tag:theconversation.com,2011:/au/topics/zealandia-42903/articlesZealandia – The Conversation2020-12-16T19:04:29Ztag:theconversation.com,2011:article/1515782020-12-16T19:04:29Z2020-12-16T19:04:29ZEastern Australia has hundreds of enigmatic volcanoes. New research shows how they formed<figure><img src="https://images.theconversation.com/files/375215/original/file-20201215-15-15pzf7a.jpg?ixlib=rb-1.1.0&rect=14%2C0%2C2367%2C1350&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/q9-KwUcNNPQ">Luisa Denu / Unsplash</a></span></figcaption></figure><p>The landscape of eastern Australia is dotted with hundreds of extinct volcanoes. They gave rise to an environment to which Aboriginal people have been connected for <a href="https://theconversation.com/when-the-bullin-shrieked-aboriginal-memories-of-volcanic-eruptions-thousands-of-years-ago-81986">tens of thousands of years</a>, and the rich soils upon which modern Australia has grown in the last <a href="https://maas.museum/inside-the-collection/2016/03/31/industrial-revolution-wool/">few hundred years</a>.</p>
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Read more:
<a href="https://theconversation.com/when-the-bullin-shrieked-aboriginal-memories-of-volcanic-eruptions-thousands-of-years-ago-81986">When the Bullin shrieked: Aboriginal memories of volcanic eruptions thousands of years ago</a>
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<p>Yet until recently, these volcanoes posed a geological mystery. There are two common ways volcanoes form: at the edges of tectonic plates, or on top of blobs of hot material called “mantle plumes”, which rise from the planet’s deep interior. For most of eastern Australia’s volcanoes, however, neither of these explanations fits the bill. </p>
<p>We have now <a href="https://advances.sciencemag.org/content/6/51/eabd0953">solved the puzzle</a>. By studying the history of the eruptions and the chemical makeup of the rocks they spat out, we discovered a previously unknown geological mechanism that links volcanoes from Far North Queensland to the southern tip of Tasmania.</p>
<h2>Australia’s volcanic connection</h2>
<p>You may be surprised to learn that hundreds of volcanoes erupted along the entire eastern side of Australia over the past 100 million years. This volcanism also extended offshore to New Zealand and the <a href="https://www.9news.com.au/national/zealandia-how-the-worlds-hidden-continent-was-formed-near-australia-science/3a06ec96-fd19-421a-8422-e7dc107dd324">submerged continent of Zealandia</a>.</p>
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Read more:
<a href="https://theconversation.com/what-are-lost-continents-and-why-are-we-discovering-so-many-126355">What are lost continents, and why are we discovering so many?</a>
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<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing Australia and Zealandia's volcanoes, mostly located down Australia's east coast" src="https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375836/original/file-20201218-17-1p83ap3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">There are many volcanoes across Australia and Zealandia. Highlights for volcano spotters include: (A) Sawn Rocks in New South Wales, (B) Glass House Mountains and (C) Undara Lava Tubes in Queensland, (D) Mt Gambier in South Australia, (E) Organ Pipes in Victoria and (F) The Nut in Tasmania.</span>
<span class="attribution"><span class="source">Jo Condon / Mahsa-Chitsaz / Luisa Denu / Jane Farquhar / Charles G / Nick Carson / Around Aus</span>, <span class="license">Author provided</span></span>
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<p>Most of the world’s volcanoes form when a process called “subduction” pushes parts of the seafloor down into Earth’s mantle, where it melts and produces volcanism at the surface. The best-known example of this kind of volcanism is the <a href="https://theconversation.com/five-active-volcanoes-on-my-asia-pacific-ring-of-fire-watch-list-right-now-90618">Ring of Fire</a> around the Pacific Ocean.</p>
<p>Alternatively, chains of volcanic islands may be built by hot material rising from the Earth’s deep interior – called “mantle plumes” – in a process that created the likes of Hawaii, Iceland, and the Galapagos Islands. These so-called “hotspot chains” track the movement of tectonic plates as new islands form over a stationary mantle plume.</p>
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<a href="https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=264&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=264&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=264&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=332&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=332&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375314/original/file-20201216-21-upi7g.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=332&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">Most volcanoes are clustered near subduction zones, where oceanic crust is recycled into the Earth’s mantle, or above hotspots which create chains of islands in the oceans.</span>
<span class="attribution"><span class="source">University of Saskatchewan</span></span>
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<p>However, most of the volcanoes in our backyard are not related to mantle plumes and are not close to plate boundaries. So why are they here?</p>
<h2>Examining Australia’s volcanic pulse</h2>
<p>Our study, <a href="https://advances.sciencemag.org/content/6/51/eabd0953">published today</a> in Science Advances, shows the frequency of volcanic eruptions in eastern Australia and Zealandia depends on what’s happening to the seafloor some 3,000 kilometres further east.</p>
<p>Why does this happen? It’s all to do with how much water and carbon dioxide are trapped in the seafloor, which is recycled down into the mantle. </p>
<p>Over many millions of years, a reservoir of these volatile ingredients has built up in the mantle, more than 410 kilometres below the surface. This reservoir stays dormant beneath the Australian plate, until tectonic forces create bursts of movement.</p>
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Read more:
<a href="https://theconversation.com/australias-volcanic-history-is-a-lot-more-recent-than-you-think-58766">Australia's volcanic history is a lot more recent than you think</a>
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<p>As slabs of seafloor are subducted at the Tonga-Kermadec Trench, which runs from New Zealand all the way to Samoa, the vibrations reach all way to the mantle reservoir beneath eastern Australia and Zealandia. As a result, water and carbon dioxide shake loose from the reservoir and rise up to produce volcanic eruptions at the surface. </p>
<p>We found our first piece of evidence for this driving process in the deep history of volcanic eruptions in the region. There were two gradual increases in volcanism, one between 60 million years ago and 21 million years ago, and the other from 10 million years ago to 2 million years ago. These periods were separated by a brief (in geological terms) lull in eruption frequency. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/ECp63U_8gBs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Reconstruction of volcanism and subduction in eastern Australia and Zealandia since 120 million years ago in map view, visualised in AuScope enabled GPlates software.</span></figcaption>
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<p>Both episodes were produced by major reorganisations of Earth’s tectonic plates, in which the plates rapidly change speed and direction. These changes led to the subduction of a massive pile of western Pacific seafloor, which in turn caused volcanic activity as water and carbon dioxide were shaken from their reservoir in the mantle.</p>
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<a href="https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Our model in section view together with a graph of volcanism through time." src="https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375331/original/file-20201216-13-lrijul.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Our new model of volcanism shown as a slice through the Earth (sectional view), visualised together with the region’s volcanism over the last 100 million years.</span>
<span class="attribution"><span class="source">Jo Condon / Ben Mather</span></span>
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<h2>Fingerprinting Australia’s mystery volcanoes</h2>
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<img alt="" src="https://images.theconversation.com/files/374593/original/file-20201213-15-1qvrg46.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/374593/original/file-20201213-15-1qvrg46.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374593/original/file-20201213-15-1qvrg46.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374593/original/file-20201213-15-1qvrg46.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374593/original/file-20201213-15-1qvrg46.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374593/original/file-20201213-15-1qvrg46.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374593/original/file-20201213-15-1qvrg46.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">
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<span class="caption">In 2019 we travelled aboard the CSIRO research vessel Investigator to collect rock samples from underwater volcanoes and map thousands of kilometres of seafloor.</span>
<span class="attribution"><span class="source">Supplied</span></span>
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<p>This subduction process is not unique to the Australian east coast. What sets the east Australia-Zealandia region apart is that the seafloor being pushed under the continent from the western Pacific is rich in materials that contain water and carbon dioxide. </p>
<p>Not only that, but these materials seem to collect at a shallow depth in the mantle over a long period of time, rather than sink deeper into Earth’s interior. This creates a zone deep in the mantle right under the east coast of Australia that is enriched with volatile materials.</p>
<p>We examined the chemical composition of rocks produced by these ancient eruptions across the region and found the vast majority shared common chemical fingerprints. These fingerprints told us the eruptions across the eastern third of Australia and Zealandia came from a common mantle reservoir, which could only have formed from the subduction of ancient seafloor. This was the final piece of the puzzle that helped us connect seemingly random volcanoes over 100 million years of history.</p>
<h2>New ‘eyes’ to explore abroad and at home</h2>
<p>Combining the perspectives of volcanic history, tectonic plate movements and geochemistry may also help us to unlock other explosive mysteries of our natural world. We hope to test our model further in other enigmatic regions where volcanoes appear in the middle of tectonic plates, such as the western United States, eastern China, and around Bermuda.</p>
<p>In the meantime, we hope our discoveries give you a new way to look at the many beautiful volcanic hills and other features of eastern Australia. If you’re driving around the countryside this summer, here are our top five volcanic highlights for your travelling pleasure:</p>
<ul>
<li><p><a href="https://www.discovertasmania.com.au/attraction/thenut">The Nut</a>, Tasmania</p></li>
<li><p><a href="https://discovermountgambier.com.au/experience/geological-wonders/">Mount Gambier</a>, South Australia</p></li>
<li><p><a href="https://www.parks.vic.gov.au/places-to-see/parks/organ-pipes-national-park">Organ Pipes National Park</a>, Victoria</p></li>
<li><p><a href="https://www.visitnarrabri.com.au/narrabri-directory/sawn-rocks/">Sawn Rocks Narrabri</a>, New South Wales</p></li>
<li><p><a href="https://www.tropicalnorthqueensland.org.au/things-to-do/geological-wonders/lava-tubes/">Undara lava tubes</a>, Queensland</p></li>
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<p><em>This study was carried out by researchers from the University of Sydney, <a href="https://www.monash.edu/science/schools/earth-atmosphere-environment">Monash University</a> and <a href="https://www.gns.cri.nz/">GNS Science</a> in Dunedin, New Zealand. It was enabled by Australia’s National Collaborative Research Infrastructure Strategy (<a href="https://www.education.gov.au/national-collaborative-research-infrastructure-strategy-ncris">NCRIS</a>) via <a href="https://www.auscope.org.au">AuScope</a> and <a href="https://www.chiefscientist.nsw.gov.au">The Office of the Chief Scientist and Engineer</a>, NSW Department of Industry.</em></p>
<p><em>CORRECTION: This article originally referred to Cradle Mountain in Tasmania, which is not in fact volcanic. It should have referred to <a href="https://www.discovertasmania.com.au/attraction/thenut">The Nut</a>, which is. This has been amended.</em></p><img src="https://counter.theconversation.com/content/151578/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Mather works for The University of Sydney, supported by funds from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Dietmar Müller receives funding from the Australian Research Council, the AuScope National Collaborative Research Infrastructure and the NSW Department of Industry.</span></em></p><p class="fine-print"><em><span>Jo Condon works for AuScope, a non-profit organisation funded by the Australian Government (NCRIS) that helped to enable this research. </span></em></p><p class="fine-print"><em><span>Maria Seton receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Oliver Nebel receives funding from the Australian Research Council</span></em></p>From far north Queensland to the southern tip of Tasmania, there is a common geological mechanism that links Eastern Australia’s volcanic history.Ben Mather, Computational Geophysicist, University of SydneyDietmar Müller, Professor of Geophysics, University of SydneyJo Condon, Honorary researcher, The University of MelbourneMaria Seton, Senior Lecturer, University of SydneyOliver Nebel, Associate Professor, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1308602020-02-06T19:02:28Z2020-02-06T19:02:28ZExpedition reveals the violent birth of Earth’s hidden continent Zealandia, forged in a ring of fire<figure><img src="https://images.theconversation.com/files/313190/original/file-20200202-41485-19x7k9a.jpg?ixlib=rb-1.1.0&rect=4%2C59%2C1592%2C708&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">IODP</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Three years ago, the <a href="https://www.geosociety.org/gsatoday/archive/27/3/article/GSATG321A.1.htm">identification of Zealandia as a continent</a> made <a href="https://www.bbc.com/news/world-asia-39000936">global headlines</a>. </p>
<p>Now, newly <a href="https://doi.org/10.1130/G47008.1">published results</a> from our <a href="https://iodp.tamu.edu/scienceops/expeditions/tasman_frontier_subduction_climate.html">scientific drilling expedition</a> reveal the largely submerged Zealandia continent, which stretches across five million square kilometres beneath the southwest Pacific Ocean, was shaped by two tectonic events. </p>
<p>First it was ripped away from Australia and Antarctica, and then it was carved by forces that started the <a href="https://www.nationalgeographic.com/science/earth/ring-of-fire/">Pacific Ring of Fire</a>. </p>
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<figcaption><span class="caption">The drilling expedition investigated Zealandia, a continent hidden below the sea.</span></figcaption>
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<h2>Why Zealandia is so different to other continents</h2>
<p>Zealandia has an unusual geography for a continent. More than half the surface area of Earth’s other six continents are composed of low-lying land and shallow seas, and they have relatively narrow mountain ranges and steep continental slopes in the deep ocean. </p>
<p>In contrast, Zealandia is mostly hidden beneath more than one kilometre of water and could be classified as more than 90% continental slope. This makes it a challenge to explore. </p>
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<img alt="" src="https://images.theconversation.com/files/313188/original/file-20200202-41490-frfdpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313188/original/file-20200202-41490-frfdpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313188/original/file-20200202-41490-frfdpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313188/original/file-20200202-41490-frfdpm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313188/original/file-20200202-41490-frfdpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313188/original/file-20200202-41490-frfdpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313188/original/file-20200202-41490-frfdpm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&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">The world’s continents and Zealandia, at the southern end of the Pacific Ring of Fire.</span>
<span class="attribution"><span class="license">Author provided</span></span>
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<p>The first scientific drilling expedition to sample in the area where we now know Zealandia is took place in 1972 between Australia, New Zealand and New Caledonia. The <a href="http://deepseadrilling.org/21/dsdp_toc.htm">results</a> suggested tectonic forces stretched and thinned Zealandia’s crust until it was ripped from the ancient supercontinent Gondwana about 85 million years ago, during the time of dinosaurs. This created a deep ocean: the Tasman Sea. </p>
<p>The evidence remains compelling that this is at least part of the answer to how the geography of Zealandia formed. But detailed surveys during the 1990s and 2000s, carried out to establish sovereignty over the Zealandia continental mass by New Zealand, Australia and France, suggested other contributing factors.</p>
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Read more:
<a href="https://theconversation.com/what-are-lost-continents-and-why-are-we-discovering-so-many-126355">What are lost continents, and why are we discovering so many?</a>
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<h2>How the Pacific Ring of Fire shaped Zealandia</h2>
<p>In 2017, we led a nine-week expedition into the southwest Pacific as part of the International Ocean Discovery Program (<a href="http://www.iodp.org/">IODP</a>), with 32 scientists on board the research vessel <a href="https://joidesresolution.org/">JOIDES Resolution</a>. Our aim was to unravel why Zealandia is so different from the other continents.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313192/original/file-20200202-41485-cwfyp9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313192/original/file-20200202-41485-cwfyp9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313192/original/file-20200202-41485-cwfyp9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313192/original/file-20200202-41485-cwfyp9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313192/original/file-20200202-41485-cwfyp9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313192/original/file-20200202-41485-cwfyp9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313192/original/file-20200202-41485-cwfyp9.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">
<figcaption>
<span class="caption">Sanny Saito (Japan), Rupert Sutherland (New Zealand), Thomas Westerhold (Germany), and Edo Dallanave (Italy) on the drill floor of the JOIDES Resolution.</span>
<span class="attribution"><span class="source">Michelle Drake</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our <a href="https://doi.org/10.1130/G47008.1">newly published results</a> have been drawn from that expedition 371, where we collected new samples and sought to test our hypothesis that formation of the Pacific Ring of Fire played a key role in shaping Zealandia.</p>
<p>We collected sediment cores from up to 864 metres beneath the seabed at six sites far away from land or shallow water. At the deepest site, the water was five kilometres deep and our drill weighed 300 tonnes. We used fossils from three of the sites to show northern Zealandia became much shallower and likely even had land areas between 50 and 35 million years ago. At about that time, two other sites became submerged into deeper water, and then the whole region subsided an additional kilometre to its present depth. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313191/original/file-20200202-41503-tblt6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313191/original/file-20200202-41503-tblt6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=562&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313191/original/file-20200202-41503-tblt6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=562&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313191/original/file-20200202-41503-tblt6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=562&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313191/original/file-20200202-41503-tblt6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=706&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313191/original/file-20200202-41503-tblt6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=706&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313191/original/file-20200202-41503-tblt6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=706&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The expedition drilled for samples at six sites, marked on this map with stars.</span>
<span class="attribution"><span class="source">IODP</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>These dramatic changes in northern Zealandia, an area about the size of India, coincided with buckling of rock layers (known as strata) and the formation of underwater volcanoes throughout the western Pacific.</p>
<p>The Pacific Ring of Fire is a zone of volcanoes and earthquakes running along the west coasts of north and south America, past Alaska and Japan, and then through the western Pacific to New Zealand. The violent geological activity in this zone reflects deeper unrest at the boundaries of tectonic plates, caused by “subduction processes” – where one tectonic plate converges on another and sinks back deep into the earth. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313219/original/file-20200203-41541-1hgzs9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313219/original/file-20200203-41541-1hgzs9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=267&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313219/original/file-20200203-41541-1hgzs9h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=267&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313219/original/file-20200203-41541-1hgzs9h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=267&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313219/original/file-20200203-41541-1hgzs9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=336&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313219/original/file-20200203-41541-1hgzs9h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=336&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313219/original/file-20200203-41541-1hgzs9h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=336&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Scientists on the expedition identify fossils in sediment cores.</span>
<span class="attribution"><span class="source">IODP</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explorers-probe-hidden-continent-of-zealandia-83406">Explorers probe hidden continent of Zealandia</a>
</strong>
</em>
</p>
<hr>
<p>We know the Pacific Ring of Fire formed about 50 million years ago, but the process remains a mystery. We propose a “subduction rupture event” – a process similar to a massive slow-moving earthquake – spread around the whole of the western Pacific at that time. We suggest this process resurrected ancient subduction faults, which had lain dormant for many millions of years but were primed to start moving again. </p>
<p>This concept of “subduction resurrection” is a new idea and may help explain a range of different geological observations. The subduction rupture event included unique geological phenomena that that have no present-day comparison, and there may have been fewer than 100 such massive events since Earth formed. Our new evidence from Zealandia shows these events can dramatically alter the geography of continents. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/CpCN5W4rV1Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>What were the consequences of these geographic changes for plants, animals and regional climate? Can we make a computer model of the geological processes that happened at depth? We are still figuring some of this out, but we do know the event changed the direction and speed of movement of most tectonic plates on Earth. </p>
<p>It was an event of truly global significance – and we now have really good observations and ideas to help us get to the bottom of what happened and why.</p><img src="https://counter.theconversation.com/content/130860/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Our expedition drilled into the recently discovered underwater continent of Zealandia, revealing a new picture of the violent geological forces that created it.Rupert Sutherland, Professor of tectonics and geophysics, Te Herenga Waka — Victoria University of WellingtonGerald Dickens, Professor of Earth, Environmental and Planetary Sciences, Rice UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1263552019-11-24T19:05:19Z2019-11-24T19:05:19ZWhat are lost continents, and why are we discovering so many?<figure><img src="https://images.theconversation.com/files/303106/original/file-20191122-74588-1h7i1ci.jpg?ixlib=rb-1.1.0&rect=41%2C137%2C3944%2C2850&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lord Howe Island is one of the few places where the lost continent of Zealandia is exposed above sea level. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1383726818?src=8cdca944-3b36-41dd-a084-4fbdd2c81e59-1-0&size=huge_jpg">SHUTTERSTOCK</a></span></figcaption></figure><p>For most people, continents are Earth’s seven main large landmasses. </p>
<p>But geoscientists have a different take on this. They look at the type of rock a feature is made of, rather than how much of its surface is above sea level. </p>
<p>In the past few years, we’ve seen an increase in the discovery of lost continents. Most of these have been plateaus or mountains made of <a href="https://en.wikipedia.org/wiki/Continental_crust">continental crust</a> hidden from our view, below sea level. </p>
<p>One example is <a href="https://www.bbc.com/news/world-asia-39000936">Zealandia</a>, the world’s eighth continent that extends underwater from New Zealand. </p>
<p>Several smaller lost continents, called microcontinents, have also recently been discovered submerged in the <a href="http://www.cmar.csiro.au/datacentre/process/data_files/cruise_docs/ss2011_v06_summary.pdf">eastern</a> and <a href="https://www.nationalgeographic.com/news/2013/2/130225-microcontinent-earth-mauritius-geology-science/">western Indian Ocean</a>. </p>
<p>But why, with so much geographical knowledge at our fingertips, are we still discovering lost continents in the 21st century?</p>
<h2>We may have found another</h2>
<p>In August, we undertook a <a href="https://research.csiro.au/educator-on-board/category/in2019_t04/">28-day voyage</a> on the research vessel RV Investigator to explore a possible lost continent in a remote part of the Coral Sea. The area is home to a large underwater plateau off Queensland, called the <a href="https://en.wikipedia.org/wiki/Louisiade_Plateau">Louisiade Plateau</a>, which represents a major gap in our knowledge of Australia’s geology. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-the-rv-investigators-role-in-marine-science-35239">Explainer: the RV Investigator’s role in marine science</a>
</strong>
</em>
</p>
<hr>
<p>On one hand, it could be a lost continent that broke away from Queensland about 60 million years ago. Or it could have formed as a result of a massive volcanic eruption taking place around the same time. We’re not sure, because nobody had recovered rocks from there before - until now. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300798/original/file-20191107-10940-1ejlfph.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An extremely violent eruption formed this volcanic rock we recovered.</span>
<span class="attribution"><span class="source">Author supplied</span></span>
</figcaption>
</figure>
<p>We spent about two weeks collecting rocks from this feature, and recovered a wide variety of rock types from parts of the seafloor as deep as 4,500m. </p>
<p>Most were formed through volcanic eruptions, but some show hints that continental rocks are hiding beneath. Lab work over the next couple of years will give us more certain answers.</p>
<h2>Down to the details</h2>
<p>There are many mountains and plateaus below sea level scattered across the oceans, and these have been mapped from space. They are the lighter blue areas you can see on Google Maps. </p>
<iframe src="https://www.google.com/maps/d/u/0/embed?mid=1-BXL84yHMfY85995MPKhFQf44Ze0z8rb" width="100%" height="480"></iframe>
<hr>
<p>However, not all submerged features qualify as lost continents. Most are made of materials quite distinct from what we traditionally think of as continental rock, and are instead formed by massive outpourings of magma. </p>
<p>A good example is <a href="https://www.youtube.com/watch?v=hLGp6lRaSs0&t=">Iceland</a> which, despite being roughly the size of New Zealand’s North Island, is not considered continental in geological terms. It’s made up mainly of volcanic rocks deposited over the past 18 million years, meaning it’s relatively young in geological terms.</p>
<p>The only foolproof way to tell the difference between massive submarine volcanoes and lost continents is to collect rock samples from the deep ocean.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300796/original/file-20191107-10905-1of0bqe.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Plenty of soft, gloopy sediment covers the bottom of the Coral Sea.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Finding the right samples is challenging, to say the least. Much of the seafloor is covered in soft, gloopy sediment that obscures the solid rock beneath. </p>
<p>We use a sophisticated mapping system to search for steep slopes on the seafloor, that are more likely to be free of sediment. We then send a metal rock-collecting bucket to grab samples.</p>
<p>The more we explore and sample the depths of the oceans, the more likely we’ll be to discover more lost continents.</p>
<h2>The ultimate lost continent</h2>
<p>Perhaps the best known example of a lost continent is <a href="https://www.bbc.com/news/world-asia-39000936">Zealandia</a>. While the geology of New Zealand and New Caledonia have been known for some time, it’s only recently their common heritage as part of a much larger continent (which is 95% underwater) has been accepted. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explorers-probe-hidden-continent-of-zealandia-83406">Explorers probe hidden continent of Zealandia</a>
</strong>
</em>
</p>
<hr>
<p>This acceptance has been the culmination of years of painstaking research, and exploration of the geology of deep oceans through sample collection and geophysical surveys.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/300800/original/file-20191107-10973-1ve9lhc.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">Continental rocks recovered from a microcontinent in the Indian Ocean are similar to rocks found in Western Australia.</span>
<span class="attribution"><span class="source">Author supplied</span></span>
</figcaption>
</figure>
<p>New discoveries continue to be made. </p>
<p>During a 2011 expedition, we discovered <a href="https://www.nationalgeographic.com/news/2011/11/111121-dinosaurs-gondwana-ancient-rocks-science/">two lost continental fragments</a> more than 1,000km west of Perth. </p>
<p>The granite lying in the middle of the deep ocean there looked similar to what you would find around Cape Leeuwin, in Western Australia. </p>
<h2>Other lost continents</h2>
<p>However, not all lost continents are found hidden beneath the oceans. </p>
<p>Some existed only in the geological past, millions to billions of years ago, and later collided with other continents as a result of plate tectonic motions. </p>
<p>Their only modern-day remnants are small slivers of rock, usually squished up in mountain chains such as the Himalayas. One example is <a href="https://www.nationalgeographic.com.au/science/lost-continent-revealed-in-new-reconstruction-of-geologic-history.aspx">Greater Adria</a>, an ancient continent now embedded in the mountain ranges across Europe.</p>
<p>Due to the perpetual motion of tectonic plates, it’s the fate of all continents to ultimately reconnect with another, and form a supercontinent. </p>
<p>But the fascinating life and death cycle of continents is the topic of another story.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-earths-continents-became-twisted-and-contorted-over-millions-of-years-116168">How Earth's continents became twisted and contorted over millions of years</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/126355/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Maria Seton receives funding from the Australian Research Council and has received ship time funding through Australia's Marine National Facility.</span></em></p><p class="fine-print"><em><span>Joanne Whittaker receives funding from the Australian Research Council, the Australian Antarctic Division, and ship time through Australia's Marine National Facility. </span></em></p><p class="fine-print"><em><span>Simon Williams is affiliated with the University of Sydney and Northwest University, Xi'an. He receives funding from the Australian Research Council and the Natural Science Foundation of China, and ship time through Australia's Marine National Facility. </span></em></p>We undertook a 28-day voyage to explore a possible lost continent in a remote part of the Coral Sea, in an area off the coast of Queensland. Here’s what we found.Maria Seton, ARC Future Fellow, University of SydneyJoanne Whittaker, Associate Professor, University of TasmaniaSimon Williams, Research Fellow, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/834062017-09-11T04:44:59Z2017-09-11T04:44:59ZExplorers probe hidden continent of Zealandia<figure><img src="https://images.theconversation.com/files/184410/original/file-20170902-27261-1a08rs6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Joides Resolution</span> <span class="attribution"><span class="source">Tim Fulton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Zealandia made global headlines earlier this year when scientists announced that it counts as <a href="https://www.geosociety.org/gsatoday/archive/27/3/article/GSATG321A.1.htm">a new continent</a>.</p>
<p>Now it is coming under closer scientific scrutiny. We are currently halfway through an expedition to drill into this vast underwater plateau of continental crust, and we can already reveal that Zealandia’s geography changed more dramatically and more recently than anyone had thought. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6qCQAvAXLOU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">As the first core samples from Zealandia emerge, chief scientists Rupert Sutherland and Jerry Dickens explain what that means for the continent’s evolution.</span></figcaption>
</figure>
<h2>Earth’s hidden continent</h2>
<p>There are seven continents on Earth: Eurasia, North America, South America, Africa, Antarctica, Australia and now Zealandia. </p>
<p>Zealandia is about two-thirds the size of Australia, but 94% of it lies deep below the southwest Pacific Ocean. Its only major landmasses are New Zealand to the south and New Caledonia to the north.</p>
<p>Very little is known about it, because most of it lies more than a kilometre deep beneath the Pacific Ocean.</p>
<p>The Zealandia continent also encompasses some smaller bits of land, including Norfolk Island, the Lord Howe group and some sub-antarctic islands. These islands were discovered hundreds of years ago, but the submerged part was only recognised as a continent in recent decades. It remains sparsely surveyed and sampled. We have better maps of the moon.</p>
<p>We are a team of 32 scientists from 12 different countries and our expedition is part of the <a href="http://iodp.tamu.edu/">International Ocean Discovery Program</a>, which coordinates seagoing explorations of Earth’s history recorded in sediments and rocks beneath the ocean floor.</p>
<p>Our ship, the <a href="http://joidesresolution.org/">Joides Resolution</a> is a floating village and laboratory, equipped with a drill rig that can take core samples from the seafloor. The samples we have collected so far show clear signs of major geographic changes and volcanic eruptions that were related to formation of the <a href="https://www.universetoday.com/59341/pacific-ring-of-fire/">Pacific Ring of Fire</a>, a chain of undersea volcanoes, ocean trenches, seamounts and hydrothermal vents that formed some 40 to 50 million years ago.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/184511/original/file-20170904-17899-1t9m5lw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/184511/original/file-20170904-17899-1t9m5lw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/184511/original/file-20170904-17899-1t9m5lw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/184511/original/file-20170904-17899-1t9m5lw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/184511/original/file-20170904-17899-1t9m5lw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/184511/original/file-20170904-17899-1t9m5lw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/184511/original/file-20170904-17899-1t9m5lw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">IODP research vessel Joides Resolution leaving Townsville in July at the start of its voyage to Zealandia.</span>
<span class="attribution"><span class="source">Mark Leckie, University of Massachusetts Amherst</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Zealandia exposed</h2>
<p>There is a buzz of excitement on the ship. After more than a month at sea we are mid-way through our expedition and have drilled into the seabed at four sites. You can’t beat the old-fashioned thrill of exploration and discovery. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/184512/original/file-20170904-17952-fro8aw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/184512/original/file-20170904-17952-fro8aw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=515&fit=crop&dpr=1 600w, https://images.theconversation.com/files/184512/original/file-20170904-17952-fro8aw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=515&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/184512/original/file-20170904-17952-fro8aw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=515&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/184512/original/file-20170904-17952-fro8aw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=647&fit=crop&dpr=1 754w, https://images.theconversation.com/files/184512/original/file-20170904-17952-fro8aw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=647&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/184512/original/file-20170904-17952-fro8aw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=647&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Co-chief scientists Jerry Dickens (left), Rice University, USA, and Rupert Sutherland (right), Victoria University of Wellington, New Zealand, drain excess sea water from a newly-collected sediment core.</span>
<span class="attribution"><span class="source">Tim Fulton, IODP/TAMU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We are re-writing the geological history of Zealandia on our voyage. Zealandia was first recognised about 50 years ago and ideas for how it formed were published then, but the only previous expedition that has drilled deep enough into the seabed to collect useful evidence was undertaken in 1971. </p>
<p>It appeared back then that Zealandia separated from Australia and Antarctica about 80 million years ago, when dinosaurs roamed the Earth. It then subsided deep beneath the waves and was lost. </p>
<p>However, fossils and volcanic rocks show that northern Zealandia, an area about the size of India, was radically affected by formation of the Pacific Ring of Fire. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/184509/original/file-20170904-16064-162wmqa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/184509/original/file-20170904-16064-162wmqa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=419&fit=crop&dpr=1 600w, https://images.theconversation.com/files/184509/original/file-20170904-16064-162wmqa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=419&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/184509/original/file-20170904-16064-162wmqa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=419&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/184509/original/file-20170904-16064-162wmqa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=526&fit=crop&dpr=1 754w, https://images.theconversation.com/files/184509/original/file-20170904-16064-162wmqa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=526&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/184509/original/file-20170904-16064-162wmqa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=526&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">To collect sediment cores from deep beneath the seabed we need a drill that may be more than 5000 metres long and weigh more than 200 tonnes.</span>
<span class="attribution"><span class="source">Tim Fulton, IODP/TAMU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our preliminary observations suggest that regions now under more than 1000 metres of water became land or shallow seas, and other regions that are now under 3000 metres of water may have been much shallower, or even land. Changes in geography were massive, and may help explain how the unique plants and animals of the southwest Pacific were able to disperse and evolve. </p>
<h2>Undersea exploration</h2>
<p>Explorers are normal people doing extraordinary things. Exploration isn’t easy. Not everything goes to plan. The hours are long, you share a small room with someone you didn’t know before the voyage, and you miss your family and friends. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/184508/original/file-20170904-17907-fgqrql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/184508/original/file-20170904-17907-fgqrql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=472&fit=crop&dpr=1 600w, https://images.theconversation.com/files/184508/original/file-20170904-17907-fgqrql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=472&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/184508/original/file-20170904-17907-fgqrql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=472&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/184508/original/file-20170904-17907-fgqrql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=593&fit=crop&dpr=1 754w, https://images.theconversation.com/files/184508/original/file-20170904-17907-fgqrql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=593&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/184508/original/file-20170904-17907-fgqrql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=593&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Texas A&M University technical staff process a recently-collected sediment core.</span>
<span class="attribution"><span class="source">Rupert Sutherland</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Sea sickness is not your friend if you spend 14 hours a day looking down a microscope at fossils that are so small you could fit hundreds on the head of a pin. So why do we do it? </p>
<p>It is hard to describe the excitement of discovery. Every time we get a new core on deck it is like unwrapping a present. What will it be? A curiosity to keep you busy for another few days, or key evidence to reconstruct the history of a hidden continent?</p>
<p>Our goals are to understand why Earth’s surface moves (the study of plate tectonics) and how greenhouse climate systems work (climate change). The southwest Pacific location makes Zealandia ideal for testing ideas on how the earth works. </p>
<p>The formation of the Pacific Ring of Fire changed the way our planet moved: new volcanoes and mountains grew, natural resources formed, and the changes had long-term effects on global climate. </p>
<p>Zealandia was closer to the South Pole 50 million years ago, but had a warm climate. How was this possible? If computer models can’t predict such warm conditions in the past, could models of future global warming also be underestimates? </p>
<p>The answers to these and many more questions lie beneath the waves, recorded in sediment layers that have accumulated over millions of years.</p><img src="https://counter.theconversation.com/content/83406/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rupert Sutherland receives funding from the New Zealand Government. </span></em></p>We have better maps of the moon than Earth’s newest continent, Zealandia. That’s about to change as an international expedition probes the vast undersea plateau of continental crust.Rupert Sutherland, Professor of tectonics and geophysics, Te Herenga Waka — Victoria University of WellingtonLicensed as Creative Commons – attribution, no derivatives.