://theconversation.com/how-did-ancient-moa-survive-the-ice-age-and-what-can-they-teach-us-about-modern-climate-change-183350">More complete understanding</a> of how landscapes and ecosystems were transformed in the past will in turn help us conserve the animals, plants and environments we have today, and minimise the negative impacts of future anthropogenic climatic change.</p><img src="https://counter.theconversation.com/content/189125/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Milo Barham receives funding from the Minerals Research Institute of Western Australia, as well as Iluka Resources Ltd. for investigating mineral sands, including on the margins of the Nullarbor Plain. </span></em></p><p class="fine-print"><em><span>Dr. Matej Lipar receives funding from Slovenian Research Agency, Australian Speleological Federation Karst Conservation Fund, and German Aerospace Centre TandemX.</span></em></p>Southern Australia’s Nullarbor Plain is offering up evidence of Earth’s past landscapes and ecosystems, exceptionally preserved for millions of years.Milo Barham, Senior Lecturer, Earth and Planetary Sciences, Curtin UniversityMatej Lipar, Research Associate, Physical Geography, ZRC SAZULicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1865482022-07-14T13:20:52Z2022-07-14T13:20:52ZHow the Tour de France helped me think about geology in a new way<p>As I write this, the Tour de France has reached its halfway point, with the cyclists climbing the Alps. Or, to put it another way, the race has left Armorican continent and entered the folded relics of the Valais Ocean and the Briançonnais microcontinent. </p>
<p>For me, as an academic geologist and cycling enthusiast, this year’s edition of the world’s biggest cycle race is particularly exciting as colleagues and I launched the <a href="https://geotdf.org">Geology of the Tour de France</a> blog and the <a href="https://twitter.com/geotdf">@GeoTdF twitter account</a>. </p>
<p>The project first came about when we noticed how much time the TV commentators had to fill while the riders cycle through interesting landscapes. Though viewers watch for hours in anticipation of the action that will end every stage, for most of that time 150 riders are chasing five or so others with little change to the status quo. In that time, the broadcasters explain everything about almost everything you can see on screen. </p>
<p>Organisers of cycling races therefore provide the commentators with a Lonely Planet-style route book with information about castles, cities and individuals. And then it struck me: we are not only watching potential holiday destinations, but also geological excursions. All we had to do is provide the commentators with geo-information. </p>
<p>So I assembled a team of <a href="http://geotdf.org/team-geotdf">28 geoscientists and web developers</a>, several from my department at Utrecht University in the Netherlands, but also from institutes in France, Germany, Denmark, Spain, the UK and the US, who together wrote 29 blogs about the geology along the Tour de France stages, and translated these into seven languages. </p>
<p>For the men’s tour, each blog explains a geological phenomenon or process whose signatures are visible along the stage route. We’re looking at many different topics, from the <a href="http://geotdf.org/men-2022/stage-2-roskilde-nyborg-early-danian">extinction of the dinosaurs</a> to the subduction zones of the Alps, and from the origin of the volcanoes of the Massif Central to the question why the <a href="http://geotdf.org/men-2022/stage-8-dole-lausanne-france-s-youngest-mountain-range">Jura Mountains of stage 8</a> are a separate range from the Alps.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ASOUf0kcqX8?wmode=transparent&start=3" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientists used sand to show how the Alps and Jura may have formed in one related process, despite being some distance apart.</span></figcaption>
</figure>
<p>The Tour de France Femmes begins on the day the men’s tour finishes, and the women’s peloton will race over older rocks every day in the Paris Basin and the Vosges mountains of eastern France. Each blog of the Tour de France Femmes explains what the world would have looked like if the race was held when the rocks below the road formed. The blogs offer a five minute read, but if you read them every day, you end up with a extended geology class.</p>
<h2>Public and scientific benefits</h2>
<p>The GeoTdF project aims to be a light-hearted way to educate people about processes that impact our society, from <a href="http://geotdf.org/men-2022/stage-10-morzine-megeve-landslides">landslides</a> and <a href="http://geotdf.org/men-2022/stage-18-lourdes-hautacam-seismic-crisis">earthquakes</a> to the finding of <a href="http://geotdf.org/men-2022/stage-15-rodez-carcassone-hard-rock-with-element-lithium">ore deposits</a> that we need for the green energy revolution. And the public can respond and ask questions through Twitter.</p>
<p>But the project also has scientific benefits. It provides geoscientists and our colleagues with a platform to showcase our findings, for all of us who want to share knowledge and insight freely and enthusiastically. </p>
<p>This is why I like the project so much. Scientists are always trying to find where they are wrong, for that is where they can learn and advance. As a result, they are always scrutinising themselves and each other, through peer review, discussion, debates. The criticism is vocal, the appreciation silent. That wears me down at times. The sense of community and enthusiasm around the GeoTdF project is a nice change. So if you have something to tell or ask, please join in. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1544942865851322375"}"></div></p>
<p>At the same time, letting something as random as cycling routes determine the order in which you read up on geology turns out to be an idea and knowledge generator. Natural scientists logically tend to choose the boundaries of their study areas based on interpreted system boundaries, and dig deeper into the details to find how the natural world works, but it comes with the risk of tunnel vision. </p>
<p>I have studied plate tectonics and mountain building, through systematically finding the same geological systems and boundaries and reconstructing them (for instance in the <a href="https://www.sciencedirect.com/science/article/pii/S1342937X19302230">Mediterranean region</a>). </p>
<p>But cycling route designers force me to cross all those boundaries. No geologist would read up on a region along such a geologically non-organised and random route as a Tour de France stage – and doing so is eye-opening. I learned that the cliffs of Stevns Klint in Denmark close to stage 2, and of Calais in north west France in stage 4 are the same formation of upper Cretaceous chalks. And that the uplift in the past 20 million years of the <a href="http://geotdf.org/men-2022/stage-6-binche-longwy-pushed-up-sleeve">Ardennes hills of stage 6</a> and the Massif Central of stage 15 are both associated with formation of intraplate volcanic fields that may suggest a common underlying process. </p>
<p>Many of these chance observations connect pieces of knowledge that I picked up during my career, and some of them challenge systems that I thought I understood. As the writer Isaac Asimov is <a href="https://quoteinvestigator.com/2015/03/02/eureka-funny/">believed to have said</a>, scientific discovery rarely starts with “Eureka!” but normally with “Hey, that’s funny.” Whether the GeoTdF project will lead to the former remains to be seen, but it certainly is fun.</p><img src="https://counter.theconversation.com/content/186548/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Douwe van Hinsbergen receives funding from the Netherlands Organization of Scientific Research (NWO) and Utrecht University. </span></em></p>The world’s biggest cycling race is a great way to teach people about geology – and test our own ideas.Douwe van Hinsbergen, Chair in Global Tectonics and Paleogeography, Utrecht UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1796732022-03-30T19:09:04Z2022-03-30T19:09:04ZVolcanoes, diamonds, and blobs: a billion-year history of Earth’s interior shows it’s more mobile than we thought<figure><img src="https://images.theconversation.com/files/454466/original/file-20220326-23-11mnxve.png?ixlib=rb-1.1.0&rect=0%2C837%2C8606%2C6725&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Earth’s interior 80 million years ago with hot structures in yellow to red (darker is shallower) and cold structures in blue (darker is deeper).</span> <span class="attribution"><span class="source">Ömer Bodur/Nature</span></span></figcaption></figure><p>Deep in the Earth beneath us lie two blobs the size of continents. One is under Africa, the other under the Pacific Ocean. </p>
<p>The blobs have their roots 2,900km below the surface, almost halfway to the centre of the Earth. They are thought to be the birthplace of rising columns of hot rock called “deep mantle plumes” that reach Earth’s surface.</p>
<p>When these plumes first reach the surface, giant volcanic eruptions occur – the kind that contributed to the extinction of the dinosaurs 65.5 million years ago. The blobs may also control the eruption of a kind of rock called kimberlite, which brings diamonds from depths 120-150km (and in some cases up to around 800km) to Earth’s surface.</p>
<p>Scientists have known the blobs existed for a long time, but how they have behaved over Earth’s history has been an open question. In new research, we modelled a billion years of geological history and discovered <a href="https://www.nature.com/articles/s41586-022-04538-y">the blobs gather together and break apart</a> much like continents and supercontinents.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/454511/original/file-20220327-15-tltpwx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454511/original/file-20220327-15-tltpwx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=508&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454511/original/file-20220327-15-tltpwx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=508&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454511/original/file-20220327-15-tltpwx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=508&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454511/original/file-20220327-15-tltpwx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=638&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454511/original/file-20220327-15-tltpwx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=638&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454511/original/file-20220327-15-tltpwx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=638&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Earth’s blobs as imaged from seismic data. The African blob is at the top and the Pacific blob at the bottom.</span>
<span class="attribution"><span class="source">Ömer Bodur</span></span>
</figcaption>
</figure>
<h2>A model for Earth blob evolution</h2>
<p>The blobs are in the mantle, the thick layer of hot rock between Earth’s crust and its core. The mantle is solid but slowly flows over long timescales. We know the blobs are there because they slow down waves caused by earthquakes, which suggests the blobs are hotter than their surroundings.</p>
<p>Scientists generally agree the blobs are linked to the movement of tectonic plates at Earth’s surface. However, how the blobs have changed over the course of Earth’s history has puzzled them. </p>
<p>One school of thought has been that the present blobs have acted as anchors, locked in place for hundreds of millions of years while other rock moves around them. However, we know tectonic plates and mantle plumes move over time, and research suggests <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL059875">the shape of the blobs is changing</a>.</p>
<p><a href="https://www.nature.com/articles/s41586-022-04538-y">Our new research</a> shows Earth’s blobs have changed shape and location far more than previously thought. In fact, over history they have assembled and broken up in the same way that continents and supercontinents have at Earth’s surface. </p>
<p>We used Australia’s <a href="https://nci.org.au/">National Computational Infrastructure</a> to run advanced computer simulations of how Earth’s mantle has flowed over a billion years. </p>
<p>These models are based on <a href="https://theconversation.com/a-map-that-fills-a-500-million-year-gap-in-earths-history-79838">reconstructing the movements of tectonic plates</a>. When plates push into one another, the ocean floor is pushed down between them in a process known as subduction. The cold rock from the ocean floor sinks deeper and deeper into the mantle, and once it reaches a depth of about 2,000km it pushes the hot blobs aside.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bljnLFHd1cQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The past 200 million years of Earth’s interior. Hot structures are in yellow to red (darker is shallower) and cold structures in blue (darker is deeper).</span></figcaption>
</figure>
<p>We found that just like continents, the blobs can assemble – forming “superblobs” as in the current configuration – and break up over time. </p>
<p>A key aspect of our models is that although the blobs change position and shape over time, they still fit the pattern of volcanic and kimberlite eruptions recorded at Earth’s surface. This pattern was previously a key argument for the blobs as unmoving “anchors”.</p>
<p>Strikingly, our models reveal the African blob assembled as recently as 60 million years ago – in stark contrast to previous suggestions the blob could have existed in roughly its present form <a href="https://www.pnas.org/doi/10.1073/pnas.1318135111">for nearly ten times as long</a>.</p>
<h2>Remaining questions about the blobs</h2>
<p>How did the blobs originate? What exactly are they made of? We still don’t know.</p>
<p>The blobs may be denser than the surrounding mantle, and as such they could consist of material separated out from the rest of the mantle <a href="https://www.nature.com/articles/nature06355">early in Earth’s history</a>. This could explain why the mineral composition of the Earth is different from that expected from models based on the composition of meteorites.</p>
<p>Alternatively, the density of the blobs could be explained by the accumulation of dense oceanic material from slabs of rock pushed down by tectonic plate movement. </p>
<p>Regardless of this debate, our work shows sinking slabs are more likely to transport fragments of continents to the African blob than to the Pacific blob. Interestingly, this result is consistent with recent work suggesting the source of mantle plumes rising from the African blob contains continental material, whereas plumes rising from the Pacific blob do not. </p>
<h2>Tracking the blobs to find minerals and diamonds</h2>
<p>While our work addresses fundamental questions about the evolution of our planet, it also has practical applications. </p>
<p>Our models provide a framework to more accurately target the location of minerals associated with mantle upwelling. This includes diamonds brought up to the surface by kimberlites that seem to be associated with the blobs.</p>
<p>Magmatic sulfide deposits, which are the world’s primary reserve of nickel, are also associated with mantle plumes. By helping target minerals such as nickel (an essential ingredient of lithium-ion batteries and other renewable energy technologies) our models can contribute to the transition to a low-emission economy.</p><img src="https://counter.theconversation.com/content/179673/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicolas Flament receives funding from the Australian Research Council and from De Beers.</span></em></p><p class="fine-print"><em><span>Andrew Merdith was supported by the Deep Carbon Observatory and the Richard Lounsbery Foundation.</span></em></p><p class="fine-print"><em><span>Ömer F. Bodur receives funding from the Australian Research Council and from De Beers.</span></em></p><p class="fine-print"><em><span>Simon Williams receives funding from the Australian Research Council and the National Natural Science Foundation of China. </span></em></p>Ancient blobs deep inside the Earth gather together and break apart like continents, according to new research.Nicolas Flament, Senior Lecturer, University of WollongongAndrew Merdith, Research fellow, University of LeedsÖmer F. Bodur, Postdoctoral research fellow, University of WollongongSimon Williams, Research Fellow, Northwest University, Xi'anLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1727532021-11-29T19:10:57Z2021-11-29T19:10:57ZUp to half of Earth’s water may come from solar wind and space dust<figure><img src="https://images.theconversation.com/files/434310/original/file-20211129-21-1wwqtl0.jpg?ixlib=rb-1.1.0&rect=0%2C14%2C2400%2C1182&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Curtin University</span></span></figcaption></figure><p>Water is vital for life on Earth, and <a href="https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256">some experts say</a> we should all drink around two litres every day as part of a healthy lifestyle. But beyond the tap, where does our water come from? </p>
<p>It flows from local rivers, reservoirs and aquifers. But where has that water originated from? Over geological time, Earth cycles water through living organisms, the atmosphere, rivers, oceans, the rocks beneath our feet, and even through the planet’s deep interior. </p>
<p>But what about before that? Where did Earth get its water in the first place? Scientists have long searched for answers to this question.</p>
<p>We studied tiny pieces of an asteroid to find out – and we think a rain of protons from the Sun may be <a href="https://www.nature.com/articles/s41550-021-01487-w">producing water all the time</a> on rocks and dust throughout the Solar System. In fact, up to half of Earth’s water may have been produced this way and arrived here with falling space dust.</p>
<h2>The water puzzle</h2>
<p>We know Earth’s water likely came from outer space early in our Solar System’s history. So, what was the primordial delivery service that gave Earth its water? </p>
<p>Water-rich asteroids are currently the best candidates for the delivery of water, as well as carbon-hydrogen compounds, which together make possible our beautiful habitable blue planet teeming with life. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/water-water-everywhere-in-our-solar-system-but-what-does-that-mean-for-life-76315">Water, water, everywhere in our Solar system but what does that mean for life?</a>
</strong>
</em>
</p>
<hr>
<p>However, water from asteroids contains a specific ratio of ordinary hydrogen to a heavier kind, or isotope, called deuterium. If all of Earth’s water were from asteroids, we would expect it to have this same ratio – but Earth water has less deuterium, so there must also be some other source of water in space with less deuterium. </p>
<p>However, the only thing we know of in the Solar System with lots of hydrogen but a lower ratio of deuterium than Earth is the Sun itself. This puts us in a bit of a pickle, as it’s hard to see how the hydrogen in Earth’s water could have come from the Sun.</p>
<p>Excitingly, we might finally have an answer to this conundrum.</p>
<h2>Tiny pieces of asteroid</h2>
<p>Back in 2011, the Japanese Space Agency (JAXA) sent the Hayabusa mission to take samples of the asteroid Itokawa and bring them back to Earth. In 2017, we were lucky enough to be allocated three extremely rare mineral particles from the sample, each about the width of a human hair. </p>
<p>Our aim was to study the outer surfaces of these dust particles in a brand new way to see if they have been affected by “space weathering”. This is a combination of processes which are known to affect all surfaces exposed in space, such as harmful galactic cosmic rays, micrometeorite impacts, solar radiation and solar wind. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=295&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=295&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=295&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=370&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=370&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434426/original/file-20211129-27-1tzhy1v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=370&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The asteroid Itokawa was the source of grains of dust which contained a surprising layer of water.</span>
<span class="attribution"><span class="source">JAXA</span></span>
</figcaption>
</figure>
<p>We worked in a huge team involving experts from three continents, using a relatively new technique called atom probe tomography which analyses tiny samples at an atomic level. This let us measure the abundance and positions of individual atoms and molecules in 3D.</p>
<p>Near the surface of the Itokawa particles, we found a layer rich in hydroxide molecules (OH, containing one oxygen atom and one hydrogen) and, more importantly, water (H₂O, containing two hydrogen atoms and one oxygen). </p>
<p>This discovery of water was very unexpected! By everything we knew, these minerals from the asteroid should have been as dry as a bone.</p>
<h2>How solar wind makes water</h2>
<p>The most likely source of the hydrogen atoms required to form this water later is the solar wind: hydrogen ions (atoms with a missing electron) streaming through space from the Sun, then lodging in the surfaces of the dust particles.</p>
<p>We tested this theory in the lab by firing heavy hydrogen ions (deuterium) to simulate those in the solar wind at minerals like those in asteroids, and found that these ions react with the mineral particles and steal oxygen atoms to produce hydroxide and water. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/plumbing-the-depths-the-search-for-water-in-our-solar-system-and-beyond-10825">Plumbing the depths: the search for water in our solar system and beyond</a>
</strong>
</em>
</p>
<hr>
<p>Water created by the solar wind represents a previously unconsidered reservoir in our Solar System. And what’s more, every airless world or lump of rock across the galaxy could be home to a slowly renewed water resource powered by their suns.</p>
<p>This is fantastic news for future human space exploration. This life-giving water resource could potentially also be split into hydrogen and oxygen to make rocket fuel. </p>
<h2>Back down to Earth</h2>
<p>So how does this revelation relate to the origin of Earth’s water?</p>
<p>When Earth and its oceans were forming, the Solar System was teeming with objects from kilometre-wide asteroids to micrometre-scale dust particles. These objects have been falling onto our planet (and others) ever since.</p>
<p>Scaling up from our small space-weathered grain, we estimated that a cubic meter of asteroid dust could contain as much as 20 litres of water. So with all the space dust that has fallen to Earth over the aeons, a lot of water from the Sun (with less deuterium) would have arrived alongside the heavier water from larger asteroids. </p>
<p>We calculated that around a 50:50 mix of water-rich dust and asteroids would be a perfect match for the isotopic composition of Earth’s water. </p>
<p>So, while sipping your next glass of water, ponder the curious thought that Earth derived up to half its water from the Sun.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-did-the-earth-get-its-water-asteroid-sample-gives-a-surprising-answer-116381">How did the Earth get its water? Asteroid sample gives a surprising answer</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/172753/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luke Daly receives funding from the UK Science Technology Facilities Council (STFC). He is affiliated with University of Glasgow, University of Oxford, and University of Sydney. </span></em></p><p class="fine-print"><em><span>Professor Martin R. Lee receives funding from the UK Science and Technology Facilities Council (STFC)</span></em></p><p class="fine-print"><em><span>Nick Timms and Phil Bland do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Tiny pieces of an asteroid have revealed an unlikely origin for much of the water in Earth’s oceans.Luke Daly, Lecturer in Planetary Geoscience, School of Geographical and Earth Sciences, University of GlasgowMartin R. Lee, Head of the School of Geographical and Earth Sciences, University of GlasgowNick Timms, Associate Professor, Curtin UniversityPhil Bland, ARC Laureate Fellow, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1718332021-11-22T15:29:22Z2021-11-22T15:29:22ZCurious Kids: Why are there so few impact craters on Earth?<figure><img src="https://images.theconversation.com/files/431908/original/file-20211115-21-g451m1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An illustration shows how, about 65 million years ago, a large asteroid collided with Earth. It hit what is today Mexico and created the Chicxulub crater.</span> <span class="attribution"><span class="source">Mark Garlick/Science Photo Library/Getty Images</span></span></figcaption></figure><p><em>Curious Kids is <a href="https://theconversation.com/africa/topics/curious-kids-36782">a series</a> for children in which we ask experts to answer questions from kids.</em></p>
<p><strong>Why are there so few craters on Earth? (Ivon, 11, Butterworth, South Africa)</strong></p>
<p>Thank you for the great question, Ivon. Scientists call these “impact craters”: a bowl-shaped depression in the rocky crust of a planet, moon or asteroid that is caused by another rocky piece of space debris slamming into it really fast. This high-speed collision – over 36000 kilometres per hour! – releases a huge amount of energy that causes a lot of destruction. </p>
<p>I am a geoscientist who studies impact sites in Africa and on other continents. Scientists like me have identified the remains of around 200 impact craters across our planet. Some people might think that 200 is quite a big number, but you are right – compared to the Moon and the other rocky planets and moons in our solar system, it is exceptionally low. There are several reasons for this.</p>
<h2>Understanding Earth</h2>
<p>The first reason is that Earth’s surface is continuously changing because we live on a geologically active planet. Impact craters are relatively shallow, so these “dents” in Earth’s rocky crust (the surface bit we can see with our eyes) can be easily buried or wiped out by erosion. For instance, the giant, 160-km-wide <a href="https://www.nationalgeographic.com/science/article/last-day-dinosaurs-reign-captured-stunning-detail">Chicxulub crater</a> in Mexico that wiped out most of the dinosaurs and many other species 65 million years ago is only 1-2 km deep and is hidden beneath younger layers of sediment. In contrast, the much older, equally famous, <a href="https://whc.unesco.org/en/list/1162/">Vredefort crater</a> in South Africa has experienced millions of years of erosion by rivers or glaciers so that the crater itself has been erased. Fortunately, ring-shaped patterns in the rocks indicate that something very violent and unusual happened in the distant past. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/431909/original/file-20211115-13-17nd3qw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/431909/original/file-20211115-13-17nd3qw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/431909/original/file-20211115-13-17nd3qw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/431909/original/file-20211115-13-17nd3qw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/431909/original/file-20211115-13-17nd3qw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/431909/original/file-20211115-13-17nd3qw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/431909/original/file-20211115-13-17nd3qw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Barringer Meteor Crater near Winslow, Arizona.</span>
<span class="attribution"><span class="source">Independent Picture Service/Universal Images Group via Getty Images</span></span>
</figcaption>
</figure>
<p>The next reason is that two-thirds of Earth’s rocky crust is hidden beneath the oceans. We actually know less about many parts of the deep ocean floor than the surfaces of other planets in the solar system. Could there be lots of craters hidden beneath the oceans? We don’t know the answer for sure, but probably not, because there is something unusual about Earth’s oceanic crust: it is much, much younger than the continental crust on which we live and the crusts of the Moon and other planets. </p>
<p>Let me explain. Since the 1960s we have known that new ocean crust is being created almost continuously along giant rifts (called mid-ocean ridges). At the same time, other parts of this basalt crust are sinking back into the mantle along subduction zones. This is like a conveyor belt and is part of what we call <a href="https://www.nationalgeographic.org/encyclopedia/plate-tectonics/">plate tectonics</a>. The key point is that we can’t find any oceanic crust that is older than 200 million years. This means that any crater that formed more than 200 million years ago in an ocean has been destroyed. That sounds like a long time, right? But it’s a very small time window compared with the <a href="https://www.nationalgeographic.org/topics/resource-library-age-earth/">4.6 billion years</a> that Earth and the other planets have existed. </p>
<p>The presence of so much deep water on Earth means many smaller asteroids that would definitely make impact craters on dry land do not produce craters in the oceanic crust. This is because the water column absorbs all or most of the impact energy, maybe creating a short-lived tsunami but leaving no other trace. </p>
<p>Earth’s atmosphere also plays a role in reducing the number of impact craters. One of the remarkable observations from the Apollo programme that studied the moon was that every single sample showed signs of high-speed impacts, down to micro-craters. Up until the 1970s many scientists thought the reason there were so few craters on Earth compared to the Moon was because our atmosphere caused the small asteroid debris to burn up (as meteors) and slow down as it passed through the atmosphere so that it didn’t have enough energy left to blast a crater in the crust. </p>
<p>In some cases the atmosphere even “bounced” asteroids back into outer space, much like you can skip a stone across a pool of water. As there will be many more smaller craters – because there are many smaller asteroids – we can see that the atmosphere acts as both a filter and a shield to reduce the number of impacts.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-the-moon-is-such-a-cratered-place-118842">Why the Moon is such a cratered place</a>
</strong>
</em>
</p>
<hr>
<h2>Looking for impact craters</h2>
<p>Finally, we need to consider our own role in your question: how good are scientists and ordinary people at recognising impact craters? There are thousands of craters on Earth, but craters can also be formed in other ways, such as volcanic eruptions and sinkholes. </p>
<p>So, geoscientists need to carefully collect and examine all the evidence before they can confirm that a crater (or, rather, what’s left of it) was formed by impact. Impact crater studies didn’t really exist until about 60 years ago. Up until then, most of the craters on Earth were thought to be caused by volcanic eruptions. </p>
<p>Then scientists working on underground military nuclear explosions started looking into the physics of shock waves in rocks caused by the nuclear explosions. Others began scrutinising the thousands of craters on the Moon as preparation for the <a href="https://www.britannica.com/science/Apollo-space-program">Apollo moon landings</a>. When they went looking for similar craters on Earth, they started to find unusual evidence that the rocks in and around some craters had been affected by exceptional shock pressures and temperatures that could not be explained by volcanic eruptions. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-a-moroccan-crater-reveals-about-a-rare-double-whammy-from-the-skies-61406">What a Moroccan crater reveals about a rare double whammy from the skies</a>
</strong>
</em>
</p>
<hr>
<p>So geoscientists have to be a bit like detectives: we need to collect evidence to prove that a crater was caused by an impact rather than by anything else. Every few years another crater is added to the list as the proof is presented to, and accepted by, the international geoscientific community. </p>
<p>There are many hundreds of possible, or suspected, impact craters on Earth that await confirmation or rejection, including dozens <a href="https://books.google.co.za/books?hl=en&lr=&id=cn6jLdR-DtoC&oi=fnd&pg=PA6&dq=Reimold,+W.U.+%26+Gibson,+R.L.+2009.+Meteorite+Impact!&ots=8MnBv5Po9T&sig=rBknaBFMQCYzEeZHQkJZ710p7WI#v=onepage&q&f=false">right here</a> on the African continent where we live. Even though it’s really big, Africa still has only 20 confirmed impact sites and is definitely underrepresented in the <a href="http://passc.net/EarthImpactDatabase/New%20website_05-2018/Index.html">global list</a>. This may be partly because of its geology but it is also because too few African geoscientists are looking for impact craters in Africa – maybe one day you can join us, Ivon, and help in the search!</p><img src="https://counter.theconversation.com/content/171833/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Lawrence Gibson has previously received research funding from the National Research Foundation. </span></em></p>Impact craters are relatively shallow, so these bowl-shaped “dents” in Earth’s rocky crust can be easily buried or erased by erosion.Roger Lawrence Gibson, Professor of Structural Geology and Metamorphic Petrology, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1638222021-07-14T20:13:22Z2021-07-14T20:13:22ZTravelling through deep time to find copper for a clean energy future<figure><img src="https://images.theconversation.com/files/410519/original/file-20210709-27-mocuom.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Stunning mosaic of oxidised copper in the form of azurite (blue) and malachite (green) in a rock. </span> <span class="attribution"><span class="source">Dimitri Houtteman</span>, <span class="license">Author provided</span></span></figcaption></figure><p>More than 100 countries, including the United States and members of the European Union, have committed to net-zero carbon emissions by 2050. The world is going to need a lot of metal, particularly copper.</p>
<p>Recently, the International Energy Agency <a href="https://www.iea.org/reports/the-role-of-critical-minerals-in-clean-energy-transitions">sounded the warning bell</a> on the global supply of copper as the most widely used metal in renewable energy technologies. With Goldman Sachs <a href="https://www.forbes.com/sites/greatspeculations/2021/06/01/the-race-for-copper-the-metal-of-the-future/?sh=75b2cf60319a">predicting</a> copper demand to grow up to 600% by 2030 and global supply becoming increasingly strained, it is clear we need to find new and large deposits of copper fast.</p>
<p>Getting this much copper will be impossible unless we discover significant new copper deposits. But there has been little exploration for copper over the past decade, as prices have been relatively low.</p>
<p>We have been developing software to model Earth in four dimensions to look deep inside the planet and back into the past to <a href="https://authors.elsevier.com/c/1dHMNcTGy8cG3">discover</a> where copper deposits formed along ancient mountain ranges. This software, called <a href="https://www.gplates.org/">GPlates</a>, is a powerful four-dimensional information system for geologists.</p>
<h2>How large copper deposits form</h2>
<p>Many of the world’s richest copper deposits formed along volcanic mountain chains such as the Andes and the Rocky Mountains. In these regions, an oceanic tectonic plate and a continent collide, with the oceanic plate sinking under the edge of the continent in a process called subduction.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411177/original/file-20210714-19-vn1mup.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mountain ranges like the Andes are formed through subduction and can be rich in copper deposits.</span>
<span class="attribution"><span class="source">Adèle Beausoleil / Unsplash</span></span>
</figcaption>
</figure>
<p>This process creates a variety of igneous rocks and copper deposits to form along the edge of the continent, at depths of between one and five kilometres in the crust, where hot magmatic fluids containing copper (and other elements) circulate within networks of faults. After millions of years of further plate movement and erosion, these treasures move close to the surface – ready to be discovered. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/410521/original/file-20210709-25-1bbsx55.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410521/original/file-20210709-25-1bbsx55.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410521/original/file-20210709-25-1bbsx55.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410521/original/file-20210709-25-1bbsx55.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410521/original/file-20210709-25-1bbsx55.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410521/original/file-20210709-25-1bbsx55.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410521/original/file-20210709-25-1bbsx55.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A sample of copper hosted in a quartz vein in the form of a mineral called chalcopyrite. When exposed to air, the surface oxidises to create this metallic ‘peacock’ lustre.</span>
<span class="attribution"><span class="source">Marek Novotňák / Wikimedia Commons</span></span>
</figcaption>
</figure>
<h2>Searching for copper</h2>
<p>Geologists typically use a set of well-established tools to look for copper. These include geological mapping, geochemical sampling, geophysical surveys and remote sensing. However, this approach does not consider the origin of the magmatic fluids in space and time as the driver of copper formation.</p>
<p>We know these magmatic fluids come from the “mantle wedge”, a wedge-shaped piece of the mantle between the two plates that is fed by oceanic fluids escaping from the downgoing plate. The oceanic plate heats up on its way down, releasing fluids that rise into the overlying continental crust, which in turn drives volcanic activity at the surface and the accumulation of metals such as copper.</p>
<figure class="align-center ">
<img alt="Cross section of the Earth showing one tectonic plate going under the other, creative volcanism and copper deposits directly above" src="https://images.theconversation.com/files/411209/original/file-20210714-17-ps4hkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411209/original/file-20210714-17-ps4hkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411209/original/file-20210714-17-ps4hkp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411209/original/file-20210714-17-ps4hkp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411209/original/file-20210714-17-ps4hkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411209/original/file-20210714-17-ps4hkp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411209/original/file-20210714-17-ps4hkp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Copper deposits tend to form above subduction zones along volcanic chains. This schematic is not to scale.</span>
<span class="attribution"><span class="source">Modified from Shutterstock</span></span>
</figcaption>
</figure>
<p>Differences in how subduction occurs and the characteristics of the oceanic plate may hold the secret to better understanding where and when copper deposits form. However, this information is traditionally not used in copper exploration.</p>
<h2>Building a virtual Earth</h2>
<p>At the <a href="https://www.earthbyte.org/">EarthByte</a> research group, we are building a virtual Earth powered by our <a href="https://www.gplates.org/">GPlates</a> plate tectonic software, which lets us look deep below the surface and travel back in time. One of its many applications is to understand where copper deposits have formed along mountain belts.</p>
<p>In a <a href="https://authors.elsevier.com/c/1dHMNcTGy8cG3">recent paper</a>, we outline how it works. We focus on the past 80 million years because most of the known economic copper deposits along mountain belts formed during this period. This period is also most accurate for <a href="https://www.earthbyte.org/category/resources/data-models/global-regional-plate-motion-models/">our models</a>.</p>
<p>We used machine learning to find links between known copper deposits along mountain belts and the evolution of the associated subduction zone. Our model looks at several different subduction zone parameters and determines how important each one is in terms of association with known ore deposits.</p>
<p>So what turns out to be important? How fast the plates are moving towards each other, how much calcium carbonate is contained in the subducting crust and in deep-sea sediments, how old and thick the subducting plate is, and how far it is to the nearest edge of a subduction zone.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Xm7O9kuc4i0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Plate motions and age of the ocean crust, with age-coded porphyry copper-gold deposits overlaid. Animation by Michael Chin.</span></figcaption>
</figure>
<p>Using our <a href="https://github.com/EarthByte/porphyry_copper_spatiotemporal_exploration">machine learning</a> approach, we can look at different parts of the world and see whether they would have experienced conditions conducive to forming copper deposits at different times. We identified several candidate regions in the US, including in central Alaska, southern Nevada, southern California and Arizona, and numerous regions in Mexico, Chile, Peru and Ecuador.</p>
<p>Knowing when copper ore deposits may have formed is important, as it helps explorers to focus their efforts on rocks of particular ages. In addition, it reveals how much time given deposits might have had to move closer to the surface.</p>
<p>Australia has similar deposits, including the <a href="https://en.wikipedia.org/wiki/Cadia-Ridgeway_Mine">Cadia copper-gold district</a> in New South Wales. However, these rocks are significantly older (roughly 460 million to 430 million years old) and require virtual Earth models to look much further back in time than those applied to the Americas.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/5-rocks-any-great-australian-rock-collection-should-have-and-where-to-find-them-163578">5 rocks any great Australian rock collection should have, and where to find them</a>
</strong>
</em>
</p>
<hr>
<h2>The future of mineral exploration</h2>
<p>Finding <a href="https://www.bloomberg.com/news/articles/2021-03-19/the-world-will-need-10-million-tons-more-copper-to-meet-demand">10 million tonnes of copper by 2030</a> – the equivalent of eight of the largest copper deposits that we mine today – presents an enormous challenge.</p>
<p>With support over a decade from <a href="https://www.auscope.org.au/">AuScope</a> and the National Collaborative Research Infrastructure Strategy <a href="https://www.dese.gov.au/ncris">(NCRIS)</a>, we are in a position to imagine tackling this challenge. By supercharging GPlates in Australia’s <a href="https://www.auscope.org.au/news-features/building-australias-downward-looking-telescope">Downward Looking Telescope</a>, together with AI and supercomputing, we can meet it head on.</p>
<p>These emerging technologies are increasingly being used by Australian startups like <a href="https://lithodat.com/">Lithodat</a> and <a href="http://www.deeperx.com/">DeeperX</a> and mining companies in collaboration with universities to develop AI’s enormous potential for <a href="https://iea.blob.core.windows.net/assets/24d5dfbb-a77a-4647-abcc-667867207f74/TheRoleofCriticalMineralsinCleanEnergyTransitions.pdf">critical minerals</a> discovery.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/clean-energy-the-worlds-demand-for-copper-could-be-catastrophic-for-communities-and-environments-157872">Clean energy? The world’s demand for copper could be catastrophic for communities and environments</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/163822/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dietmar Müller receives funding from the Australian Research Council, the National Collaborative Research Infrastructure Strategy (NCRIS) via AuScope, and BHP. </span></em></p><p class="fine-print"><em><span>Jo Condon works for AuScope, a non-profit organisation funded by NCRIS that enables the GPlates software used in this research.</span></em></p><p class="fine-print"><em><span>Rohitash Chandra receives funding from Australian Research Council - Industrial Transformation Training Centre in Data Analytics for Resources and Environments.</span></em></p><p class="fine-print"><em><span>Julian Diaz does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Using geology and AI, a virtual model of how the Earth’s tectonic plates have evolved can help reveal deposits of copper.Dietmar Müller, Professor of Geophysics, University of SydneyJo Condon, Honorary researcher, The University of MelbourneJulian Diaz, Exploration Geologist, University of SydneyRohitash Chandra, Senior Lecturer, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1575092021-04-12T19:18:14Z2021-04-12T19:18:14ZCurious Kids: how and when did Mount Everest become the tallest mountain? And will it remain so?<figure><img src="https://images.theconversation.com/files/394649/original/file-20210412-15-3zdmdj.jpg?ixlib=rb-1.1.0&rect=97%2C44%2C4895%2C3278&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><blockquote>
<p>Most people know that Mount Everest is the tallest mountain but I want to know for how long it has been the tallest, and for how long in the future it will remain so (…) Which range preceded it? (…) When will something else overtake it? — Nigel, age 14, Christchurch</p>
</blockquote>
<p><a href="https://theconversation.com/au/topics/curious-kids-36782"><img src="https://images.theconversation.com/files/291898/original/file-20190911-190031-enlxbk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=90&fit=crop&dpr=1" width="100%"></a></p>
<p>Nigel, thank you for this wonderful and insightful question. The answer is actually quite complex, since the height (or <em>elevation</em>) of mountain ranges in the past can be difficult to know. </p>
<p>However, it is a very important question as mountains have a huge role in the environment. They can disturb air flow, affect global and regional climate and <a href="https://doi.org/10.3389/fpls.2019.00195">provide opportunities</a> for plants and animals to evolve.</p>
<h2>Understanding the history of mountain ranges</h2>
<p>Geoscientists address questions about ancient mountain heights by looking at <a href="https://en.wikipedia.org/wiki/Sedimentary_basin">sedimentary basins</a> within mountain ranges. These are low areas where <a href="https://www.nationalgeographic.org/encyclopedia/sediment/">sediment</a> materials such as pollen and plant leaves collect and minerals form in the soil. </p>
<p>A basin today may be much higher or lower than it was when sediment entered it. The fossilised pollen, leaves and minerals that date back to the time when the sediment was deposited can reveal how the landscape’s elevation changed over time.</p>
<p>If we look at fossilised pollen, we may find it comes from plants which likely grew in a particular range of elevation, and we may also notice the absence of certain other plants. (We can figure out where ancient plants likely grew by looking at their modern relatives.)</p>
<p>So by dating the pollen we find, we can calculate the landscape’s possible range of <a href="https://doi.org/10.1130/G33420.1">elevation in the past</a>. We can conclude the landscape was too high for <em>plant A</em>, high enough for <em>plant B</em> (which gave us the pollen), but not high enough for <em>plant C.</em></p>
<p>That is a pretty powerful capability, especially if the elevation of the landscape has changed significantly since the sediment was first deposited.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/393013/original/file-20210401-19-o5h4j2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393013/original/file-20210401-19-o5h4j2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=263&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393013/original/file-20210401-19-o5h4j2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=263&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393013/original/file-20210401-19-o5h4j2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=263&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393013/original/file-20210401-19-o5h4j2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=330&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393013/original/file-20210401-19-o5h4j2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=330&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393013/original/file-20210401-19-o5h4j2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=330&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Podocarp (southern hemisphere conifer) pollen on the left grew in Timor about 2.5 million years ago. A modern relative is shown on the right. These plants grew at elevations greater than 1.2km and are not present in older sediments. Their abrupt appearance in the sediment getting washed off the ancient island tells when parts of the island had grown to at least 1.2km high.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>We can also look at the different kinds (or <em>isotopes</em>) of certain elements (particularly oxygen) contained in plant waxes, clays and carbonate minerals that form by chemical reactions in the soil. These plants and minerals incorporate rainwater. </p>
<p>As a band of rain reaches a mountain range, water with heavier oxygen isotopes falls out first. This means rainwater at higher elevations contains lighter oxygen isotopes, which then pass into the plants and minerals there.</p>
<p>If we find sediment that was deposited into a low basin 30 million years ago, but is now much higher, it will still contain oxygen isotopes that reveal the elevation at which it first formed. We can measure these isotopes to estimate how much higher the landscape has become.</p>
<h2>How long has Everest been the tallest?</h2>
<p>Everest is part of the Himalayas, a mountain range that stands at the southern edge of the vast Tibetan Plateau which is around 4-5km above sea level. Scientists have used the methods described above to understand the history of the plateau, which evolved as a result <a href="https://academic.oup.com/nsr/article/8/1/nwaa091/5829861">of several ancestral mountain ranges joining up</a>. </p>
<p>Parts of the modern plateau were already higher than 3.5km by <a href="https://advances.sciencemag.org/content/6/50/eaba7298.full">26 million years ago</a>. The southernmost of those ranges was a great, Andes-like mountain range called the <a href="https://www.sciencedirect.com/science/article/pii/S0012821X14000612">Gangdese mountains</a>. </p>
<p>These seem to have existed for more than 50 million years at elevations similar to those of the Andes today (about 4.5km). </p>
<p>However, south of the Gangdese, where we have today’s highest mountains, geologists found 34.5-million-year-old <a href="https://www.sciencedirect.com/science/article/pii/S1342937X15000519">sediments from a shallow sea</a> only a few dozen kilometres east of Mount Everest (locally called <a href="https://www.montana.edu/everest/facts/naming.html"><em>Qomolangma</em></a>). </p>
<p>This tells us the part of the Himalayas that includes Everest, which now dominates the skyline, was not a mountain range back then. In fact, it was at sea level. It has grown more than 8km in the last 30 million years.</p>
<p>Everest, now the big kid on the block, is currently more than 100 metres higher than its closest rival. But a new victor will emerge with time. </p>
<h2>What happens next?</h2>
<p>To understand how Everest might lose its highest mountain status, we need to understand how mountain ranges are built. The largest mountain belts today were built from collisions between blocks of continental crust in Earth’s outer layer, the <a href="https://en.wikipedia.org/wiki/Lithosphere">lithosphere</a>.</p>
<p>As these blocks collide, they crumple and slices of rocky crust get stacked on one another, as seen in the right half of the cross section below. This gives birth to high mountains, which continuously rise and shift and change as the collision continues. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="General cross section of lithosphere in the Himalayan Region" src="https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=260&fit=crop&dpr=1 600w, https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=260&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=260&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=327&fit=crop&dpr=1 754w, https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=327&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/394519/original/file-20210412-19-fdqjji.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=327&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This is a general cross section of lithosphere in the Himalayan region. The lithosphere consists of all of the crust and part of the mantle, down as far as the partially-molten asthenosphere.</span>
<span class="attribution"><span class="source">x</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The video below helps visualise this process. It simulates the squeezing of a block of lithosphere in the Himalayas. You can refer to the “Sandbox Video” part of the cross section above to see where this process would occur.</p>
<figure>
<iframe src="https://player.vimeo.com/video/528128128" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">University of Melbourne’s School of Geography, Earth and Atmospheric Science students squeeze layered sediments in a sandbox to see how they will deform.</span></figcaption>
</figure>
<p>You’ll notice the mountains begin to rise as soon as the collision begins. The arm pushing the sand represents the already thickened crust of the high Himalayas and the sand pile being pushed represents the Indian upper crust which lies below the mountain range.</p>
<p>The thickening moves to different spots over time. While the youngest and smallest mountain is furthest from the collision itself, the highest peak isn’t always in the oldest part of the range (where the collision began).</p>
<h2>Eroding and growing</h2>
<p>Large mountain ranges “erode” when changes in temperature, wind and water break down the rock and ultimately carry it away. Interestingly, erosion actually causes mountains to slowly grow over time. </p>
<p>This is a fascinating process geoscientists call “<a href="https://en.wikipedia.org/wiki/Isostasy">isostasy</a>” which can be measured using GPS. The diagram below shows how the process is comparable to blocks of wood floating in water. </p>
<p>If intact blocks of a certain type of wood float in a pool, the same percentage of the overall volume will always protrude above the surface. So, if material is removed from one block, that block will rise. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=220&fit=crop&dpr=1 600w, https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=220&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=220&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=276&fit=crop&dpr=1 754w, https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=276&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/394520/original/file-20210412-19-bbk457.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=276&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This diagram shows how erosion of mountains — akin to cutting slots in blocks of wood — causes mountain peaks to increase in elevation.</span>
<span class="attribution"><span class="source">x</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We can compare these columns of wood to lithospheric blocks. As more erosion occurs, the mountain’s surface increases in elevation. This gives a way for deeply buried rocks to rise within the mountain range. </p>
<h2>Hard to beat</h2>
<p>Despite having 82,350km of <a href="http://rses.anu.edu.au/%7Enick/papers/tecto2010b.pdf">convergent boundaries on Earth</a> (where two plates meet and push together), it’s unlikely other mountain ranges will surpass the height of the Himalayas anytime soon.</p>
<p>This is because the Himalayas were built by the collision of two large continents composed of rocks with lower than average density. They therefore sit higher than the oceanic lithosphere. </p>
<p>One day in the distant future a new boundary will form somewhere and the forces creating the Himalayas will be removed. </p>
<p>The range will then collapse and eventually erode to become like the modern-day <a href="https://en.wikipedia.org/wiki/Alleghanian_orogeny">Appalachians</a> in North America, which was an active mountain belt from between 325 and 260 million years ago. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-mountains-form-108246">Curious Kids: how do mountains form?</a>
</strong>
</em>
</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
<p><em>* Email your question to curiouskids@theconversation.edu.au <br>
* Tell us on <a href="https://twitter.com/ConversationEDU">Twitter</a> by tagging <a href="https://twitter.com/ConversationEDU">@ConversationEDU</a> with the hashtag #curiouskids, or <br>
* Tell us on <a href="http://www.facebook.com/conversationEDU">Facebook</a></em></p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/157509/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Everest didn’t become the highest mountain overnight. This process was excruciatingly slow; a result of complex interactions between the solid earth, the atmosphere and the biosphere.Brendan Duffy, Fellow in Structural Geology and Tectonics, The University of MelbourneSandra McLaren, Associate professor, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1473742020-10-07T11:15:27Z2020-10-07T11:15:27ZGrímsvötn: Iceland’s most active volcano may be about to erupt<p>The ice-covered Grímsvötn volcano on Iceland produced an unusually large and <a href="https://earthobservatory.nasa.gov/images/50684/eruption-of-grimsvotn-volcano-iceland">powerful eruption in 2011</a>, sending ash 20km into the atmosphere, causing the cancellation of about 900 passenger flights. In comparison, the much smaller 2010 eruption of <a href="http://news.bbc.co.uk/1/hi/world/europe/8634944.stm">Eyjafjallajökull</a> led to the <a href="https://ec.europa.eu/commission/presscorner/detail/en/MEMO_11_346">cancellation of about 100,000 flights</a>.</p>
<p>Understandably, any mention of another explosive eruption from an Icelandic volcano will raise concerns in the air travel industry, which is <a href="https://theconversation.com/why-airlines-that-can-pivot-to-ultra-long-haul-flights-will-succeed-in-the-post-coronavirus-era-140466">currently reeling</a> from the COVID-19 pandemic. But there are clear signs that the Grímsvötn volcano is getting ready to erupt again. As a result, the authorities have recently <a href="https://en.vedur.is/about-imo/news/the-aviation-color-code-for-grimsvotn-changed-from-green-to-yellow">raised the threat level</a> for this volcano.</p>
<p>Grímsvötn is a peculiar volcano, as it lies almost wholly beneath ice, and the only permanently visible part is an old ridge on its south side which forms the edge of a large crater (a caldera). And it is along the base of this ridge, under the ice, that most recent eruptions have occurred.</p>
<p>Another peculiarity is that the heat output from the volcano is extraordinarily high (2000-4000MW), and this melts the overlying ice and produces a hidden subglacial lake of meltwater. This is up to 100 metres deep and has ice up to about 260 metres thick floating on it. Fresh ice is continually flowing into the caldera, where it melts, and so the water level just keeps rising and rising.</p>
<figure class="align-center ">
<img alt="Picture of the lake at Grímsvötn." src="https://images.theconversation.com/files/362147/original/file-20201007-14-1ecfns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362147/original/file-20201007-14-1ecfns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=328&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362147/original/file-20201007-14-1ecfns.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=328&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362147/original/file-20201007-14-1ecfns.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=328&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362147/original/file-20201007-14-1ecfns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=413&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362147/original/file-20201007-14-1ecfns.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=413&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362147/original/file-20201007-14-1ecfns.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=413&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The roughly 1.5km wide hole melted in the ice by the 2011 eruption.</span>
<span class="attribution"><span class="source">Dave McGarvie</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This meltwater can escape suddenly, and after travelling southwards beneath the ice for about 45km it emerges at the ice margin as a flood, which in the past has <a href="https://www.irishtimes.com/news/bridges-destroyed-as-icelandic-flood-triggered-by-volcano-peaks-1.103502">washed away roads and bridges</a>. Fortunately, the passage of meltwater beneath the ice to its outlet can be tracked, and so roads are closed in good time to avoid travellers getting caught in the flood and killed.</p>
<p>Yet another important peculiarity of Grímsvötn is that it can have a hair-trigger response to pressure. This happens when the meltwater lake drains – removal of the water from across the top of the volcano rapidly reduces the pressure. This can trigger an eruption – it’s like lifting the lid off a pressure cooker. This has happened many times at Grímsvötn.</p>
<p>Grímsvötn is Iceland’s most frequently erupting volcano, and over the past 800 years some 65 eruptions <a href="https://volcano.si.edu/volcano.cfm?vn=373010">are known</a> with some certainty. The time gaps between eruptions are variable – and, for example, prior to the larger 2011 eruption there were smaller eruptions in 2004, 1998 and 1983 with gaps of between four and 15 years. Crucially, and with the next eruption in mind, Grímsvötn appears to have a pattern of infrequent larger eruptions that occur every 150-200 years (for example 2011, 1873, 1619), with smaller and more frequent eruptions occurring roughly once a decade in between. </p>
<h2>Signs of activity</h2>
<p>A high frequency of eruptions at a volcano allows scientists to detect patterns that lead to eruptions (precursors). And if these are repeated each time a volcano erupts then it becomes possible for scientists to be more confident that an eruption is likely to happen in the near future. It is, however, <a href="https://theconversation.com/why-cant-we-predict-when-a-volcano-will-erupt-53898">seldom possible to be precise</a> about the exact day.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/362150/original/file-20201007-22-ywpmmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/362150/original/file-20201007-22-ywpmmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362150/original/file-20201007-22-ywpmmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362150/original/file-20201007-22-ywpmmo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362150/original/file-20201007-22-ywpmmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362150/original/file-20201007-22-ywpmmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362150/original/file-20201007-22-ywpmmo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Old ridge of Grímsvötn.</span>
<span class="attribution"><span class="source">Dave McGarvie</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Icelandic scientists have been carefully monitoring Grímsvötn since its 2011 eruption, and have seen <a href="http://icelandicvolcanoes.is/?volcano=GRV#">various signals</a> that suggest the volcano is getting ready to erupt. For example, the volcano has been inflating as new magma moves into the plumbing system beneath it (think of burying a balloon in the sand and then inflating it). Increasing thermal activity has been melting more ice and there has also been a recent increase in earthquake activity.</p>
<p>So what happens next? Again, based on the pattern observed at past eruptions, an intense swarm of earthquakes lasting a few hours (one to ten hours) will signal that magma is moving towards the surface and that an eruption is imminent. In cases where the hidden subglacial lake drains and triggers the eruption, the earthquakes occur after the lake has drained and just before the eruption.</p>
<p>The smaller Grímsvötn eruptions expend a lot of energy when they interact with water and ice at the surface. That means the resulting ash gets wet and sticky and so falls from the sky relatively quickly. Ash clouds therefore only travel a few tens of kilometres from the eruption site. This is a good scenario for Icelanders and also for air travel, as it prevents the formation of substantial ash clouds that could drift around and close off airspace.</p>
<p>But will it be a small eruption? If Grímsvötn’s past pattern of occasional large eruptions with more numerous smaller eruptions occurring in between continues into the future, then the next eruption should be a small one (given there was a large one in 2011). And the word “should” is important here – Iceland’s volcanoes are complex natural systems and patterns are not always followed faithfully.</p><img src="https://counter.theconversation.com/content/147374/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dave McGarvie does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Icelandic authorities have recently raised the threat level of the Grímsvötn volcano.Dave McGarvie, Volcanologist, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1435642020-07-29T18:04:02Z2020-07-29T18:04:02ZStonehenge: how we revealed the original source of the biggest stones<figure><img src="https://images.theconversation.com/files/349929/original/file-20200728-21-igjyf1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Andre Pattenden/English Heritage</span></span></figcaption></figure><p>Stonehenge, an icon of European prehistory that attracts more than a million visitors a year, is rarely out of the news. Yet, surprisingly, there is much we don’t know about it. Finding the sources of the stones used to build the monument is a fundamental question that has vexed antiquaries and archaeologists for over four centuries.</p>
<p>Our interdisciplinary team, including researchers from four UK universities (Brighton, Bournemouth, Reading and UCL) and English Heritage, has used a novel geochemical approach to examine the large “sarsen” stones at Stonehenge. <a href="https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abc0133">Our results</a> confirm that the nearby Marlborough Downs were the source region for the sarsens, but also pinpoint a specific area as the most likely place from where the stones were obtained.</p>
<p>Two main types of stone are present at Stonehenge: sarsen sandstone for the massive framework of upright stones capped by horizontal lintels; and a mix of igneous rocks and sandstones collectively known as “bluestones” for the smaller elements within the central area. </p>
<figure class="align-center ">
<img alt="Part of Stonehenge casting shadows." src="https://images.theconversation.com/files/349935/original/file-20200728-27-rvvein.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349935/original/file-20200728-27-rvvein.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=441&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349935/original/file-20200728-27-rvvein.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=441&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349935/original/file-20200728-27-rvvein.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=441&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349935/original/file-20200728-27-rvvein.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=554&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349935/original/file-20200728-27-rvvein.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=554&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349935/original/file-20200728-27-rvvein.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=554&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Inside the sarsen circle.</span>
<span class="attribution"><span class="source">James Davies/English Heritage</span></span>
</figcaption>
</figure>
<p><a href="https://www.cambridge.org/core/journals/antiquity/article/megalith-quarries-for-stonehenges-bluestones/AAF715CC586231FFFCC18ACB871C9F5E/core-reader?sfns=mo">Research in the last decade</a> has confirmed that the igneous bluestones were brought to Stonehenge from the Preseli Hills in Pembrokeshire, over 200km to the west. The sandstones have been tracked to eastern Wales although the exact outcrops have yet to be found. However, the origins of the sarsen stones has, until now, remained a mystery.</p>
<p>Stonehenge is a complicated and long-lived monument <a href="https://www.cambridge.org/core/journals/antiquity/article/stonehenge-remodelled/A118920A90FB7CCB2838CEEB10BE477D">constructed in five main phases</a>. The earliest, dated to about 3000BC, comprised a roughly 100m-diameter circular enclosure bounded by a bank and external ditch. Inside were various stone and timber structures, and numerous cremation burials. </p>
<p>The sarsen structures visible today were erected around 2500BC and comprised five trilithons (the doorway-like structures formed from two uprights joined by a lintel) surrounded by a circle of a further 30 uprights linked by lintels. The trilithons were arranged in a horseshoe formation with its principal axis aligned to the rising midsummer sun in the northeast and the setting midwinter sun to the southwest.</p>
<h2>Locating the sarsen source</h2>
<p>Conventional wisdom holds that the sarsens were brought to Stonehenge from the Marlborough Downs, some 30km to the north, the closest area with substantial scatters of large sarsen boulders. However, the Marlborough Downs are extensive and greater precision is needed to understand how prehistoric peoples used the landscape and its resources. </p>
<p>Our research has identified what might be termed the “geochemical fingerprint” of the Stonehenge sarsens. We started by analysing the geochemistry of all 52 remaining sarsens at Stonehenge (28 of those originally present are now missing, having been removed long ago). </p>
<p>This phase of the work involved using a non-destructive technology called portable x-ray fluorescence spectrometry (PXRF). Carrying out the PXRF analyses required access to the monument when it was closed to visitors and included several night shifts and one early morning analysing the lintel stones from a mobile scaffold tower. Data collection is never easy!</p>
<figure class="align-center ">
<img alt="Diagram of Stonehenge layout" src="https://images.theconversation.com/files/349931/original/file-20200728-29-5kkqcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349931/original/file-20200728-29-5kkqcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349931/original/file-20200728-29-5kkqcy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349931/original/file-20200728-29-5kkqcy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349931/original/file-20200728-29-5kkqcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349931/original/file-20200728-29-5kkqcy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349931/original/file-20200728-29-5kkqcy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Most sarsens had the same chemical signature.</span>
<span class="attribution"><span class="source">David Nash, University of Brighton</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Analysis of the PXRF data showed that the geochemistry of most of the stones at Stonehenge was highly consistent, and only two sarsens (stones 26 and 160) had a statistically different chemical signature. This was an interesting result as it suggested we were looking for a single main source. </p>
<p>Then came a major stroke of luck. We were able to analyse three small samples that had been taken from one of <a href="https://www.bbc.co.uk/news/uk-england-wiltshire-48190588">the stones in 1958</a>, Stone 58, part of the group of sarsens with a consistent chemistry. Using a method known as inductively coupled plasma mass spectrometry (ICP-MS) gave a high-resolution geochemical fingerprint for the Stonehenge sarsen. Like all good detectives, we could now compare our fingerprint with those of the potential sources.</p>
<figure class="align-center ">
<img alt="Man examining stone rod." src="https://images.theconversation.com/files/349938/original/file-20200728-29-ptxuq9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349938/original/file-20200728-29-ptxuq9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349938/original/file-20200728-29-ptxuq9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349938/original/file-20200728-29-ptxuq9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349938/original/file-20200728-29-ptxuq9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349938/original/file-20200728-29-ptxuq9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349938/original/file-20200728-29-ptxuq9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">David Nash examining the core from Stone 58.</span>
<span class="attribution"><span class="source">Sam Frost/English Heritage</span></span>
</figcaption>
</figure>
<p>Sarsen blocks are found widely scattered across southern Britain, broadly south of a line from Devon to Norfolk. We sampled stones from 20 areas, including six in the Marlborough Downs, and analysed them using ICP-MS. </p>
<p>Comparing the geochemical signature from Stone 58 against our resulting data revealed only one direct chemical match: the area known as West Woods to the south-west of Marlborough. We could therefore conclude that most of the Stonehenge sarsens were from West Woods.</p>
<p>Our results not only identify a specific source for most of the sarsens used to build Stonehenge, but also open up debate about many connected issues. Researchers have previously <a href="https://www.cambridge.org/core/journals/antiquity/article/stonehenge-remodelled/A118920A90FB7CCB2838CEEB10BE477D">suggested several routes</a> by which the sarsens may have been transported to Stonehenge, without actually knowing where they came from. </p>
<figure class="align-center ">
<img alt="Aerial view of Stonehenge" src="https://images.theconversation.com/files/349933/original/file-20200728-35-1e5a8up.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349933/original/file-20200728-35-1e5a8up.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349933/original/file-20200728-35-1e5a8up.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349933/original/file-20200728-35-1e5a8up.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349933/original/file-20200728-35-1e5a8up.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349933/original/file-20200728-35-1e5a8up.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349933/original/file-20200728-35-1e5a8up.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many mysteries remain.</span>
<span class="attribution"><span class="source">Andre Pattenden/English Heritage</span></span>
</figcaption>
</figure>
<p>Now these can be revisited as we better appreciate the effort of moving <a href="https://research.historicengland.org.uk/Report.aspx?i=15106&ru=%252fResults.aspx%253fp%253d1%2526n%253d10%2526ry%253d2012%2526t%253dstonehenge%2526ns%253d1">boulders as long as 9m and weighing over 30 tonnes</a> some 25km across the undulating landscape of Salisbury Plain. We can feel the pain of the Neolithic people who took part in this collective effort and think about how they managed such a Herculean task. </p>
<p>We can also ask what was special about the West Woods plateaux and its sarsens. Was it simply their shape and size that attracted attention? Or was there some more deep-seated reason rooted in the beliefs and identities of the people that built Stonehenge? </p>
<p>Revealing that all the stones came from a single main source is also important and accords with the evidence that the sarsens were all erected at much the same time. But what about the two sarsens whose fingerprints differ from the main source? Where did they come from? The quest continues, and the questions just keep coming.</p><img src="https://counter.theconversation.com/content/143564/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Nash received funding for the research described in this article from the British Academy and The Leverhulme Trust.</span></em></p><p class="fine-print"><em><span>Timothy Darvill received funding for the research described in this article from the British Academy and The Leverhulme Trust.</span></em></p>How we traced the origin of the sarsen stones.David Nash, Professor of Physical Geography, University of BrightonTimothy Darvill, Professor of Archaeology, Department of Archaeology and Anthropology, Bournemouth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1424512020-07-28T12:16:34Z2020-07-28T12:16:34ZMarie Tharp pioneered mapping the bottom of the ocean 6 decades ago – scientists are still learning about Earth’s last frontier<figure><img src="https://images.theconversation.com/files/349770/original/file-20200727-35-1udrgwj.jpg?ixlib=rb-1.1.0&rect=0%2C17%2C1198%2C883&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tharp with an undersea map at her desk. Rolled sonar profiles of the ocean floor are on the shelf behind her.</span> <span class="attribution"><a class="source" href="https://www.ldeo.columbia.edu/news-events/join-us-celebrating-marietharp100">Lamont-Doherty Earth Observatory and the estate of Marie Tharp</a></span></figcaption></figure><p>Despite all the deep-sea expeditions and samples taken from the seabed over the past 100 years, humans still know very little about the ocean’s deepest reaches. And there are good reasons to learn more. </p>
<p>Most <a href="https://www.noaa.gov/education/resource-collections/ocean-coasts/tsunamis">tsunamis</a> start with earthquakes under or near the ocean floor. The seafloor provides habitat for fish, corals and <a href="https://ocean.si.edu/ocean-life/invertebrates/hydrothermal-vent-creatures">complex communities</a> of microbes, crustaceans and other organisms. Its topography controls currents that <a href="https://oceanexplorer.noaa.gov/facts/climate.html#:%7E:text=Ocean%20currents%20act%20as%20conveyer,influencing%20both%20weather%20and%20climate.&text=The%20ocean%20doesn't%20just,distribute%20heat%20around%20the%20globe.">distribute heat</a>, helping to regulate Earth’s climate.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&rect=31%2C4%2C2968%2C1715&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing geographic features of world's oceans" src="https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&rect=31%2C4%2C2968%2C1715&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=347&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=347&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=347&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=436&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=436&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349478/original/file-20200726-29-189de0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=436&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hand-painted rendition of Heezen-Tharp 1977 ‘World ocean floor’ map, by Heinrich Berann.</span>
<span class="attribution"><a class="source" href="https://www.loc.gov/resource/g9096c.ct003148/">Library of Congress, Geography and Map Division</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><a href="https://www.ldeo.columbia.edu/news-events/remembered-marie-tharp-pioneering-mapmaker-ocean-floor">Marie Tharp</a>, born in 1920, was a geologist and oceanographer who created maps that changed the way people imagine two-thirds of the world. Beginning in 1957, Tharp and her research partner, Bruce Heezen, began publishing the first comprehensive maps that showed the main features of the ocean bottom – mountains, valleys and trenches. </p>
<p><a href="https://scholar.google.com/citations?user=ruUF3z4AAAAJ&hl=en">As a geoscientist</a>, I believe Tharp should be as famous as Jane Goodall or Neil Armstrong. Here’s why.</p>
<h2>Traversing the Atlantic</h2>
<p>Well into the 1950s, many scientists assumed the seabed was featureless. Tharp showed that it contained rugged terrain, and that much of it was laid out in a systematic way. </p>
<p>Her images were critical to the development of <a href="https://www.britannica.com/science/plate-tectonics">plate tectonic theory</a> – the idea that plates, or large sections of Earth’s crust, interact to generate the planet’s seismic and volcanic activity. Earlier researchers – <a href="https://www.livescience.com/37529-continental-drift.html">particularly Alfred Wegener</a> – noticed how well the coastlines of Africa and South America fit together and proposed the continents had once been connected; Tharp identified mountains and a rift valley in the center of the Atlantic Ocean where the two continents could have been ripped apart.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="sketch of undersea profile" src="https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=296&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=296&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=296&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=371&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=371&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349739/original/file-20200727-63428-1lb6xwh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=371&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tharp’s East-West profiles across the North Atlantic.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1130/SPE65-p1">The Floors of the Ocean, 1959</a></span>
</figcaption>
</figure>
<p>Thanks to Tharp’s hand-drawn renditions of the ocean floor, I can imagine a walk across the Atlantic Ocean bottom from New York City to Lisbon. The journey would take me out along the continental shelf. Then downward towards the <a href="https://www.britannica.com/place/Sohm-Abyssal-Plain">Sohm Abyssal Plain</a>. I’d need to detour around underwater mountains, called <a href="https://oceanservice.noaa.gov/facts/seamounts.html">seamounts</a>. Then I’d start a slow climb up the <a href="https://www.britannica.com/place/Mid-Atlantic-Ridge">Mid-Atlantic Ridge</a>, a submerged north-south mountain range. </p>
<p>After ascending to 8,200 feet (2,500 meters) below sea level to the ridge’s peak, I would descend several hundred feet, cross the ridge’s central rift valley and proceed up over the ridge’s eastern edge. Then back down to the ocean floor, until I began trekking up the European continental slope to Lisbon. The total walk would be about 3,800 miles (6,000 kilometers) – almost twice the length of the Appalachian Trail.</p>
<h2>Mapping the unseen</h2>
<p>Born in Ypsilanti, Michigan, Tharp studied English and music in college. But then in 1943 she enrolled in a University of Michigan master’s degree program designed to train women to be petroleum geologists during World War II. “Girls were needed to fill the jobs left open because the guys were off fighting,” <a href="https://www.whoi.edu/news-insights/content/marie-tharp/">Tharp later recalled</a>.</p>
<p>After working for an oil company in Oklahoma, Tharp sought a geology job at Columbia University in 1948. Women couldn’t go on research ships, but Tharp could draft, and was hired to assist male graduate students.</p>
<p>Tharp worked with Bruce Heezen, a grad student who gave her seafloor profiles to draft. These are long paper rolls that show the depth of the seafloor along a linear path, measured from a ship using sonar.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="sketches of undersea features based on sonar" src="https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=967&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=967&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=967&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1216&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1216&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349741/original/file-20200727-15-69lzu4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1216&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An illustration of Marie Tharp’s mapping process. (a) shows the position of two ship tracks (A, B) moving across the surface. (b) plots depth recordings as profiles, exaggerating their height to make features easier to visualize. (c) sketches features shown on the profiles.</span>
<span class="attribution"><a class="source" href="http://mirrorservice.org/sites/gutenberg.org/4/9/0/6/49069/49069-h/49069-h.htm">The Floors of the Ocean, 1959, Fig. 1</a></span>
</figcaption>
</figure>
<p>Starting with a large blank sheet of paper, Tharp marked lines of latitude and longitude. Then she’d carefully mark where the ship had traveled. Next she’d read the depth at each location off the sonar profile, mark it on the ship’s track and create her own condensed profile, showing the depth to the ocean floor versus the distance the ship had traveled. </p>
<p>One of her important innovations was creating sketches depicting what the seafloor would look like. These views made it easier to visualize the ocean floor’s topography and create a physiographic map.</p>
<p>Tharp’s careful plotting of six east-to-west profiles across the North Atlantic revealed something no one had ever described before: a cleft in the center of the ocean, miles wide and hundreds of feet deep. Tharp suggested that it was a rift valley – a type of long trough that was known to exist on land.</p>
<p>Heezen <a href="https://www.whoi.edu/news-insights/content/marie-tharp/">called this idea “girl talk</a>” and told Tharp to recalculate and redraft. When she did, the rift valley was still there. </p>
<p>Another research assistant was plotting locations of earthquake epicenters on a map of the same size and scale. Comparing the two maps, Heezen and Tharp realized that the earthquake epicenters fell inside the rift valley. This discovery was critical to the development of plate tectonic theory: It suggested that movement was occurring in the rift valley, and that the continents might actually be drifting apart.</p>
<p>This insight was revolutionary. When Heezen, as a newly-minted Ph.D., gave a talk at Princeton in 1957 and showed the rift valley and epicenters, geology department chair <a href="https://www.whoi.edu/news-insights/content/marie-tharp/">Harry Hess replied</a>, “You have shaken the foundations of geology.” </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bGye6vlOpbY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Exploring mid-ocean ridges provides vast amounts of information about life on Earth.</span></figcaption>
</figure>
<h2>Tectonic resistance</h2>
<p>In 1959 the Geological Society of America published “<a href="https://doi.org/10.1130/SPE65-p1">The Floors of the Oceans: I. The North Atlantic</a>” by Heezen, Tharp and “Doc” Ewing, director of the Lamont Observatory, where they worked. It contained Tharp’s ocean profiles, ideas and access to Tharp’s physiographic maps. </p>
<p>Some scientists thought the work was brilliant, but most didn’t believe it. French undersea explorer Jacques Cousteau was determined to prove Tharp wrong. Sailing aboard his research vessel, the Calypso, he purposely crossed the mid-Atlantic Ridge and lowered an underwater movie camera. To Cousteau’s surprise, the film showed that a rift valley existed.</p>
<p>“There’s truth to the old cliché that a picture is worth a thousand words and that seeing is believing,” Tharp observed in a <a href="https://www.whoi.edu/news-insights/content/marie-tharp/">1999 retrospective essay</a>.</p>
<p>What could have created the rift? Princeton’s Hess proposed some ideas <a href="http://scilib.ucsd.edu/sio/hist_oceanogr/hess-history-of-ocean-basins.pdf">in a 1962 paper</a>. It postulated that hot magma rose from inside the Earth at the rift, expanded as it cooled and pushed two adjoining plates further apart. This idea was a key contribution to plate tectonic theory, but Hess failed to reference the critical work presented in “The Floors of the Oceans” – one of the few publications that included Tharp as a co-author. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Portrait of Marie Tharp in 2001" src="https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349691/original/file-20200727-25-1kaavmd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Marie Tharp in July 2001.</span>
<span class="attribution"><span class="source">Bruce Gilbert, Lamont-Doherty Earth Observatory</span></span>
</figcaption>
</figure>
<h2>Still surveying</h2>
<p>Tharp continued working with Heezen to bring the ocean floor to life. Their collaboration included an <a href="https://www.lib.uchicago.edu/collex/exhibits/marie-tharp-pioneering-oceanographer/1967-indian-ocean-map/">Indian Ocean map</a>, published by National Geographic in 1967, and a 1977 <a href="https://www.lib.uchicago.edu/collex/exhibits/marie-tharp-pioneering-oceanographer/1977-world-ocean-floor-map/">World Ocean Floor map</a> that is now held at the Library of Congress. </p>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p>
<p>After Heezen died in 1977, Tharp continued her work until her death in 2006. In October 1978, Heezen (posthumously) and Tharp were awarded the <a href="https://physicstoday.scitation.org/do/10.1063/PT.6.6.20180730a/full/">Hubbard Medal</a>, the National Geographic Society’s highest honor, joining the ranks of explorers and discoverers such as Ernest Shackleton, Louis and Mary Leakey and Jane Goodall.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p>
<p>Today ships use a <a href="https://youtu.be/8ijaPa-9MDs">method called swath mapping</a>, which measures depth over a ribbon-like path rather than along a single line. The ribbons can be stitched together to create an accurate seafloor map.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=249&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=249&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=249&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=313&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=313&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349692/original/file-20200727-33-wfsk35.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=313&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Left. Detail of Canary Islands from Marie Tharp’s physiographic map of the North Atlantic. Right. Modern swath mapping depiction of the same area. Colors indicate depth.</span>
<span class="attribution"><span class="source">Vicki Ferrini, Lamont-Doherty Earth Observatory.</span></span>
</figcaption>
</figure>
<p>But because ships move slowly, it would take one ship 200 years to completely map the seafloor. An international effort to map the entire ocean floor in detail by 2030 is under way, using multiple ships, led by the <a href="https://www.nippon-foundation.or.jp/en/">Nippon Foundation</a> and the <a href="https://www.gebco.net/">General Bathymetric Chart of the Oceans</a>. </p>
<p>This information is critical to beginning to understand what the seafloor looks like on a neighborhood scale. Marie Tharp was the first person to show the rich topography of the ocean floor and its different neighborhoods.</p><img src="https://counter.theconversation.com/content/142451/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Suzanne OConnell does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Born on July 30, 1920, geologist and cartographer Tharp changed scientific thinking about what lay at the bottom of the ocean – not a featureless flat, but rugged and varied terrain.Suzanne OConnell, Harold T. Stearns Professor of Earth Science, Wesleyan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1234282020-01-06T12:06:32Z2020-01-06T12:06:32ZA new way to identify a rare type of earthquake in time to issue lifesaving tsunami warnings<figure><img src="https://images.theconversation.com/files/308024/original/file-20191219-11946-1t4d9ok.jpg?ixlib=rb-1.1.0&rect=350%2C0%2C5065%2C3700&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This unusual earthquake type generates an outsized tsunami. </span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/1fEYDfuGli0">camila castillo/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Just a few times in a century, somewhere on the globe, a rare “tsunami earthquake” occurs. These are mysterious because, while they’re just medium-sized as earthquakes go, they cause disproportionately large and devastating tsunamis. This type of midsized earthquake is very different than an event like the <a href="http://www.tectonics.caltech.edu/outreach/highlights/sumatra/what.html">2004 earthquake in Sumatra</a> – a very big magnitude 9.2 event which unsurprisingly produced a huge tsunami.</p>
<p>The most recent tsunami earthquake happened in 2010. <a href="https://doi.org/10.1029/2010GL046552">A magnitude 7.8 earthquake</a> <a href="http://itic.ioc-unesco.org/index.php?option=com_content&view=article&id=1673:301&catid=1444&Itemid=1444">off the Mentawai Islands in Indonesia</a> <a href="https://doi.org/10.1029/2010GL046498">set off a tsunami</a> that was <a href="https://doi.org/10.1029/2012JB009159">over 50 feet in height</a> in some places – much greater than seismologists would predict based just on the earthquake’s size. <a href="https://earthobservatory.sg/outreach/natural-hazard-outreach/west-sumatra-tectonics-and-tsunami-hazard">509 people were killed</a>, and 15,000 more were displaced or left homeless. </p>
<p>Tsunami earthquakes are particularly destructive and dangerous because the massive tsunami waves can hit local coastal communities within just five to 15 minutes – before officials can issue a warning. But <a href="https://doi.org/10.1029/2019GL083989">based on our analysis</a> of previously unavailable closeup observations of the 2010 Mentawai event, my colleagues <a href="https://scholar.google.com/citations?user=8YD_3R8AAAAJ&hl=en&oi=ao">and I</a> think there is a way to determine that an event is a tsunami earthquake in time to warn people that an unexpectedly large wave is on the way.</p>
<h2>Earthquakes under the ocean</h2>
<p>The Earth’s surface is made up of <a href="https://theconversation.com/plate-tectonics-new-findings-fill-out-the-50-year-old-theory-that-explains-earths-landmasses-55424">floating tectonic plates</a> that fit together like a slightly imperfect jigsaw puzzle. These plates are moving next to, under or away from each other.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=372&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=372&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=372&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308389/original/file-20200102-11904-tusj3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An earthquake along a subduction zone happens when the leading edge of the overriding plate breaks free and springs seaward, raising the seafloor and the water above it. This uplift starts a tsunami.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/earthquake-starts-tsunami">USGS</a></span>
</figcaption>
</figure>
<p>In <a href="https://www.livescience.com/43220-subduction-zone-definition.html">a subduction zone</a>, one tectonic plate is sinking beneath another. This builds up stresses over time and will eventually create an earthquake. Most typical subduction-zone earthquakes occur roughly 10 to 30 miles down, in an area where the rocks are rigid and strong on the fault between the two tectonic plates.</p>
<p>Meanwhile, the shallowest area of a subduction zone, closest to the seafloor, is made up of soft sediments that are not very strong. Earthquakes rarely occur only here, because stresses mostly don’t build up in these soft, weak rocks.</p>
<p>Geoscientists define an earthquake’s overall size with its magnitude. Earthquake magnitude describes how much “work” is accomplished by the earthquake moving the fault – more work for either more movement, or for moving more rigid rock.</p>
<p>Very large earthquakes, like the magnitude 9 Tohoku earthquake in Japan in 2011, are so big that they break the deeper part of the subduction zone, but also continue upwards to break the shallow part of a subduction zone. This rapid earthquake motion moves the seafloor and <a href="https://www.iris.edu/hq/inclass/animation/subduction_zone_tsunamis_generated_by_megathrust_earthquakes">creates a tsunami</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=267&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=267&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=267&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=336&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=336&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293875/original/file-20190924-51434-1ytyrz6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=336&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cartoon depicting the amount of movement in five earthquakes. The 2010 Mentawai tsunami earthquake moved the fault much more – over 65 feet compared to about 15 feet for the others – and the movement occurred much closer to the seafloor than in any of the other earthquakes.</span>
<span class="attribution"><span class="source">Sahakian et al. (2019), GRL</span></span>
</figcaption>
</figure>
<h2>What sets tsunami quakes apart</h2>
<p>“Tsunami earthquakes” are strange in that they happen almost entirely in the soft, weak section of the fault.</p>
<p>Because tsunami earthquakes break such soft rock, they happen slower, and create much more movement on or near the seafloor in comparison to a normal subduction-zone earthquake of the same size that happens in rigid rock. This in turn creates a much larger tsunami than expected. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=314&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=314&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=314&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=395&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=395&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306913/original/file-20191214-85412-1b87exs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=395&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seismograms showing how much the ground shook from six similarly sized earthquakes, at seismometers all about the same distance from their earthquake. You’d expect the shaking to be comparable. The 2010 Mentawai earthquake seismogram is at the bottom in orange, and shows significantly less shaking than any of the others.</span>
<span class="attribution"><span class="source">Modified from Sahakian et al. (2019), GRL.</span></span>
</figcaption>
</figure>
<p>A tsunami earthquake might have the same magnitude as an earthquake that occurs in rigid rock but produces much less of what seismologists call high-frequency energy. </p>
<p>Think of breaking a thick slab of concrete – which is strong and would produce an audible bang with both low and high-pitched noise – versus breaking a loaf of bread, which makes almost no sound at all. In the Earth, “sound” is the shaking you feel under your feet. The soft bread break is like a tsunami earthquake that doesn’t release a lot of high-frequency energy, and thus doesn’t create as much shaking as we would expect for its magnitude.</p>
<h2>Sensing quakes in time to warn</h2>
<p>Currently, officials rely on knowing an earthquake’s magnitude and location to issue tsunami warnings within tens of minutes. But this doesn’t work in the case of tsunami earthquakes, because the earthquake’s magnitude doesn’t match up with the size of the tsunami it produces.</p>
<p>Instead, to figure out whether an earthquake is in fact a tsunami earthquake, scientists compare its seismic magnitude measured from afar with the amount of high frequency radiated energy it produced, as recorded by far away stations.</p>
<p>If the ratio of energy to magnitude is very low, it’s a tsunami earthquake – basically, its shaking was far too weak for its magnitude because it was breaking soft rock. Instead, its energy is of the low-frequency type: Rather than strong shaking, its energy goes into large slow movement of the seafloor and the ensuing tsunami.</p>
<p>The problem is that in the past, scientists had never recorded one of these elusive earthquakes closeup in what we call the near-field – within about 180 miles (300 kilometers) or so. Instead, scientists have had to find an earthquake’s energy-to-magnitude ratio using seismic waves that have traveled all the way from the epicenter of the earthquake across the world to where researchers can measure them. This process is relatively slow, so we haven’t been able to identify tsunami earthquakes quickly enough to warn people in time, before the wave hits the coast.</p>
<p>Now my colleagues and I have for the first time analyzed data recorded by seismic stations that happened to be near the epicenter of the 2010 Mentawai earthquake. We think we have figured out a new way to identify the danger of a future tsunami earthquake, faster.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308439/original/file-20200103-11951-8wlrvt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tsunamis can take a terrible toll, as for this Indonesian family that lost their father and their home in the Mentawai disaster.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Indonesia-Disasters/77a6343c59ee46199456933fc238e848/4/0">AP Photo/Tundra Laksamana</a></span>
</figcaption>
</figure>
<h2>Closer and quicker proxies</h2>
<p>Our new study used the same concept of comparing the energy released by an earthquake to its seismic magnitude – but based on data from geographically close to the event. Instead of looking at energy measurements recorded at a distance, we used two proxies.</p>
<p>To look directly at how much the ground shook, we used seismic stations onshore near the epicenters of 16 earthquakes, including the Mentawai one in 2010. Because the amount the ground accelerates when seismic waves pass through illustrates how much high frequency energy is in the earthquake, this information was a stand-in for the data we would traditionally get from the far-flung teleseismic stations. Low accelerations mean little high frequency energy.</p>
<p>For the normal earthquakes we looked at, the accelerations from near-field seismometers were close to what we’d expect for each earthquake’s magnitude. In comparison, the 2010 Mentawai earthquake’s accelerations were closer to what we would expect for a magnitude 6.3 earthquake – whereas the earthquake was actually a magnitude 7.8, and produced a tsunami we’d expect for an event of greater than magnitude 8.</p>
<p>We also looked at GPS stations close to the earthquakes. They can show us how much the ground actually moved or was displaced, and measure the earthquake magnitude itself.</p>
<p>Using these measurements together allowed us to compare the amount of energy in the earthquake with respect to its magnitude – without waiting for the seismic waves to travel across the globe. Instead, we would have been able to identify a tsunami earthquake immediately by looking at how low the accelerations were on local seismometers in comparison to the magnitude of the earthquake based on GPS readings.</p>
<p>We think our finding is really promising because these near-field measurements are available immediately – even while an earthquake is happening. Seismologists could use this approach in the future, to identify a tsunami earthquake right after it happens, and provide warning to the nearby coast before the tsunami wave arrives.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/123428/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Valerie Sahakian does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A tricky kind of earthquake that happens in the soft rock of the ocean floor causes much larger tsunamis than their magnitude would predict. New research pinpoints a way to identify the danger fast.Valerie Sahakian, Assistant Professor of Geophysics, University of OregonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1109562019-09-09T19:45:55Z2019-09-09T19:45:55ZThe profound perspective of geoscience can unite students<figure><img src="https://images.theconversation.com/files/289528/original/file-20190826-8893-1bfb52y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Prof. Stephen Meyers and his Geoscience 100 class at the University of Wisconsin-Madison. Photo by Ethan Parrish</span> <span class="attribution"><span class="source">Author provided</span></span></figcaption></figure><p>It’s 1 p.m. and students gather in long lines as they wait to enter the lecture hall, a spacious wood-adorned auditorium at the top of Henry Mall at the University of Wisconsin-Madison. It’s a charismatic octagonal space that is 116 years old and the largest lecture hall on campus. </p>
<p>The course is Geoscience 100: Introductory Geology, and on this particular day, music spills out through the closed doors as the students await playbills for a lecture called “<a href="https://www.youtube.com/watch?v=JUG0ZI7uzsw">Beginnings</a>.” The lecture is a musical-video-poetic performance in four acts that communicates scientific concepts from the big bang, to the origin of our solar system and our planet.</p>
<p>As the doors to the lecture hall open, the students stream in to a live band performing at the front of the auditorium. Students will be treated to a newly commissioned instrumental piece from the band (Mr. Chair) on the formation of the Solar System, called “Nebulebula,” which subsequently became the title track of a <a href="https://mrchairmusic.com">Mr. Chair album.</a> </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/1Z3AiEoqueA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Approximately 300 students attend the class. Most are non-science majors taking the course to fulfil a graduation requirement. </p>
<p>As a science educator, I believe that every one of them is a scientist.</p>
<p>The feeling I had as I took in this scene is in stark contrast to how I felt just one year earlier as I faced a disappointing moment in my scientific career. </p>
<p>The distortion and misreporting of my <a href="https://www.nature.com/articles/nature21402">scientific research</a> by a conservative <a href="https://climatefeedback.org/evaluation/scientists-we-know-what-really-causes-climate-james-barrett-the-daily-wire">media site</a> led to a digital cascade of misinformation about the role that humans play in climate change. I was frustrated about this misrepresentation of my work, which was circulated and amplified through the internet. </p>
<p>My initial confusion about how to deal with this misuse of my research, ultimately gave way to <a href="https://news.wisc.edu/geoscience-beginnings">new creative ideas</a> for how to cultivate a scientifically receptive and engaged public. </p>
<p>I decided to go back to the foundations: the human dimension of science and what it is to be a scientist. One central question loomed large. How can we foster a world where decision-making is based on sound science, sound logic and reason and also empathy for our fellow travellers on this planet?</p>
<p>My new creative line of thinking culminated in an experimental collaboration between science education and communication called the “tadada Scientific Lab.” </p>
<h2>Connection events</h2>
<p>The objective of tadada is to inspire scientific literacy, nurture emotional connections to science and cultivate a scientific identity within each student. </p>
<p>With these objectives came a re-envisioning of the parameters that define a science classroom. I believe one way to inspire scientific literacy and cultivate a scientific identity is through experiences that emphasize a personal-emotional connection to science. I call these moments “connection events.”</p>
<p>While developing the idea, I joined forces with the Madison, Wis.-based photojournalist and social documentary photographer, Gigi Cohen. Cohen helped develop deeper artistic, psychological and emotional perspectives for the project. Cohen said: “Science can be a great unifier of people, it captures a truth about the vast history of life and humanity that connects us all.”</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mixing-science-and-art-to-make-the-truth-more-interesting-than-lies-100221">Mixing science and art to make the truth more interesting than lies</a>
</strong>
</em>
</p>
<hr>
<p>“Beginnings” was a connection event. Another successful event was “The Deep Groove: A Sonic Journey into the Earth’s Interior,” a performance in five acts that explores the science of seismology, earthquakes and how (sound) waves tell us about the Earth’s interior. It debuted in the Geoscience 100 classroom in April 2019, a hallmark of the second year of tadada.</p>
<p>The Deep Groove includes another commissioned musical piece by Mr. Chair called “Ground Underground.” The musical composition interprets a journey through the Earth. This connection event also showcases numerous film segments, such as an exploration of <a href="https://youtu.be/1Z3AiEoqueA">how echos reveal Earth’s interior</a>, and a seismic experiment with percussionist Mike Koszewski on a frozen Lake Mendota.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/290974/original/file-20190904-175663-qvp79s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290974/original/file-20190904-175663-qvp79s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=445&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290974/original/file-20190904-175663-qvp79s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=445&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290974/original/file-20190904-175663-qvp79s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=445&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290974/original/file-20190904-175663-qvp79s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=559&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290974/original/file-20190904-175663-qvp79s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=559&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290974/original/file-20190904-175663-qvp79s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=559&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Grace in Space’ is a comic book exam. Cover illustrated by Pan Jun Rader.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In a third connection event, “The Print of Time,” artist and master printer <a href="https://crownoverart.com/bruces-art">Bruce Crownover</a> joined me in teaching students how the creation of a reductive woodcut — one of the oldest forms of printmaking — relates to geologic processes. We explored how the masterpiece of Earth’s geological history is revealed through the accumulation of layers and the concept of <a href="https://en.wikipedia.org/wiki/Deep_time">deep time</a> and how geoscience inspires his art.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-ways-scientists-can-help-put-science-back-into-popular-culture-84955">New ways scientists can help put science back into popular culture</a>
</strong>
</em>
</p>
<hr>
<p>The tadada Scientific Lab also became a place to workshop a final exam for my intro to geoscience course. The result was, “Grace in Space: The Comic Book Exam.” “Grace in Space,” follows Gracie, a fictional Geoscience 100 student on a transformative journey to discover her connection to this planet, its vast history, its changing climate and her role in deciding the planet’s future. The comic book exam emphasizes the key course concepts and their interconnections.</p>
<h2>Bringing a science identity to the classroom</h2>
<p>Research in <a href="https://www.nap.edu/catalog/23674/communicating-science-effectively-a-research-agenda">science communication</a> suggests that scientific data and facts more effectively reach and influence people when they are presented in a way that speaks to their values. </p>
<p>In other words, it is not enough to simply provide scientific information with the hope of filling a deficit in knowledge.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/291179/original/file-20190905-175663-1jrn03e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291179/original/file-20190905-175663-1jrn03e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291179/original/file-20190905-175663-1jrn03e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291179/original/file-20190905-175663-1jrn03e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291179/original/file-20190905-175663-1jrn03e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291179/original/file-20190905-175663-1jrn03e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291179/original/file-20190905-175663-1jrn03e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Percussionist Mike Koszewski on Lake Mendota, filming for the tadada Scientific Lab production ‘The Deep Groove: A Sonic Journey into the Earth’s Interior.’ Photo by Gigi Cohen.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>Instead we need to ask questions. How can we speak to individuals’ values or cultivate an identity that is receptive to sound science? How can educators cultivate a scientific identity in students? </p>
<p>Rather than focusing exclusively on scientific literacy in our classrooms, let’s also consider how we can inspire scientific literacy that will continue to inform students in their lives outside of the classroom. Let’s facilitate their exploration and curiosity for the deep emotional connection — wonderment — that drives many scientists.</p>
<p>Climate change, clean water and social justice are just a few of the daunting challenges that face our world, our students, our families. They require us to think anew about how we can be effective educators that help both present and future generations thrive. </p>
<p>Solutions are within our reach, within our classrooms and within our communities. The tadada Scientific Lab is working to re-envision the science classroom, while also cultivating a new generation of scientific communicators and educators (musicians, artists, filmmakers, photographers, poets) that cross the traditional disciplinary boundaries.</p>
<p>Imagine if every person could see all the possibilities that exist for them, while understanding how interconnected our collective well-being is. How amazing it is that we get to share a bit of the 4.54 billion year history of this lovely planet we call home. This is a profound perspective that geoscience brings, and it is a powerful message to share.</p>
<p><em>Gigi Cohen, co-founder of tadada Scientific Lab, contributed to this article</em></p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/110956/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen R. Meyers and Gigi Cohen live with their son in Madison, Wisconsin.</span></em></p>A science researcher’s work gets twisted by a conservative news site; he considers this his wake-up call to educate as many students as possible about the importance of science to our world.Stephen R. Meyers, Professor of Geoscience, University of Wisconsin-MadisonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1167682019-05-13T15:07:50Z2019-05-13T15:07:50ZThe moon is still geologically active, study suggests<figure><img src="https://images.theconversation.com/files/273963/original/file-20190512-183096-u3nv9u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The International Space station transits the "Blue moon" in late June 2015.</span> <span class="attribution"><a class="source" href="http://apod.nasa.gov/apod/ap150731.html">Dylan O'Donnell</a></span></figcaption></figure><p>We tend to think of the moon as the archetypal “dead” world. Not only is there no life, almost all its volcanic activity <a href="http://volcano.oregonstate.edu/oldroot/volcanoes/planet_volcano/lunar/Overview.html">died out billions of years ago</a>. Even the youngest lunar lava is old enough to have become scarred by numerous impact craters that have been collected over the aeons as cosmic debris crashed into the ground.</p>
<p>Hints that the moon is not quite geologically dead though have been around since the Apollo era, 50 years ago. Apollo missions 12, 14, 15 and 16 <a href="https://moon.nasa.gov/resources/13/apollo-11-seismic-experiment/">left working “moonquake detectors”</a> (seismometers) on the lunar surface. These transmitted recorded data to Earth until 1977, showing vibrations caused by internal “moonquakes”. But no one was sure whether any of these were associated with actual moving faults breaking the surface of the moon or purely internal movements that could also cause tremors. Now a new study, <a href="https://www.nature.com/articles/s41561-019-0362-2">published in Nature Geoscience</a>, suggests the moon may indeed have active faults today.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273346/original/file-20190508-183112-vgh97g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The seismometer deployed on the moon by Apollo 14 (nearest of the three instruments).</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Another clue that something is still going on at the moon came in 1972 when Apollo 17 astronauts <a href="https://www.nasa.gov/astronautprofiles/cernan">Gene Cernan</a> and <a href="https://www.space.com/39009-apollo-17-astronaut-harrison-schmitt-interview.html">Jack Schmitt</a> inspected a step in the terrain, a few tens of metres high, that they called “the <a href="https://airandspace.si.edu/multimedia-gallery/web11563-2010hjpg">Lee-Lincoln scarp</a>”. They, and their team of advisers back on Earth thought it might be a geological fault (where one tract of crustal rock has moved relative to another), but they weren’t sure.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=606&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=606&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=606&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=762&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=762&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273376/original/file-20190508-183089-cyek8x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=762&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Lee-Lincoln scarp sweeping across the valley floor and making a turn as it cuts up the valley side on the right.</span>
<span class="attribution"><span class="source">NASA Apollo 17 image library (frame AS17-137-20897)</span></span>
</figcaption>
</figure>
<p>A handful of similar examples were noted in photographs taken from Apollo craft as they orbited near the moon’s equator, but it was not until 2010 that the <a href="https://www.lroc.asu.edu/">Lunar Reconniassance Orbiter Camera</a>, capable of recording details less than a metre across, revealed that such scarps can be found scattered across the whole globe. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=537&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=537&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=537&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=674&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=674&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273353/original/file-20190508-183093-nd32s5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=674&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 3.5km wide view of part of the moon disturbed by faults.</span>
</figcaption>
</figure>
<p>It is now widely agreed that these are thrust faults, caused as the moon cools down from <a href="https://theconversation.com/how-old-is-our-moon-71036">its hot birth</a>. As it does, “thermal contraction” causes its volume to shrink and compresses the surface. That means that <a href="https://www.nasa.gov/mission_pages/LRO/news/shrinking-moon.html">the moon is shrinking slightly</a>. However, thrust faults don’t necessarily have to be active and moving, causing more further tremors. The same thing has been happening on Mercury on a far grander scale, where the planetary radius has shrunk by 7km during the past 3m years. There, the biggest scarps are nearly a hundred times larger than those on the moon.</p>
<h2>Active faults</h2>
<p>Analysis shows that these faults are relatively young, not older than about 50m years. But are they active and still moving today? In the new study, <a href="https://airandspace.si.edu/people/staff/thomas-watters">Tom Watters of the Smithsonian Institution</a> in the US and colleagues employed a new way to pinpoint the locations of the near-surface moonquakes in the Apollo data more precisely than was previously possible. </p>
<p>The team discovered that of the 28 detected shallow quakes, eight are close to (within 30km of) fault scarps, suggesting these faults may indeed be active. Six of them happened when the moon was almost at the greatest distance from Earth in its orbit. At this point, the contraction stress across the surface would be expected to peak, and quakes most likely to be triggered.</p>
<p>The team also investigated fresh looking tracks left by boulders that have been dislodged. This was presumably a result of the ground shaking, because they are also seen close to fault scarps – and have rolled or bounced down a slope. There are also traces of landslide deposits. This, they say, all adds up to a strong case that fault movements are still occurring on the moon.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=502&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=502&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=502&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=631&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=631&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273349/original/file-20190508-183106-110pbgj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=631&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The tracks of two boulders that rolled downhill towards the Apollo 17 landing site. Each boulder is at the southern end of its track, where it casts a shadow to its left.</span>
<span class="attribution"><span class="source">NASA/GSFC/Arizona State University</span></span>
</figcaption>
</figure>
<p>So does this mean that the moon is unsafe for human exploration? The US recently <a href="https://theconversation.com/us-wants-a-crewed-mission-to-the-moon-in-five-years-but-can-and-should-that-be-done-114951">announced plans to go there</a> in the next five years, with the aim to set up a lunar base. Luckily, none of the new findings mean that the moon is a hotbed of ground tremors. Moonquakes are rarer and weaker than on Earth, but there are definitely a few places close to the faults where it might be best to avoid when it comes to planning moon bases.</p><img src="https://counter.theconversation.com/content/116768/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Rothery is co-leader of the European Space Agency's Mercury Surface and Composition Working Group, and a Co-Investigator on MIXS (Mercury Imaging X-ray Spectrometer) that is now on its way to Mercury on board the European Space Agency's Mercury orbiter BepiColombo. He has received funding from the UK Space Agency and the Science & Technology Facilities Council for work related to Mercury BepiColombo, and is currently funded by the European Commission under its Horizon 2020 programme for work on planetary geological mapping (776276 Planmap). He is author of Planet Mercury - from Pale Pink Dot to Dynamic World (Springer, 2015), Moons: A Very Short Introduction (Oxford University Press, 2015) and Planets: A Very Short Introduction (Oxford University Press, 2010). He is Educator on the Open University's free learning Badged Open Course (BOC) on Moons and its equivalent FutureLearn Moons MOOC, and chair of the Open University's level 2 course on Planetary Science and the Search for Life.</span></em></p>New analysis of data from the Apollo era shows that moonquakes occur close to visible faults, which may matter when setting up a moon base.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1145532019-05-06T10:36:49Z2019-05-06T10:36:49Z60 days in Iceberg Alley, drilling for marine sediment to decipher Earth’s climate 3 million years ago<figure><img src="https://images.theconversation.com/files/272054/original/file-20190501-113852-15dg0x7.JPG?ixlib=rb-1.1.0&rect=614%2C0%2C4226%2C2948&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The research vessel must dodge dangerous icebergs as it drills for sediment core samples.</span> <span class="attribution"><span class="source">Phil Christie/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Competition is stiff for one of the 30 scientist berths on the <a href="https://joidesresolution.org/">JOIDES Resolution</a> research vessel. I’m one of the lucky ones, granted the opportunity to work 12-hour days, seven days a week for 60 days as part of <a href="https://joidesresolution.org/expedition/382/">Expedition 382 “Iceberg Alley”</a> in the Scotia Sea, just north of the Antarctic Peninsula.</p>
<p><a href="https://scholar.google.com/citations?user=ruUF3z4AAAAJ&hl=en&oi=ao">I’m a geologist who specializes in paleoceanography</a>. My research focuses on how Earth’s oceans and climate operated in the past; I’m especially interested in how much and how fast the Antarctic ice sheets melted between 2.5 to 4 million years ago, the last time atmospheric carbon dioxide levels were about 400 parts per million, as they are today. This work depends on collecting sediment samples from the ocean floor that were deposited during that time. These sediment layers are like a library of the Antarctic’s past environment.</p>
<p>The JOIDES Resolution is the only ship in the world with the drilling tools to collect both soft sediment and hard rock from the ocean – material that we recover in long cylinders called cores. No wonder researchers from all over the world, at all career stages, are excited to have traveled from India, Japan, Korea, the Netherlands, Germany, Spain, Switzerland, Brazil, China, Germany, Australia, the United Kingdom and, of course, the United States to join the expedition.</p>
<h2>Fieldwork 1,000 miles (1600 km) from port</h2>
<p>Two months is actually a short amount of time in which to address scientific research questions, but there have been years of careful planning and detailed preparation in advance of this expedition. We scientists onboard make best use of our limited time by drilling at what we’ve already agreed should be the most informative locations.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/4wJOt4fEVnU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">An animation explains the drilling process.</span></figcaption>
</figure>
<p>When the ship arrives at the designated GPS location, the captain, the lab officer and the drilling engineer all check the position coordinates several times. With the ship’s thrusters keeping it precisely in place, workers lower coring equipment, including drill pipe, through an opening in the center of the ship. When the drill pipe reaches the coring depth – in our case ranging from 2,600 feet (800 meters) to 12,500 ft (3,800 m) – we lower a coring tool on a wireline down through the pipe.</p>
<p>Most of our cores are taken with an advanced hydraulic piston corer. In a process similar to using an elaborate cookie cutter, it punches through the ocean floor and collects a thin cylinder of the rock and sediment: our core sample. The wireline brings the 31-ft-long (9.5 m) core back to the ship. In the ship’s lab, we split the core lengthwise into an archive half – to be photographed and described – and a working half. This is the one we sample onboard for density, chemistry and magnetic properties.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272319/original/file-20190502-103057-irmf68.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Co-chief scientist Michael Weber and sedimentologists (core describers) Suzanne O'Connell and Thomas Ronge examine the archive half of a split core at the describing table.</span>
<span class="attribution"><span class="source">Stefanie Brachfeld/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Today the Greenland and Antarctic <a href="https://nsidc.org/cryosphere/quickfacts/icesheets.html">ice sheets contain 99% of Earth’s fresh water</a>. If all the Antarctic ice were to melt, average sea level would rise 200 feet (60 m). This won’t happen in your lifetime. But knowing how fast an event like this can occur – based on how fast ice has melted in the past – is critical to preparing for the sea level rise already accompanying Earth’s currently warming temperatures. Helping to understand that past change is one of the goals of our work on this expedition.</p>
<p>Establishing when it was that melting glaciers originally deposited the sediments we’re collecting is crucial and difficult. Only by dating this process can we figure out how fast the ice sheets disintegrated. There are two complementary approaches that researchers have traditionally used.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272581/original/file-20190503-103068-ch7ai.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A microscopic fossil of diatom <em>Actinocyclus actinochilus</em>.</span>
<span class="attribution"><span class="source">Jonathan Warnock/Indiana University of Pennsylvania</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1016/j.gloplacha.2012.05.017">Paleontologists look at tiny microfossils</a> from organisms such as <a href="https://doi.org/10.1038/nature08057">diatoms</a>, <a href="https://www.radiolaria.org/">radiolaria</a> and <a href="https://www.marum.de/Karin-Zonneveld/dinocystkey.html">dinocysts</a> that are found in the sediment cores. Then they can match up the species they spot in the samples with the timeframes they were known to exist. For instance, a paleontologist might know from previous research that a particular species of diatom lived between 1.8 and 2.6 million years ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272318/original/file-20190502-103057-knhn72.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sediment samples, called cubes, taken for future paleomagnetic research and marked styrofoam plugs identify where samples were taken for ‘moisture and density’ (MAD) measurements.</span>
<span class="attribution"><span class="source">Stefanie Brachfeld/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>A second method of dating depends on paleomagnetists measuring the strength and direction of the sediments’ magnetism. Over Earth’s history, the magnetic field has reversed, with magnetic north flipping to point south, at irregular intervals. Scientists <a href="https://wikipedia.org/wiki/Paleomagnetism">know when the reversals occurred</a>. In the period from 1.8 to 2.6 million years ago, for example, the magnetic field flipped four times.</p>
<p><a href="https://doi.org/10.1029/2012PA002308">The paleomagnetists look for reversals</a> in the alignment of magnetic minerals in the sediment we collect, and if they find them, they <a href="https://www.researchgate.net/profile/Ted_Moore/publication/272713726_Time_is_of_the_Essence/links/569cd6ae08ae2f0bdb8beab4/Time-is-of-the-Essence.pdf">can better identify when</a>, within that 1.8 to 2.6-million-year time interval, the sediment was deposited. If reversals are not present, it might mean the sediment accumulated so fast that only one magnetic interval is represented, or that part of the sediment record is missing. To determine which possibility is more likely, they talk to the people describing the visual properties of the core to see if there are abrupt changes that might indicate a disruption in the sedimentary record.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272594/original/file-20190504-103068-i1law1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Suzanne O'Connell points out details of the core on the description table.</span>
<span class="attribution"><span class="source">Lee Stephens/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This sort of observation and consultation proceeds continuously as the cores come up and scientists work their shifts. For me, the joy of this at-sea experience is collaborating with other scientists on the same problem at the same time. If each of us was working in isolation in our own lab, collecting this much data would take years.</p>
<h2>Shipboard life</h2>
<p>Working alongside the scientists are 30 technicians who know how to operate the lab equipment, curate the hundreds of cores and keep all the computers running, and two outreach educators. All of this work is made possible by 65 people including a drilling crew, who operate the heavy equipment that collects the cores; the marine crew, who drive and maintain the ship; and the stewards who prepare the food, do the laundry and clean the ship.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272316/original/file-20190502-103082-1pijf22.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Loading food onto the JOIDES Resolution in Punta Arenas, Chile, to keep everyone fed during the two month expedition.</span>
<span class="attribution"><span class="source">Suzanne O'Connell/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To feed 120 people for two months, 17 pallets of food are onloaded at each port call; each grocery order includes 12,000 eggs, a ton (976 kilograms) of potatoes and 800 lbs (360 kg) of butter. There’s a full-time baker, and the cooks prepare four full meals a day and provide snacks for four coffee breaks. A small gym is available to help to offset the abundant food. On some expeditions, people run on the helipad on the ship’s stern.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272322/original/file-20190502-103045-1bhy1nm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Humpback whales are visible right alongside the JOIDES Resolution.</span>
<span class="attribution"><span class="source">Bridget Lee/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>It’s too cold and the seas are too rough for that on this expedition. Instead, we have the thrilling opportunity to see icebergs, whales and penguins. Few places in the ocean offer such a view – but plenty of danger comes with it.</p>
<p>With drill pipe extending 10,500 ft (3,200 m) – about two miles – to the sea floor and as much as a further 2,000 feet (600 m) into the hole, we would not be able to move quickly out of the way of an approaching iceberg. It can take two hours to remove the pipe from the hole. Since the ship is attached to the drill pipe, if an iceberg were fast approaching, there might not be enough time to retrieve the drill pipe – we’d have to break the connection with explosives. Hence, there’s a strict protocol for dealing with icebergs and an experienced ice observer onboard who helps monitor the speed and direction of the nearby icebergs.</p>
<h2>A drilling program that’s grown over decades</h2>
<p>Shipboard life has changed since <a href="https://theconversation.com/scientists-have-been-drilling-into-the-ocean-floor-for-50-years-heres-what-theyve-found-so-far-100309">my first participation in the scientific ocean drilling program</a> almost 40 years ago. Back then, onboard the program’s first drill ship, the Glomar Challenger, the internet and email were not an option. To contact a person on land, an amateur radio operator on the ship would contact a shore-based shortwave radio operator who would then place a collect call to the person you wanted to speak with. If the call was accepted, you could converse, ending each part of your message with “Over” to let the recipient know it was their turn to speak. Since the entire ship could hear the conversation, as well as anyone in the world listening on the radio, it wasn’t conducive to personal communication.</p>
<p>There are many other changes onboard. Core sections are now scanned by multiple machines that improve the interpretation of the data, and new tools allow better core recovery.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=597&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=597&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272328/original/file-20190502-103082-1y11wat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=597&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Co-chief scientists Michael Weber and Maureen Raymo in the JOIDES Resolution engine room.</span>
<span class="attribution"><span class="source">Sarah Kachovich/IODP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The most remarkable change, however, is in the composition of the scientific party. Today, half the scientists who go out are women, including the co-chief scientists – the people ultimately responsible for planning the expedition and for it reaching its scientific goals. During the entire Glomar Challenger program, from 1968 to 1983, only three of the 192 co-chief scientists were women.</p>
<p>Soon the expedition will be over, but the research will have only begun. After we’ve returned to our normal lives on land, we’ll continue to collaborate. I’ll be analyzing the size and composition of different parts of the sediment that came from land. Which parts were brought by icebergs, where did they originate, and when were they most active? How much of the sediment was transported by deep ocean currents or even by wind? Colleagues will be addressing the same questions but in the younger sediment, or determining the environmental conditions in which the microfossil communities thrived.</p>
<p>In two years, we’ll reconvene and spend several days presenting the results of our individual research. Each is a part of the larger puzzle about past climates and the rates and causes of climate change before the process was accelerated by human activity.</p><img src="https://counter.theconversation.com/content/114553/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Suzanne O'Connell receives funding from the U.S. Science Support Program, IODP, for participation in this expedition. She and her students have received funding to conduct research on prior scientific ocean drilling sediment samples, primarily from the Keck Geology Consortium, which is funded by the members schools (including Wesleyan University) and the National Science Foundation. She serves on the U.S. Advisory Committee for Scientific Ocean Drilling (USAC).</span></em></p>A paleooceanographer describes her ninth sea expedition, this time retrieving cylindrical ‘cores’ of the sediment and rock that’s as much as two miles down at the ocean floor.Suzanne OConnell, Professor of Earth & Environmental Sciences, Wesleyan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1095002019-01-21T18:41:43Z2019-01-21T18:41:43ZVideo games could teach spatial skills lost to a society dependent on devices<figure><img src="https://images.theconversation.com/files/254653/original/file-20190121-100282-p9hany.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Players of Red Dead Redemption 2 use a detailed topographic map to navigate the landscape.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/727794478?size=huge_jpg">Shutterstock</a></span></figcaption></figure><p>Video games have long been criticised for encouraging <a href="https://www.ncbi.nlm.nih.gov/pubmed/20192553">violence</a> and <a href="https://www.pnas.org/content/115/40/9882">antisocial behaviour</a>. And parents often express concern that they could have <a href="https://theconversation.com/curious-kids-why-do-adults-think-video-games-are-bad-76699">detrimental effects</a> on their child’s learning abilities. </p>
<p>But <a href="https://www.annualreviews.org/doi/10.1146/annurev-psych-010418-102744">research has shown</a> that off-the-shelf video games can also aid learning – particularly when it comes to the development of spatial skills.</p>
<p>These issues have arisen once more with the most recent release from <a href="https://www.rockstargames.com/">Rockstar Games</a>: Red Dead Redemption 2 (RDR2). The game certainly contains a lot of violence, but it might inadvertently aid development of spatial skills – perhaps even more so than other video games.</p>
<h2>What are spatial skills and why do we need them?</h2>
<p>Spatial skills <a href="https://pubs.geoscienceworld.org/gsa/geosphere/article/14/2/668/527298/spatial-skills-in-undergraduate-students-influence">refer to our ability</a> to rotate and conceptualise 3D objects, and to decipher maps, graphs and diagrams. These are essential skills within the science, technology, engineering and mathematics (STEM) sector. </p>
<p>One spatial skill that is common to several engineering and science disciplines is the ability to <a href="https://youtu.be/hoa1RBk4dTo">visualise a 2D cross-section through a 3D object</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/hoa1RBk4dTo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The development of spatial skills is particularly relevant to the field of geoscience. We use these skills every day when we graph and interpret results of various measurements and experiments, and when we create traditional 2D maps. </p>
<p>These skills are also incredibly important when it comes to extrapolating the 3D geometry of rock layers beneath the Earth’s surface. Take for example the <a href="https://www.bgs.ac.uk/discoveringGeology/geologyOfBritain/minecraft/images/Ingleborough_Geology_and_Topo.jpg">below</a> 3D geological model, which was created using Minecraft. This image shows the layers of rock beneath the ground and how these interact with the surface of the landscape.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/253779/original/file-20190114-43541-ep8y0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253779/original/file-20190114-43541-ep8y0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=529&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253779/original/file-20190114-43541-ep8y0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=529&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253779/original/file-20190114-43541-ep8y0c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=529&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253779/original/file-20190114-43541-ep8y0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=665&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253779/original/file-20190114-43541-ep8y0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=665&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253779/original/file-20190114-43541-ep8y0c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=665&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The British Geological Survey created 3D maps of parts of Britain using the game Minecraft. This example shows how the landscape surface (topography) interacts with layers of rock (light green and purple) beneath the surface.</span>
<span class="attribution"><span class="source">British Geological Survey</span></span>
</figcaption>
</figure>
<p>My experience teaching undergraduate geology and field-based mapping classes in the UK and Australia has shown me that students really struggle with the higher-level spatial skills. This is not a new problem, but it is perhaps more challenging for today’s students who have grown up navigating using Google Maps rather than a street directory. </p>
<p>Research <a href="https://www.tandfonline.com/doi/abs/10.1080/00330124.2018.1479970">has shown</a> that our dependence on satellite navigational systems, such as those in our smartphones, is having a long term detrimental impact on spatial awareness and our ability to navigate. So, we need to consider other means to help students develop these skills. </p>
<h2>How does RDR2 teach spatial skills?</h2>
<p>In RDR2, you play the character of an outlaw in a fictional part of the Western United States in 1899. During the game, the outlaw protagonist struggles to find his place in a society that is increasingly introducing more law and order. The protagonist embarks on numerous missions, which guide the player through a linear story line.</p>
<p>The game also allows and encourages players to freely explore and interact with a virtual <a href="https://en.wikipedia.org/wiki/Open_world">open world</a> before, after or between the story line missions. </p>
<p>The virtual world in RDR2 is <a href="https://theconversation.com/red-dead-redemption-2-can-a-video-game-be-too-realistic-106404">incredibly detailed</a> because it is derived from 3D laser scans and drone imagery of <a href="https://www.wired.co.uk/article/quixel-scanning-red-dead-redemption-2">real-world landscapes</a>. </p>
<p>This complex landscape requires players to navigate using a detailed topographic map. A topographic map is a map with contour lines that show places of equal height. Closely spaced lines indicate a steep slope, and widely spaced lines indicate a gradual slope. </p>
<p>Players constantly use this map to visualise the terrain as they move around, allowing them to navigate and avoid obstacles – like falling off a cliff.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/253777/original/file-20190114-43510-18a8p4y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253777/original/file-20190114-43510-18a8p4y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253777/original/file-20190114-43510-18a8p4y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253777/original/file-20190114-43510-18a8p4y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253777/original/file-20190114-43510-18a8p4y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253777/original/file-20190114-43510-18a8p4y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253777/original/file-20190114-43510-18a8p4y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The virtual world of Red Dead Redemption 2 is incredibly realistic as it was built using landscapes found in the real-world.</span>
<span class="attribution"><span class="source">Screenshot/Lloyd White</span></span>
</figcaption>
</figure>
<p>Moving from place to place in the game can take considerable time because the player typically travels to most places on horseback, or on foot. But players can save time by deviating from roads using the topographic map to plot out a faster route. </p>
<p>This saves time getting from A to B, so players are rewarded for learning to read the map. </p>
<p>Players are also encouraged to look for treasure and seek out unique hunting and fishing locations. Players need to use a series of clues and interpret mud maps to find these special locations. These experiences likely simulate the same thought patterns we use examining and interpreting maps of the real world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=759&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=759&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=759&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=954&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=954&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253775/original/file-20190114-43532-9al6ne.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=954&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An example of the topographic map used in Red Dead Redemption 2. Players need to use this map to navigate. While the game will suggest a path between two points, this often isn’t the fastest route, or may not even be a possible route. Players can figure this out for themselves by reading the map.</span>
<span class="attribution"><span class="source">Rockstar Games/Lloyd White</span></span>
</figcaption>
</figure>
<h2>Exercising our map reading muscles</h2>
<p>While RDR2 is certainly a violent game (rated M15+), I hope parents and players might both appreciate the potential learning benefit relative to other games. </p>
<p>It’s safe to say we should expect future video games to match or better the level of detail within RDR2. This level of realism combined with detailed maps will hopefully help to develop those spatial skills we’re losing by our dependence on location-based technology. </p>
<p>Another potential positive is that the entertainment industry will need to recruit future STEM graduates to help them build factual and increasingly realistic virtual worlds.</p><img src="https://counter.theconversation.com/content/109500/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lloyd White is affiliated with the University of Wollongong. He has received funding from the Australian Research Council, Australian and New Zealand International Ocean Discovery Program (ANZIC) consortium as well as from minerals and oil and gas companies. He is also an Honorary Research Fellow at Royal Holloway University of London.</span></em></p>Red Dead Redemption 2 has been criticised for its portrayals of violence, but it could also be teaching players the lost art of reading a map.Lloyd White, Lecturer (Geology), University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/967182018-09-16T20:16:27Z2018-09-16T20:16:27ZAn artist’s surreal view of Australia – created from satellite data captured 700km above Earth<figure><img src="https://images.theconversation.com/files/233665/original/file-20180827-75981-h6vbep.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Infrared and visible light satellite data is recoloured to produce striking images of Australia. </span> <span class="attribution"><span class="source">Grayson Cooke </span>, <span class="license">Author provided</span></span></figcaption></figure><p>There are more than <a href="https://www.pixalytics.com/sats-orbiting-the-earth-2018/">4,800 satellites</a> orbiting Earth. They bristle with sensors – trained towards Earth and into space – recording and transmitting many different wavelengths of electromagnetic radiation. </p>
<p>Governments and media corporations rely on the data these satellites collect. But artists use it too, as a new way to image and view the Earth. </p>
<p>I work with <a href="http://www.ga.gov.au/home">Geoscience Australia</a> and the “<a href="http://www.ga.gov.au/about/projects/geographic/digital-earth-australia">Digital Earth Australia</a>” platform to produce time-lapse images and video of Australian landforms using satellite data. </p>
<p>My Open Air project, produced through a collaboration with Australian painter <a href="https://www.emmawalker.com.au/">Emma Walker</a> and the music of <a href="http://www.thenecks.com/">The Necks</a>, features macro-photography of Emma Walker’s paintings set against time-lapse satellite imagery of Australia. </p>
<p>Open Air will be <a href="https://www.nfsa.gov.au/events/open-air">launched</a> in Canberra on September 20, 2018. </p>
<figure>
<iframe src="https://player.vimeo.com/video/235270150" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Trailer: Open Air – showing Lake Gairdner in South Australia with turquoise desert, red salt lakes and pink clouds (Grayson Cooke 2017).</span></figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-satellites-get-back-to-earth-82447">Curious Kids: How do satellites get back to Earth?</a>
</strong>
</em>
</p>
<hr>
<h2>Open access to satellite data</h2>
<p>We see satellites as moving pin-pricks in the night sky, or occasionally – as with the recent return to Earth of the Chinese <a href="https://theconversation.com/chinas-falling-space-station-highlights-the-problem-of-space-junk-crashing-to-earth-93295">Tiangong space station</a> – as streaks of light. And most us would have heard about satellite data being used for surveillance, for GPS tracking and for media broadcasting. </p>
<p>But artists can divert satellite data away from a purely instrumental approach. They can apply it to produce new ways of seeing, understanding and <em>feeling</em> the Earth. </p>
<p>Of course satellites are expensive to launch and maintain. The main players are either powerful corporate providers like <a href="http://www.intelsat.com/">Intelsat</a>, enormous public sector agencies like <a href="https://www.nasa.gov/">NASA</a> and the European Space Agency (<a href="https://www.esa.int/ESA'">ESA</a>), or <a href="https://www.planet.com/">private sector startups</a> with links to these groups.</p>
<p>Luckily, many of these agencies make their data freely available to the public. </p>
<p>The NASA/US Geological Survey <a href="https://landsat.usgs.gov/">Landsat program</a> makes 40 years of Earth imaging data available through <a href="https://earthexplorer.usgs.gov/">Earth Explorer</a>. The ESA provides data from their Sentinel satellites to users of the <a href="https://scihub.copernicus.eu/dhus/#/home">Copernicus Open Access Hub</a>. </p>
<p>In Australia, Geoscience Australia‘s <a href="http://www.ga.gov.au/dea">Digital Earth Australia</a> platform provides researchers and the public with access to Australian satellite data from a range of agencies.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=477&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=477&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=477&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235516/original/file-20180910-18990-1haj8z9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Landsat 8 image acquired in Australia in May 2013 over Cambridge Gulf and the Ord River estuary in Western Australia. Visible light bands highlight the different types of water within the estuary. Shortwave and near infrared bands highlight the mangroves and vegetation on the land.</span>
<span class="attribution"><span class="source">Geoscience Australia</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Understanding and processing the data</h2>
<p>Making satellite imaging data accessible, though, is not the same thing as making it usable. There is considerable technical know-how required to process satellite data.</p>
<p>The Landsat and Sentinel satellites are used by scientists and the private sector to monitor environmental change over time, using what is known as “remote sensing”. They travel in the <a href="https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-orbit-58.html">low Earth orbit</a> range, around <a href="https://landsat.usgs.gov/landsat-8-mission">700km above the Earth</a> and circle the Earth in around 90 minutes. After numerous orbits, they return to the exact same spot every 16 days. </p>
<p>Landsat and Sentinel satellites are equipped with sensors that record reflected electromagnetic radiation in a <a href="https://landsat.gsfc.nasa.gov/landsat-8/landsat-8-overview/">range of wavelengths</a>. Some of these wavelengths fall within the visible light part of the spectrum (between 390-700 nanometers). In that sense, satellites image the Earth in a way comparable to a digital camera. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=416&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=416&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=416&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=523&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=523&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235484/original/file-20180909-18990-s2j4vc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=523&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This image shows the percentage of time since 1987 that water was observed by the Landsat satellites on the floodplain around Burketown and Normanton in northern Queensland. The water frequency is shown in a colour scale from red to blue, with areas of persistent water observations shown in blue colouring, and areas of very infrequent water observation shown in red colouring.</span>
<span class="attribution"><span class="source">Geoscience Australia</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-sports-car-and-a-glitter-ball-are-now-in-space-what-does-that-say-about-us-as-humans-91156">A sports car and a glitter ball are now in space – what does that say about us as humans?</a>
</strong>
</em>
</p>
<hr>
<p>But the satellites also record other wavelengths, particularly in the near and shortwave infrared range. Vegetation, water and geological formations reflect and absorb infrared light differently to visible light. Recording these wavelengths allows scientists to track, for instance, changes in vegetation density or <a href="http://www.ga.gov.au/scientific-topics/hazards/flood/wofs">surface water location</a> that indicate drought, flood or fire.</p>
<p>A single satellite image is made up of numerous bands recording data in very specific wavelengths. Getting a full-colour image requires processing in a <a href="https://qgis.org/en/site/">GIS application</a> to combine them, and assign the bands to either red, green or blue in an output image. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219154/original/file-20180516-155616-zlm9yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Images collected over 12 months at the Gulf of Carpentaria - 2016.</span>
<span class="attribution"><span class="source">Grayson Cooke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Bringing creativity to the data</h2>
<p>This is where creativity can enter the picture. Being able to create false colour images that combine infrared and visible light in different ways allows me to produce beautifully surreal images of Australian landforms. </p>
<p>The image below shows the variance in environmental conditions over 12 months in 2016 at the Stirling Range National Park in WA.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219547/original/file-20180518-140786-no7x6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A false colour image of Stirling Range National Park created by combining data relating to infrared and visible light.</span>
<span class="attribution"><span class="source">Grayson Cooke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Because geoscientists need clear images of the earth’s surface to analyse, they filter clouds from the data. I chose to take the opposite approach, highlighting the incredible array of meteorological conditions experienced by the country. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=200&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=200&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=200&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=252&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=252&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235485/original/file-20180909-90568-18jcb89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=252&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Clouds passing over the Eyre Peninsula in 2016.</span>
<span class="attribution"><span class="source">Grayson Cooke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>There are many other artists working with satellite data. Clement Valla’s <a href="http://www.postcards-from-google-earth.com/">Postcards from Google Earth</a> focuses on glitches in Google’s mapping algorithm, and bio-artist <a href="http://suzanneanker.com/artwork/?wppa-album=21&wppa-cover=0&wppa-occur=1">Suzanne Anker</a> uses satellite imaging to produce extruded 3D environments in petri dishes. </p>
<p>Working with the Nevada Museum of Art, photographer Trevor Paglen will launch the <a href="http://www.orbitalreflector.com/">Orbital Reflector</a> satellite as an inflatable, visible sculpture, a prompt for wonder and reflection.</p>
<p>Artists place satellite data and usage in new contexts. They question surveillance practices and expose scientific tools and representations to new audiences outside science and the private sector. </p>
<p>The thousands of satellites winging their way around the Earth represent power and possibility, a chance to look again at the intersection between humankind and a changing planet. </p>
<hr>
<p><em>“Open Air” will be officially launched at the <a href="https://www.nfsa.gov.au/events/open-air">National Film and Sound Archive</a> in Canberra on September 20. It will also screen at the <a href="https://spectra.org.au/">Spectra</a> conference in Adelaide in October.</em></p><img src="https://counter.theconversation.com/content/96718/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grayson Cooke's creative work has been undertaken with the assistance of resources from Geoscience Australia and the National Computational Infrastructure (NCI), which is supported by the Australian Government.</span></em></p>The Open Air project features satellite data interpreted and coloured to produce beautiful, surreal images of Australian landforms.Grayson Cooke, Associate Professor, Deputy Head of School (Research), Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.