tag:theconversation.com,2011:/ca/topics/geology-153/articlesGeology – The Conversation2024-03-27T17:06:06Ztag:theconversation.com,2011:article/2265542024-03-27T17:06:06Z2024-03-27T17:06:06ZThe Anthropocene already exists in our heads, even if it’s now officially not a geological epoch<p>An international subcommittee of geologists recently voted to reject a proposal to make the Anthropocene an official new geological epoch, defined by humanity’s enormous impact on the planet. Assuming some protests do not <a href="https://www.nature.com/articles/d41586-024-00868-1">overturn the ruling</a>, it will now take another decade for the decision to be reviewed.</p>
<p>That may seem a long time given climate change concerns, but it is of course far less than a blink in planetary terms. The Earth can certainly wait, even if we can’t.</p>
<p>But sometimes big ideas like the Anthropocene take time to find meaning in our lives and perhaps their answer. How do I know? Let me tell you a story.</p>
<p>Nine years ago, I was in Munich visiting friends. We went on a family outing to the Deutsche Museum, a world class celebration of technology and engineering in a vast building on an islet of the River Isar. The entrance was framed on either side by very tall vertical banners, fluttering in the breeze. </p>
<p>Each blue-green banner had an image of the Earth with a thumbprint overlay. And in bold white lettering, variously: “Welcome to the Anthropocene / Willkommen in Anthropozän”. The subtitle read: “The Earth in Our Hands”.</p>
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<a href="https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Banner saying 'Welcome to the Anthropocene'" src="https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584218/original/file-20240325-10418-iqzb07.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>
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<span class="caption">Willkommen.</span>
<span class="attribution"><span class="source">Kevin Collins</span></span>
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<p>I had to forgo the exhibition because my family wanted to see just about everything else. But even as I stood on the steps at the entrance, with my young son clutching my hand, it struck me as a curious title. </p>
<p>Why would anyone welcome anyone to the Anthropocene? Who would really want to go to that party? The invitation was, well, distinctly uninviting.</p>
<h2>Why ‘welcome’?</h2>
<p>I have thought about this troubling invitation on and off in the intervening years. Was “welcome” being ironic or even cynical perhaps – an invitation of despair and inevitability? But that contradicted the ethos of the museum and the academic Rachel Carson Centre which co-hosted the exhibition, where insight, learning and practical science are celebrated. So my question has remained: why “welcome”?</p>
<p>I finally realised an answer during a recent conversation with my PhD student <a href="https://www.researchgate.net/profile/Houda-Khayame">Houda Khayame</a> who is building on work between myself and colleague Ray Ison to explore how systems thinking and acting in the Anthropocene might improve <a href="https://www.open.ac.uk/blogs/govan/?page_id=23">governance of our environment</a>. We were talking about how geologists have been searching for a “golden spike” in the mud or soil or Earth’s geological record as <a href="https://theconversation.com/dawn-of-the-anthropocene-five-ways-we-know-humans-have-triggered-a-new-geological-epoch-52867">evidence of the Anthropocene</a> ever since the term was popularised in 2000. </p>
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Read more:
<a href="https://theconversation.com/dawn-of-the-anthropocene-five-ways-we-know-humans-have-triggered-a-new-geological-epoch-52867">Dawn of the Anthropocene: five ways we know humans have triggered a new geological epoch</a>
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<p>I found myself advising that the only thing that really matters about the Anthropocene is that it reframes ourselves as a part of the human-earth dynamic. The evidence for the Anthropocene is not in the soil or mud. The golden spike is to be found in our heads. It is in the way we think about our human relationship to the Earth. </p>
<p>As soon as I had said it, I realised I had found the answer to the invitation that had been patiently waiting for a reply many years before in Munich. The invitation was to welcome the Anthropocene in a positive sense because until we do, we will not be in a position to alter our thinking to address the global agendas we face as we change the planet. </p>
<p>To welcome the Anthropocene as an idea is to reframe our relationship with the planet and move away from being recipients to active creators of the world we live in. </p>
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<a href="https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=325&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=325&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=325&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584784/original/file-20240327-24-uj15i7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=408&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Humans are ‘active creators of the world we live in’.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/monochrome-interchange-overpasses-mopac-expressway-highway-683338168">Roschetzky Photography / shutterstock</a></span>
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<p>In moving away from geology I would also shift terminology from “golden spike” to “golden thread” since this is both a more pleasing image if we are talking about heads and ideas and is also less dependent on the measurement and graphics of science. Importantly, a thread connects the different parts of our lives and can be extended to connect with others. </p>
<h2>The Anthropocene doesn’t depend on geology</h2>
<p>The geologists’ rejection of the Anthropocene is understandable in their need for scientific evidence. It may seem to be a <a href="https://theconversation.com/what-the-anthropocenes-critics-overlook-and-why-it-really-should-be-a-new-geological-epoch-225493">missed opportunity</a>, but it does not really matter because how we live in and experience the world does not depend on a signal in the geology. </p>
<p>Indeed, even in their official rejection, the International Union of Geological Scientists noted the Anthropocene as a concept is <a href="https://www.iugs.org/_files/ugd/f1fc07_40d1a7ed58de458c9f8f24de5e739663.pdf?index=true">part of popular culture</a>, as evidenced by the museum exhibition but also various <a href="https://www.tate.org.uk/whats-on/tate-modern/anthropocene-project">artworks</a> and <a href="https://www.theguardian.com/books/2016/apr/01/generation-anthropocene-altered-planet-for-ever">books</a>.</p>
<p>The extent to which the Anthropocene really exists depends on our recognition and acceptance of the golden thread that we are all in an active back and forth relationship with the Earth. A socio-ecological relationship that has and will continue to shape our human-environment past, present and future.</p>
<p>Although I regretted missing the exhibition, I realise now that I did not need to see it. The banner at the entrance was enough to spark the inquiry. Accepting its welcome offers us the potential to make huge, golden strides in how we think about ourselves and our environment, and how we might live more sustainably.</p>
<p>Welcome, at last, to the Anthropocene.</p><img src="https://counter.theconversation.com/content/226554/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Collins 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>The idea cannot be stopped, even if geologists have voted not to recognise a new epoch.Kevin Collins, Senior Lecturer, Environment & Systems, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2254542024-03-12T19:14:54Z2024-03-12T19:14:54ZNew evidence for an unexpected player in Earth’s multimillion-year climate cycles: the planet Mars<figure><img src="https://images.theconversation.com/files/580914/original/file-20240311-30-ef6q0e.JPG?ixlib=rb-1.1.0&rect=0%2C8%2C6000%2C3979&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Dietmar Muller</span></span></figcaption></figure><p>Our existence is governed by natural cycles, from the daily rhythms of sleeping and eating, to longer patterns such as the turn of the seasons and the quadrennial round of <a href="https://theconversation.com/leap-of-imagination-how-february-29-reminds-us-of-our-mysterious-relationship-with-time-and-space-224503">leap years</a>. </p>
<p>After looking at seabed sediment stretching back 65 million years, we have found a previously undetected cycle to add to the list: an ebb and flow in deep sea currents, tied to a 2.4-million-year swell of global warming and cooling driven by a gravitational tug of war between Earth and Mars. Our research is <a href="https://doi.org/10.1038/s41467-024-46171-5">published in Nature Communications</a>.</p>
<h2>Milankovitch cycles and ice ages</h2>
<p>Most of the natural cycles we know are determined one way or another by Earth’s movement around the Sun. </p>
<p>As the German astronomer <a href="https://www.jpl.nasa.gov/news/the-history-of-johannes-kepler">Johannes Kepler</a> first realised four centuries ago, the orbits of Earth and the other planets are not quite circular, but rather slightly squashed ellipses. And over time, the gravitational jostling of the planets changes the shape of these orbits in a predictable pattern.</p>
<p>These alterations affect our long-term climate, influencing the coming and going of ice ages. In 1941, Serbian astrophysicist <a href="https://www.amnh.org/learn-teach/curriculum-collections/earth-inside-and-out/milutin-milankovitch-seeking-the-cause-of-the-ice-ages">Milutin Milankovitch</a> recognised that changes in the shape of Earth’s orbit, the tilt of its axis, and the wobbling of its poles all affect the amount of sunlight we receive. </p>
<p>Known as “<a href="https://www.nature.com/scitable/knowledge/library/milankovitch-cycles-paleoclimatic-change-and-hominin-evolution-68244581/">Milankovitch cycles</a>”, these patterns occur with periods of 405,000, 100,000, 41,000 and 23,000 years. Geologists have found traces of them throughout Earth’s deep past, even in <a href="https://www.nature.com/scitable/knowledge/library/milankovitch-cycles-paleoclimatic-change-and-hominin-evolution-68244581/">2.5-billion-year old rocks</a>.</p>
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<a href="https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo shows rocky pillars and cliffs in the ocean." src="https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580915/original/file-20240311-17800-u3fw0j.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>
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<span class="caption">Fine layering in the Port Campbell Limestone by the Great Ocean Road in Victoria is the product of Earth’s orbital eccentricity and obliquity.</span>
<span class="attribution"><span class="source">Adriana Dutkiewicz</span></span>
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<h2>Earth and Mars</h2>
<p>There are also slower rhythms, called astronomical “grand cycles”, which cause fluctuations over millions of years. One such cycle, related to the slow rotation of the orbits of Earth and Mars, recurs every 2.4 million years. </p>
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<a href="https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing the orbits of Earth and Mars around the Sun." src="https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580907/original/file-20240311-22-m3lfms.jpeg?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>
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<span class="caption">The orbits of Earth and Mars exert a subtle influence on each other in a cycle that repeats every 2.4 million years.</span>
<span class="attribution"><span class="source">NASA</span></span>
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<p>The cycle is predicted by <a href="https://www.aanda.org/articles/aa/full_html/2011/08/aa16836-11/aa16836-11.html">astronomical models</a>, but is <a href="https://www.pnas.org/doi/10.1073/pnas.1714342115">rarely detected</a> in geological records. The easiest way to find it would be in sediment samples that continuously cover a period of many millions of years, but these are rare.</p>
<p>Much like the shorter Milankovitch cycles, this grand cycle affects the amount of sunlight Earth receives and has an impact on climate. </p>
<h2>Gaps in the record</h2>
<p>When we went hunting for signs of these multimillion-year climate cycles in the rock record, we used a “big data” approach. <a href="https://www.iodp.org/about-iodp/history">Scientific ocean drilling</a> data collected since the 1960s have generated a treasure trove of information on deep-sea sediments through time across the global ocean. </p>
<p>In our study, published in <a href="https://doi.org/10.1038/s41467-024-46171-5">Nature Communications</a>, we used sedimentary sequences from more than 200 drill sites to discover a previously unknown connection between the changing orbits of Earth and Mars, past global warming cycles, and the speeding up of deep-ocean currents. </p>
<p>Most studies focus on complete, high-resolution records to detect climate cycles. Instead, we concentrated on the parts of the sedimentary record that are missing — breaks in sedimentation called hiatuses. </p>
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Read more:
<a href="https://theconversation.com/how-plate-tectonics-mountains-and-deep-sea-sediments-have-maintained-earths-goldilocks-climate-183725">How plate tectonics, mountains and deep-sea sediments have maintained Earth's 'Goldilocks' climate</a>
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<p>A deep-sea hiatus indicates the action of vigorous bottom currents that eroded seafloor sediment. In contrast, continuous sediment accumulation indicates calmer conditions. </p>
<p>Analysing the timing of hiatus periods across the global ocean, we identified hiatus cycles over the past 65 million years. The results show that the vigour of deep-sea currents waxes and wanes in 2.4 million year cycles coinciding with changes in the shape of Earth’s orbit.</p>
<p>Astronomical models suggest the interaction of Earth and Mars drives a 2.4 million year cycle of more sunlight and warmer climate alternating with less sunlight and cooler climate. The warmer periods correlate with more deep-sea hiatuses, related to more vigorous deep-ocean currents. </p>
<h2>Warming and deep currents</h2>
<p>Our results fit with recent <a href="https://www.nature.com/articles/s41558-021-01006-9">satellite data</a> and <a href="https://www.nature.com/articles/s41558-021-01212-5">ocean models</a> mapping short-term ocean circulation changes. Some of these suggest that ocean mixing has become more intense over the last decades of global warming. </p>
<p>Deep-ocean <a href="https://www.gfdl.noaa.gov/ocean-mesoscale-eddies/">eddies</a> are predicted to intensify in a warming, more energetic climate system, particularly at <a href="https://www.nature.com/articles/s41558-023-01908-w#:%7E:text=Satellite%20altimetry%20records%20reveal%20that,from%201993%20to%2020209">high latitudes</a>, as major storms become more frequent. This makes deep ocean mixing more vigorous. </p>
<p>Deep-ocean eddies are like giant wind-driven whirlpools and often reach the deep sea floor. They result in seafloor erosion and large sediment accumulations called <a href="https://www.sciencedirect.com/science/article/pii/S0070457108100140">contourite drifts</a>, akin to snowdrifts.</p>
<h2>Can Mars keep the oceans alive?</h2>
<p>Our findings extend these insights over much longer timescales. Our deep-sea data spanning 65 million years suggest that warmer oceans have more vigorous eddy-driven circulation. </p>
<p>This process may play an important role in a warmer future. In a warming world the difference in temperature between the equator and poles diminishes. This leads to a <a href="https://insideclimatenews.org/news/09022024/climate-impacts-from-collapse-of-atlantic-meridional-overturning-current-could-be-worse-than-expected/">weakening</a> of the world’s <a href="https://www.worldatlas.com/oceans/what-is-the-ocean-conveyor-belt.html">ocean conveyor belt</a>.</p>
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Read more:
<a href="https://theconversation.com/even-temporary-global-warming-above-2-will-affect-life-in-the-oceans-for-centuries-214251">Even temporary global warming above 2℃ will affect life in the oceans for centuries</a>
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<p>In such a scenario, oxygen-rich surface waters would no longer mix well with deeper waters, potentially resulting in a <a href="https://johnmenadue.com/humanity-sinking-into-a-stagnant-ocean/#:%7E:text=%E2%80%93%20as%20the%20difference%20in%20temperature,waters%2C%20which%20then%20become%20stagnant">stagnant ocean</a>. Our results and <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev.fluid.36.050802.122121">analyses of deep ocean mixing</a> suggest that more intense deep-ocean eddies may counteract such ocean stagnation. </p>
<p>How the Earth-Mars astronomical influence will interact with shorter Milankovitch cycles and current human-driven global warming will largely depend on the future trajectory of our greenhouse gas emissions.</p><img src="https://counter.theconversation.com/content/225454/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adriana Dutkiewicz receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Dietmar Müller and Slah Boulila 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>Deep-sea sediments show how the changing orbits of Earth and Mars are linked to past global warming and the speeding up of deep-ocean eddies.Adriana Dutkiewicz, ARC Future Fellow, University of SydneyDietmar Müller, Professor of Geophysics, University of SydneySlah Boulila, Associate lecturer, Sorbonne UniversitéLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2254932024-03-12T19:00:38Z2024-03-12T19:00:38ZWhat the Anthropocene’s critics overlook – and why it really should be a new geological epoch<p>Geologists on an international subcommission recently <a href="https://www.nature.com/articles/d41586-024-00675-8">voted down a proposal</a> to formally recognise that we have entered the Anthropocene, a new geological epoch representing the time when massive, unrelenting human impacts began to overwhelm the Earth’s regulatory systems. </p>
<p>A new epoch needs a start date. The geologists were therefore asked to vote on a proposal to mark the beginning of the Anthropocene using a sharp increase in plutonium traces found in sediment at the bottom of an <a href="https://www.cbc.ca/news/science/crawford-lake-anthropocene-1.6902999">unusually undisturbed lake in Canada</a>, which aligned with many other markers of human impacts. </p>
<p>The entire process was <a href="https://www.nature.com/articles/d41586-024-00675-8">controversial</a> and the two us who are on the subcommission (chair Jan Zalasiewicz and vice-chair Martin Head) even <a href="https://www-riffreporter-de.translate.goog/de/wissen/streit-um-das-anthropozaen-fuehrender-forscher-haelt-abstimmung-fuer-ungueltig?_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp&_x_tr_hist=true">refused to cast a vote</a> as we did not want to legitimise it. In any case, the proposal ran into opposition from longstanding members.</p>
<p>Why this opposition? Many geologists, used to working with millions of years, find it hard to accept an epoch just seven decades long – that’s just one human lifetime. Yet the evidence suggests that the Anthropocene is very real. </p>
<p>Environmental scientist Erle Ellis was one critic who welcomed the decision, stating in <a href="https://theconversation.com/the-anthropocene-is-not-an-epoch-but-the-age-of-humans-is-most-definitely-underway-224495">The Conversation</a>: “If there is one main reason why geologists rejected this proposal, it is because its recent date and shallow depth are too narrow to encompass the deeper evidence of human-caused planetary change.”</p>
<p>It’s an oft-repeated argument. But it completely misses the point. When Paul Crutzen first proposed the term Anthropocene in a moment of insight at a scientific meeting in 2000, it was not from realisation that humans have been altering the functioning and geological record of the Earth, or to capture all their impacts under one umbrella term. He and his colleagues were perfectly aware that humans had been doing that for millennia. That’s nothing new.</p>
<p><a href="https://www.nature.com/articles/415023a">Crutzen’s insight</a> was wholly different. He said that the Earth system – that is, the really fundamental things like atmospheric composition, climate, all ecosystems – had recently sharply departed from the stability that they had shown for thousands of years during the Holocene epoch, a stability which allowed human civilisation to grow and flourish. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Huge cloud above city coming from large industrial chimney" src="https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=250&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=250&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=250&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=314&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=314&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581347/original/file-20240312-24-8p7qxd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=314&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Humans have destabilised the Earth system in many ways.</span>
<span class="attribution"><span class="source">mykhailo pavlenko / shutterstock</span></span>
</figcaption>
</figure>
<p>It makes no sense, Crutzen said, to use the Holocene for present time. He conceived the Anthropocene as the time when human impacts intensified, suddenly, dramatically, enough to push the Earth into a new state. The science journalist Andrew Revkin (who thought up the name “Anthrocene” even before Crutzen’s inspiration) aptly called it the “<a href="https://www.theatlantic.com/science/archive/2019/04/great-debate-over-when-anthropocene-started/587194/">big zoom</a>”.</p>
<h2>Flesh on bones</h2>
<p>We’re part of the <a href="http://quaternary.stratigraphy.org/working-groups/anthropocene/">Anthropocene Working Group (AWG)</a> that has been gathering evidence to put geological flesh on the bones of Crutzen’s concept. The AWG had a mandate: to assess the Anthropocene as a potential geological time unit during which “human modification of natural systems has become predominant”. Thus, not just any impact but a decisive one. </p>
<p>There’s now no doubt about this decisive change – nor that it has left <a href="https://journals.sagepub.com/doi/10.1177/20530196221136422">sufficient marks in recent geological layers</a> to justify the description of the Anthropocene as a geological time unit (for such a unit must be able to be read in layers of rock millions of years from now, and not just sensed as a change in conditions). These layers abound in fallout from nuclear bomb tests, microplastics, pesticides, <a href="https://neilr053.wixsite.com/gloscape">fly ash</a>, the shells of invasive species and much else.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dawn-of-the-anthropocene-five-ways-we-know-humans-have-triggered-a-new-geological-epoch-52867">Dawn of the Anthropocene: five ways we know humans have triggered a new geological epoch</a>
</strong>
</em>
</p>
<hr>
<p>But how can one show the difference between Crutzen’s idea and the “age of humans” Ellis wrote about, which he, with others, has proposed to call an “<a href="https://doi.org/10.18814/epiiugs/2021/021029">Anthropocene event</a>” extending over 50,000 years or more? We can use the very diagram they used:</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=540&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=540&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579988/original/file-20240305-20-6j3yag.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=540&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How various human activities have affected the planet over the millennia.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1002/jqs.3416">Philip Gibbard, et al., 2022</a></span>
</figcaption>
</figure>
<p>It’s a nicely laid out, easy-to-understand picture that summarises the changes caused by human activity over the last million years. All these things certainly happened. But what is lost here is any sense of the quantified rate and magnitude of change, other than by a little shading. Looking at it, you’d wonder what the fuss was all about.</p>
<p>That’s because there’s no Y-axis (the vertical one). It only has the X-axis, that of time. The Y-axis is what scientists use to show the magnitude of measurements such as temperature and mass. It’s absolutely crucial to get an objective, number-based understanding of <a href="https://www.episodes.org/journal/view.html?doi=10.18814/epiiugs/2022/022025">what really is happening</a>.</p>
<p>Now let’s see how things look when a Y-axis is added. This just shows the last 30,000 years, that includes all the Holocene, but doesn’t use a logarithmic scale (that is, it doesn’t squash up the big numbers) so it more clearly shows how things relate to time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphs showing greenhouse gas and temperature change over last 30,000 years" src="https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=363&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=363&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=363&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=456&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=456&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581344/original/file-20240312-22-ieabja.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=456&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global atmospheric concentrations from ice core records of greenhouse gases (carbon dioxide, methane and nitrous oxide) and global temperature over the past 30,000 years. There is a sharp, unprecedented uptick in values in the Anthropocene.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.18814/epiiugs/2023/023025">Adapted from Zalasiewicz et al al (2024)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The speed and magnitude of recent change jumps out at you. The sharp upturns are essentially Crutzen’s Anthropocene, representing the last 72 years of what has been called the “<a href="https://journals.sagepub.com/doi/10.1177/2053019614564785">great acceleration</a>” of population, consumption, industrialisation, technical innovation and globalisation (a more detailed way of expressing the “big zoom”). </p>
<p>Similar graphs can be drawn for species extinction and invasion rates, or the production and spread of fly ash, concrete, plastics, and a host of other things. They show that Crutzen’s Anthropocene is real, evidence based, and represents an epoch-scale change (at least). The significance for us all, of course, is that the near-vertical recent trends in these graphs are still, for the most part, rising, zooming us into a new kind of planet. The repercussions cannot fail to last for many thousands of years – and some will change the Earth for ever.</p>
<h2>Epoch vs event</h2>
<p>So the Anthropocene as an epoch is very different from the “event” of Erle Ellis and others, which encapsulates all human influence on the planet (and so is about a thousand times longer than the epoch, and differs in many other ways). They’re both valid concepts of course, and have some overlap, just like a mouse in some ways overlaps with a blue whale (they’re both mammals, and share a good deal of their genetic code). But they’re different. </p>
<p>It’s absurd, therefore, to give them the same name: to take Crutzen’s term and appropriate it for a wholly different purpose, and in doing so obscuring the real meaning of his insight and its significance. Under a different name (the Anthropolithic, perhaps?), it could perfectly well complement an Anthropocene epoch.</p>
<p>Humans have had a long and complex impact on the planet, true. For almost all that time, they left their marks on Earth – but did not utterly overwhelm it. Less than a century ago, processes that began during the Industrial Revolution swung into overdrive. That’s the Anthropocene as an epoch. It’s real, it’s already made geology, and it won’t go away. Best to acknowledge it, to help us cope with its consequences. </p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?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"></span>
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 30,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/225493/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Turner is Secretary of the Anthropocene Working Group.
Simon Turner received funding (2020-2023) from Haus der Kulturen der Welt (HKW, Berlin) as Scientific Coordinator for 'Evidence & Experiment' and 'Anthropocene Curriculum' programmes (<a href="https://www.anthropocene-curriculum.org">https://www.anthropocene-curriculum.org</a>). </span></em></p><p class="fine-print"><em><span>Colin Waters is Chair of the Anthropocene Working Group. </span></em></p><p class="fine-print"><em><span>Jan Zalasiewicz is affiliated with Subcommission on Quaternary Stratigraphy (Chair) and
Anthropocene Working Group. </span></em></p><p class="fine-print"><em><span>Martin Head is part of the Anthropocene Working Group and the Quaternary Subcommission.</span></em></p>Geologists recently voted down a proposal to formally recognise the Anthropocene.Simon Turner, Senior Research Fellow in Geography, UCLColin Waters, Honorary Professor, Department of Geology, University of LeicesterJan Zalasiewicz, Professor of Palaeobiology, University of LeicesterMartin J. Head, Professor of Earth Sciences, Brock UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2232092024-02-21T13:13:10Z2024-02-21T13:13:10ZEarth’s early evolution: fresh insights from rocks formed 3.5 billion years ago<figure><img src="https://images.theconversation.com/files/576464/original/file-20240219-24-5de047.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Barberton Makhonjwa Mountains look peaceful today - but 3.5 billion years ago the earth there was roiled by volcanoes. </span> <span class="attribution"><span class="source">Instinctively RDH/Shutterstock</span></span></figcaption></figure><p>Our Earth is <a href="https://www.amnh.org/exhibitions/darwin/the-world-before-darwin/how-old-is-earth#:%7E:text=Today%2C%20we%20know%20from%20radiometric,have%20been%20taken%20more%20seriously.">around 4.5 billion years old</a>. Way back in its earliest years, vast oceans dominated. There were frequent volcanic eruptions and, because there was no free oxygen in the atmosphere, there was no ozone layer. It was a dynamic and evolving planet.</p>
<p>Scientists know all of this – but, of course, there are still gaps in our knowledge. For instance, while we know what kind of rocks were being formed on different parts of the planet 3.5 billion years ago, we are still understanding which geological processes drove these formations. </p>
<p>Luckily the answers to such questions are available. Evidence is preserved in ancient volcanic and sedimentary rocks dating back to the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/archean-eon#:%7E:text=Thus%2C%20the%20Archean%20Eon%20is,continental%20plates%20began%20to%20form.">Archaean age</a>, between 4 billion and 2.5 billion years ago.</p>
<p>These rocks are found in the oldest parts of what are today the continents, called cratons. Cratons are pieces of ancient continents that formed billions of years ago. Studying them offers a window into how processes within and on the surface of Earth operated in the past. They host a variety of different groups of rocks, including greenstones and granites.</p>
<p>One example is the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0012825222000782">Singhbhum Craton</a>, in the Daitari Greenstone Belt in the state of Odisha in eastern India. This ancient part of the Earth’s crust has been found in previous research to date back to 3.5 billion years ago. The craton’s oldest rock assemblages are largely volcanic and sedimentary rocks also known as greenstone successions. Greenstones are rock assemblages made up mostly of sub-marine volcanic rocks with minor sedimentary rocks. </p>
<p>My research team and I recently published <a href="https://www.sciencedirect.com/science/article/pii/S0301926823000372">a study</a> in which we compared the Singhbhum Craton to cratons in South Africa and Australia. We chose these sites because they preserve the same kinds of rocks, in the same condition (not intensely deformed or metamorphosed), from the same time period – about 3.5 billion years ago. They are the best archives to study early Earth surface processes.</p>
<p>Our key findings were that explosive-style volcanic eruptions were common in what are today India, South Africa and Australia around 3.5 billion years ago. These eruptions mostly occurred under oceans, though sometimes above them.</p>
<p>Understanding these early Earth processes is vital for piecing together the planet’s evolutionary history and the conditions that may have sustained life during different geological epochs. This kind of research is also a reminder of the ancient geological wonders that surround us – and that there is much more to discover to understand the story of our planet.</p>
<h2>The research</h2>
<p>We sampled some rocks from the Singhbhum Craton so we could study them in our laboratory. Existing data from the same site, as well as sites in South Africa and India, were used for comparison purposes.</p>
<p>Our detailed field-based studies were complemented by <a href="https://link.springer.com/referenceworkentry/10.1007/978-94-007-6326-5_193-1">uranium-lead (U-Pb) radiometric-age dating</a>. This common and well-established method provides information as to when a magma crystallised; in other words, it tells us when a rock formed. In this way we were able to establish key geological timelines to illustrate what processes were underway and when.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/why-the-discovery-of-a-small-continental-fragment-in-the-indian-ocean-matters-72314">Why the discovery of a small continental fragment in the Indian Ocean matters</a>
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<p>We also found that the geology of this area shares stark similarities with the greenstone belts documented in South Africa’s <a href="https://www.sciencedirect.com/science/article/abs/pii/S0301926816300663">Barberton</a> and <a href="https://www.sciencedirect.com/science/article/abs/pii/S1342937X11002504?via%3Dihub">Nondweni</a> areas and the <a href="https://www.nature.com/articles/375574a0">Pilbara Craton</a> in western Australia. </p>
<p>Most particularly, all these areas experienced widespread submarine mafic – meaning high in magnesium oxide – volcanic eruptions between 3.5 and 3.3 billion years ago, preserved as pillowed lava and komatiites.</p>
<p>This differs from silicic (elevated concentration of silicon dioxide) volcanism, which research <a href="https://www.sciencedirect.com/science/article/abs/pii/S0040195100000585">has shown</a> was prevalent around 3.5 billion years ago.</p>
<p>These findings enrich our understanding of ancient volcanic and sedimentary processes and their significance in the broader context of Earth’s geological as well as biological evolution.</p>
<h2>Our planet’s formative years</h2>
<p>Our discoveries are pivotal for several reasons. First, they offer a clearer picture of Earth’s early tectonic activities during the Archaean times, contributing to our understanding of the planet’s formative years. </p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/four-ways-that-fossils-are-part-of-everyday-life-199193">Four ways that fossils are part of everyday life</a>
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<p>Second, the Singhbhum Craton’s unique geological features, including its greenstone belts, provide invaluable information about Earth’s surface and atmospheric processes. This is crucial for hypothesising early habitable conditions and the emergence of life on Earth. </p>
<p>Additionally, comparing the Singhbhum Craton with similar cratons in South Africa and Australia allows us to construct a more comprehensive model related to geological processes that operated during the Archaean. This can help to shed light on ancient geodynamic processes that were prevalent across different parts of the young Earth.</p>
<p>This research emphasises the need for further exploration into the geological history of ancient cratons worldwide. Understanding these early Earth processes is vital for piecing together the planet’s evolutionary history and the conditions that may have sustained life.</p><img src="https://counter.theconversation.com/content/223209/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaganmoy Jodder received funding from the DSI-NRF Centre of Excellence (CoE) for Integrated Mineral and Energy Resource Analysis (CIMERA) and Genus DSI-NRF Centre of Excellence in Palaeosciences.</span></em></p>Cratons are pieces of ancient continents that formed billions of years ago.Jaganmoy Jodder, Post-doctoral researcher, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2168532024-02-05T13:30:30Z2024-02-05T13:30:30ZStudying lake deposits in Idaho could give scientists insight into ancient traces of life on Mars<figure><img src="https://images.theconversation.com/files/568753/original/file-20240110-30-i5trcc.JPG?ixlib=rb-1.1.0&rect=23%2C398%2C3128%2C1343&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists have been studying the Clarkia site for nearly five decades.</span> <span class="attribution"><span class="source">Robert Patalano</span></span></figcaption></figure><p>Does life exist elsewhere in the universe? If so, how do scientists search for and identify it? Finding life beyond Earth is extremely difficult, partly because other planets are so far away and partly because we are not sure what to look for.</p>
<p>Yet, astrobiologists have learned a lot about <a href="https://science.nasa.gov/astrobiology/">how to find life</a> in extraterrestrial environments, mainly by studying how and when the early Earth became livable.</p>
<p>While research teams at NASA are <a href="https://mars.nasa.gov/mars2020/mission/overview/">directly combing</a> the surface of Mars for signs of life, our <a href="https://news.bryant.edu/there-life-red-planet-faculty-earns-funding-explore-theory-earth">interdisciplinary research group</a> is <a href="https://news.bryant.edu/mars-mind-bryant-students-earn-funding-nasa-ri-space-grant-consortium">using a site here on Earth</a> to approximate ancient environmental conditions on Mars. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rock face with several blocky layers of rock, in different stripes of color. The top layers are a darker clay, while the bottom layers are a lighter volcanic ash." src="https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.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">A close-up view of the Clarkia site where you can see lacustrine clay and volcanic ash layers. This site represents Mars in our work.</span>
<span class="attribution"><span class="source">Taylor Vahey</span></span>
</figcaption>
</figure>
<p>Contained within northern Idaho’s <a href="https://doi.org/10.1130/G48901.1">Clarkia Middle Miocene Fossil Site</a> are sediments that preserve some of Earth’s most diverse biological marker molecules, or <a href="https://doi.org/10.1016/j.epsl.2008.07.012">biomarkers</a>. These are remains of past life that offer glimpses into Earth’s history.</p>
<h2>An ancient lake</h2>
<p>About 16 million years ago, a lava flow in what would one day become Clarkia, Idaho, dammed a local drainage system and created a deep lake in a <a href="https://archive.org/details/latecenozoichist0000unse/page/424/mode/2up">narrow, steep-sided valley</a>. Although the lake has since dried up, weathering, erosion and <a href="https://www.facebook.com/p/Fossil-Bowl-100063724775941/">human activity</a> have exposed sediments of the former lake bed.</p>
<p>For nearly five decades, research teams like ours – being led by <a href="https://www.radcliffe.harvard.edu/people/hong-yang">Dr. Hong Yang</a> and <a href="https://www.bryant.edu/academics/faculty/leng-qin">Dr. Qin Leng</a> – have used <a href="https://doi.org/10.7717/peerj.4880">fossil remains</a> and <a href="https://doi.org/10.1016/0146-6380(95)80001-8">biogeochemistry</a> to reconstruct past environments of the Clarkia Miocene Lake region. </p>
<p>The lake’s depth created the <a href="https://www.jstor.org/stable/1303276">perfect conditions</a> for protecting microbial, plant and animal remains that fell to the lake’s bottom. In fact, the sediments are so well preserved that some of the fossilized leaves still show their autumn colors from when they sank into the water millions of years ago.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A reddish brown long, thin leaf shown embedded on a piece of smooth sediment." src="https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.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">A fossil magnolia leaf showing fall (reddish) colors. This leaf likely fell off a tree in the fall once the trees paused photosynthesis for the winter and sank to the bottom of the lake, where it was buried. The leaf retained its fall coloring for 16 million years, though once being dug up and exposed to air, it quickly oxidized and lost its color.</span>
<span class="attribution"><span class="source">Robert Patalano</span></span>
</figcaption>
</figure>
<p>Today, ancient lake beds on Earth are becoming <a href="https://doi.org/10.1146/annurev-earth-053018-060332">important settings</a> for learning about habitable environments on other planets. </p>
<h2>Biological marker molecules</h2>
<p>Clarkia’s lake sediments <a href="https://doi.org/10.1016/0146-6380(94)90045-0">contain a suite</a> of ancient biomarkers. These compounds, or classes of compounds, can reveal how organisms and their <a href="https://doi.org/10.1016/j.quascirev.2011.07.009">environments functioned</a> in the past.</p>
<p>Since the discovery of the <a href="https://www.idahogeology.org/pub/Information_Circulars/IC-33.pdf">Clarkia fossil site in 1972</a>, multiple research teams have used various <a href="https://doi.org/10.1016/S0146-6380(02)00212-7">cutting-edge technologies to analyze</a> different biomarkers. </p>
<p>Some of those found at Clarkia <a href="https://doi.org/10.1073/pnas.90.6.2246">include lignin</a>, which is the structural support tissue of plants, <a href="https://doi.org/10.1016/S0146-6380(00)00107-8">lipids like fats and waxes</a>, and possibly <a href="https://doi.org/10.1038/344656a0">DNA and amino acids</a>.</p>
<p>Understanding the origins, history and environmental factors that have allowed these biosignatures to stay so well preserved at Clarkia may also allow our team to predict the potential of organic matter preservation in ancient lake deposits on Mars.</p>
<h2>Studying life signatures on Mars</h2>
<p>In 2021, the <a href="https://mars.nasa.gov/mars2020/">Mars Perseverance Rover</a> landed on top of lake deposits in Mars’ <a href="https://doi.org/10.1126/science.abl4051">Jezero Crater</a>. Jezero is a meteorite impact crater believed to have once been flooded with water and home to an ancient river delta. Microbial life may have lived in Jezero’s crater lake, and their biomarkers might be found in lake bed sediments today. Perseverance has been drilling into the crater’s surface to collect samples that could contain ancient signs of life, with the intent of <a href="https://mars.nasa.gov/msr/#Facts">returning the samples to Earth in 2033</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&rect=14%2C7%2C4977%2C2799&q=45&auto=format&w=1000&fit=clip"><img alt="An artist's rendition of the Perseverence rover, made of metal with six small wheels, a camera and a robotic arm." src="https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&rect=14%2C7%2C4977%2C2799&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.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 Perseverance Rover is collecting samples to learn more about Mars’ environment.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/MarsLanding/c835b14b3e6645d7a0cd46558745752b/photo?Query=mars%20rover&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=530&currentItemNo=11&vs=true">NASA/JPL-Caltech via AP</a></span>
</figcaption>
</figure>
<p>Clarkia has many similarities to the Jezero Crater. Both Clarkia and Jezero Crater have ancient <a href="https://doi.org/10.1006/icar.2000.6530">lake deposits</a> derived from silica-rich, <a href="https://doi.org/10.1029/2017JE005478">basaltic rock</a> that formed under <a href="https://doi.org/10.1016/j.gloplacha.2022.103737">a climate with</a> higher temperatures, high humidity and a carbon dioxide-rich atmosphere. </p>
<p>At Clarkia, these conditions preserved microbial biomarkers in the ancient lake. Similar settings could have <a href="https://doi.org/10.1029/2012JE004115">formed lakes</a> on the surface of Mars. </p>
<p>The samples <a href="https://mars.nasa.gov/mars-rock-samples/#23">Perseverance is collecting</a> contain the geologic and climate history of the Jezero Crater landing site and may even contain preserved biomarkers of ancient life.</p>
<p>While Perseverance continues its mission, our group is <a href="https://agu.confex.com/agu/fm23/meetingapp.cgi/Paper/1367388">establishing criteria</a> for biomolecular authentication. That means we are developing ways to figure out whether ancient biomarkers from Earth, and hopefully Mars, are true echoes of life – rather than recent contamination or molecules from nonliving sources.</p>
<p>To do so, we are studying biomarkers from Clarkia’s fossil leaves and sediments and developing laboratory experiments using <a href="https://spaceresourcetech.com/collections/regolith-simulants">Martian simulants</a>. This material simulates the chemical and physical properties of Jezero Crater’s lake sediments.</p>
<p>By deciphering the sources, history and preservation of biomarkers connected with Clarkia’s ancient lake deposits, we hope to develop new strategies for studying the Perseverance Rover samples once they are back on Earth.</p><img src="https://counter.theconversation.com/content/216853/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Patalano receives funding from the NASA Rhode Island Space Grant Program. </span></em></p>While NASA rovers on the surface of Mars look for hints of life, researchers back on Earth are studying ‘echoes of life’ from ancient basins – hoping that the two sites might be similar.Robert Patalano, Lecturer of Biological and Biomedical Sciences, Bryant UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2212922024-02-04T13:33:52Z2024-02-04T13:33:52ZWhy now is the time to address humanity’s impact on the moon<figure><img src="https://images.theconversation.com/files/572329/original/file-20240131-15-x809b1.jpg?ixlib=rb-1.1.0&rect=0%2C29%2C6500%2C3532&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mining the moon for its resources is growing more and more likely.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Humans have always looked at the sky, using the stars as navigation guides or for spiritual storytelling. Every human civilization has looked to the stars and used celestial movements to measure time and find meaning.</p>
<p>This insatiable thirst for knowledge combined with technological advancements have made it possible for us to dream of travelling in space. These dreams became more and more real after the Second World War, the Industrial Revolution, the Cold War and the large-scale exploitation of the Earth’s resources.</p>
<p>Dreams of space travel started small with the <a href="https://www.nasa.gov/image-article/sputnik-1/">launch of Sputnik-1 by the Soviet Union</a>, and escalated with the <a href="https://www.nasa.gov/history/apollo-11-mission-overview/">U.S. Apollo landing on the moon in 1969</a>.</p>
<p>Six decades later, plans are ramping up for <a href="https://www.virgingalactic.com/">space tourism</a>, <a href="https://www.nasa.gov/specials/artemis/">missions to the moon and Mars</a>, and <a href="https://www.space.com/moon-mining-gains-momentum">mining on the moon</a>. </p>
<p>The <a href="https://lunarresourcesregistry.com/">Lunar Resources Registry</a>, a private business that locates valuable resources on the moon and helps investors conduct the required exploration and extraction operations, notes: “The space race is evolving into space industrialization.” </p>
<p>According to NASA, “the moon holds <a href="https://www.jpl.nasa.gov/infographics/the-lunar-gold-rush-how-moon-mining-could-work">hundreds of billions of dollars of untapped resources</a>,” including water, helium-3 and <a href="https://geology.com/articles/rare-earth-elements/">rare earth metals</a> used in electronics.</p>
<h2>The dawn of the Anthropocene</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a black and white photo of a footprint on a sedimentary surface" src="https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=608&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=608&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=608&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=764&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=764&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572349/original/file-20240131-21-a3nhp0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=764&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 close-up view of an astronaut’s footprint in the lunar soil, photographed in July 1969.</span>
<span class="attribution"><a class="source" href="https://images.nasa.gov/details/6901250">(Marshall Space Flight Center/NASA)</a></span>
</figcaption>
</figure>
<p>As a group of academics researching various aspects of environmental sustainability on Earth, we are alarmed at the speed of these developments and the impacts resource exploitation will have on lunar and space environments. </p>
<p>There is a movement among the international geologic scientific community calling for a new epoch — <a href="https://brocku.ca/and/crawford-lake/">the Anthropocene</a> — reflecting the enormous extent to which human activity has altered the planet since the end of the Second World War.</p>
<p>Stratigraphers — geologists who study the layers of rock and sediment — look for measurable global impact of human activities in the geologic record. According to their research, the starting point for the Anthropocene has been identified as beginning in the 1950s, <a href="https://education.nationalgeographic.org/resource/anthropocene/">and the fallout from nuclear testing</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-the-term-anthropocene-jumped-from-geoscience-to-hashtags-before-most-of-us-knew-what-it-meant-130130">How the term 'Anthropocene' jumped from geoscience to hashtags – before most of us knew what it meant</a>
</strong>
</em>
</p>
<hr>
<p>To shock humankind into preventing the extensive destruction in space that we have wrought on Earth, it may be effective to add a “<a href="https://doi.org/10.1038/s41561-023-01347-4">lunar Anthropocene</a>” to the moon’s geologic time scale.</p>
<p>The case for a lunar Anthropocene is interesting. It can be argued that since the first human contact with the moon’s surface, we have seen anthropogenic impact. This impact is likely to increase dramatically. This is presented as justification for a new geologic epoch for the moon. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a mushroom cloud caused by a nuclear explosion" src="https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=473&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=473&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=473&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=595&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=595&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572350/original/file-20240131-19-c72v6r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=595&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 image captured immediately after the first atomic explosion in Alamogordo, N.M., on July 16, 1945. The presence of nuclear traces of the fallout from the initial nuclear explosions is claimed to mark the beginning of the Anthropocene.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Damaging the Earth</h2>
<p>This new “human epoch” is hotly debated among stratigraphers as well as researchers in other disciplines. For humanities researchers and artists, the importance of the Anthropocene lies in the power the concept has to evoke human responsibility for bringing the Earth’s system to a <a href="https://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate/Understanding_climate_tipping_points">tipping point</a>. </p>
<p>In <a href="https://www.versobooks.com/en-ca/products/136-the-shock-of-the-anthropocene"><em>The Shock of the Anthropocene</em></a>, historians Christophe Bonneuil and Jean-Baptiste Fressoz argue that the new human epoch entails recognizing that technoscientific advances — which have driven socio-political economies relying on extractivism, consumption and waste — have led to the extent of damage we measure on Earth at present. </p>
<p>For millenia, most societies understood the importance of their relationship with the natural world for survival. But industrialization and the endlessly growing economy in developed countries has destroyed this relationship. </p>
<p>For example, trees used to be respected for providing timber, food, shade and more. But our industrial growth changed all that; in the past 100 years, <a href="https://ourworldindata.org/world-lost-one-third-forests">more trees have been cut</a> than had been felled in the preceding 9,000 years.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/killing-trees-how-true-environmental-protection-requires-a-revolution-in-how-we-talk-about-and-with-our-forests-214899">'Killing' trees: How true environmental protection requires a revolution in how we talk about, and with, our forests</a>
</strong>
</em>
</p>
<hr>
<h2>A lunar Anthropocene</h2>
<p>And now the Anthropocene, this age of human impact, is also arriving on the moon.</p>
<p>NASA estimates there are already <a href="https://www.ajc.com/news/national/500-000-pounds-human-trash-litters-the-moon-report-finds/wWeCaVjLmtz0u2ZunyqcLI/">227,000 kilos of human garbage littering the moon</a>, mostly from space explorations, including <a href="https://www.rmg.co.uk/stories/topics/strange-things-humans-have-left-on-moon">moon buggies and other equipment</a>, excrement, statues, golf balls, human ashes and flags, among other objects. </p>
<p>An increasing number of moon missions and extracting resources from the moon <a href="https://www.theguardian.com/science/2024/jan/06/moons-resources-could-be-destroyed-by-thoughtless-exploitation-nasa-warned">could destroy lunar environments</a>. This mirrors what has happened on our planet: humans have used this collection of “natural resources” and produced enough waste and degradation to bring us to the current <a href="https://www.earth.com/earthpedia-articles/its-too-late-the-6th-mass-extinction-is-here/">sixth mass extinction precipice</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_tdsia6EZY8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">With the Artemis missions, NASA is planning to reestablish a human presence on the moon.</span></figcaption>
</figure>
<p>Our throwaway society leads to not only habitat destruction on Earth, but also now on the moon and in space. We must rethink what we really need. Without a fully functional Earth system, including biodiversity and nature’s contribution to life, we will be unable to survive. </p>
<p>If the intent is to issue a word of caution and pre-emptively shock and elicit a feeling of responsibility on the part of those actors likely to impact the moon’s surface, it may very well be the right time to name a lunar Anthropocene. This may help prevent the kind of extensive and careless destruction we have caused and continue to witness on Earth.</p><img src="https://counter.theconversation.com/content/221292/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christine Daigle receives funding from the Social Sciences and Humanities Research Council. </span></em></p><p class="fine-print"><em><span>Liette Vasseur receives funding from the Exploration New Frontiers Research Funds.</span></em></p><p class="fine-print"><em><span>Jennifer Ellen Good 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>As space travel and lunar exploration becomes a near-future reality, we should consider the impact of human activities on the lunar environment.Christine Daigle, Professor of Philosophy, Brock UniversityJennifer Ellen Good, Associate Professor and Chair, Communication, Popular Culture and Film, Brock UniversityLiette Vasseur, Professor, Biological Sciences, Brock UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2182012024-01-19T13:41:44Z2024-01-19T13:41:44ZI’m an artist using scientific data as an artistic medium − here’s how I make meaning<figure><img src="https://images.theconversation.com/files/569152/original/file-20240112-27-8u7iv7.jpeg?ixlib=rb-1.1.0&rect=2%2C0%2C1393%2C932&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sarah Nance at the Bonneville Salt Flats, Utah, 2019.</span> <span class="attribution"><span class="source">Courtesy of Sarah Nance</span></span></figcaption></figure><p>As an <a href="https://www.binghamton.edu/art/profile.html?id=snance">artist working across media</a>, I’ve used everything from thread to my voice to poetically translate and express information. Recently, I’ve been working with another medium – geologic datasets. </p>
<p>While scientists use data visualization to show the results of a dataset in interesting and informative ways, my goal as an artist is a little different. In the studio, I treat geologic data as another material, using it to guide my interactions with Mylar film, knitting patterns or opera. Data, in my work, functions expressively and abstractly. </p>
<p>Two of my projects in particular, “points of rupture” and “tidal arias,” exemplify this way of working. In these pieces, my goal is to offer new ways for people to personally relate to the immense scale of geologic time.</p>
<h2>Points of rupture</h2>
<p>An early project in which I treated data as a medium was my letterpress print series “<a href="https://www.sarahnance.com/shroud/alaska">points of rupture</a>.” In this series, I encoded data from <a href="https://www.britannica.com/science/cryoseism">cryoseismic, or ice quake</a>, events to create knitting patterns. </p>
<p>Working with ice quake data was a continuation of my research into what I call “archived landscapes.” These are places that have had multiple distinct geologic identities over time, like <a href="https://www.nps.gov/gumo/learn/nature/coralreefs.htm">mountains that were once sea reefs</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="silver knitting symbols on black background" src="https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569121/original/file-20240112-17-umjli0.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">‘points of rupture (alaska glacial event 1999),’ 2020. Letterpress print of knitting pattern coded using cryoseismic data. Edition of 15. 18 x 18 in.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>Because knit textiles are made up of many individual stitches, I can use them to encode discrete data points. In a knitting pattern, or chart, each kind of stitch is represented by a specific symbol. I used the open-source program <a href="https://stitch-maps.com">Stitch Maps</a> to write the patterns for this project, translating the peaks and valleys of seismographs into individual stitch symbols. </p>
<p>Knitting charts typically display these symbols in a grid. Instead, Stitch Maps allows them to fall as they would when knitted, so the chart mimics the shape of the final textile. </p>
<p>I was drawn to the expressive possibilities of this feature and how the software allowed me to experiment. I was able to write patterns that worked only in theory and not as physical, handmade structures. This gave me more freedom to design patterns that fully expressed the datasets without having to ensure their viability as textiles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="graphite drawing of mitten knitting chart on gallery wall" src="https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568495/original/file-20240109-29-ojgmd6.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">‘and when you change the landscape, is it with bare hands or with gloves? (lichen, woodwork, grate),’ 2023. Graphite drawing of selbu mitten knitting chart. 99 x 67 linear inches as installed.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p><a href="https://nsidc.org/learn/parts-cryosphere/glaciers">Glaciers form</a> incrementally as new snowfall compacts previous layers of snow, crystallizing them into ice. A knitted fabric similarly accumulates in layers, as rows of interlocking loops. Each structure appears stable but could easily be dissolved.</p>
<p>Ice quakes occur in glaciers as a result of <a href="https://www.britannica.com/science/cryoseism">calving events or pooling meltwater</a>. Like melting glaciers, knitting is always in danger of coming apart – but instead of melting, by snagging and unraveling into formlessness. These structural similarities between glaciers and knitting are reflected in the “points of rupture” prints, where disruptive ice quakes translate into unknittable patterns. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="silver knitting symbols on black background" src="https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569080/original/file-20240112-19-758bfo.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">‘points of rupture (glacier de la plaine morte icequake 2016),’ 2020. Letterpress print of knitting pattern coded using cryoseismic data. Edition of 15. 18 x 18 in.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<h2>The loop</h2>
<p>Repeated, interlocking loops are the base units that compose the structure of a knitted textile. The loop also forms the seed of an in-progress work I pursued during an artist residency with the <a href="https://lunarscience.nasa.gov/sserviteams">NASA</a> <a href="https://www.geodes.umd.edu">GEODES</a> research group. I joined their research team in Flagstaff, Arizona, in August 2023. I assisted in gathering data from sites within the San Francisco volcanic field, while also conducting my own fieldwork: photography, drawing, note-taking and walking.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A digital map showing a crater, with a green circle indicating the path walked, around the lip of the crater." src="https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=629&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=629&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=629&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=790&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=790&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568498/original/file-20240109-21-we196t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=790&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sarah Nance’s walk at S P Crater in Arizona, as recorded in AllTrails.</span>
<span class="attribution"><span class="source">Screenshot of All Trails map</span></span>
</figcaption>
</figure>
<p>One of my walks was a trek around a particularly prominent geologic loop – the rim of the S P cinder cone volcano. This is the second crater walk I’ve completed, the first being a tracing of the subsurface rim of the <a href="https://insider.si.edu/2013/03/iowa-meteorite-crater-confirmed/">Decorah impact structure</a> in Iowa. </p>
<p>I see my paths through these landscapes as stand-ins for yarn. Over time, by taking walks that trace craters, or geologic loops, I will perform a textile. The performance of something as familiar as a textile offers me a new way to think about something that is much more difficult to comprehend – <a href="https://www.britannica.com/science/geologic-time">geologic time</a>. </p>
<hr>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A square box with the words 'Art & Science Collide' and a drawing of a lightbulb with its wire filament in the shape of a brain, surrounded by a circle." src="https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567788/original/file-20240103-23-yg479z.png?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">Art & Science Collide series.</span>
<span class="attribution"><span class="source">source</span></span>
</figcaption>
</figure>
<p><em><strong><a href="https://theconversation.com/us/topics/art-in-science-series-2024-149583">This article is part of Art & Science Collide</a></strong>, a series examining the intersections between art and science.</em></p>
<p><em>You may be interested in:</em></p>
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<p><a href="https://theconversation.com/i-wrote-a-play-for-children-about-integrating-the-arts-into-stem-fields-heres-what-i-learned-about-encouraging-creative-interdisciplinary-thinking-218001">I wrote a play for children about integrating the arts into STEM fields – here’s what I learned about interdisciplinary thinking</a> </p>
<p><a href="https://theconversation.com/art-and-science-entwined-this-course-explores-the-long-interrelated-history-of-two-ways-of-seeing-the-world-210250">Art and science entwined: This course explores the long, interrelated history of two ways of seeing the world </a></p>
<hr>
<h2>Performance and tides</h2>
<p>Performance has been a useful tool in my work, as it can help people understand and relate to geologic processes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="artist's hands holding small chunk of glacial ice" src="https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569102/original/file-20240112-21-spkjsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘transference,’ 2017. Atlantic sea ice, body heat. Documentation of site-responsive performance on the East Coast Trail, Newfoundland, Canada. Project supported in part by La Soupée, Galerie Diagonale, Montréal, Québec.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>The field of geology emerges from a <a href="https://www.upress.umn.edu/book-division/books/a-billion-black-anthropocenes-or-none">long history</a> of extraction and <a href="https://www.dukeupress.edu/geontologies">colonialist ventures</a>. In this context, land is valued for its economic importance – as raw material to be extracted or territory to be claimed. In my performances, I aim to interact with geology as its own active entity, rather than as a consumable resource. </p>
<p>In recent years, I have composed and performed two arias from tidal data. </p>
<p>The first, “<a href="https://www.sarahnance.com/marseille">marseille tidal gauge aria</a>,” sourced 130 years of sea level data collected from a tidal gauge in the Bay of Marseille, France. I converted each yearly average sea level into an individual note within my vocal range. This resulted in a composition that expresses the rising sea levels of the bay as increasingly higher pitches in the aria. </p>
<p>Its lyrics come from a somber poem in Rasu-Yong Tugen’s book “<a href="https://gnomebooks.wordpress.com/2014/02/10/songs-from-the-black-moon/">Songs From the Black Moon</a>.” Each note of the aria communicates not just the measured sea level but also my emotive response to this dataset. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Black flexi disc with gold text and image" src="https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569098/original/file-20240112-23-ffk4lg.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">‘tidal arias,’ 2022. Limited edition flexi disc with vocal performances ‘marseille tidal gauge aria’ and ‘skagway tidal aria.’</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>Last fall, “marseille tidal gauge aria” was transmitted <a href="https://www.swpc.noaa.gov/phenomena/ionosphere">to the ionosphere</a>, the boundary between Earth’s atmosphere and outer space. This was done as part of artist Amanda Dawn Christie’s project “<a href="https://ghostsintheairglow.space/transmission/august-2023">Ghosts in the Air Glow</a>,” using the <a href="https://haarp.gi.alaska.edu">High-frequency Active Auroral Research Program</a>’s ionospheric research instrument, which is an array of 180 antennas transmitting high-frequency radio waves. </p>
<p>The aria’s transmission reflected off the ionosphere, back to Earth and to shortwave radio listeners around the world.</p>
<p>For the second of these vocal pieces, “skagway tidal aria,” I used predictive as well as recorded tidal data from Skagway, Alaska. With this data, I composed an aria for <a href="https://t2051mcc.com">The 2051 Munich Climate Conference</a>, where speakers presented from the perspective of a climate-altered world 30 years in the future. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="vocal music score" src="https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569106/original/file-20240112-25-4mocnl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Score for ‘skagway tidal aria,’ 2021. Recorded and speculative tidal data from Skagway, Alaska (1945-2081), sonified as a vocal composition. Text from ‘Songs From the Black Moon’ by Rasu-Yong Tugen.</span>
<span class="attribution"><span class="source">Sarah Nance</span></span>
</figcaption>
</figure>
<p>I was drawn to this particular dataset because the falling tide levels in Skagway appear to contradict the <a href="https://theconversation.com/what-drives-sea-level-rise-us-report-warns-of-1-foot-rise-within-three-decades-and-more-frequent-flooding-177211">global trend of rising sea levels</a>. However, this is a temporary effect caused by melting glaciers releasing pressure on the land, allowing it to rise faster than water levels. The effect will flatten over the next half-century, and Skagway’s tides will start to rise again.</p>
<p>Over the next few months, I’ll be working with geophysical datasets gathered during the NASA GEODES field expedition to write new arias. I want these pieces to continue blurring the separation between the human and the geologic, inviting listeners to think more deeply about their own relationships with the lands they use and occupy.</p><img src="https://counter.theconversation.com/content/218201/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The author's projects with GEODES and Ghosts in the Air Glow were supported with funding from these organizations.</span></em></p>Sarah Nance uses geologic data and a variety of artistic media to help people think about their place in the landscapes they use and occupy.Sarah Nance, Assistant Professor of Integrated Practice in Art and Design, Binghamton University, State University of New YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2191382023-12-27T15:48:36Z2023-12-27T15:48:36ZWhere do all of James Bond’s gadgets come from? A geologist tells the raw truth<figure><img src="https://images.theconversation.com/files/563295/original/file-20230713-15-u5em9p.png?ixlib=rb-1.1.0&rect=17%2C8%2C1880%2C804&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In Spectre (2015), Daniel Craig and Ben Whishaw respectively play the world's most famous secret agent and his gadget supplier.</span> <span class="attribution"><a class="source" href="https://www.youtube.com/watch?v=SzvxegcZzPU">Spectre</a></span></figcaption></figure><p>Laser watches, fingerprint guns, explosives and, of course, over-equipped cars: the list of gadgets flaunted by James Bond is as bewildering as the mind of their inventor, Q. While some of these gadgets actually exist (laser, fingerprint recognition, back reactor), others, as we shall see, are more fanciful. </p>
<p>But they all have one thing in common: the raw materials needed to make them, and in particular the <a href="https://mineralinfo.fr/fr">mineral resources</a> that geologists are helping to extract from the earth’s crust. Below are some that jumped out of the screen for me. </p>
<h2>The fast, inconspicuous cars of the world’s most famous secret agent</h2>
<p>In 1964’s Goldfinger, James Bond (Sean Connery) has to give up his Bentley for an Aston Martin DB5 modified by Q (the unforgettable Desmond Llewelyn). This is the first of eight appearances of a car that will go on to become inseparable from 007.</p>
<figure class="align-center ">
<img alt="The Aston Martin DB5, James Bond's historic car" src="https://images.theconversation.com/files/537729/original/file-20230717-138681-wy16lv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537729/original/file-20230717-138681-wy16lv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537729/original/file-20230717-138681-wy16lv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537729/original/file-20230717-138681-wy16lv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537729/original/file-20230717-138681-wy16lv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=466&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537729/original/file-20230717-138681-wy16lv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=466&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537729/original/file-20230717-138681-wy16lv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=466&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Aston Martin DB5, which first appeared in Goldfinger in 1964. This car is made from aluminium extracted from bauxite ore.</span>
<span class="attribution"><span class="source">N. Charles</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>The auto is a good example of how products have become more complex and incorporated a greater diversity of raw materials over time. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="zoom on a pink mineral with pinkish and whitish spots" src="https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537731/original/file-20230717-248129-ixx1gi.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"></a>
<figcaption>
<span class="caption">Bauxite : the main ore of aluminium, the metal used in 007’s DB5, which takes its name from Baux-de-Provence, France.</span>
<span class="attribution"><span class="source">N. Charles</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>The DB5 contains an array of minerals, starting with aluminium, a metal known to make cars lighter. The latter is derived from bauxite, an ore mined in Jamaica near Ocho Rios, which, incidentally, served as the setting for Crab Key Island, Dr No’s hideout, in 1962.</p>
<p>The body of the DB5 is made of aluminium and magnesium alloy plates resting on a tubular steel structure. The engine block is aluminium, as are the pistons and cylinder head. The connecting rods and crankshaft are made of steel doped with chromium and molybdenum for greater strength. The aluminium rims are mounted on chromed steel hubs, as are the spokes.</p>
<p>Of course, we mustn’t forget the <a href="https://mineralinfo.fr/sites/default/files/documents/2021-03/silice_industrielle_rp-66167-fr_2016revise2020.pdf">silica in the windows</a>, the <a href="http://infoterre.brgm.fr/rapports/RP-69037-FR.pdf">copper in the electrical wiring</a>, the lead in the battery or the carbonates and <a href="https://mineralinfo.fr/sites/default/files/documents/2021-03/kaolin_argiles_kaoliniques_rp-67334-fr_2018.pdf">kaolin in the paint</a>, and the petrol to make the whole thing run at top speed.</p>
<p>The automotive industry has come a long way since 1964, and one innovation follows another, each bringing its new share of unique materials. Several dozen are needed today for a standard vehicle - and what can we say about the latest racing cars driven by 007 since 2000, such as the BMW Z3 or the Aston Martin Valhalla? </p>
<p>This goes on with electric vehicles, whose batteries rely on <a href="https://theconversation.com/relocaliser-lextraction-des-ressources-minerales-en-europe-les-defis-du-lithium-138581">lithium</a>, cobalt, graphite, <a href="https://mineralinfo.fr/fr/ecomine/sulfate-de-nickel-un-ingredient-cle-des-batteries-li-ion">nickel</a> and <a href="https://mineralinfo.fr/fr/ecomine/marche-des-terres-rares-2022-filieres-dapprovisionnement-aimants-permanents">rare earths</a>. In 1971 <em>Diamonds Are Forever</em>, James Bond can be seen flying and driving around in no less than an electric lunar module. More recently, in <em>Dying Can Wait</em> (2021), the Aston Martin Valhalla is a plug-in hybrid, but James Bond has not yet gone all-electric.</p>
<h2>Golden guns that would melt in real life</h2>
<p>Another cult item is the Walther PPK, the German pistol used by 007 in many of the Bond films. It’s a weapon made from a stainless steel alloy. Although the steel is mainly iron, it also contains other elements depending on its use and the properties required: chromium, molybdenum, nickel, manganese, carbon, silicon, copper, sulphur, nitrogen, phosphorus, boron, titanium, niobium, tungsten, vanadium, and cerium.</p>
<p>Much more precious, Francisco Scaramanga’s (Christopher Lee) pistol is made of solid gold and assembles everyday objects to go unnoticed during checks: lighter, cufflinks, fountain pen as well as a cigar case. Limited to one shot, the pistol fires bullets of 4.2 mm calibre, weighs 30 g and is made of 23-carat gold with traces of nickel. So much for fiction.</p>
<figure class="align-center ">
<img alt="gold pistol at the museum" src="https://images.theconversation.com/files/537734/original/file-20230717-129345-k99hdj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537734/original/file-20230717-129345-k99hdj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537734/original/file-20230717-129345-k99hdj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537734/original/file-20230717-129345-k99hdj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537734/original/file-20230717-129345-k99hdj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537734/original/file-20230717-129345-k99hdj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537734/original/file-20230717-129345-k99hdj.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">
<figcaption>
<span class="caption">Francisco Scaramanga’s gold pistol, solid gold here being unrealistic for dedicated use… The bullet, also in gold, is engraved</span>
<span class="attribution"><a class="source" href="https://flickr.com/photos/66857806@N02/14592496766">Gareth Milner, Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In reality, it’s hard to imagine a gun made entirely of gold, a very dense and, above all, very soft metal, which wouldn’t withstand the repeated power of a gunshot for very long. In jewellery, gold is often combined with silver, copper or zinc to make it wearable. On 4 December 2023, one kilogram of gold was trading at around €66,000, an all-time record (<a href="https://www.gold.org/">World Gold Council</a>). It’s hardly surprising, given that gold has been a precious, unalterable, shiny metal with a deep yellow colour since Antiquity, arousing covetousness and serving as a safe haven.</p>
<p>In <em>Love from Russia</em> (1963), James Bond receives 50 gold British sovereigns in a briefcase brimming with gadgets. Attracted to the gold coins, the enemy Grant opens the booby-trapped case while holding 007 at gunpoint. Tear gas escapes, saving Bond’s life.</p>
<h2>James Bond and his high-tech enemies</h2>
<p>The saga has also always been about surprising the general public with cutting-edge technology, which may be little known at the time of the film’s release.</p>
<p>What better example than the <a href="https://www.sfpnet.fr/le-laser-principe-de-fonctionnement">laser</a>, which, should we be reminded, stands short for <em>Light Amplification by Stimulated Emission of Radiation.</em> The saga likes to beam it as often as possible, alternatively adding it to pistols, watches, cars, and satellites.</p>
<figure class="align-center ">
<img alt="plastic laser gun" src="https://images.theconversation.com/files/537736/original/file-20230717-243941-ymm8xc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537736/original/file-20230717-243941-ymm8xc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=259&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537736/original/file-20230717-243941-ymm8xc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=259&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537736/original/file-20230717-243941-ymm8xc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=259&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537736/original/file-20230717-243941-ymm8xc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=326&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537736/original/file-20230717-243941-ymm8xc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=326&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537736/original/file-20230717-243941-ymm8xc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=326&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Laser guns (plastic !) from the space base in Moonraker, 1979.</span>
<span class="attribution"><span class="source">Nicolas Charles</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>In <em>Goldfinger</em> (1964), film director Guy Hamilton chooses to bypass Ian Fleming’s novel of the same name by threatening James Bond not with a chainsaw, but a laser.
The latter were also used in other Bond films: satellites in Diamonds Are Forever (1971) and Murder Another Day (2002); laser pistols in Moonraker (1979); laser watches in Never Again (1983) and Goldeneye (1995); laser-equipped cars in Killing Is No Game (1987), etc.</p>
<p>Lasers can be used to a variety of ends. For one, telemetry: from the Greek “tel” (“remote”) and “metros” (“to measure”), this practice consists in remotely measuring physical and electrical data. Other uses include cutting objects and projecting light.</p>
<p>Physicist Théodore Maiman introduced the first operational laser in the real world in May 1960 (<a href="https://www.aps.org/publications/apsnews/201005/physicshistory.cfm">American Physical Society</a>), right before James Bond. </p>
<p>This first laser used a ruby, a mineral in the corundum (aluminium oxide) family, like sapphire. But this is a <a href="https://www.gemsociety.org/article/understanding-gem-synthetics-treatments-imitations-part-4-synthetic-gemstone-guide/">synthetic ruby</a> created from aluminium oxide (<a href="https://www.rsc.org/periodic-table/element/13/aluminium">from bauxite</a>) mixed with a tiny amount of <a href="https://www.rsc.org/periodic-table/element/24/chromium">chromium</a> (mainly produced from chromite). There are different types of laser, depending on the application:</p>
<ul>
<li><p>Crystalline lasers: made of silica glass (from very pure quartz) or synthetic ruby or sapphire crystals (aluminium oxide doped with <a href="https://mineralinfo.fr/sites/default/files/documents/2020-12/fichecriticitetitane171017.pdf">titanium</a>, <a href="https://mineralinfo.fr/sites/default/files/documents/2020-12/fichecriticitechrome171003.pdf">chromium</a> or rare earths : neodymium, ytterbium, praseodymium, erbium or thulium) ;</p></li>
<li><p>Fibre lasers : composed of optical fibres based on silica (derived from ultra-pure quartz) and doped with <a href="http://infoterre.brgm.fr/rapports/RP-65330-FR.pdf">rare earths</a> (metals extracted mainly from minerals such as bastnaesite, monazite or xenotime) ;</p></li>
<li><p>Gas lasers: using helium (extracted from natural gas deposits) and neon (extracted from atmospheric air gases) or CO<sub>2</sub> ;</p></li>
<li><p>Organic dye lasers.</p></li>
</ul>
<p>The red light beam in <em>Goldfinger</em> was emitted from a laser (probably ruby) whose brightness was amplified by special effects.</p>
<p>However, the destructive nature of the laser is pure fiction. During filming, an operator used an acetylene torch under the pre-cut table even though Sean Connery was lying on it !</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/537735/original/file-20230717-210016-ygo2ez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537735/original/file-20230717-210016-ygo2ez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537735/original/file-20230717-210016-ygo2ez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537735/original/file-20230717-210016-ygo2ez.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537735/original/file-20230717-210016-ygo2ez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537735/original/file-20230717-210016-ygo2ez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537735/original/file-20230717-210016-ygo2ez.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Shark’s teeth (</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/111748974@N02/26039238632/">Shaun Versey, Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Finally, since we all know the bad guys like to bare their teeth, let’s mention the surgical steel jaw of the impressive Shark (Richard Kiel) in <em>The Spy Who Loved Me</em> (1977) and <em>Moonraker</em> (1979). It’s a stainless and corrosion-resistant steel that limits the risk of allergic reactions when it comes into contact with the skin. Its composition includes iron, nickel, chromium, manganese and molybdenum.</p>
<p>James Bond is like many other citizens, he consumes mineral raw materials on a daily basis. At a time of energy, ecological and digital transition, mineral resources are essential elements in the decarbonisation of our activities.</p><img src="https://counter.theconversation.com/content/219138/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicolas Charles ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>At Q’s of course! But he doesn’t pull them out of his sleeve. In Spectre (2015), Daniel Craig and Ben Whishaw play the famous spy and his gadget supplier.Nicolas Charles, Géologue, PhD, BRGMLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2195052023-12-20T23:25:15Z2023-12-20T23:25:15ZPeople once lived in a vast region in north-western Australia – and it had an inland sea<p>For much of the <a href="https://theconversation.com/buried-tools-and-pigments-tell-a-new-history-of-humans-in-australia-for-65-000-years-81021">65,000 years</a> of Australia’s human history, the now-submerged northwest continental shelf connected the Kimberley and western Arnhem Land. This vast, habitable realm covered nearly 390,000 square kilometres, an area one-and-a-half times larger than New Zealand is today.</p>
<p>It was likely a single cultural zone, with similarities in ground stone-axe technology, styles of rock art, and languages found by archaeologists in the Kimberley and Arnhem Land. </p>
<p>There is plenty of archaeological evidence humans once lived on continental shelves – areas that are now submerged – all around the world. Such hard evidence has been retrieved from underwater sites in the <a href="https://theconversation.com/doggerlands-lost-world-shows-melting-glaciers-have-drowned-lands-before-and-may-again-26472">North Sea</a>, <a href="https://archaeologydataservice.ac.uk/library/browse/details.xhtml?recordId=3046150">Baltic Sea</a> and <a href="https://doi.org/10.1016/j.pgeola.2018.04.008">Mediterranean Sea</a>, and along the coasts of <a href="https://doi.org/10.1016/j.pgeola.2018.04.008">North</a> and <a href="https://doi.org/10.1007/s12520-015-0275-y">South</a> America, <a href="https://journals.co.za/doi/abs/10.10520/EJC97332">South Africa</a> and <a href="https://theconversation.com/australias-coastal-waters-are-rich-in-indigenous-cultural-heritage-but-it-remains-hidden-and-under-threat-166564">Australia</a>.</p>
<p>In a newly published <a href="https://authors.elsevier.com/sd/article/S0277-3791(23)00466-3">study in Quaternary Science Reviews</a>, we reveal details of the complex landscape that existed on the Northwest Shelf of Australia. It was unlike any landscape found on our continent today.</p>
<h2>A continental split</h2>
<p>Around 18,000 years ago, the last ice age ended. Subsequent warming caused sea levels to rise and drown huge areas of the world’s continents. This process <a href="https://theconversation.com/australias-coastal-living-is-at-risk-from-sea-level-rise-but-its-happened-before-87686">split the supercontinent of Sahul into New Guinea and Australia</a>, and cut Tasmania off from the mainland. </p>
<p>Unlike in the rest of the world, the now-drowned continental shelves of Australia were thought to be environmentally unproductive and little used by First Nations peoples.</p>
<p>But mounting archaeological evidence shows this assumption is incorrect. Many large islands off Australia’s coast – islands that once formed part of the continental shelves – <a href="https://theconversation.com/cave-dig-shows-the-earliest-australians-enjoyed-a-coastal-lifestyle-77326">show signs of occupation</a> before sea levels rose.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Overhead image of a coastline with modern day outlines and what it used to look like" src="https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=246&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=246&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=246&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=309&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=309&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566496/original/file-20231219-19-p3hmw0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=309&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: Satellite image of the submerged northwest shelf region. Right: Drowned landscape map of the study area.</span>
<span class="attribution"><span class="source">US Geological Survey, Geoscience Australia</span></span>
</figcaption>
</figure>
<p><a href="https://theconversation.com/in-a-first-discovery-of-its-kind-researchers-have-uncovered-an-ancient-aboriginal-archaeological-site-preserved-on-the-seabed-138108">Stone tools</a> have also recently been found on the sea floor off the coast of the Pilbara region of Western Australia.</p>
<p>However, archaeologists have only been able to speculate about the nature of the drowned landscapes people roamed before the end of the last ice age, and the size of their populations. </p>
<p>Our new research on the Northwest Shelf fills in some of those details. This area contained archipelagos, lakes, rivers and a large inland sea.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=677&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=677&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=677&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=850&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=850&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566506/original/file-20231219-19-6sk9bk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=850&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">During lower sea levels, a vast archipelago formed on the Australian northwest continental shelf (top). A modern day example of an archipelago on a submerged continental shelf is the Åland Islands near Finland (bottom).</span>
<span class="attribution"><span class="source">US Geological Survey, Geoscience Australia</span></span>
</figcaption>
</figure>
<h2>Mapping an ancient landscape</h2>
<p>To characterise how the Northwest Shelf landscapes changed through the last 65,000 years of human history, we projected past sea levels onto high-resolution maps of the ocean floor.</p>
<p>We found low sea levels exposed a vast archipelago of islands on the Northwest Shelf of Sahul, extending 500km towards the Indonesian island of Timor. The archipelago appeared between 70,000 and 61,000 years ago, and remained stable for around 9,000 years.</p>
<p>Thanks to the rich ecosystems of these islands, people may have migrated in stages from Indonesia to Australia, using the archipelago as stepping stones. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/an-incredible-journey-the-first-people-to-arrive-in-australia-came-in-large-numbers-and-on-purpose-114074">An incredible journey: the first people to arrive in Australia came in large numbers, and on purpose</a>
</strong>
</em>
</p>
<hr>
<p>With descent into the last ice age, polar ice caps grew and sea levels dropped by up to 120 metres. This fully exposed the shelf for the first time in 100,000 years.</p>
<p>The region contained a mosaic of habitable fresh and saltwater environments. The most salient of these features was the Malita inland sea.</p>
<p>Our projections show it existed for 10,000 years (27,000 to 17,000 years ago), with a surface area greater than 18,000 square kilometres. The closest example in the world today is the <a href="https://www.google.com/maps/place/Sea+of+Marmara/@40.7576502,28.3402382,8z/data=!3m1!4b1!4m6!3m5!1s0x14b568aa4776cfa7:0x5eb5ffc8155d820f!8m2!3d40.6681407!4d28.1122679!16zL20vMDc0cWo?entry=ttu">Sea of Marmara</a> in Turkey. </p>
<p>We found the Northwest Shelf also contained a large lake during the last ice age, only 30km north of the modern day Kimberley coastline. At its maximum extent it would have been half the size of Kati Thandi (Lake Eyre). Many ancient river channels are still visible on the ocean floor maps. These would have flowed into Malita sea and the lake.</p>
<h2>A thriving population</h2>
<p>A <a href="https://theconversation.com/the-first-australians-grew-to-a-population-of-millions-much-more-than-previous-estimates-142371">previous study</a> suggested the population of Sahul could have grown to millions of people.</p>
<p>Our ecological modelling reveals the now-drowned Northwest Shelf could have supported between 50,000 and 500,000 people at various times over the last 65,000 years. The population would have peaked at the height of the last ice age about 20,000 years ago, when the entire shelf was dry land. </p>
<p>This finding is supported by new <a href="https://www.nature.com/articles/s41586-023-06831-w">genetic research</a> indicating large populations at this time, based on data from people living in the Tiwi Islands just to the east of the Northwest Shelf. </p>
<p>At the end of the last ice age, rising sea levels drowned the shelf, compelling people to fall back as waters encroached on once-productive landscapes. </p>
<p>Retreating populations would have been forced together as available land shrank. New rock art styles appeared at this time in both <a href="https://www.science.org/doi/full/10.1126/sciadv.aay3922">the Kimberley</a> and <a href="https://www.sciencedirect.com/science/article/pii/S2352409X16304059?casa_token=Fjcbovqs0NcAAAAA:SG4045quovcQgEInsZOFFxW6rLIjCpnDVFi13xrWC2e7ALnXn2kKhttJzCkPzqlWXzKg3RDKUw">Arnhem Land</a>.</p>
<p>Rising sea levels and the drowning of the landscape is also recorded in the <a href="https://theconversation.com/ancient-aboriginal-stories-preserve-history-of-a-rise-in-sea-level-36010">oral histories</a> of First Nations people from all around the coastal margin, thought to have been passed down for over 10,000 years. </p>
<p>This latest revelation of the complex and intricate dynamics of First Nations people responding to rapidly changing climates lends growing weight to <a href="https://theconversation.com/ancient-knowledge-is-lost-when-a-species-disappears-its-time-to-let-indigenous-people-care-for-their-country-their-way-172760">the call</a> for more Indigenous-led environmental management in this country and elsewhere.</p>
<p>As we face an uncertain future together, deep-time Indigenous knowledge and experience will be essential for successful adaptation.</p><img src="https://counter.theconversation.com/content/219505/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kasih Norman received funding from an Australian Government Research Training Program Award and the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Corey J. A. Bradshaw receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Frédérik Saltré receives funding from Australian Research Council</span></em></p><p class="fine-print"><em><span>Tristen Anne Norrie Jones receives funding from Australian Research Council. </span></em></p><p class="fine-print"><em><span>Chris Clarkson 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 new study reveals a mosaic of habitable landscapes – now submerged by the ocean – once supported up to 500,000 people living in Australia’s northwest.Kasih Norman, Research Fellow, Griffith UniversityChris Clarkson, Professor in Archaeology, The University of QueenslandCorey J. A. Bradshaw, Matthew Flinders Professor of Global Ecology and Models Theme Leader for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders UniversityFrédérik Saltré, Research Fellow in Ecology for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders UniversityTristen Anne Norrie Jones, Academic Fellow, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2186412023-12-05T16:56:40Z2023-12-05T16:56:40ZThe climate change we caused is here for at least 50,000 years – and probably far longer<p>In February 2000, Paul Crutzen rose to speak at the International Geosphere-Biosphere Programme in Mexico. And when he spoke, people took notice. He was then one of the world’s most cited scientists, a Nobel laureate working on huge-scale problems – the ozone hole, the effects of a nuclear winter. </p>
<p>So little wonder that a word he improvised took hold and spread widely: this was the <a href="https://desertreport.org/the-anthropocene/">Anthropocene</a>, a proposed new geological epoch, representing an Earth transformed by the effects of industrialised humanity.</p>
<p>The idea of an entirely new and human-created geological epoch is a sobering scenario as context for the current UN climate summit, <a href="https://theconversation.com/uk/topics/cop28-132366">COP28</a>. The impact of decisions made at these and other similar conferences will be felt not just beyond our own lives and those of our children, but perhaps beyond the life of human society as we know it.</p>
<p>The Anthropocene is now in wide currency, but when Crutzen first spoke this was still a novel suggestion. In support of his new brain-child, Crutzen cited many planetary symptoms: enormous deforestation, the mushrooming of dams across the world’s large rivers, overfishing, a planet’s nitrogen cycle overwhelmed by fertiliser use, the rapid rise in greenhouse gases. </p>
<p>As for climate change itself, well, the warning bells were ringing, certainly. Global mean surface temperatures had risen by about half a degree since the mid-20th century. But, they were still within the norm for an interglacial phase of the ice ages. Among many emerging problems, climate seemed one for the future.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Heat danger sign, desert background" src="https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563662/original/file-20231205-15-omkrvg.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">Death Valley in California recently recorded one of the highest temperatures ever.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/road-sign-death-valley-warning-travelers-180367781">travelview / shutterstock</a></span>
</figcaption>
</figure>
<p>A little more than two decades on, the future has arrived. By 2022, global temperature had climbed another half a degree, the past nine years being the hottest since records began. And 2023 has seen climate records being not just broken, but smashed. </p>
<p>By September there had already been 38 days when global average temperatures exceeded pre-industrial ones by 1.5°C, the <a href="https://www.ipcc.ch/2018/10/08/summary-for-policymakers-of-ipcc-special-report-on-global-warming-of-1-5c-approved-by-governments/">safe limit of warming</a> set by the UN Convention on Climate Change (UNFCCC) in the Paris agreement. In previous years that was rare, and before 2000 this milestone had never been recorded. </p>
<p>With this leap in temperatures came record-breaking heatwaves, wildfires and floods, exacerbated by other local human actions. Climate has moved centre stage on an Anthropocene Earth.</p>
<p>Why this surge in temperatures? In part, it’s been the inexorable rise in greenhouse gases, as fossil fuels continue to dominate human energy use. When Crutzen spoke in Mexico, atmospheric carbon dioxide levels were about 370 parts per million (ppm), already up from the pre-industrial 280 ppm. They’re now <a href="https://gml.noaa.gov/ccgg/trends/">around 420 ppm</a>, and climbing by some 2 ppm per year.</p>
<p>In part, the warming results from cleaner skies in the past few years, both on land and at sea, thanks to new regulations <a href="https://www.washingtonpost.com/business/energy/2023/03/27/climate-change-how-cleaning-up-pollution-may-heat-the-planet/dd7496b0-ccdc-11ed-8907-156f0390d081_story.html">phasing out old power stations and dirty sulphur-rich fuels</a>. As the industrial haze clears, more of the sun’s energy makes it through the atmosphere and onto land, and the full force of global warming kicks in. </p>
<p>In part, our planet’s heat-reflecting mirrors are shrinking, as sea ice melts away, initially in the Arctic, and in the last two years, precipitously, around Antarctica too. And climate feedbacks seem to be taking effect, too. A new, <a href="https://theconversation.com/rising-methane-could-be-a-sign-that-earths-climate-is-part-way-through-a-termination-level-transition-211211">sharp rise in atmospheric methane</a> – a far more potent greenhouse gas than carbon dioxide – since 2006 seems to be sourced from an increase in rotting vegetation in tropical wetlands in a warming world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="https://www.shutterstock.com/image-photo/aerial-view-coal-power-plant-high-2136951757" src="https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563669/original/file-20231205-19-5o41co.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">There is about 50% more carbon dioxide in the atmosphere compared to before the industrial revolution.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aerial-view-coal-power-plant-high-2136951757">Bilanol / shutterstock</a></span>
</figcaption>
</figure>
<p>This latest warming step has already taken the Earth into levels of climate warmth not experienced for some 120,000 years, into those of the last interglacial phase, <a href="https://www.nature.com/articles/s41586-020-03155-x">a little warmer</a> than the current one. There is yet more warming <a href="https://academic.oup.com/oocc/article/3/1/kgad008/7335889?searchresult=1">in the pipeline</a> over coming centuries, as various feedbacks take effect. </p>
<p>A <a href="https://www.nature.com/articles/s41558-023-01818-x">recent study</a> on the effects of this warming on Antarctica’s ice suggests that “policymakers should be prepared for several metres of sea-level rise over the coming centuries” as the pulse of warmth spreads through the oceans to undermine the great polar ice-sheets. </p>
<p>This remains the case even in the most optimistic scenario where carbon dioxide emissions are reduced quickly. But emissions continue to rise steeply, to deepen the climate impact.</p>
<h2>Controls have been overridden</h2>
<p>To see how this might play out on a geological timescale, we need to look through the lens of the Anthropocene. A delicately balanced planetary machinery of regular, multi-millennial variations in the Earth’s spin and orbit has tightly controlled patterns of warm and cold for millions of years. </p>
<p>Now, suddenly, this control machinery has been overridden by a trillion tons of carbon dioxide injected into the atmosphere in little more than a century.</p>
<p>Modelling the effects of this pulse through the Earth System shows that this new, suddenly disrupted, climate pattern is here for <a href="https://doi.org/10.5194/esd-12-1275-2021">at least 50,000 years</a> and probably far longer. It’s a large part of the way our planet has changed fundamentally and irreversibly, to become comparable to some of the great climate change events in deep Earth history.</p>
<p>So will this particular COP meeting, with fossil fuel interests <a href="https://theconversation.com/cop28-inside-the-united-arab-emirates-the-oil-giant-hosting-2023-climate-change-summit-217859">so strongly represented</a>, make a difference? The bottom line is that attaining, and stabilising carbon emissions at “net zero” is only a crucial first step. </p>
<p>To retrieve the kind of climate optimal for humanity, and for life as a whole to thrive, negative emissions are needed, to take carbon out of the atmosphere and ocean system and put it back underground. For future generations, there is much at stake.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?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">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<hr><img src="https://counter.theconversation.com/content/218641/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jens Zinke receives funding for his general research from the Royal Society, NERC and the German DFG. </span></em></p><p class="fine-print"><em><span>Colin Waters, Jan Zalasiewicz, and Mark Williams 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>The Anthropocene began quickly, but will last deep into the geological future.Jan Zalasiewicz, Professor of Palaeobiology, University of LeicesterColin Waters, Honorary Professor, Department of Geology, University of LeicesterJens Zinke, Professor of Palaeobiology, University of LeicesterMark Williams, Professor of Palaeobiology, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2172862023-11-29T23:11:39Z2023-11-29T23:11:39ZNew unified theory shows how past landscapes drove the evolution of Earth’s rich diversity of life<p>Earth’s surface is the living skin of our planet – it connects the physical, chemical and biological systems.</p>
<p>Over geological time, this surface evolves. Rivers fragment the landscape into an environmentally diverse range of habitats. These rivers also transfer sediments from the mountains to the continental plains and ultimately the oceans. </p>
<p>The idea that landscapes have influenced the trajectory of life on our planet has a long history, dating back to the early 19th century scientific narratives of German polymath <a href="https://learningfromlandscapes.com/2019/06/11/humboldt-the-invention-of-nature/">Alexander von Humboldt</a>. While we’ve learnt more since then, many aspects of biodiversity evolution remain enigmatic. For example, it’s still unclear why there is a 100-million-year gap between the explosion of marine life and the development of plants on continents.</p>
<p>In research <a href="https://www.nature.com/articles/s41586-023-06777-z">published in Nature</a> today, we propose a new theory that relates the evolution of biodiversity over the past 540 million years to sediment “pulses” controlled by past landscapes.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Uxutnt44NKU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>10 years of computational time</h2>
<p>Our simulations are based on an open-source code released as part of a <a href="https://theconversation.com/scientists-just-revealed-the-most-detailed-geological-model-of-earths-past-100-million-years-200898">Science paper</a> published earlier this year.</p>
<p>To drive the evolution of the landscape through space and time in our computer model, we used a series of reconstructions for what the climate and tectonics were like in the past.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two colourful computer simulated Earth globes side by side" src="https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=291&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=291&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=291&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=365&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=365&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558304/original/file-20231108-27-yqmk6n.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=365&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These two globes from our simulation show landscapes 200 million years ago (just before the Pangea supercontinent broke up, left) and 15 million years ago (right), after the formation of the Andes, Alps and Himalayas.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>We then compared the results of our global simulations with reconstructions of marine and continental biodiversity over the past 540 million years.</p>
<p>To perform our computer simulations, we took advantage of Australia’s <a href="https://nci.org.au/">National Computational Infrastructure</a> running on several hundreds of processors. The combined simulations presented in our study are equivalent to ten years of computational time.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-the-earths-last-supercontinent-broke-apart-to-form-the-world-we-have-today-131632">How the Earth's last supercontinent broke apart to form the world we have today</a>
</strong>
</em>
</p>
<hr>
<h2>Marine life and river sediment were closely linked</h2>
<p>In our model, we discovered that the more sediment rivers carried into the oceans, the more the sea life diversified (a positive correlation). You can see this tracked by the red line in the chart below. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=222&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=222&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=222&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=279&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=279&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560720/original/file-20231121-3914-t01a3j.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=279&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reconstructed sediment fluxes to the oceans (red line) versus diversity of marine animals (black line, adapted from C. Bentley using Sepkoski’s compendium) from the Cambrian through to the Neogene.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>As the continents weather, rivers don’t just carry sediment into the oceans, they also bring a large quantity of nutrients. These nutrients, such as carbon, nitrogen and phosphorus, are essential to the <a href="https://www.britannica.com/science/biogeochemical-cycle">biological cycles</a> that move vital elements through all living things.</p>
<p>This is why we think rivers delivering more or less nutrients to the ocean – on a geological timescale of millions of years – is related to the diversification of marine life.</p>
<p>Perhaps even more surprisingly, we found that episodes of mass extinctions in the oceans happened shortly after significant decreases in sedimentary flow. This suggests that a lack or deficiency of nutrients can destabilise biodiversity and make it vulnerable to catastrophic events (like asteroid impacts or volcanic eruptions).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-a-mass-extinction-and-are-we-in-one-now-122535">What is a 'mass extinction' and are we in one now?</a>
</strong>
</em>
</p>
<hr>
<h2>Landscapes also drove the diversity of plants</h2>
<p>On the continents, we designed a variable that integrates sediment cover and landscape ruggedness to describe the continents’ capacity to host diverse species. </p>
<p>Here we also found a striking correlation (see below) between our variable and plant diversification for the past 400 million years. This highlights how changes in landscape also have a strong influence on species diversifying on land. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=232&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=232&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=232&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=291&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=291&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560719/original/file-20231121-27-hlx0p3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=291&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 cover in continental regions (black line) versus the long-term trend in land-plant diversity. Illustrations from Rebecca Horwitt.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>We hypothesise that as Earth’s surface was gradually covered with thicker soil, richer in nutrients deposited by rivers, plants could develop and diversify with more elaborate root systems. </p>
<p>As plants slowly expanded across the land, the planet ended up hosting varied environments and habitats with favourable conditions for plant evolution, such as the emergence of flowering plants some 100 million years ago.</p>
<h2>A living planet</h2>
<p>Overall, our findings suggest the diversity of life on our planet is strongly influenced by landscape dynamics. At any given moment, Earth’s landscapes determine the maximum number of different species continents and oceans can support.</p>
<p>This shows it’s not just tectonics or climates, but their interactions that determine the long-term evolution of biodiversity. They do this through sediment flows and changes to the landscapes at large.</p>
<p>Our findings also show that biodiversity has always evolved at the pace of plate tectonics. That’s a pace incomparably slower than the current rate of extinction caused by human activity.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/five-ways-you-can-help-stop-biodiversity-loss-in-your-area-and-around-the-world-196746">Five ways you can help stop biodiversity loss in your area – and around the world</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/217286/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This research was undertaken with resources from the National Computational Infrastructure supported by the Australian Government and from Artemis HPC supported by the University of Sydney. This work was supported by an Australian Research Council grant.</span></em></p><p class="fine-print"><em><span>Beatriz Hadler Boggiani, Laurent Husson, and Manon Lorcery 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>For decades, scientists have tried to uncover the cause of long-term changes in Earth’s biodiversity. New simulations point at geography playing a critical role.Tristan Salles, Senior Lecturer, University of SydneyBeatriz Hadler Boggiani, PhD Candidate, University of SydneyLaurent Husson, Earth sciences researcher, Université Grenoble Alpes (UGA)Manon Lorcery, PhD Candidate, Université Grenoble Alpes (UGA)Licensed 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">
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<span class="caption"></span>
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<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>
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<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>
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<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>
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</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>
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<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/2134792023-11-08T13:53:29Z2023-11-08T13:53:29ZTurkana stone beads tell a story of herder life in a drying east Africa 5,000 years ago<p>On the shores of Lake Turkana in east Africa, about 5,000 to 4,000 years ago, pastoralists buried their dead in communal cemeteries that were marked by stone circles and pillars. <a href="https://doi.org/10.1073/pnas.1721975115">The north-west Kenya “pillar sites”</a> were built around the same time as Stonehenge in the UK. But these places have a different story to tell: about how mortuary traditions reflect people’s environments, behaviours and reactions to change.</p>
<p>The burial sites appeared at a time of major <a href="https://www.sciencedirect.com/science/article/pii/S027737912200021X">environmental</a> and economic <a href="https://www.sciencedirect.com/science/article/pii/S0012825217303331">change</a> in the region. The Sahara, which received enough rainfall 9,000-7,000 years ago to sustain populations of fisher-hunter-gatherers and pastoralists, was <a href="https://pastglobalchanges.org/publications/pages-magazines/pages-magazine/7413">drying</a>, causing groups of people to move east and south. Even in eastern Africa, lake levels were dropping dramatically; grassy plains were expanding. Around Lake Turkana, people began herding animals in addition to fishing and foraging. </p>
<p>At several of the pillar sites around Lake Turkana, archaeologists have found that hundreds of people were <a href="https://link.springer.com/article/10.1007/s12520-019-00914-4">ceremonially interred</a> under large, circular platform mounds. Many of those individuals were found wearing remarkable colourful stone beads, some as part of necklaces, bracelets, earrings, and other jewellery worn, for example, around the waist. These beautiful personal ornaments include blue-green amazonite, soft pink zeolite, deep red chalcedony, purple fluorite and green talc, among other minerals and rocks.</p>
<p>I study relationships between humans and their environments, especially at times of major economic transformations, using scientific techniques applied to archaeology. I recently led a team of experts in geology and archaeology of the region to conduct the first comprehensive mineralogical <a href="https://www.tandfonline.com/doi/full/10.1080/00934690.2023.2232703">analysis</a> of the Turkana stone beads. </p>
<p>The focus of our study was to discover what types of minerals and rocks the early herders had used to make adornments, and where these materials came from. </p>
<p>This kind of information can tell archaeologists about the role of artefacts in the society that used them.</p>
<h2>Wearing beads</h2>
<p>Humans have been making and wearing beads for over <a href="https://www.science.org/doi/10.1126/sciadv.abi8620">140,000 years</a>. Beads are one of the oldest forms of symbolism and are often used as <a href="https://theconversation.com/the-tiny-ostrich-eggshell-beads-that-tell-the-story-of-africas-past-128577">adornment</a> in a culture. Wearing something on your body is an expressive choice that can have many meanings, such as protection, acknowledgement of friendships and bonds, status or role in society. Personal ornaments like beads may indicate a common cultural understanding. </p>
<p>Analysis of <a href="https://theconversation.com/what-excavated-beads-tell-us-about-the-when-and-where-of-human-evolution-53695">beads in archaeological sites</a> has shown that we can learn many things from them. </p>
<p>At the Turkana pillar sites, the stone bead tradition was clearly important, partly because of the number of beads found accompanying burials, and partly because the practice persisted for hundreds of years. </p>
<p>Knowing the range of materials helps us understand landscape use in the past: where people were buried, where they watered their animals, seasonal movements for grazing, special yearly trips to significant places and other movements. Pastoralists recorded or marked their worlds by what they left behind and what they took with them. Patterns in the composition of the bead collections may indicate there was communication and exchange of objects across the region.</p>
<h2>Sorting the stone beads</h2>
<p>Of the six pillar sites that have been excavated by archaeologists, three have yielded substantial assemblages of stone beads: Lothagam North, Manemanya and Jarigole. Our team began by sorting the stone beads by site, and by their mineral and rock types.</p>
<p>Our study identified the mineral characteristics of 806 stone beads. We looked at properties like <a href="https://www.britannica.com/science/specific-gravity">specific gravity</a>, crystal and molecular structure, and the characteristic emissions that are particular to certain minerals. </p>
<p>What we found was a strikingly diverse set of beads that varied by site. The visual characteristics of some of the beads – colour, lustre and so on – may have made them particularly valuable or had a special meaning economically, socially, spiritually or symbolically. Their source and workability may also have given them a certain value. </p>
<p>Pink zeolites and turquoise amazonites were the most common stone beads at the site of Lothagam North, comprising over three-quarters of the assemblage. This was very similar to the site of Jarigole, located across the lake. The sites are hundreds of kilometres apart, with Lake Turkana in between – suggesting a cultural connection between them.</p>
<p>In contrast, the kinds of beads at Manemanya were different: mostly softer and paler pink and off-white calcite beads that were quite large. Further, while at Lothagam North there often were just a few beads found with any individual, one person at Manemanya was buried with over 300 stone beads and over 10,000 ostrich eggshell beads. </p>
<p>This suggests that although having stone beads was a commonality across the sites, distinctions – and distinct meanings for different people – did exist. </p>
<h2>Sourcing stones</h2>
<p>We also wanted to know whether the beads were produced from local sources (within a few days’ walk) or acquired through long-distance journeys or trade. Sourcing allows us to partially reconstruct how the earliest pastoralists moved around the landscape during the year.</p>
<p>A survey of the areas west of Lake Turkana and a search of the published literature on the geology of the region identified places where these materials might have come from.</p>
<p>There are possible sources for most of these materials within about 150km of the pillar sites. Limestone rocks may have been procured easily near the lake. Some of the tougher materials, like the chalcedonies, could have been carried to the lake area by rivers, to be picked up perhaps by someone watering cattle or fetching water from a stream. Other minerals come from a specific source. The variety of bead types demonstrates that people knew their landscape well.</p>
<p>Sometimes, they went out of their way to get certain minerals, or perhaps traded for them. The closest known sources for amazonite and fluorite are, respectively, 225 km, in southern Ethiopia; and 350 km, near the modern city of Eldoret, Kenya. </p>
<p>These suggest that bead making was not just a casual affair; material selection was intentional.</p>
<h2>Local landscapes</h2>
<p>Early herders in the Turkana Basin obtained materials from both local and distant places, and shaped them into personal adornments. These stone beads were placed with the dead, in numbers and combinations that differed by individual and place. We don’t yet fully know what they meant – but future research in the Turkana Basin will continue to explore the lives and legacies of these pioneering herders as they negotiated new environmental and social landscapes.</p>
<p><em>Edits and comments for this article were provided by Late Prehistory of West Turkana project co-directors Drs. Elizabeth Hildebrand and Katherine Grillo, project minerologist Mark Helper, and Emmanuel Ndiema, who helped lead the sourcing study.</em></p><img src="https://counter.theconversation.com/content/213479/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Funding for Klehm's research on the pillar site stone beads was provided by the Wenner-Gren Foundation.</span></em></p>Mineralogical analysis of 5,000-year-old stone beads from Turkana, Kenya suggest a novel mortuary tradition by early pastoralists.Carla Klehm, Research Assistant Professor, Center for Advanced Spatial Technologies, University of ArkansasLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2157072023-10-17T19:08:01Z2023-10-17T19:08:01ZNASA’s Psyche asteroid mission: a 3.6 billion kilometre ‘journey to the centre of the Earth’<figure><img src="https://images.theconversation.com/files/554157/original/file-20231017-17-gr95ww.jpg?ixlib=rb-1.1.0&rect=11%2C41%2C3982%2C3652&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA24471">NASA / JPL-Caltech / ASU</a></span></figcaption></figure><p>Psyche was the Greek goddess of the soul, born a mere mortal and later married to Eros, the God of love. Who knows why the Italian astronomer Annibale de Gasparis gave her name to a celestial object he observed one night in 1852?</p>
<p>Psyche was only the 16th “asteroid” ever discovered: inhabitants of the Solar System that were neither the familiar planets nor the occasional visitors known as comets. Today we know the asteroid belt between the orbits of Mars and Jupiter contains millions of space rocks, ranging in size from the dwarf planet Ceres down to tiny pebbles and grains of dust.</p>
<p>Among all these, Psyche is still special. With an average diameter of around 226km, the potato-shaped planetoid is the largest “M-type” asteroid, made largely of iron and nickel, much like Earth’s core. </p>
<p>Last week NASA <a href="https://www.jpl.nasa.gov/missions/psyche">launched a spacecraft to rendezvous with Psyche</a>. The mission will take a six-year, 3.6 billion kilometre journey to gather clues that Earth scientists like me will interrogate for information about the inaccessible interior of our own world. </p>
<h2>Natural laboratories</h2>
<p>M-type asteroids like Psyche are thought to be the remnants of planets destroyed in the early years of the Solar System. In these asteroids, heavier elements (like metals) sank toward the centre and lighter elements floated up to the outer layers. Then, due to collisions with other objects, the outer layers were torn away and most of the material was ejected into space, leaving behind the metal-rich core.</p>
<p>These metallic worlds are perfect “natural laboratories” for studying planetary cores.</p>
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Read more:
<a href="https://theconversation.com/nasas-psyche-mission-is-set-for-launch-heres-how-it-could-unveil-the-interior-secrets-of-planets-215547">Nasa's Psyche mission is set for launch – here's how it could unveil the interior secrets of planets</a>
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<p>Our current methods for studying Earth’s core are quite indirect. We sometimes get tiny glimpses into the Solar System’s early history – and hence our planet’s own history – from metallic meteorites, parts of asteroids that fall to Earth. However, this view is very limited.</p>
<p>Another way to study the core is using seismology: studying how the vibrations caused by earthquakes travel through the planet’s interior, in much the same way doctors can use ultrasound to see the inside of our bodies.</p>
<p>However, on Earth we have fewer seismographs in the oceans and in the Southern Hemisphere, which restrict what we can see of the core.</p>
<p>What’s more, the core is buried beneath the planet’s outer layers, which obscure our view even further. It is like looking at a distant object through an imperfect lens.</p>
<p>As well as seismology, we learn about the core through lab experiments attempting to recreate the high pressures and temperatures of Earth’s interior.</p>
<p>We take the observations from seismology and lab experiments and try to explain them using computer simulations. In <a href="https://www.nature.com/articles/s41467-023-41725-5">a recent paper in Nature Communications</a>, we discussed the current challenges in studying Earth’s core – and the ways forward.</p>
<h2>What the Psyche mission hopes to discover</h2>
<p>We can think of NASA’s mission to Psyche as a journey to the centre of Earth without having to travel down through the planet’s rocky crust, the slowly moving mantle and the liquid core.</p>
<p>The mission aims to find out whether Psyche really is the core of a destroyed planet, that was initially hot and molten but slowly cooled and solidified like the core of our planet. On the other hand it’s possible Psyche is made of material that was never melted at all.</p>
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Read more:
<a href="https://theconversation.com/what-are-asteroids-made-of-a-sample-returned-to-earth-reveals-the-solar-systems-building-blocks-176548">What are asteroids made of? A sample returned to Earth reveals the Solar System's building blocks</a>
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<p>NASA also wants to discover how old Psyche’s surface is, which would reveal how long ago it lost its outer layers. The mission will also investigate the asteroid’s chemical composition: whether it contains lighter elements alongside iron and nickel, such as oxygen, hydrogen, carbon, silicon and sulphur. The presence or absence of these could give us clues about our own planet’s evolution.</p>
<p>Information about Psyche’s shape, mass, and gravity distribution will also be gathered. Also, the potential for future mineral exploration should be studied.</p>
<p>All of this will be possible with the broad-spectrum cameras, spectrometers, magnetometers, gravimeters and other instruments the spacecraft carries. Scientists like me will follow with impatience the mission’s long journey through space.</p><img src="https://counter.theconversation.com/content/215707/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hrvoje Tkalčić receives funding from the Australian Research Council. </span></em></p>A distant lump of space rock may have a surprising amount in common with the core of our own planet.Hrvoje Tkalčić, Professor, Head of Geophysics, Director of Warramunga Array, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2136752023-10-02T15:01:33Z2023-10-02T15:01:33ZMercury: shrinking planet is still getting smaller – new research<figure><img src="https://images.theconversation.com/files/548561/original/file-20230915-15-alw9f3.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1664%2C749&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Perspective view of a lobate scarp on Mercury named Carnegie Rupes, colour-coded according to surface altitude. The crater near the middle is nearly 40 km across.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/a-striking-perspective">NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington</a></span></figcaption></figure><p>Planetary scientists have long known that Mercury has been shrinking for billions of years. Despite being the closest planet to the Sun, its interior has been cooling down as internal heat leaks away. This means that the rock (and, within that, the metal) of which it is composed must have contracted slightly in volume. </p>
<p>It is unknown, however, to what extent the planet is still shrinking today – and, if so, for how long that is likely to continue. Now our new paper, <a href="https://www.nature.com/articles/s41561-023-01281-5">published in Nature Geoscience</a>, offers fresh insight.</p>
<p>Because Mercury’s interior is shrinking, its surface (crust) has progressively less area to cover. It responds to this by developing “thrust faults” – where one tract of terrain gets pushed over the adjacent terrain (see image below). This is like the wrinkles that form on an apple as it ages, except that an apple shrinks because it is drying out whereas Mercury shrinks because of thermal contraction of its interior.</p>
<p>The first evidence of Mercury’s shrinkage came in 1974 when the Mariner 10 mission transmitted pictures of kilometres-high scarps (ramp-like slopes) snaking their way for hundreds of kilometres across the terrain. Messenger, which orbited Mercury 2011-2015, showed many more “lobate scarps” (as they had become known) in all parts of the globe. </p>
<p>From such observations, it was possible to deduce that gently dipping geological faults, known as thrusts, approach the surface below each scarp and are a response to Mercury having shrunk in radius by a total of about 7km. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Block diagram showing a thrust fault" src="https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548543/original/file-20230915-17-tn3nfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&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 cross-section though Mercury’s crust.</span>
<span class="attribution"><span class="source">D A Rothery</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But when did this happen? The accepted way to work out the age of Mercury’s surface is to count the density of impact craters. The older the surface, the more craters. But this method is tricky, because the rate of impacts that produce craters was much greater in the deep past.</p>
<p>However, it was always clear that Mercury’s scarps must be fairly ancient, because although they cut through some older craters, quite a few younger craters are superimposed upon the scarps and so the scarps must be older than those.</p>
<h2>When did that scarp last move?</h2>
<p>The consensus view is that Mercury’s scarps are mostly about 3 billion years old. But are all of them that old? And did the older ones cease moving long ago or are they still active today?</p>
<p>We should not expect that the thrust fault below each scarp has moved only once. The biggest earthquake on Earth in recent years, the magnitude 9 <a href="https://education.nationalgeographic.org/resource/tohoku-earthquake-and-tsunami/">Tohoku earthquake</a> offshore of Japan in 2011 which caused the Fukushima disaster, was the result of a sudden jump by 20 metres along a 100km length of the responsible thrust fault.</p>
<p>Mercury’s biggest “earthquakes” are probably smaller. To accumulate the 2-3km of total shortening that can be measured across a typical scarp on Mercury would take hundreds of magnitude 9 “earthquakes”, or more likely millions of smaller events, which could have been spread out over billions of years.</p>
<p>Getting a handle on the scale and duration of fault movements on Mercury is important, because we would not expect Mercury’s thermal contraction to have entirely finished, even though this should be slowing down.</p>
<h2>Cracking up</h2>
<p>Until now, evidence has been sparse. But our team found unambiguous signs that many scarps have continued to move in geologically recent times, even if they were initiated billions of years ago.</p>
<p>This work was triggered when a PhD student at Open University in the UK, Ben Man, noticed that some scarps have small fractures piggy-backing on their stretched upper surfaces. He interpreted these as “grabens”, the geological word to describe a strip of ground dropped down between two parallel faults. </p>
<p>This typically happens when the crust is stretched. Stretching may seem surprising on Mercury, where overall the crust is being compressed, but Man realised that these grabens would occur if a thrust slice of crust has been bent as it is pushed over the adjacent terrain. If you try to bend a piece of toast, it may crack in a similar way.</p>
<p>The grabens are less than 1km wide and less than about 100 meters deep. Such comparatively small features must be much younger than the ancient structure on which they sit, otherwise they would have already been erased from view by impacts tossing material across the surface in a process aptly named “<a href="https://en.wikipedia.org/wiki/Impact_gardening">impact gardening</a>”.</p>
<p>Based on the rate of blurring resulting from impact gardening, we calculated that the majority of grabens are less than about 300 million years old. This suggests that the latest movement must have happened equally “recently”. </p>
<figure class="align-center ">
<img alt="Lobate scarp, with visible grabens on its crest." src="https://images.theconversation.com/files/548553/original/file-20230915-23-q7pp3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548553/original/file-20230915-23-q7pp3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=457&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548553/original/file-20230915-23-q7pp3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=457&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548553/original/file-20230915-23-q7pp3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=457&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548553/original/file-20230915-23-q7pp3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=574&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548553/original/file-20230915-23-q7pp3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=574&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548553/original/file-20230915-23-q7pp3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=574&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lobate scarp, with visible grabens on its crest.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Working with the most detailed images provided by MESSENGER, Man found 48 large lobate scarps that definitely have small grabens. A further 244 were topped by “probable” grabens – which aren’t seen quite clearly enough on the best MESSENGER images.</p>
<figure class="align-center ">
<img alt="Global map of shortening structures atop lobate scarps" src="https://images.theconversation.com/files/548554/original/file-20230915-17-kpyawm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548554/original/file-20230915-17-kpyawm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548554/original/file-20230915-17-kpyawm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548554/original/file-20230915-17-kpyawm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548554/original/file-20230915-17-kpyawm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=380&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548554/original/file-20230915-17-kpyawm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=380&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548554/original/file-20230915-17-kpyawm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=380&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Global map of shortening structures atop lobate scarps. Triangles = definite. Circles = probable.</span>
<span class="attribution"><span class="source">D A Rothery</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>These are now prime targets for confirmation by the imaging system of the joint European/Japanese <a href="https://theconversation.com/europe-blasts-off-to-mercury-heres-the-rocket-science-104641">BepiColombo</a> mission, which should start operating in orbit around Mercury early in 2026. </p>
<h2>Lessons from the Moon</h2>
<p>The Moon has also cooled and contracted. Its lobate scarps are considerably smaller and less spectacular than those on Mercury, but on the Moon we know for sure that as well as being geologically recent, some are active today. </p>
<p>This is because <a href="https://theconversation.com/the-moon-is-still-geologically-active-study-suggests-116768">recent reanalysis</a> of the locations of moonquakes recorded by seismometers (vibration detectors) left on the Moon’s surface by several Apollo missions shows that moonquakes are clustered close to lobate scarps. </p>
<p>Also, the most detailed images of the Moon’s surface from orbit reveal the tracks made by boulders bouncing down scarp faces, presumably after being dislodged by moonquakes. Much smaller in scale than Mercury’s grabens, similar logic applies to these boulder tracks: they would become erased from visibility after only a few million years, so they must be young. </p>
<p>BepiColombo won’t be landing and so we have no prospect of collecting any seismic data on Mercury. However, as well as showing small grabens more clearly, its most detailed images might reveal boulder tracks that could be additional evidence of recent quakes. I am looking forward to finding out.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/bepicolombos-first-close-up-pictures-of-mercurys-surface-hint-at-answers-to-the-planets-secrets-168159">BepiColombo's first close-up pictures of Mercury's surface hint at answers to the planet's secrets</a>
</strong>
</em>
</p>
<hr>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-more-we-learn-about-mercury-the-weirder-it-seems-55972">The more we learn about Mercury, the weirder it seems</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/213675/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Rothery is Professor of Planetary Geosciences at the Open University. He 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 and BepiColombo, and from 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>Mercury has shrunk by7 km. Most of this happened long ago, but now we have evidence that it continues.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2143092023-10-02T15:01:31Z2023-10-02T15:01:31ZGlaciers can give us clues about when a volcano might erupt<figure><img src="https://images.theconversation.com/files/550281/original/file-20230926-23-2qa2o3.jpg?ixlib=rb-1.1.0&rect=0%2C588%2C4000%2C2396&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/skier-snowy-volcano-niseko-hokkaido-japan-2139353883">Mayumi.K.Photography/Shutterstock</a></span></figcaption></figure><p>Globally, there is about one volcano erupting <a href="https://volcanoes.usgs.gov/vsc/file_mngr/file-153/FAQs.pdf">each week</a>. Volcanic unrest kills an average of <a href="https://doi.org/10.1186/s13617-017-0067-4">500 people every year</a> and costs the global economy roughly US$7 billion (£5.7 billion). With <a href="https://www.sciencedirect.com/science/article/abs/pii/S1464286702000025#:%7E:text=Using%20recently%20compiled%20databases%20of,during%20the%20last%2010%2C000%20years.">one in 20 people</a> living somewhere at risk of volcanic activity, every effort that can be made to improve the monitoring of volcanoes is important. </p>
<p>This is especially true for volcanoes covered by glaciers – <a href="https://doi.org/10.1016/j.gloplacha.2020.103356">roughly 18%</a> of all volcanoes on Earth. When these erupt, the consequences can be among the deadliest of all natural disasters. </p>
<p>The Nevado del Ruiz volcano in Colombia killed nearly 25,000 people in 1985 when its eruption caused the near-instantaneous melting of overlying glacier ice and snow, forming a deadly mix of water and eruptive material (mostly ash and gas) that hurtled down a populated valley at incredible speed. Glaciers on volcanoes are not only dangerous, they make monitoring volcanoes from the ground and from above using satellites particularly tricky.</p>
<figure class="align-center ">
<img alt="A mountainous scene with a large smoking crater covered in snow." src="https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&rect=0%2C0%2C799%2C501&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=473&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=473&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550278/original/file-20230926-29-z15x8u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=473&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The crater of Nevado del Ruiz in 2023.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Nevado_del_Ruiz#/media/File:Volcan_Nevado_del_Ruiz-2023.png">Portal Servicio Geológico Colombiano</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Fortunately, in <a href="https://doi.org/10.1130/G51411.1">a new study</a>, we found that these glaciers can offer clues about what’s happening to the volcano below. This could help improve the monitoring of volcanoes that might erupt in the future.</p>
<h2>Hotting up</h2>
<p>Research has tentatively revealed that volcano temperatures change over time and <a href="https://www.nature.com/articles/s41561-021-00705-4">increase towards an eruption</a>. In some cases, these changes can be recorded over several years before visible unrest begins. It’s possible to monitor this via satellite, but the signal can be masked by clouds or disrupted by the ice or snow sitting on top of a volcano.</p>
<figure class="align-center ">
<img alt="A volcano spewing ash, seen from a distant grassland." src="https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550283/original/file-20230926-25-rlduxr.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">
<figcaption>
<span class="caption">Vaporised snow and ash combine during eruptions of ice-clad volcanoes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/karimskiy-volcano-volcanic-eruption-kamchatka-ash-468722087">LukaKikina/Shutterstock</a></span>
</figcaption>
</figure>
<p>Although thought to move very slowly, glaciers are quite dynamic. These rivers of ice flow faster or slower depending on what’s happening in their environment. This may come as no surprise – most glaciers around the world are now shrinking due to rising global temperatures, and many will soon disappear.</p>
<p>But glaciers are sensitive to other changes too. For example, if a volcano’s temperature increases over time, the glacier sitting on it will melt faster and shrink to higher elevations. We thought this shrinking might indicate that something is brewing in the volcano below, so we analysed the elevation of 600 glaciers that either sat on or near (between 1km and 15km) 37 ice-clad volcanoes in South America using computer models. </p>
<figure class="align-center ">
<img alt="A volcano with an ice-covered summit seen from a distance." src="https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550277/original/file-20230926-15-6d5e4q.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">Ice-clad Cotopaxi volcano in the Andes mountains, Ecuador.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cotopaxi-volcano-appears-clouds-light-snow-484202014">Ecuadorpostales/Shutterstock</a></span>
</figcaption>
</figure>
<p>Normally, elevation does not vary much from glacier to glacier within the same climate region. But our results showed that, in some cases, glacier elevation progressively decreases with distance from a volcano. In other words, glaciers further from a volcano tended to reach further down the mountain valley that hosted them.</p>
<p>The drop in glacier elevation moving away from a volcano can be as much as 600 metres. This is bigger than what we would expect to see with natural variation alone, especially for the relatively small glaciers we investigated. </p>
<h2>A sign from below</h2>
<p>Glaciers sitting on volcanoes are typically confined to higher elevations (230 metres higher, on average) compared with those nearby. Most importantly, our study showed that this difference is linked to measured volcanic temperatures: volcanoes with higher measured temperatures hosted glaciers at particularly high elevations.</p>
<p>This is really exciting because it paves the way for using glaciers to improve volcano monitoring. If the elevation of a glacier on top of a volcano changes over a short period (five to ten years, say), and the speed of this change cannot be attributed to climate change, it might signal a forthcoming period of volcanic unrest.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bylTVZFQOsE?wmode=transparent&start=1" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Glaciers sitting on volcanoes act as icy thermometers in volcano monitoring. This insight could help create early-warning systems capable of reducing the deadliness of erupting ice-clad volcanoes.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?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">
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<p class="fine-print"><em><span>Matteo Spagnolo receives funding from NERC and the Leverhulme Trust. </span></em></p><p class="fine-print"><em><span>Brice Rea receives funding from NERC. </span></em></p><p class="fine-print"><em><span>Iestyn Barr receives funding from the Leverhulme Trust and NERC </span></em></p>Like icy thermometers, glaciers overlying volcanoes shift according to temperature changes below.Matteo Spagnolo, Professor of Geography and the Environment, School of Geosciences, University of AberdeenBrice Rea, Professor of Geography, University of AberdeenIestyn Barr, Reader in Physical Geography, Manchester Metropolitan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2129502023-09-22T12:31:11Z2023-09-22T12:31:11ZChandrayaan-3’s measurements of sulfur open the doors for lunar science and exploration<figure><img src="https://images.theconversation.com/files/548875/original/file-20230918-17-zzsqlo.png?ixlib=rb-1.1.0&rect=3%2C3%2C1119%2C1119&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Chandrayaan-3's Pragyan rover has traveled 328 feet
(100 meters) and measured the chemistry of the lunar soil</span> <span class="attribution"><a class="source" href="https://www.isro.gov.in/chandrayaan3_gallery.html">ISRO</a></span></figcaption></figure><p>In an exciting milestone for <a href="https://theconversation.com/indias-chandrayaan-3-landed-on-the-south-pole-of-the-moon-a-space-policy-expert-explains-what-this-means-for-india-and-the-global-race-to-the-moon-212171">lunar scientists around the globe</a>, <a href="https://www.isro.gov.in/chandrayaan3_gallery.html">India’s Chandrayaan-3 lander</a> touched down <a href="https://www.lroc.asu.edu/posts/1314">375 miles (600 km)</a> from the <a href="https://bit.ly/45M9Mvn">south pole of the Moon</a> on Aug. 23, 2023. </p>
<p>In just under 14 Earth days, Chandrayaan-3 provided scientists with valuable new data and further <a href="https://blog.jatan.space/p/moon-monday-issue-143">inspiration to explore the Moon</a>. And the <a href="https://www.isro.gov.in/">Indian Space Research Organization</a> has shared these <a href="https://www.isro.gov.in/Ch3_ScienceResults.html">initial results</a> with the world.</p>
<p>While the data from <a href="https://robotsguide.com/robots/pragyan">Chandrayaan-3’s rover</a>, named Pragyan, or “wisdom” in Sanskrit, showed the <a href="https://www.lpi.usra.edu/publications/books/lunar_sourcebook/pdf/Chapter07.pdf">lunar soil</a> contains expected elements such as iron, titanium, aluminum and calcium, it also showed <a href="https://www.isro.gov.in/LIBSResults.html">an unexpected surprise – sulfur</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/rrTtLze5Ydk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">India’s lunar rover Pragyan rolls out of the lander and onto the surface.</span></figcaption>
</figure>
<p><a href="https://scholar.google.com/citations?user=wKuEBj0AAAAJ&hl=en&oi=ao">Planetary scientists like me</a> have known that <a href="https://space.nss.org/wp-content/uploads/Lunar-Bases-conference-2-509-Uses-Of-Lunar-Sulfur.pdf">sulfur exists in lunar rocks and soils</a>, but only at a very low concentration. These new measurements imply there may be a higher sulfur concentration than anticipated. </p>
<p>Pragyan has two instruments that analyze the elemental composition of the soil – an <a href="https://mars.nasa.gov/msl/spacecraft/instruments/apxs/for-scientists/">alpha particle X-ray spectrometer</a> and <a href="https://hha.hitachi-hightech.com/en/blogs-events/blogs/2018/01/03/what-is-libs/">a laser-induced breakdown spectrometer</a>, or <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011JE003898">LIBS</a> for short. Both of these instruments measured sulfur in the soil near the landing site.</p>
<p>Sulfur in soils near the Moon’s poles might help astronauts live off the land one day, making these measurements an example of science that enables exploration. </p>
<h2>Geology of the Moon</h2>
<p>There are <a href="https://pubs.usgs.gov/publication/pp1348">two main rock types</a> on <a href="https://www.lpi.usra.edu/lunar/moon101/#intro">the Moon’s surface</a> – dark volcanic rock and the brighter highland rock. The <a href="https://www.usgs.gov/news/national-news-release/usgs-releases-first-ever-comprehensive-geologic-map-moon">brightness difference</a> between these two materials forms the familiar “<a href="https://moon.nasa.gov/">man in the moon</a>” face or “rabbit picking rice” image to the naked eye.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The Moon, with the dark regions outlined in red, showing a face with two ovals for eyes and two shapes for the nose and mouth." src="https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=592&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=592&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=592&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=744&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=744&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548879/original/file-20230918-21-groebf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=744&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 dark regions of the Moon have dark volcanic soil, while the brighter regions have highland soil.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Man_in_the_Moon.png">Avrand6/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Scientists measuring lunar rock and soil compositions in labs on Earth have found that materials from the dark volcanic plains <a href="https://www.lpi.usra.edu/publications/books/lunar_sourcebook/pdf/Chapter08.pdf">tend to have more sulfur</a> than the brighter highlands material.</p>
<p><a href="https://doi.org/10.3133/pp1348">Sulfur mainly comes from</a> volcanic activity. Rocks deep in the Moon contain sulfur, and when these rocks melt, the sulfur becomes part of the magma. When the melted rock nears the surface, most of the sulfur in the magma becomes a gas that is released along with water vapor and carbon dioxide.</p>
<p>Some of the sulfur does stay in the magma and is retained within the rock after it cools. This process explains why sulfur is primarily associated with the Moon’s dark volcanic rocks. </p>
<p>Chandrayaan-3’s measurements of sulfur in soils are the first to occur on the Moon. The exact amount of sulfur cannot be determined until the data calibration is completed. </p>
<p>The <a href="https://www.isro.gov.in/Ch3_ScienceResults.html">uncalibrated data</a> collected by the LIBS instrument on Pragyan suggests that the Moon’s highland soils near the poles might have a higher sulfur concentration than highland soils from the equator and possibly even higher than the dark volcanic soils.</p>
<p>These initial results give <a href="https://scholar.google.com/citations?user=wKuEBj0AAAAJ&hl=en&oi=ao">planetary scientists like me</a> who study the Moon new insights into how it works as a geologic system. But we’ll still have to wait and see if the fully calibrated data from the Chandrayaan-3 team confirms an elevated sulfur concentration.</p>
<h2>Atmospheric sulfur formation</h2>
<p>The measurement of sulfur is interesting to scientists for at least two reasons. First, these findings indicate that the highland soils at the lunar poles could have fundamentally different compositions, compared with highland soils at the lunar equatorial regions. This compositional difference likely comes from the different environmental conditions between the two regions – the poles get less direct sunlight. </p>
<p>Second, these results suggest that there’s somehow more sulfur in the polar regions. Sulfur concentrated here <a href="https://moon.nasa.gov/news/26/an-atmosphere-around-the-moon/">could have formed</a> from the exceedingly thin lunar atmosphere. </p>
<p>The polar regions of the Moon receive less direct sunlight and, as a result, experience <a href="https://www.space.com/18175-moon-temperature.html">extremely low temperatures</a> compared with the rest of the Moon. If the surface temperature falls, below -73 degrees C (-99 degrees F), then sulfur from the lunar atmosphere could collect on the surface in solid form – like frost on a window. </p>
<p>Sulfur at the poles could also have originated from <a href="https://pubs.usgs.gov/publication/pp1348">ancient volcanic eruptions</a> occurring on the lunar surface, or from meteorites containing sulfur that struck the surface and vaporized on impact.</p>
<h2>Lunar sulfur as a resource</h2>
<p>For long-lasting space missions, many agencies have thought about building some sort <a href="https://www.nasa.gov/feature/goddard/2021/nasa-s-artemis-base-camp-on-the-moon-will-need-light-water-elevation">of base on the Moon</a>. Astronauts and robots could travel from the south pole base to collect, process, store and use naturally occurring materials like sulfur on the Moon – a concept called <a href="https://www.nasa.gov/isru">in-situ resource utilization</a>. </p>
<p>In-situ resource utilization means fewer trips back to Earth to get supplies and more time and energy spent exploring. Using sulfur as a resource, astronauts could build solar cells and batteries that use sulfur, mix up sulfur-based fertilizer and make <a href="https://ntrs.nasa.gov/api/citations/19980001900/downloads/19980001900.pdf">sulfur-based concrete for construction</a>.</p>
<p><a href="https://doi.org/10.1061/40339(206)67">Sulfur-based concrete</a> actually has several benefits compared with the concrete normally used in <a href="http://www.sulphurinstitute.org/about-sulphur/sulphur-construction-materials/">building projects on Earth</a>. </p>
<p>For one, sulfur-based concrete hardens and becomes strong within hours rather than weeks, and <a href="https://doi.org/10.2514/6.2005-1436">it’s more resistant to wear</a>. It also doesn’t require water in the mixture, so astronauts could save their valuable water for drinking, crafting breathable oxygen and making rocket fuel.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The gray surface of the Moon as seen from above, with a box showing the rover's location in the center." src="https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/546711/original/file-20230906-15-hryv7w.png?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">The Chandrayaan-3 lander, pictured as a bright white spot in the center of the box. The box is 1,108 feet (338 meters) wide.</span>
<span class="attribution"><span class="source">NASA/GSFC/Arizona State University</span></span>
</figcaption>
</figure>
<p>While <a href="https://www.planetary.org/space-missions/every-moon-mission">seven missions</a> are currently operating on or around the Moon, the <a href="https://doi.org/10.1093/mnrasl/slad106">lunar south pole region</a> hasn’t been studied from the surface before, so Pragyan’s new measurements will help planetary scientists understand the geologic history of the Moon. It’ll also allow lunar scientists like me to ask new questions about how the Moon formed and evolved.</p>
<p>For now, the scientists at Indian Space Research Organization are busy processing and calibrating the data. On the lunar surface, Chandrayaan-3 is hibernating through the two-week-long lunar night, where temperatures will drop to -184 degrees F (-120 degrees C). The night will last until September 22. </p>
<p>There’s no guarantee that the lander component of Chandrayaan-3, called Vikram, or Pragyan will survive the extremely low temperatures, but should Pragyan awaken, scientists can expect more valuable measurements.</p><img src="https://counter.theconversation.com/content/212950/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeffrey Gillis-Davis 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>India’s Chandrayaan-3 rover has found sulfur on the Moon’s surface at higher concentrations than previously seen. Sulfur, a useful resource, could pave the way for future Moon bases.Jeffrey Gillis-Davis, Research Professor of Physics, Arts & Sciences at Washington University in St. LouisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2120192023-09-19T20:08:47Z2023-09-19T20:08:47ZMost pink diamonds were birthed by a disintegrating supercontinent. Where can we find more?<p>There is nothing quite like a diamond. For many they are the ultimate “I love you” gift, and jewellers will tell you the ultra-hard stones have unmatched “fire” and “brilliance”. The sentimental and aesthetic value of the gems is matched by their price, which can run to tens of thousand dollars per carat – and even more for coloured diamonds, especially if they are blue, green, violet, orange, red or pink.</p>
<p>But why are diamonds so expensive? How do they form? Do we really find diamonds in volcanoes? What is the link to supercontinents and ancient lifeforms? </p>
<p>In <a href="https://doi.org/10.1038/s41467-023-40904-8">new research</a> published in Nature Communications, we answer some of these questions by studying the world’s largest diamond deposit, Argyle in Western Australia, the source of more than 90% of pink diamonds.</p>
<p>We found that at Argyle, diamonds crystallised deep in Earth’s interior were brought to the surface when a supercontinent, Nuna, began to break apart. As continents break up, their edges stretch, allowing small pockets of diamond-rich magma to rise to the surface.</p>
<h2>Why are pink diamonds so special?</h2>
<p>Only about 20% of mined diamonds are of gemstone quality. If you think of diamonds as cars, 80 of every 100 on the road would be old, beat-up rides and 20 would be luxury cars. </p>
<p>One in every 10,000 would be the equivalent of a supercar: a rare and precious coloured diamond.</p>
<p>However, some places in the world are special. Just as you might see a greater proportion of supercars in Monaco or Hollywood, so too do some places produce more coloured diamonds. </p>
<p>When it comes to pink diamonds, one place stands alone. More than 90% of all the pink diamonds ever found come from a single mine in the Kimberley region of Western Australia: Argyle.</p>
<p>The Argyle mine closed in 2020, and the price of pink diamonds has skyrocketed while the supply dwindles.</p>
<p>While pink diamonds are highly prized, they are also in a sense “damaged goods”.</p>
<p>Diamonds are made of carbon atoms arranged in a compact, regular lattice. Clear, perfect diamonds sparkle because light reflects off their internal surfaces. </p>
<p>However, when diamonds are subject to intense pressure deep inside Earth, the lattice of atoms can twist and bend. This causes small imperfections that diffract light and bring colour to the gem. </p>
<h2>Why is Argyle so well-endowed in pink diamonds?</h2>
<p>All diamonds are found in pipelike volcanoes, or in their eroded remnants. These volcanoes have deep roots under continents, which is where diamonds reside.</p>
<p>The roots need to be deep. If they’re shallow, the carbon that might become diamonds will instead be in the form of graphite, which is not nearly as appealing on an engagement ring.</p>
<p>The story of the Argyle volcano begins some 1,800 million years ago, when the continental plate beneath the Kimberley smashed into the rest of WA to form the first supercontinent, Nuna. Five hundred million years later, Nuna ripped apart again while Australia hung together. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three maps of the world at different times, showing the creation of the volcano that led tot he Argyle diamond deposit." src="https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=263&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=263&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=263&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=331&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=331&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545152/original/file-20230829-28-61r2sk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=331&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 Argyle volcano was created when the Nuna supercontinent was torn apart.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41467-023-40904-8">Olierook et al. / Nature Communications</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Yet old wounds never fully heal. The suture between the Kimberley and the rest of the continent was stretched open as Nuna split up, and the Argyle volcano shot to the surface, bringing pink diamonds with it. The death of a supercontinent gave birth to Argyle. </p>
<p>So what made Argyle’s diamonds pink? The force that damaged the deep diamonds, resulting in their beautiful hue, probably came from the continental collision that formed the supercontinent in the first place. But the diamonds remained deep below this old wound for a long time before being brought to the surface.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/perfectly-imperfect-the-discovery-of-the-second-largest-pink-diamond-has-left-the-world-in-awe-what-gives-diamonds-their-colour-187852">Perfectly imperfect: the discovery of the second-largest pink diamond has left the world in awe. What gives diamonds their colour?</a>
</strong>
</em>
</p>
<hr>
<p>Will we find another trove of pink diamonds? With Argyle now closed, the search is on to meet the demand for these illustrious gems. </p>
<p>The ingredients appear to be continental breakup, the edges of ancient continents and volcanic pipes. </p>
<h2>Is carbon recycled in Earth’s interior?</h2>
<p>Finding diamonds is no mere quest for glitz and glamour. It’s an exploration of Earth’s deepest history. </p>
<p>Diamonds are ancient time capsules from the depths of our planet. They are relics of a past so remote it challenges comprehension.</p>
<p>We know they are made of pure carbon – but where did this carbon come from?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/more-than-just-a-sparkling-gem-what-you-didnt-know-about-diamonds-101115">More than just a sparkling gem: what you didn't know about diamonds</a>
</strong>
</em>
</p>
<hr>
<p>Most of the carbon is remnants of carbon-rich asteroids that clumped together to form Earth 4.5 billion years ago. </p>
<p>However, some diamonds contain carbon that was once part of living organisms. Organic carbon, from organisms that once thrived on Earth’s surface, got buried deep down by geological processes. </p>
<p>The Argyle diamonds, for instance, hold such organic imprints, like echoes from an ancient world long vanished. In these glimmers of the distant past, we find more than beauty; we find keys to unlock the most profound secrets of our planet’s history.</p><img src="https://counter.theconversation.com/content/212019/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Denis Fougerouse receives funding from The Mineral Research Institute of Western Australia. </span></em></p><p class="fine-print"><em><span>Hugo Olierook receives funding from various minerals industry partners and the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Luc Doucet receives funding from the Australian Research Council and China University of Geoscience, Wuhan. </span></em></p>More than 90% of the world’s pink diamonds came from a single mine that closed in 2020. Geologists are only now beginning to understand the forces that create the rare, highly prized gems.Denis Fougerouse, Research Fellow, School of Earth and Planetary Sciences, Curtin UniversityHugo Olierook, Research Fellow in Geology, Curtin UniversityLuc Doucet, ARC Future Fellow at the Earth Dynamics Research Group, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2133372023-09-13T12:28:34Z2023-09-13T12:28:34ZWhat causes earthquakes? A geologist explains where they’re most common and why<figure><img src="https://images.theconversation.com/files/547877/original/file-20230912-15-58zzx2.jpg?ixlib=rb-1.1.0&rect=0%2C17%2C6000%2C3970&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A man works his way through the rubble of buildings in Marrakesh, Morocco, after a magnitude 6.8 earthquake on Sept. 8, 2023.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/resident-navigates-through-the-rubble-following-a-6-8-news-photo/1653682958?adppopup=true">Fadel Senna/AFP via Getty Images</a></span></figcaption></figure><p>Earthquakes, large and small, <a href="https://earthquake.usgs.gov/earthquakes/map/">happen every single day</a> along zones that wrap around the world like seams on a baseball. Most don’t bother anybody, so they don’t make the news. But every now and then a catastrophic earthquake hits people somewhere in the world with horrific destruction and immense suffering. </p>
<p>On Oct. 7, 2023, a 6.3 magnitude earthquake struck near the historic city of Herat, Afghanistan, leaving <a href="https://www.aljazeera.com/news/2023/10/11/afghanistan-hit-by-second-strong-earthquake-in-days">more than 1,000 people</a> dead in the rubble, according to estimates. It was followed by <a href="https://apnews.com/article/afghanistan-earthquake-usgs-aftershocks-63-magnitude-8f6055342900e320ec5a5e4ea898399a">two more earthquakes, just as powerful</a>, on Oct. 11 and Oct. 15. A few weeks earlier, on Sept. 8, a 6.8 magnitude earthquake <a href="https://www.nature.com/articles/d41586-023-02880-3">shook ancient villages apart</a> in the Atlas Mountains of Morocco, killing nearly 3,000 people. In February 2023, a large area of <a href="https://www.dw.com/en/turkey-syria-earthquakes-still-living-in-the-rubble-6-months-later/a-66444041">Turkey and Syria</a> was devastated by two major earthquakes that hit in close succession.</p>
<p>As <a href="https://scholar.google.com/citations?user=r8FqGBEAAAAJ&hl=en">a geologist</a>, I study the forces that cause earthquakes. Here’s why some seismic zones are very active while others may be quiet for generations before the stress builds into a catastrophic event.</p>
<h2>Earth’s crust crashes into itself and pulls apart</h2>
<p>Earthquakes are part of the normal behavior of the Earth. They occur with the movement of the tectonic plates that form the <a href="https://www.usgs.gov/media/images/crust-mantle-and-core-earth">outer layer of the planet</a>.</p>
<p>You can think of the plates as a more or less rigid outer shell that has to shift to allow the Earth to give off its internal heat.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A world map shows dots for major earthquakes clustered along tectonic plate boundaries." src="https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=333&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=333&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=333&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=418&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=418&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547854/original/file-20230912-21-phdrl7.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=418&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 map of all earthquakes greater than magnitude 5 from 1960 to 2023 clearly shows the outlines of the tectonic plates.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/programs/earthquake-hazards/earthquakes">USGS/GMRT</a></span>
</figcaption>
</figure>
<p>These plates carry the continents and the oceans, and they are continuously in <a href="https://oceanexplorer.noaa.gov/facts/plate-boundaries.html">slow-motion crashes</a> with one another. The cold and dense oceanic plates dive under continental plates and back into Earth’s mantle in a process <a href="https://youtu.be/T1QKPoxMdGg">known as subduction</a>. As an oceanic plate sinks, it drags everything behind it and opens a rift somewhere else that is filled by rising hot material from the mantle that then cools. These rifts are long chains of underwater volcanoes, known as <a href="https://oceanexplorer.noaa.gov/facts/mid-ocean-ridge.html">mid-ocean ridges</a>. </p>
<p>Earthquakes accompany both subduction and rifting. In fact, that is how the plate boundaries were first discovered.</p>
<p>In the 1950s, when a <a href="https://www.ldeo.columbia.edu/%7Erichards/EARTHmat.html">global seismic network was established</a> to monitor nuclear tests, geophysicists noticed that most earthquakes occur along relatively narrow bands that either fringe the edges of ocean basins, as in the Pacific, or cut right down the middle of basins, <a href="https://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Divergent/Mid-Atlantic-Ridge">as in the Atlantic</a>. </p>
<p>They also noticed that earthquakes along subduction zones are shallow on the oceanic side but <a href="https://www.mheducation.com/highered/product/exploring-geology-reynolds-johnson/M9781260722215.html">get deeper under the continent</a>. If you plot the earthquakes in 3D, they define slablike features that trace the plates sinking into the mantle.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two images show a map of Japan, with the Pacific Plate evident to the east, and a side view of earthquake depths that highlight that subducting plate." src="https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=661&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=661&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=661&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=831&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=831&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547879/original/file-20230912-17-ed8b9v.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=831&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ten thousand earthquake locations from 1980 to 2009 trace the Pacific Plate as it subducts under northern Japan. The top image is a side view showing the depth of the earthquakes beneath the rectangle on the map.</span>
<span class="attribution"><span class="source">Jaime Toro</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>An experiment: How an earthquake works</h2>
<p>To understand what happens during an earthquake, put the palms of your hands together and press with some force. You are modeling a plate boundary fault. Each hand is one plate, and the surface of your hands is the fault. Your muscles are the plate tectonic system.</p>
<p>Now, add some forward force to your right hand. You will find that it will eventually jerk forward when the forward force overcomes the friction between your palms. That sudden forward jerk is the earthquake. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map shows two creeks with abrupt shifts in their location over the fault." src="https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=474&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=474&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547862/original/file-20230912-17-mhw68w.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=474&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 Google Earth image of creeks offset by movement along the San Andreas Fault in Southern California as the Pacific Plate moves to the northwest with respect to North America.</span>
<span class="attribution"><a class="source" href="https://earth.google.com/web/">Jaime Toro</a></span>
</figcaption>
</figure>
<p>Scientists explain earthquakes using what’s known as the <a href="https://earthquake.usgs.gov/earthquakes/events/1906calif/18april/reid.php">elastic rebound theory</a>.</p>
<p>Fast plates move at up to 8 inches (20 centimeters) per year, driven mostly by the oceanic slabs sinking at subduction zones. Over time, they become stuck to each other by friction at the plate boundary. The attempted motion deforms the plate boundary zone elastically, like a loaded spring. At some point, the accumulated elastic energy overcomes the friction and the plate jerks forward, causing an earthquake.</p>
<p>But the <a href="https://oceanservice.noaa.gov/facts/tectonics.html">plate-driving forces</a> do not stop, so the plate boundary starts to accumulate elastic energy again, which will cause another earthquake – perhaps soon or perhaps far in the future.</p>
<p>In the oceans, plate boundaries are narrow and well defined because the underlying rocks are very stiff. But within the continents, plate boundaries are often broad zones of deformed mountainous terrain crisscrossed by many faults. Those faults may persist for eons, even if the plate boundary becomes inactive. That is why sometimes earthquakes occur far from plate boundaries.</p>
<h2>Earthquakes, fast and slow</h2>
<p>The cyclic behavior of faults allows seismologists to <a href="https://www.usgs.gov/faqs/can-you-predict-earthquakes">estimate earthquake risks statistically</a>. Plate boundaries with fast motions, such as the ones along the Pacific rim, accumulate elastic energy rapidly and have the potential for frequent large-magnitude earthquakes.</p>
<p>Slow-moving plate boundary faults take longer to reach a critical state. Along some faults, hundreds or even thousands of years can pass between large earthquakes. This allows time for towns to grow and for people to lose ancestral memory of past earthquakes.</p>
<figure class="align-center ">
<img alt="The few standing walls of a house are severely cracked. The roof is gone, and rubble lies on the floor." src="https://images.theconversation.com/files/553081/original/file-20231010-29-h855wn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553081/original/file-20231010-29-h855wn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553081/original/file-20231010-29-h855wn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553081/original/file-20231010-29-h855wn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553081/original/file-20231010-29-h855wn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553081/original/file-20231010-29-h855wn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553081/original/file-20231010-29-h855wn.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">The earthquake near Herat, Afghanistan, on Oct. 7, 2023, shook rural homes apart.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/herat-afghanistan-cracked-walls-and-rubble-are-seen-in-a-news-photo/1713772432?adppopup=true">Muhammad Balabuluki/Middle East Images/Middle East Images via AFP</a></span>
</figcaption>
</figure>
<p>The earthquake in Morocco is an example. Morocco is located on the boundary <a href="https://www.youtube.com/watch?v=cqK-CbuM3Eo">between the African and the Eurasian plates</a>, which are slowly crashing into each other.</p>
<p>The huge belt of mountains that extends from the Atlas of North Africa to the Pyrenees, Alps and most of the mountains across southern Europe and the Middle East is the product of this plate collision. Yet because these plate motions are slow near Morocco, large earthquakes are not so frequent.</p>
<p>Afghanistan is <a href="https://earthquake.usgs.gov/earthquakes/eventpage/us6000le6y/region-info">more prone to earthquakes</a>. It has numerous faults created by the collision of India against Eurasia. The Indian Plate, which is old and stiff, has been plowing into the southern margin of Eurasia for the past 40 million years. You can see evidence of this slow-moving collision in the way the mountain chains – and the earthquakes – wrap around either side of India.</p>
<h2>Preparing for the big one</h2>
<p>An important fact about catastrophic earthquakes is that, in most cases, the earthquakes don’t kill people – falling buildings do.</p>
<p>Most Americans have heard of <a href="https://www.nytimes.com/2023/06/07/us/san-andreas-fault-researchers.html">California’s San Andreas Fault</a> and the seismic risk to San Francisco and Los Angeles. The last major earthquake along the San Andreas Fault <a href="https://www.conservation.ca.gov/cgs/earthquakes/loma-prieta">hit at Loma Prieta</a>, in the San Francisco Bay area, in 1989. Its magnitude, 6.9, was comparable to that of the earthquake in Morocco, yet 63 people died compared with thousands. That’s largely because building codes in these earthquake-prone U.S. cities are now designed to keep structures standing when the Earth shakes.</p>
<p>The <a href="https://www.youtube.com/watch?v=ILlyfwDwJVs">exceptions are tsunamis</a>, the huge waves generated when an earthquake shifts the seafloor, displacing the water above it. A tsunami that hit <a href="https://www.ncei.noaa.gov/news/day-2011-japan-earthquake-and-tsunami">Japan in 2011</a> had horrific consequences, regardless of the quality of engineering in coastal towns.</p>
<p>Unfortunately, earthquake scientists <a href="https://theconversation.com/seismologists-cant-predict-an-impending-earthquake-but-longer-term-forecasts-and-brief-warnings-after-one-starts-are-possible-199666">can’t predict exactly when</a> an earthquake might occur; they can only estimate the hazard.</p>
<p><em>This article, originally published Sept. 13, 2023, has been updated with another powerful earthquake in Afghanistan.</em></p><img src="https://counter.theconversation.com/content/213337/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaime Toro has received funding from NSF, USGS and DOE in the past.</span></em></p>A deadly earthquake in Afghanistan, following one in Morocco, highlights the risks in the region.Jaime Toro, Professor of Geology, West Virginia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2116192023-08-17T00:58:14Z2023-08-17T00:58:14ZA dramatic volcano eruption changed lives in Fiji 2,500 years ago. 100 generations have kept the story alive<figure><img src="https://images.theconversation.com/files/542953/original/file-20230816-20-ud5god.JPG?ixlib=rb-1.1.0&rect=126%2C205%2C3663%2C2571&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Author provided</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Can you imagine a scientist who could neither read nor write, who spoke their wisdom in riddles, in tales of fantastic beings flying through the sky, fighting each another furiously and noisily, drinking the ocean dry, and throwing giant spears with force enough to leave massive holes in rocky headlands?</p>
<p>Our newly published research <a href="https://journal.oraltradition.org/driva-qele-stealing-earth-oral-accounts-of-the-volcanic-eruption-of-nabukelevu-mt-washington-kadavu-island-fiji-2500-years-ago/">in the journal Oral Tradition</a> shows memories of a volcanic eruption in Fiji some 2,500 years ago were encoded in oral traditions in precisely these ways.</p>
<p>They were never intended as fanciful stories, but rather as the pragmatic foundations of a system of local risk management.</p>
<h2>Life-changing events</h2>
<p>Around 2,500 years ago, at the western end of the island of Kadavu in the southern part of Fiji, the ground shook, the ocean became agitated, and clouds of billowing smoke and ash poured into the sky.</p>
<p>When the clouds cleared, the people saw a new mountain had formed, its shape resembling a mound of earth in which yams are grown. This gave the mountain its name – Nabukelevu, the giant yam mound. (It was renamed Mount Washington during Fiji’s colonial history.)</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of a flat-topped volcano with a beach in front, and a drawing of a similar mountain in the top left corner" src="https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542950/original/file-20230816-17-71orq5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nabukelevu from the northeast, its top hidden in cloud. Inset: Nabukelevu from the west in 1827 after the drawing by the artist aboard the <em>Astrolabe</em>, the ship of French explorer Dumont d’Urville. It is an original lithograph by H. van der Burch after original artwork by Louis Auguste de Sainson.</span>
<span class="attribution"><span class="source">Wikimedia Commons; Australian National Maritime Museum</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>So dramatic, so life-changing were the events <a href="https://www.sciencedirect.com/science/article/abs/pii/S0377027303004141">associated with this eruption</a>, the people who witnessed it told stories about it. These stories have endured more than two millennia, faithfully passed on across roughly 100 generations to reach us today.</p>
<p>Scientists used to dismiss such stories as fictions, devalue them with labels like “myth” or “legend”. But the situation is changing. </p>
<p>Today, we are starting to recognise that many such “stories” are authentic memories of human pasts, encoded in oral traditions in ways that represent the worldviews of people from <a href="https://www.bloomsbury.com/au/edge-of-memory-9781472943286/">long ago</a>.</p>
<p>In other words, these stories served the same purpose as scientific accounts, and the people who told them were trying to understand the natural world, much like scientists do today.</p>
<h2>Battle of the <em>vu</em></h2>
<p>The most common story about the 2,500-year-old eruption of Nabukelevu is one involving a “god” (<em>vu</em> in Fijian) named Tanovo from the island of Ono, about 56km from the volcano.</p>
<p>Tanovo’s view of the sunset became blocked one day by this huge mountain. Our research identifies this as a volcanic dome that was created during the eruption, raising the height of the mountain several hundred feet.</p>
<p>Enraged, Tanovo flew to Nabukelevu and started to tear down the mountain, a process described by local residents as <em>driva qele</em> (stealing earth). This explains why even today the summit of Nabukelevu has a crater.</p>
<p>But Tanovo was interrupted by the “god” of Nabukelevu, named Tautaumolau. The pair started fighting. A chase ensued through the sky and, as the two twisted and turned, the earth being carried by Tanovo started falling to the ground, where it is said to have “created” islands.</p>
<p>We conclude that the sequence in which these islands are said to have been created is likely to represent the movement of the ash plume from the eruption, as shown on the map below.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map showing a jagged landmass with an inset showing a plume of ash swirling across it" src="https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=513&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=513&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=513&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=645&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=645&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542959/original/file-20230816-19-96orcs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=645&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Smaller offshore islands named in seven versions of the Nabukelevu story as having formed following the Nabukelevu eruption. Inset shows the possible trace of the ash cloud based on the stories.</span>
<span class="attribution"><span class="source">Author provided</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>‘Myths’ based in fact</h2>
<p>Geologists would today find it exceedingly difficult to deduce such details of an ancient eruption. But here, in the oral traditions of Kadavu people, this information is readily available.</p>
<p>Another detail we would never know if we did not have the oral traditions is about the tsunami the eruption caused. </p>
<p>In some versions of the story, one of the “gods” is so frightened, he hides beneath the sea. But his rival comes along and drinks up all the water at that place, a detail our research interprets as a memory of the ocean withdrawing prior to tsunami impact.</p>
<p>Other details in the oral traditions recall how one god threw a massive spear at his rival but missed, leaving behind a huge hole in a rock. This is a good example of how landforms likely predating the eruption can be retrofitted to a narrative.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An orange rock jutting out of the water with a large hole within" src="https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542952/original/file-20230816-23-afpteq.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">The hole made when a spear was thrown by one god at the other, on the north coast of eastern Kadavu.</span>
<span class="attribution"><span class="source">Author provided</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our study adds to the growing body of scientific research into “myths” and “legends”, showing that many have a basis in fact, and the details they contain add depth and breadth to our understanding of human pasts.</p>
<p>The <a href="https://kaidravuni.com/">Kadavu volcano stories</a> discussed here also show ancient societies were no less risk aware and risk averse than ours are today. The imperative was to survive, greatly aided by keeping alive memories of all the hazards that existed in a particular place.</p>
<p>Australian First Peoples’ cultures are <a href="https://theconversation.com/when-the-bullin-shrieked-aboriginal-memories-of-volcanic-eruptions-thousands-of-years-ago-81986">replete with similar stories</a>.</p>
<p>Literate people, those who read and write, tend to be impressed by the extraordinary time depth of oral traditions, like those about the 2,500-year old eruption of Nabukelevu. But not everyone is.</p>
<p>In early 2019, I was sitting and chatting to Ratu Petero Uluinaceva in Waisomo Village, after he had finished relating the Ono people’s story of the eruption. I told him this particular story recalled events which occurred more than two millennia ago – and thought he might be impressed. But he wasn’t.</p>
<p>“We know our stories are that old, that they recall our ancient history,” he told me with a grin. “But we are glad you have now learned this too!”</p>
<hr>
<p><em>Acknowledgements: The original research was conducted in collaboration with Loredana Lancini and Rita Compatangelo-Soussignan (University of Le Mans), Meli Nanuku and Kaliopate Tavola (Fiji Museum), Taniela Bolea (University of the Sunshine Coast) and Paul Geraghty (University of the South Pacific).</em></p><img src="https://counter.theconversation.com/content/211619/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patrick D. Nunn receives funding from the Australian Research Council, the Australia Pacific Climate Partnership, the Asia-Pacific Network, the Natural Environment Research Council (UK) and the British Academy.
The original research was conducted in collaboration with Loredana Lancini and Rita Compatangelo-Soussignan (University of Le Mans), Meli Nanuku and Kaliopate Tavola (Fiji Museum), Taniela Bolea (University of the Sunshine Coast) and Paul Geraghty (University of the South Pacific).</span></em></p>Many ‘myths’ are authentic memories of human pasts, told by people who passed down precise accounts of their history.Patrick D. Nunn, Professor of Geography, School of Law and Society, University of the Sunshine CoastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2111142023-08-13T20:04:02Z2023-08-13T20:04:02ZRising seas and a great southern star: Aboriginal oral traditions stretch back more than 12,000 years<figure><img src="https://images.theconversation.com/files/541869/original/file-20230809-16-26pa2s.jpeg?ixlib=rb-1.1.0&rect=0%2C19%2C4340%2C2245&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aerial-photo-neck-on-bruny-island-2270935801">Shutterstock</a></span></figcaption></figure><p><em>Content note: this article mentions genocide and acts of colonial violence against Aboriginal people.</em></p>
<hr>
<p>How long do you think stories can be passed down, generation to generation? </p>
<p>Hundreds of years? Thousands?</p>
<p>Today, we publish new research in the <a href="https://www.sciencedirect.com/science/article/pii/S0305440323000997">Journal of Archaeological Science</a> demonstrating that traditional stories from Tasmania have been passed down for more than 12,000 years. And we use multiple lines of evidence to show it.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-memory-code-how-oral-cultures-memorise-so-much-information-65649">The Memory Code: how oral cultures memorise so much information</a>
</strong>
</em>
</p>
<hr>
<h2>Tasmania’s violent colonial history</h2>
<p>Within months of establishing a colonial outpost on the island in 1803, British officials had committed several <a href="https://www.cambridge.org/core/books/abs/cambridge-world-history-of-genocide/genocide-in-van-diemens-land-tasmania-18031871/ED82A107B2C76801551EB3F51CA6179D">acts of genocide</a> against Aboriginal Tasmanian (Palawa) people. By the mid-1820s, soldiers, convicts, and free settlers had taken up arms to fight what became known as the “Black War”, aimed at capturing or killing Palawa and dispossessing them of their Country.</p>
<p>Tasmania’s colonial government appointed George Augustus Robinson to “conciliate” with the Palawa. From 1829 to 1835, Robinson travelled with a small group of Palawa, including <a href="https://en.wikipedia.org/wiki/Truganini">Trukanini</a> and her husband, Wurati. By 1832, Robinson’s “friendly mission” had turned to forced removals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustrated postcard showing the (so-called) 'Friendly Mission', led by George Augustus Robinson (1941)" src="https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541689/original/file-20230808-19-8664yu.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">A postcard showing the (so-called) ‘Friendly Mission’, led by George Augustus Robinson (1941), colourised version.</span>
<span class="attribution"><span class="source">State Library of Victoria</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/coming-to-terms-with-tasmanias-forgotten-war-11333">Coming to terms with Tasmania's forgotten war</a>
</strong>
</em>
</p>
<hr>
<p>Robinson kept a daily journal, which included records of Palawa languages and traditions. Over time, Palawa men and women slowly began to share some of their knowledge, explaining how their ancestors came to Tasmania (Lutruwita) by land from the far north, before the sea formed and turned their home into an island. They also spoke about the Sun-man, the Moon-woman, and a bright southern star. </p>
<p>These stories are of immense importance to today’s Palawa families who survived the devastating impact of colonisation, and who continue to share these unique creation stories. Through careful investigation of colonial records, and collaborating with Palawa knowledge-holders, we found something remarkable.</p>
<h2>Rising seas and the formation of Lutruwita</h2>
<p>Over the past 65,000 years, Australia’s First Peoples witnessed natural disasters and significant changes to the land, sea and sky. Volcanoes spewed fire, earthquakes shook the land, tsunamis inundated the coastlines, droughts plagued the continent, meteorites fell to the earth, and the stars shifted in the night sky. </p>
<p>Some 20,000 years ago, the world was in the grip of an ice age. Australia was conspicuously drier than it is today, and the ocean was significantly lower. All of that sea water was bound up in glaciers that swathed vast tracts of land, particularly across the Northern Hemisphere, and polar ice caps much larger than ours today.</p>
<p>As time passed, temperatures gradually rose and the ice began to melt. After 10,000 years, the sea level had risen 125 metres; a process that dramatically transformed coastlines and submerged landscapes that had been ancestral Country for thousands of generations. This forced humans to change where and how they lived.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-aboriginal-stories-preserve-history-of-a-rise-in-sea-level-36010">Ancient Aboriginal stories preserve history of a rise in sea level</a>
</strong>
</em>
</p>
<hr>
<p>During the ice age, both Lutruwita and Papua New Guinea were connected to mainland Australia by dry land, forming a landmass called <a href="https://www.thoughtco.com/sahul-pleistocene-continent-172704">Sahul</a>. As the seas rose, Tasmania’s connection gradually narrowed to form what geologists call the Bassian Land Bridge.</p>
<figure class="align-center ">
<img alt="Topographic map of the Bass Strait" src="https://images.theconversation.com/files/541680/original/file-20230808-27-2tqj1z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541680/original/file-20230808-27-2tqj1z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=725&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541680/original/file-20230808-27-2tqj1z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=725&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541680/original/file-20230808-27-2tqj1z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=725&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541680/original/file-20230808-27-2tqj1z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=910&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541680/original/file-20230808-27-2tqj1z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=910&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541680/original/file-20230808-27-2tqj1z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=910&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A topographic map of the Bass Strait, showing the conditions before the Bassian Land Bridge was submerged. The yellow shaded area represents geography of the land bridge, while the broken red line indicated the last vestige of a continuous Bassian Land Bridge between Tasmania and the mainland.</span>
<span class="attribution"><span class="source">Patrick Nunn</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>People continued to live on this “land bridge”, but by 12,700 years ago it had narrowed to just 5 kilometres wide (lime-green shading on the map above). Habitable land was gradually reduced as the sea closed in. Less than 300 years later, the “land bridge” was gone and Lutruwita was completely surrounded by water.</p>
<p>Palawa traditions from that time survived hundreds of generations of retelling, forming part of a larger canon of Aboriginal and Torres Strait Islander stories around Australia. They described rising seas and submerging coastlines as the ice sheets melted before levelling off around 7,000 years ago. Stories of similar antiquity are known from other parts of the <a href="https://www.bloomsbury.com/au/worlds-in-shadow-9781472983497/">world</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-aboriginal-stories-preserve-history-of-a-rise-in-sea-level-36010">Ancient Aboriginal stories preserve history of a rise in sea level</a>
</strong>
</em>
</p>
<hr>
<h2>A great south star</h2>
<p>Aboriginal and Torres Strait Islander cultures developed rich and complex <a href="http://www.thefirstastronomers.com">knowledge systems</a> about the stars, which are still used today. They describe the movements of the Sun, Moon, and stars, as well as rare cosmic events, such as <a href="https://www.abc.net.au/science/articles/2011/06/15/3244593.htm">eclipses</a>, supernovae, and <a href="https://theconversation.com/finding-meteorite-impacts-in-aboriginal-oral-tradition-38052">meteorite impacts</a>.</p>
<p>In the 1830s, a Palawa Elder spoke about a time when the star Moinee was near the south celestial pole. He laid down a pair of spears in the sand and drew a few reference stars to triangulate its position.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/stories-from-the-sky-astronomy-in-indigenous-knowledge-33140">Stories from the sky: astronomy in Indigenous knowledge</a>
</strong>
</em>
</p>
<hr>
<p>Colonists seemed perplexed about the presence of an antipodean counterpart to Polaris, as no southern pole star exists today. Some tried to identify the stars on the star map, but seemed confused and labelled them incorrectly, as they were unaware of an important astronomical process called <a href="https://en.wikipedia.org/wiki/Axial_precession">axial precession</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2JJjNc1xPKw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>As the Earth rotates, it wobbles on its axis like a spinning top. This shifts the location of the celestial poles, tracing out a large circle every 26,000 years. As thousands of years pass by, the positions of the stars in the sky slowly change.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/stars-that-vary-in-brightness-shine-in-the-oral-traditions-of-aboriginal-australians-85833">Stars that vary in brightness shine in the oral traditions of Aboriginal Australians</a>
</strong>
</em>
</p>
<hr>
<p>Long ago, Canopus was at its southernmost point in the sky. Lying just over 10 degrees from the south celestial pole, it appeared to always hover in the southern skies each night. That last occurred 14,000 years ago, before rising seas turned Lutruwita into an island.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A star map showing the location of Canopus 14,000 years ago." src="https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=310&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=310&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=310&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=390&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=390&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542074/original/file-20230810-17-uh89zk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=390&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stars in the southern sky as they would have appeared 14,000 years ago, accounting for precession, nutation, and proper motion. Canopus is very close to the south celestial pole (SCP).</span>
<span class="attribution"><a class="source" href="https://stellarium-web.org/">Stellarium</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Exciting collaborative futures</h2>
<p>We can see through independent lines of evidence that Palawa stories have been passed down for more than twelve millennia. We also find here the only example in the world of an oral tradition describing a star’s position as it would have appeared in the sky over 10,000 years ago.</p>
<p>Our investigation of colonial records that record traditional systems of knowledge has demonstrated a powerful cross-cultural way of better understanding deep human history. This also recognises the immense value of Aboriginal and Torres Strait Islander traditions today.</p>
<hr>
<p><em>This research was co-authored by graduate Michelle Gantevoort from RMIT University, and student researchers Ka Hei Andrew Law from the University of Melbourne and Mel Miles from Swinburne University of Technology.</em></p><img src="https://counter.theconversation.com/content/211114/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Duane W. Hamacher receives funding from the Australian Research Council and the Lady Foundation.</span></em></p><p class="fine-print"><em><span>Greg Lehman receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Patrick D. Nunn receives funding from the Australian Research Council, the Asia-Pacific Network, and the British Academy</span></em></p><p class="fine-print"><em><span>Rebe Taylor receives funding from Australian Research Council. </span></em></p>Ancient stories of the sea and the sky date back to the end of the last ice age.Duane Hamacher, Associate Professor, The University of MelbourneGreg Lehman, Pro Vice Chancellor, Aboriginal Leadership, University of TasmaniaPatrick D. Nunn, Professor of Geography, School of Law and Society, University of the Sunshine CoastRebe Taylor, Associate Professor of History, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2095932023-08-10T03:24:09Z2023-08-10T03:24:09ZNew evidence suggests the world’s largest known asteroid impact structure is buried deep in southeast Australia<figure><img src="https://images.theconversation.com/files/542059/original/file-20230810-25-7n4kt.png?ixlib=rb-1.1.0&rect=43%2C0%2C2600%2C1005&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Google Maps</span></span></figcaption></figure><p><em>Acknowledgment: I’d like to thank my colleague Tony Yeates, who originated the view of the Deniliquin multi-ring structure as an impact structure – and who was instrumental to this work.</em></p>
<p>In <a href="https://www.sciencedirect.com/science/article/abs/pii/S0040195122002487">recent research</a> published by myself and my colleague Tony Yeates in the journal Tectonophysics, we investigate what we believe – based on many years of experience in asteroid impact research – is the world’s largest known impact structure, buried deep in the earth in southern New South Wales.</p>
<p>The Deniliquin structure, yet to be further tested by drilling, spans up to 520 kilometres in diameter. This exceeds the size of the near-300km-wide <a href="https://en.wikipedia.org/wiki/Vredefort_impact_structure">Vredefort</a> impact structure in South Africa, which to date has been considered the world’s largest.</p>
<h2>Hidden traces of Earth’s early history</h2>
<p>The history of Earth’s bombardment by asteroids is largely concealed. There are a few reasons for this. The first is erosion: the process by which gravity, wind and water slowly wear away land materials through time. </p>
<p>When an asteroid strikes, it creates a crater with an uplifted core. This is similar to how a drop of water splashes upward from a transient crater when you drop a pebble in a pool. </p>
<p>This central uplifted dome is a key characteristic of large impact structures. However, it can erode over thousands to millions of years, making the structure difficult to identify.</p>
<p>Structures can also be buried by sediment through time. Or they might disappear as a result of subduction, wherein tectonic plates can collide and slide below one another into Earth’s mantle layer.</p>
<p>Nonetheless, new geophysical discoveries are unearthing signatures of impact structures formed by asteroids that may have reached tens of kilometres across – heralding a paradigm shift in our understanding of how Earth evolved over eons. These include pioneering discoveries of impact “ejecta”, which are the materials thrown out of a crater during an impact. </p>
<p><a href="https://www.sciencedirect.com/science/article/abs/pii/S1387647317300714">Researchers think</a> the oldest layers of these ejecta, found in sediments in early terrains around the world, might signify the tail end of the Late Heavy Bombardment of Earth. The <a href="https://www.sciencedirect.com/science/article/abs/pii/S1387647317300714">latest evidence</a> suggests Earth and the other planets in the Solar System were subject to intense asteroid bombardments until about 3.2 billion years ago, and sporadically since.</p>
<p>Some large impacts are correlated with mass extinction events. For example, the <a href="https://en.wikipedia.org/wiki/Alvarez_hypothesis">Alvarez hypothesis</a>, named after father and son scientists Luis and Walter Alvarez, explains how non-avian dinosaurs were wiped out as a result of a large asteroid strike some 66 million years ago.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-found-the-worlds-oldest-asteroid-strike-in-western-australia-it-might-have-triggered-a-global-thaw-130192">We found the world's oldest asteroid strike in Western Australia. It might have triggered a global thaw</a>
</strong>
</em>
</p>
<hr>
<h2>Uncovering the Deniliquin structure</h2>
<p>The Australian continent and its predecessor continent, <a href="https://en.wikipedia.org/wiki/Gondwana">Gondwana</a>, have been the target of numerous asteroid impacts. These have resulted in at least 38 confirmed and 43 potential impact structures, ranging from relatively small craters to large and completely buried structures.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=649&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=649&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541853/original/file-20230809-24-hpgo51.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=649&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 map shows the distribution of circular structures of uncertain, possible or probable impact origin on the Australian continent and offshore. Green dots represent confirmed impact craters. Red dots represent confirmed impact structures that are more than 100km wide, whereas red dots inside white circles are more than 50km wide. Yellow dots represent likely impact structures.</span>
<span class="attribution"><span class="source">Andrew Glikson and Franco Pirajno</span></span>
</figcaption>
</figure>
<p>As you’ll recall with the pool and pebble analogy, when a large asteroid hits Earth, the underlying crust responds with a transient elastic rebound that produces <a href="https://www.lpi.usra.edu/publications/books/CB-954/CB-954.pdf">a central dome</a>. </p>
<p>Such domes, which can slowly erode and/or become buried through time, may be all that’s preserved from the original impact structure. They represent the deep-seated “root zone” of an impact. Famous examples are found in the Vredefort impact structure and the 170km-wide <a href="https://en.wikipedia.org/wiki/Chicxulub_crater">Chicxulub crater</a> in Mexico. The latter represents the impact that caused the extinction of the dinosaurs.</p>
<p>Between 1995 and 2000, Tony Yeates suggested magnetic patterns beneath the Murray Basin in New South Wales <a href="https://www.aseg.org.au/publications/preview-old">likely represented</a> a massive, buried impact structure. An analysis of the region’s updated geophysical data between 2015 and 2020 confirmed the existence of a 520km diameter structure with a seismically defined dome at its centre.</p>
<p>The Deniliquin structure has all the features that would be expected from a large-scale impact structure. For instance, magnetic readings of the area reveal a symmetrical rippling pattern in the crust around the structure’s core. This was likely produced during the impact as extremely high temperatures created intense magnetic forces.</p>
<p>A central low magnetic zone corresponds to 30km-deep deformation above a seismically defined mantle dome. The top of this dome is about 10km <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL065345">shallower than the top</a> of the regional mantle.</p>
<p>Magnetic measurements also show evidence of “radial faults”: fractures that radiate from the centre of a large impact structure. This is further accompanied by small magnetic anomalies which may represent igneous “dikes”, which are sheets of magma injected into fractures in a pre-existing body of rock. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=565&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=565&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=565&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=710&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=710&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541855/original/file-20230809-27-qpfxif.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=710&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 ‘total magnetic intensity’ image of the Deniliquin impact structure portrays its 520km-diameter multi-ring pattern, the central core, radial faults and the location of shallow drill holes.</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/abs/pii/S0040195122002487">Data from Geoscience Australia, published in Glikson and Yeates, 2022</a></span>
</figcaption>
</figure>
<p>Radial faults, and igneous sheets of rocks that form within them, are typical of large impact structures and can be found in the Vredefort structure and the <a href="https://journals.uair.arizona.edu/index.php/maps/article/viewFile/14921/14892">Sudbury impact structure</a> in Canada.</p>
<p>Currently, the bulk of the evidence for the Deniliquin impact is based on geophysical data obtained from the surface. For proof of impact, we’ll need to collect physical evidence of shock, which can only come from drilling deep into the structure.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/these-5-spectacular-impact-craters-on-earth-highlight-our-planets-wild-history-197618">These 5 spectacular impact craters on Earth highlight our planet's wild history</a>
</strong>
</em>
</p>
<hr>
<h2>When did the Deniliquin impact happen?</h2>
<p>The Deniliquin structure was likely located on the eastern part of the Gondwana continent, prior to it splitting off into several continents (including the Australian continent) much later.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541858/original/file-20230809-21-qpfxif.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&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 Deniliquin structure was likely created in eastern Gondwana during the Late Ordovician.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s41598-022-08941-3#rightslink">Zhen Qiu et al, 2022</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The impact that caused it may have occurred during what’s known as the Late Ordovician mass extinction event. Specifically, I think it may have triggered what’s called the <a href="https://www.britannica.com/science/Ordovician-Silurian-extinction">Hirnantian glaciation stage</a>, which lasted between 445.2 and 443.8 million years ago, and is also defined as the <a href="https://www.sciencedirect.com/science/article/abs/pii/S1342937X23000655">Ordovician-Silurian extinction event</a>. </p>
<p>This huge glaciation and mass extinction event <a href="https://www.britannica.com/science/Ordovician-Silurian-extinction">eliminated</a> about 85% of the planet’s species. It was more than double the scale of the <a href="https://en.wikipedia.org/wiki/Alvarez_hypothesis">Chicxulub impact</a> that killed off the dinosaurs. </p>
<p>It is also possible the Deniliquin structure is older than the Hirnantian event, and may be of an early Cambrian origin (about 514 million years ago). The next step will be to gather samples to determine the structure’s exact age. This will require drilling a deep hole into its magnetic centre and dating the extracted material. </p>
<p>It’s hoped further studies of the Deniliquin impact structure will shed new light on the nature of early <a href="https://www.livescience.com/37584-paleozoic-era.html">Paleozoic</a> Earth.</p><img src="https://counter.theconversation.com/content/209593/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Glikson 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>Research on the Deniliquin structure points to an asteroid impact that would have been more than double the scale of the one that killed the dinosaurs.Andrew Glikson, Adjunct professor, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2108412023-08-08T14:58:15Z2023-08-08T14:58:15ZHow climate change might trigger more earthquakes and volcanic eruptions<figure><img src="https://images.theconversation.com/files/541708/original/file-20230808-21-64ruai.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2423%2C2337&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A volcanic eruption at the Reykjanes peninsula in Iceland in May 2021.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/geldingadalir-iceland-may-11-2021-small-1973100038">Thorir Ingvarsson/Shutterstock</a></span></figcaption></figure><p>Earth’s climate is changing rapidly. In some areas, escalating temperatures are increasing the frequency and likelihood of <a href="https://link.springer.com/article/10.1007/s10584-022-03409-9">wildfires and drought</a>. In others, they are making <a href="https://www.nature.com/articles/s41598-020-70816-2">downpours</a> and <a href="https://tyndall.ac.uk/wp-content/uploads/2021/03/sciencebrief_review_cyclones_mar2021.pdf">storms</a> more intense or accelerating the pace of glacial melting.</p>
<p>The past month is a stark illustration of exactly this. <a href="https://www.bbc.co.uk/news/world-europe-66435160">Parts of Europe</a> and <a href="https://www.reuters.com/graphics/CANADA-WILDFIRE/HISTORIC/znvnzebmavl/">Canada</a> are being devastated by wildfires, while Beijing has recorded <a href="https://apnews.com/article/china-beijing-rainfall-floods-1a8f968799bd539d11f3421010b8f2a9">its heaviest rainfall</a> in at least 140 years. Looking back further, between 2000 and 2019 the world’s glaciers lost around <a href="https://www.nature.com/articles/s41586-021-03436-z">267 gigatonnes of ice</a> per year. Melting glaciers contribute to rising sea levels (currently rising by about <a href="https://climate.copernicus.eu/climate-indicators/sea-level">3.3mm per year</a>) and more coastal hazards such as flooding and erosion.</p>
<p>But research suggests that our changing climate may not solely influence hazards at the Earth’s surface. Climate change – and specifically rising rainfall rates and glacial melting – could also exacerbate dangers beneath the Earth’s surface, such as earthquakes and volcanic eruptions.</p>
<p>Drought in <a href="https://news.sky.com/story/nearly-half-of-european-union-land-slides-into-drought-12921475">Europe</a> and <a href="https://www.ncei.noaa.gov/news/us-drought-weekly-report-august-1-2023">North America</a> has received a lot of recent media coverage. But the Intergovernmental Panel on Climate Change’s <a href="https://www.ipcc.ch/report/ar6/wg1/">Sixth Assessment Report</a> in 2021 revealed that average rainfall has actually increased in many world regions since 1950. A warmer atmosphere can retain more water vapour, subsequently leading to higher levels of precipitation.</p>
<p>Interestingly, geologists have long <a href="https://www.newscientist.com/article/dn13371-heavy-rain-can-trigger-earthquakes/">identified a relationship</a> between rainfall rates and seismic activity. In the Himalayas, for example, the <a href="http://tectonics.caltech.edu/publications/pdf/bettinelli_avouacEPSLfeb08.pdf">frequency of earthquakes</a> is influenced by the annual rainfall cycle of the summer monsoon season. <a href="https://www.sciencedirect.com/science/article/pii/S1674984722000404">Research</a> reveals that 48% of Himalayan earthquakes strike during the drier pre-monsoon months of March, April and May, while just 16% occur in the monsoon season.</p>
<p>During the summer monsoon season, the weight of up to 4 metres of rainfall compresses the crust both vertically and horizontally, stabilising it. When this water disappears in the winter, the effective “rebound” destabilises the region and increases the number of earthquakes that occur. </p>
<p><strong>The number of earthquakes that occurred seasonally from 2003-2020</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph showing the seasonal fluctuation in earthquake occurrence with more earthquakes happening pre-monsoon." src="https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=160&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=160&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=160&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=201&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=201&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541704/original/file-20230808-21-1g5opa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=201&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In the pre-monsoon period, the number of earthquakes increases.</span>
<span class="attribution"><a class="source" href="https://creativecommons.org/licenses/by-nc-nd/4.0/">Shashikant Nagale et al. (2022)/Geodesy and Geodynamics</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Climate change could intensify this phenomenon. <a href="https://www.science.org/doi/10.1126/sciadv.abg3848">Climate models</a> project that the intensity of monsoon rainfall in southern Asia will increase in the future as a result of climate change. This could feasibly enhance the winter rebound and cause more seismic events. </p>
<p>The impact of water’s weight on the Earth’s crust goes beyond just precipitation; it extends to glacial ice as well. As the last ice age came to an end roughly 10,000 years ago, the thawing of heavy glacial ice masses caused parts of the Earth’s crust to rebound upwards. This process, called <a href="https://www.newscientist.com/article/mg17723774-900-the-word-isostatic-rebound/">isostatic rebound</a>, is evidenced by raised beaches in Scotland – some of which are up to 45 metres above current sea level. </p>
<p><a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL069359">Evidence from Scandinavia</a> suggests that such uplift, coupled with the destabilisation of the region’s tectonics, triggered numerous earthquake events between 11,000 and 7,000 years ago. Some of these earthquakes even exceeded a magnitude of 8.0 which indicates <a href="https://www.britannica.com/science/Richter-scale">severe destruction and loss of life</a>. The concern is that the continued melting of glacial ice today could result in similar effects elsewhere.</p>
<figure class="align-center ">
<img alt="Raised beaches at Tongue Bay, Scotland." src="https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541702/original/file-20230808-27-44b8nb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Raised beaches at Tongue Bay in Scotland.</span>
<span class="attribution"><a class="source" href="https://www.geos.ed.ac.uk/~rsgs/ifa/gems/landformraisedbeach.html">Patrick Bailey/Royal Scottish Geographical Society</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>How about volcanic activity?</h2>
<p><a href="https://pubs.geoscienceworld.org/gsa/geology/article/46/1/47/521232/Climatic-control-on-Icelandic-volcanic-activity">Research</a> has also found a correlation between glacial-load changes on the Earth’s crust and the occurrence of volcanic activity. Approximately 5,500–4,500 years ago, Earth’s climate briefly cooled and glaciers began to expand in Iceland. Analysis of volcanic ash deposits spread throughout Europe suggest that volcanic activity in Iceland markedly reduced during this period. </p>
<p>There was a subsequent increase in volcanic activity following the end of this cool period, albeit with a delay of several hundred years. </p>
<p>This phenomenon can be explained by the weight of glaciers compressing both the Earth’s crust and the underlying mantle (the mostly solid bulk of Earth’s interior). This kept the material that makes up the mantle under higher pressure, preventing it from melting and forming the magma required for volcanic eruptions. </p>
<p>However, deglaciation and the associated loss of weight on the Earth’s surface allowed a process called <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GC008222">decompression melting</a> to occur, where lower pressure facilitates melting in the mantle. Such melting resulted in the formation of the liquid magma that fuelled the subsequent volcanic activity in Iceland. </p>
<p>Even today, this process is responsible for driving some volcanic activity in Iceland. Eruptions at two volcanoes, Grímsvötn and Katla, <a href="https://academic.oup.com/gji/article/181/3/1510/604035?login=false">consistently occur during the summer period</a> when glaciers retreat.</p>
<p>It is therefore feasible that ongoing glacial retreat due to global warming could potentially increase volcanic activity in the future. However, the time lag between glacial changes and the volcanic response is reassuring for now. </p>
<figure class="align-center ">
<img alt="The Katla volcano covered by the Mýrdalsjökull glacier." src="https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541703/original/file-20230808-27-u2dvxt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Katla volcano covered by the Mýrdalsjökull glacier.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/katla-volcano-glacier-iceland-2287047711">muratart/Shutterstock</a></span>
</figcaption>
</figure>
<p>The impacts of a changing climate are becoming more evident, with unusual weather events having become the norm rather than the exception. However, the indirect impacts of climate change on the ground beneath our feet are neither widely known or discussed. </p>
<p>This must change if we are to minimise the effects of the changing climate that have already been set firmly in motion.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?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"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Matthew Blackett 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>Climate change is causing increasingly severe weather – but it’s not just hazards at the Earth’s surface we should be concerned about.Matthew Blackett, Reader in Physical Geography and Natural Hazards, Coventry UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2097882023-08-07T00:46:05Z2023-08-07T00:46:05ZPlastic rocks, plutonium, and chicken bones: the markers we’re laying down in deep time<figure><img src="https://images.theconversation.com/files/540679/original/file-20230802-23-6zixs7.jpg?ixlib=rb-1.1.0&rect=13%2C13%2C2982%2C1553&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>Rocks keep time. Not on our human-scale time, but deep time: the almost unimaginable span of billions of years which have already come and gone. </p>
<p>Let’s say you’re in the far future and you’re looking for evidence of previous civilisations. Where would you look? The first place would be in the rocks. </p>
<p>For decades, experts have debated whether our world-spanning impact on the planet represents the sign of a new geological period, the Anthropocene. Only recently, scientists selected a <a href="https://theconversation.com/a-canadian-lake-holds-the-key-to-the-beginning-of-the-anthropocene-a-new-geological-epoch-209576">small lake</a> in Canada as the site that best records our impact.</p>
<p>That’s because the waters of the lake don’t mix, which means sediment falling into the lake is laid down neatly and in incredible detail. Over long periods, the lake’s <a href="https://www.antarcticglaciers.org/glacial-geology/varves/">varved sediments</a> have preserved an excellent, undisturbed record of the Anthropocene. </p>
<p>But what would have to be in those sediments to leave indelible evidence of our presence? Here are five of the markers we’re leaving for the future. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1678814180848050177"}"></div></p>
<h2>What markers are we laying down in rock?</h2>
<p>We break up deep time into parts. Everyone is familiar with periods such as the Jurassic. But what separates them? Usually, a change in the global environment so large it leaves permanent evidence visible in the rock layers. That could be an <a href="https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event">asteroid strike</a>, gargantuan <a href="https://www.amnh.org/exhibitions/dinosaurs-ancient-fossils/extinction/deccan-traps-volcanoes">volcanic eruptions</a> in what is now India or trillions of bacteria <a href="https://asm.org/Articles/2022/February/The-Great-Oxidation-Event-How-Cyanobacteria-Change">injecting oxygen</a> into the atmosphere and making respiration possible. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="ocean cliffs" src="https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540660/original/file-20230802-27-iod8xt.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">Experts learn to read rock layers like a book of deep time. Each layer on these cliffs tells a story of changing environments over millions of years.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>So to declare that we’re in a new geological epoch – and that we’ve left the balmy post-ice age Holocene behind – requires finding evidence of unmistakably clear markers. Here are five possibilities. </p>
<h2>1. Plastics and plastic rocks</h2>
<p>Plastics aren’t naturally produced – they’re manufactured from feedstock such as oil, coal, cellulose and fossil gas. Finding plastics in a sediment or rock layer is a clear sign that the layer dates from modern times. </p>
<p>There are also plastiglomerates, the mutant offspring of plastics and rock. These have been found in several places worldwide. They can be produced when plastic is heated, such as <a href="https://phys.org/news/2023-03-scientists-disturbing-remote-island-plastic.html">in campfires</a>, or in bushfires. But they’re also being found in other places <a href="https://www.nature.com/articles/d41586-023-01037-6">such as creeks</a>.</p>
<h2>2. Concrete</h2>
<p>Concrete is now the <a href="https://www.anthropocene-curriculum.org/contribution/concrete-a-stratigraphic-marker-for-the-anthropocene">most abundant</a> human-made “rock” on the planet’s surface. Future archaeologists could dig down through mud and detritus to identify when widescale use of concrete first became obvious. This would tell them they’d struck the 20th century. Concrete, of course, has been used for millennia – ancient Roman concrete is <a href="https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106">still standing</a> in some places. But it didn’t become ubiquitous until recently. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="tunelboca beach anthropocene" src="https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540649/original/file-20230802-27-6zixs7.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">Cement, brick and industrial waste has been laid down in newly formed beachrock at Tunelboca beach in Spain.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>3. Chicken bones</h2>
<p>Humans like chicken. As of 2018, we <a href="https://www.nytimes.com/2018/12/11/science/chicken-anthropocene-archaeology.html">were eating</a> about 65 billion of these birds a year. At any one time, there are 23 billion chickens alive. But why would chicken bones be a telltale sign we were here? Because of how common they are – and because our long reliance on these birds has changed them dramatically. They no longer resemble their sleek <a href="https://www.science.org/content/article/how-wild-jungle-fowl-became-chicken">jungle fowl</a> antecedents – they’re far larger, grow quicker and eat differently. Broiler (meat) chickens can’t survive without human intervention. These changes are <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.180325">so profound </a>that it’s as if we’ve bred a new species, according to paleobiology and Anthropocene expert Jan Zalasiewicz, who <a href="https://phys.org/news/2023-07-proof-humans-reshaped-world-chickens.html">told AFP</a>: “It usually takes millions of years […] but here it has taken just decades to produce a new form of animal.” </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="broiler chicken farm" src="https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540657/original/file-20230802-29-yj4k10.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">Broiler chickens grow much faster than their wild ancestors – and we breed billions upon billions every year.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>4. Plutonium and nuclear residue</h2>
<p>Nuclear testing began in the 1940s and accelerated through the 1950s and 60s before being phased out. Testing of new bombs <a href="https://www.wired.com/story/nuclear-tests-have-changed-but-they-never-really-stopped/">now happens</a> without exploding them. But those decades of testing in the 20th century have left behind a pollution time marker in our environment. </p>
<p>Explosive testing scattered traces of radiation across the entire planet. Plutonium, in particular, makes an excellent marker of 20th century human impact. While it does <a href="https://www.scientificamerican.com/article/do-transuranic-elements-s">occur naturally</a>, it’s only at incredibly low levels. The amount of plutonium spread by testing has left a clear spike, like a fingerprint, in the environment. Even now, we can identify samples from the 1950s and 1960s by <a href="https://www.anthropocene-curriculum.org/contribution/radioactive-fallout-as-a-marker-for-the-anthropocene">the presence</a> of plutonium and other radionuclides. </p>
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<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>
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<hr>
<h2>5. Fossil fuels and climate change</h2>
<p>We’ve been digging up and burning fossil fuels for a long time. People were using coal for heat thousands of years ago. But we really got going during what’s been dubbed the <a href="https://www.hup.harvard.edu/catalog.php?isbn=9780674545038">Great Acceleration</a> in the mid-20th century, as many countries got richer, populations exploded, and demand for cars, planes and electricity soared. Burning these fuels leaves behind large volumes of fly ash and carbon particles, which fall to Earth, are laid down in rock in some areas. The carbon (CO2) pollution from burning the fuels will also eventually be recorded in rock. Future civilisations would be able to detect our presence because of the remarkably fast spike in carbon dioxide in the atmosphere. </p>
<h2>Markers upon markers</h2>
<p>There are many more markers, from sudden shifts in distribution of animal species, soil erosion and pollution, to refined metals, to looming mass extinctions of species. </p>
<p>Even so, the Anthropocene has not yet been declared. And it may never be. That’s because there are still many questions to sort out. Will these markers be recognisable long term? And – as some geologists argue – can we even say this is a distinct epoch, given it’s only just begun in geological terms? </p>
<p>All of this will be hashed out in discussions through this year. By the end of next year, we’ll learn the scientific fate of the Anthropocene. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/did-the-anthropocene-start-in-1950-or-much-earlier-heres-why-debate-over-our-world-changing-impact-matters-209869">Did the Anthropocene start in 1950 – or much earlier? Here's why debate over our world-changing impact matters</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/209788/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Duncan Cook receives funding from the Australian Research Council.</span></em></p>We’re having a big impact on the planet. But what marks will we leave behind in deep time?Duncan Cook, Associate Professor in Geography, Australian Catholic UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2071522023-08-06T19:59:54Z2023-08-06T19:59:54ZHow algae conquered the world – and other epic stories hidden in the rocks of the Flinders Ranges<figure><img src="https://images.theconversation.com/files/539439/original/file-20230726-21-y5r0d0.JPG?ixlib=rb-1.1.0&rect=32%2C44%2C4249%2C2798&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Alan Collins</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Earth was not always so hospitable. Evidence of how it came to be so beautiful and nurturing is locked in the rocks of South Australia’s Flinders Ranges – a site now vying for <a href="https://www.environment.sa.gov.au/topics/flinders-ranges-world-heritage-nomination">World Heritage listing</a>.</p>
<p>Our <a href="https://www.cambridge.org/core/journals/geological-magazine/article/geochronology-and-formal-stratigraphy-of-the-sturtian-glaciation-in-the-adelaide-superbasin/1D635EDFDB155C19FF8481D178F86AC7">new</a> <a href="https://oap.unige.ch/journals/sdk/article/view/1083">research</a> seeks to better understand this near billion-year-old story. We discovered immense planetary upheaval recorded in the ranges.</p>
<p>In two related research projects, we’ve mapped how the continent that later became Australia responded to the most extreme climate change known in Earth’s history. We then dated this event. </p>
<p>The changes gave rise to <a href="https://www.anu.edu.au/news/all-news/anu-led-study-solves-mystery-of-how-first-animals-appeared-on-earth">algae</a>. Their legacy is the oxygen we breathe and the <a href="https://theconversation.com/ancient-sponges-or-just-algae-new-research-overturns-chemical-evidence-for-the-earliest-animals-150635">evolution of the first animals</a> more than 500 million years ago. The soft bodies of these animals have been exceptionally preserved at the new <a href="https://www.parks.sa.gov.au/parks/nilpena-ediacara-national-park">Nilpena-Ediacara National Park</a>, which opened in April 2023. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1603543240816627713"}"></div></p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/friday-essay-histories-written-in-the-land-a-journey-through-adnyamathanha-yarta-124001">Friday essay: histories written in the land - a journey through Adnyamathanha Yarta</a>
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</em>
</p>
<hr>
<h2>A superbasin on the shores of the Pacific</h2>
<p>The rocks of the Flinders Ranges formed at the same time as the Pacific Ocean basin. The plate tectonic “<a href="https://theconversation.com/a-map-that-fills-a-500-million-year-gap-in-earths-history-79838">dance of the continents</a>” tore North America away from Australia 800 million years ago. This created a valley that became an ocean where sand and mud was deposited. </p>
<p>Geologists call this the <a href="https://www.sciencedirect.com/science/article/pii/S0301926820300875">Adelaide Superbasin</a>. “Super” because it is huge, and “basin” because it formed a depression where sediment could accumulate. </p>
<p>The superbasin stretches from Kangaroo Island in the south, to north of the Flinders Ranges and from Coober Pedy in the west to the Barrier Ranges of New South Wales in the east.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of South Australia marking out the area of the Adelaide Superbasin" src="https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=565&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=565&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=565&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=710&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=710&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=710&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the Adelaide Superbasin. The national parks highlighted form part of the World Heritage nomination: Ikara-Flinders Ranges, Vulkathanana-Gammon Ranges and Nilpena Ediacara national parks.</span>
<span class="attribution"><span class="source">Alan Collins, with Google Earth basemap</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>At special places such as <a href="https://www.arkaroola.com.au/">Arkaroola</a> and the national parks of <a href="https://www.parks.sa.gov.au/parks/vulkathunha-gammon-ranges-national-park">Vulkathunha-Gammon Ranges</a> and <a href="https://www.parks.sa.gov.au/parks/ikara-flinders-ranges-national-park">Ikara-Flinders</a>, rocks of the Adelaide Superbasin tell us how our planet came to be the way it is today. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-map-that-fills-a-500-million-year-gap-in-earths-history-79838">A map that fills a 500-million year gap in Earth's history</a>
</strong>
</em>
</p>
<hr>
<h2>Land of fire and ice</h2>
<p>Until about 800 million years ago, Earth was an oxygen-poor but stable planet. So stable, in fact, this time has been nicknamed the “<a href="https://theconversation.com/earths-boring-billion-years-of-stagnant-stinking-oceans-might-actually-have-been-rather-dynamic-120134">Boring Billion</a>”. </p>
<p>That all changed 716 million years ago. The planet plunged into an 80-million-year Ice Age, the likes of which has never been seen again. It’s known as the <a href="https://stratigraphy.org/chart">Cryogenian</a> Period. </p>
<p>The Cryogenian contains a least two global glaciations when the planet became covered in ice - an occurrence earth scientists refer to as “Snowball Earth”. What caused this incredible cooling is still a mystery. But many researchers think it relates to <a href="https://theconversation.com/ancient-volcanic-eruptions-disrupted-earths-thermostat-creating-a-snowball-planet-82215">huge volcanic eruptions</a> that directly preceded the icy conditions. The heavily worn remains of these volcanoes have <a href="https://www.science.org/content/article/massive-lava-outburst-may-have-led-snowball-earth">recently been discovered</a> in Arctic Canada and Alaska.</p>
<p>We know lava from volcanoes reacts with CO₂, dragging it out of the atmosphere. Scientists believe this reversed the pre-historic greenhouse effect and the <a href="https://www.science.org/content/article/massive-lava-outburst-may-have-led-snowball-earth">planet cooled</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-volcanic-eruptions-disrupted-earths-thermostat-creating-a-snowball-planet-82215">Ancient volcanic eruptions disrupted Earth's thermostat, creating a 'Snowball' planet</a>
</strong>
</em>
</p>
<hr>
<h2>Part One: Picturing the world before the first animals</h2>
<p>The first part of our <a href="https://doi.org/10.57035/journals/sdk.2023.e11.1083">new research</a> reconstructs the shores of the balmy Pacific as this climate shock hit, causing vast ice sheets to lumber north and smother the region for millions of years. </p>
<p>The glaciers ploughed through hills and valleys, planing off the country and leaving behind vast swathes of boulder clay that now forms rocks over much of the Flinders Ranges.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A coloured graphic showing the correlations between rock sections from across the Flinders Ranges" src="https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Correlation of rock sections across the northern Flinders Ranges. Blue represents rocks deposited during and after the Sturt glaciation. These sequences overlie rocks deposited in warm, tropical conditions (pink).</span>
<span class="attribution"><a class="source" href="https://oap.unige.ch/journals/sdk/article/view/1083">Georgina Virgo, from Virgo et al. (2023) Sedimentologika</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our research analysed unusual magnesium-rich sedimentary rocks in part formed by microscopic bacteria. Hundreds of millions of years later, small variations in the concentration of critical elements are still preserved. We used these variations to build a picture of highly saline shallow seas rich in bacterial life, but devoid of much else. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of ancient rock in the northern Flinders Ranges, with a pink pen laid on top to show the scale." src="https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=540&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=540&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=540&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 ancient rock called diamictites was deposited by the Sturtian glaciers in the northern Flinders Ranges.</span>
<span class="attribution"><span class="source">Georgina Virgo</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Part Two: Dating Snowball Earth</h2>
<p>Dating sedimentary rocks is challenging. The grains of sand and pebbles that make up the rock formed elsewhere. They were carried by wind or water to the beach, or river, where they were deposited. Then, gradually, new rock formed. </p>
<p>Using established methods we can date one of the minerals in the sand (zircon). This <a href="https://en.wikipedia.org/wiki/Uranium%E2%80%93lead_dating">uranium–lead method</a> gives us the oldest possible age for sedimentary rock. That’s a reliable maximum age, but the true age of the rock could be much younger.</p>
<p>In the second part of our <a href="https://doi.org/10.1017/S0016756823000390">research</a> we combined this established method with a new technique called “<a href="https://doi.org/10.1130/G49187.1">in-situ rubidium–strontium dating</a>”. This enabled us to more accurately date the Snowball Earth rocks in the Flinders Ranges called the Sturt Formation.</p>
<p>The new technique attempts to directly date the “glue” that holds the grains of sedimentary rocks together. So we’re using a laser to date minerals that form as the sediment turns to rock. Some of these “authigenic” minerals (minerals that form “in place”) contain tiny amounts of radioactive rubidium. Over time, rubidium changes to strontium by radioactive decay. </p>
<p>Our study dates mudrock deposited within the glaciation. It is the first study to directly date sedimentary rocks that formed during the Snowball Earth event. This mudrock (a part of the Sturt Formation) formed around 684 million years ago. </p>
<p>Our “detrital zircon” method also gave us maximum ages of about 698 million years for a boulder clay below the mudrock, and about 663 million years from a boulder clay above the mudrock. These dates fit with estimates from elsewhere on the globe, suggesting the icy time likely lasted 50 million years.</p>
<p>Put together, the results of these two projects suggest the “Sturtian” glaciation took place between 716 and 663 million years ago and may have been more dynamic than previously thought. It’s likely there were at least two ice-advance and ice-retreat events, or two separate glacial times. So the planet experienced more of a cold period rather than a completely frigid snowball. </p>
<h2>The rise of the algae</h2>
<p>These two research projects using rocks within the proposed World Heritage area, along with work from many other researchers, develops a picture of the world that led to the evolution of the first animals. The geological processes and their timing helps us understand how the Earth system came to be.</p>
<p>The frozen world of the Cryogenian stressed the microbial life that dominated the oceans way back then. Glaciers ground rock to powder and this powder turned the oceans of the day to a nutrient soup. </p>
<p>So when warmer times came, a previously minor player in the biosphere bloomed. This newcomer was <a href="https://www.anu.edu.au/news/all-news/anu-led-study-solves-mystery-of-how-first-animals-appeared-on-earth">algae</a>, life with cells containing a nucleus. Essentially, seaweed.</p>
<p>They were larger than the life that existed before and better at photosynthesising. They pumped their oxygen waste into the oceans and atmosphere, inadvertently providing the fuel for microbes to combine to form more complex multicellular life forms (metazoans) and ultimately, the first animals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of the Flinders Ranges with a tree in the foreground and hills in the background, layers of ancient rock are visible" src="https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.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">The hills in the background contain layers of 800 million year old rocks from the northern part of the ‘Adelaide Superbasin’ in the Flinders Ranges.</span>
<span class="attribution"><span class="source">Alan Collins</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A place of true world heritage</h2>
<p>The rocks of the Flinders Ranges preserve so many stories, from the <a href="https://theconversation.com/friday-essay-histories-written-in-the-land-a-journey-through-adnyamathanha-yarta-124001">Dreamtime-formed shapes of the ranges</a>, to the scars of the early mining history. </p>
<p>Our research into these rocks links the interdependence of Earth systems. Here we find stories about how plate tectonics and volcanoes control the climate, how the climate helps feed life with nutrients and how the resulting life changes the chemistry of the ocean and atmosphere, feeding back into powering new forms of life.</p>
<p>The stories locked in the hills of the Flinders Ranges undoubtedly give the region a heritage value to the world. We eagerly await news of world heritage listing, which is <a href="https://www.theguardian.com/australia-news/2022/aug/21/south-australias-flinders-ranges-nominated-for-unesco-world-heritage-status">not expected until 2025</a> at the earliest.</p><img src="https://counter.theconversation.com/content/207152/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alan Collins receives funding from the Australian Research Council, MinEx CRC, BHP, Santos, Empire Energy, Teck Resources and the NT, SA and WA Governments. He is affiliated with the Geological Society of Australia and the Australian Institute of Geoscientists. </span></em></p><p class="fine-print"><em><span>Georgina Virgo received funding from the Geological Survey of South Australia as part of her PhD project at The University of Adelaide. </span></em></p><p class="fine-print"><em><span>Jarred Lloyd receives funding from the Australian Research Council through the Australian Critical Minerals Research Centre at the University of Adelaide, and his research position is also supported by the SA Government. He is affiliated with the Geological Society of Australia. </span></em></p>New research dating and reading the rocks of the Flinders Ranges in South Australia reveals a fascinating story about how complex life emerged on our planet.Alan Collins, Professor of Geology, University of AdelaideGeorgina Virgo, Research assistant, University of AdelaideJarred Lloyd, Postdoctoral research fellow, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.