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Volcanic arcs recycle crustal carbon

From Department of Earth Sciences. Published on Jul 20, 2017.

New research by Cambridge scientists is helping answer a key question about the origin of carbon emitted from Earth’s volcanoes.

Link identified between continental breakup, volcanic carbon emissions and evolution

By sc604 from University of Cambridge - Department of Earth Sciences. Published on Jul 20, 2017.

The researchers, from the University of Cambridge, used existing measurements of carbon and helium from more than 80 volcanoes around the world in order to determine its origin. Carbon and helium coming out of volcanoes can either come from deep within the Earth or be recycled near the surface, and measuring the chemical fingerprint of these elements can pinpoint their source. When the team analysed the data, they found that most of the carbon coming out of volcanoes is recycled near the surface, in contrast with earlier assumptions that the carbon came from deep in the Earth’s interior. “This is an essential piece of geological carbon cycle puzzle,” said Dr Marie Edmonds, the senior author of the study.

Over millions of years, carbon cycles back and forth between Earth’s deep interior and its surface. Carbon is removed from the surface from processes such as the formation of limestone and the burial and decay of plants and animals, which allows atmospheric oxygen to grow at the surface. Volcanoes are one way that carbon is returned to the surface, although the amount they produce is less than a hundredth of the amount of carbon emissions caused by human activity. Today, the majority of carbon from volcanoes is recycled near the surface, but it is unlikely that this was always the case.

Volcanoes form along large island or continental arcs where tectonic plates collide and one plate slides under the other, such as the Aleutian Islands between Alaska and Russia, the Andes of South America, the volcanoes throughout Italy, and the Mariana Islands in the western Pacific. These volcanoes have different chemical fingerprints: the ‘island arc’ volcanoes emit less carbon which comes from deep in the mantle, while the ‘continental arc’ volcanoes emit far more carbon which comes from closer to the surface.

Over hundreds of millions of years, the Earth has cycled between periods of continents coming together and breaking apart. During periods when continents come together, volcanic activity was dominated by island arc volcanoes; and when continents break apart, continental volcano arcs dominate. This back and forth changes the chemical fingerprint of carbon coming to Earth’s surface systematically over geological time, and can be measured through the different isotopes of carbon and helium.

Variations in the isotope ratio, or chemical fingerprint, of carbon are commonly measured in limestone. Researchers had previously thought that the only thing that could change the carbon fingerprint in limestone was the production of atmospheric oxygen. As such, the carbon isotope fingerprint in limestone was used to interpret the evolution of habitability of Earth’s surface. The results of the Cambridge team suggest that volcanoes played a larger role in the carbon cycle than had previously been understood, and that earlier assumptions need to be reconsidered.

“This makes us fundamentally re-evaluate the evolution of the carbon cycle,” said Edmonds. “Our results suggest that the limestone record must be completely reinterpreted if the volcanic carbon coming to the surface can change its carbon isotope composition.”

A great example of this is in the Cretaceous Period, 144 to 65 million years ago. During this time period there was a major increase in the carbon isotope ratio found in limestone, which has been interpreted as an increase in atmospheric oxygen concentration. This increase in atmospheric oxygen was causally linked to the proliferation of mammals in the late Cretaceous. However, the results of the Cambridge team suggest that the increase in the carbon isotope ratio in the limestones could be almost entirely due to changes in the types of volcanoes at the surface.

“The link between oxygen levels and the burial of organic material allowed life on Earth as we know it to evolve, but our geological record of this link needs to be re-evaluated,” said co-author Dr Alexandra Turchyn, also from the Department of Earth Sciences.

The research was funded by the Alfred P. Sloan Foundation, the Deep Carbon Observatory and the European Research Council.

Reference:
Emily Mason, Marie Edmonds, Alexandra V. Turchyn. ‘Remobilization of crustal carbon may dominate volcanic arc emissions.’ Science (2017). DOI: 10.1126/science.aan5049.

Inset Image: Schematic diagram to show the possible sources of carbon in a subduction zone volcanic system.

Researchers have found that the formation and breakup of supercontinents over hundreds of millions of years controls volcanic carbon emissions. The results, reported in the journal Science, could lead to a reinterpretation of how the carbon cycle has evolved over Earth’s history, and how this has impacted the evolution of Earth’s habitability. 

The link between oxygen levels and the burial of organic material allowed life on Earth as we know it to evolve, but our geological record of this link needs to be re-evaluated.
Alexandra Turchyn
ISS013-E-24184 (23 May 2006) --- Eruption of Cleveland Volcano, Aleutian Islands, Alaska is featured in this image photographed by an Expedition 13 crewmember on the International Space Station.

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Global cooling from a less leaky Ice Age Ocean

From Department of Earth Sciences. Published on Jul 13, 2017.

A new survey and analysis of global radiocarbon dates derived from ocean-dwelling micro-organisms is providing important new measures of the difference between the ocean today and 20,000 years ago, at the height of the last Ice Age.

Shape-shifting rangeomorphs cut fractal frills to grow and grow

From Department of Earth Sciences. Published on Jul 10, 2017.

Around 571 million years ago life first made a grade-change from organisms that were only a few centimetres in size to those that grew to two metres or so high. The organisms that were able to take off in this way were the extinct rangeomorphs, softbodied frondose organisms that grew rooted in the seabed of late Precambrian times.

Big, shape-shifting animals from the dawn of time

By sc604 from University of Cambridge - Department of Earth Sciences. Published on Jul 10, 2017.

Why did life on Earth change from small to large when it did? Researchers from the University of Cambridge and the Tokyo Institute of Technology have determined how some of the first large organisms, known as rangeomorphs, were able to grow up to two metres in height, by changing their body size and shape as they extracted nutrients from their surrounding environment.

The results, reported in the journal Nature Ecology and Evolution, could also help explain how life on Earth, which once consisted only of microscopic organisms, changed so that huge organisms like dinosaurs and blue whales could ultimately evolve.

Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Some rangeomorphs were only a few centimetres in height, while others were up to two metres tall.

These organisms were ocean dwellers that lived during the Ediacaran period, between 635 and 541 million years ago. Their soft bodies were made up of branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen today in things like lungs, ferns and snowflakes.

Since rangeomorphs don’t resemble any modern organism, it’s difficult to understand how they fed, grew or reproduced, let alone how they might link with any modern group. However, although they look somewhat like plants, scientists believe that they may have been some of the earliest animals to live on Earth.

“What we wanted to know is why these large organisms appeared at this particular point in Earth’s history,” said Dr Jennifer Hoyal Cuthill of Cambridge’s Department of Earth Sciences and Tokyo Tech’s Earth-Life Science Institute, the paper’s first author. “They show up in the fossil record with a bang, at very large size. We wondered, was this simply a coincidence or a direct result of changes in ocean chemistry?”

The researchers used micro-CT scanning, photographic measurements and mathematical and computer models to examine rangeomorph fossils from south-eastern Newfoundland, Canada, the UK and Australia.

Their analysis shows the earliest evidence for nutrient-dependent growth in the fossil record. All organisms need nutrients to survive and grow, but nutrients can also dictate body size and shape. This is known as ‘ecophenotypic plasticity.’ Hoyal Cuthill and her co-author Professor Simon Conway Morris suggest that rangeomorphs not only show a strong degree of ecophenotypic plasticity, but that this provided a crucial advantage in a dramatically changing world. For example, rangeomorphs could rapidly “shape-shift”, growing into a long, tapered shape if the seawater above them happened to have elevated levels of oxygen.

“During the Ediacaran, there seem to have been major changes in the Earth’s oceans, which may have triggered growth, so that life on Earth suddenly starts getting much bigger,” said Hoyal Cuthill. “It’s probably too early to conclude exactly which geochemical changes in the Ediacaran oceans were responsible for the shift to large body sizes, but there are strong contenders, especially increased oxygen, which animals need for respiration.”

This change in ocean chemistry followed a large-scale ice age known as the Gaskiers glaciation. When nutrient levels in the ocean were low, they appear to have kept body sizes small. But with a geologically sudden increase in oxygen or other nutrients, much larger body sizes become possible, even in organisms with the same genetic makeup. This means that the sudden appearance of rangeomorphs at large size could have been a direct result of major changes in climate and ocean chemistry.

However, while rangeomorphs were highly suited to their Ediacaran environment, conditions in the oceans continued to change and from about 541 million years ago the ‘Cambrian Explosion’ began – a period of rapid evolutionary development when most major animal groups first appeared in the fossil record. When the conditions changed, the rangeomorphs were doomed and nothing quite like them has been seen since.

Reference
Jennifer F. Hoyal Cuthill and Simon Conway Morris. ‘Nutrient-dependent growth underpinned the Ediacaran transition to large body size.’ Nature Ecology and Evolution (2017). DOI: 10.1038/s41559-017-0222-7.

Major changes in the chemical composition of the world’s oceans enabled the first large organisms – possibly some of the earliest animals – to exist and thrive more than half a billion years ago, marking the point when conditions on Earth changed and animals began to take over the world. 

We wanted to know why these large organisms appeared at this particular point in Earth’s history.
Jennifer Hoyal Cuthill
Artist's impression of rangeomorphs

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Don’s Diary

From Department of Earth Sciences. Published on Jul 05, 2017.

This article first appeared in CAM - the Cambridge Alumni Magazine – Issue 81 Easter 2017. Professor Marian Holness is Professor of Petrology and a Fellow of Trinity College.

‘Bulges’ in volcanoes could be used to predict eruptions

By sc604 from University of Cambridge - Department of Earth Sciences. Published on Jun 28, 2017.

Using a technique called ‘seismic noise interferometry’ combined with geophysical measurements, the researchers measured the energy moving through a volcano. They found that there is a good correlation between the speed at which the energy travelled and the amount of bulging and shrinking observed in the rock. The technique could be used to predict more accurately when a volcano will erupt. Their results are reported in the journal Science Advances.

Data was collected by the US Geological Survey across Kīlauea in Hawaii, a very active volcano with a lake of bubbling lava just beneath its summit. During a four-year period, the researchers used sensors to measure relative changes in the velocity of seismic waves moving through the volcano over time. They then compared their results with a second set of data which measured tiny changes in the angle of the volcano over the same time period.

As Kīlauea is such an active volcano, it is constantly bulging and shrinking as pressure in the magma chamber beneath the summit increases and decreases. Kīlauea’s current eruption started in 1983, and it spews and sputters lava almost constantly. Earlier this year, a large part of the volcano fell away and it opened up a huge ‘waterfall’ of lava into the ocean below. Due to this high volume of activity, Kīlauea is also one of the most-studied volcanoes on Earth.

The Cambridge researchers used seismic noise to detect what was controlling Kīlauea’s movement. Seismic noise is a persistent low-level vibration in the Earth, caused by everything from earthquakes to waves in the ocean, and can often be read on a single sensor as random noise. But by pairing sensors together, the researchers were able to observe energy passing between the two, therefore allowing them to isolate the seismic noise that was coming from the volcano.

“We were interested in how the energy travelling between the sensors changes, whether it’s getting faster or slower,” said Clare Donaldson, a PhD student in Cambridge’s Department of Earth Sciences, and the paper’s first author. “We want to know whether the seismic velocity changes reflect increasing pressure in the volcano, as volcanoes bulge out before an eruption. This is crucial for eruption forecasting.”

One to two kilometres below Kīlauea’s lava lake, there is a reservoir of magma. As the amount of magma changes in this underground reservoir, the whole summit of the volcano bulges and shrinks. At the same time, the seismic velocity changes. As the magma chamber fills up, it causes an increase in pressure, which leads to cracks closing in the surrounding rock and producing faster seismic waves – and vice versa.

“This is the first time that we’ve been able to compare seismic noise with deformation over such a long period, and the strong correlation between the two shows that this could be a new way of predicting volcanic eruptions,” said Donaldson.

Volcano seismology has traditionally measured small earthquakes at volcanoes. When magma moves underground, it often sets off tiny earthquakes, as it cracks its way through solid rock. Detecting these earthquakes is therefore very useful for eruption prediction. But sometimes magma can flow silently, through pre-existing pathways, and no earthquakes may occur. This new technique will still detect the changes caused by the magma flow.

Seismic noise occurs continuously, and is sensitive to changes that would otherwise have been missed. The researchers anticipate that this new research will allow the method to be used at the hundreds of active volcanoes around the world.

Reference
C. Donaldson et al. ‘Relative seismic velocity variations correlate with deformation at Kīlauea volcano’. Science Advances (2017) DOI: 10.1126/sciadv.1700219 

Inset image: Lava Waterfall, Kilauea Volcano, Hawaii. Credit: Dhilung Kirat

A team of researchers from the University of Cambridge have developed a new way of measuring the pressure inside volcanoes, and found that it can be a reliable indicator of future eruptions.

This could be a new way of predicting volcanic eruptions.
Clare Donaldson
Kiauea

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‘Plumerang’ health risk

From Department of Earth Sciences. Published on Jun 21, 2017.

Scientists have discovered that significant changes can occur in the composition of volcanic eruptive plumes whilst circulating high above the atmosphere. Nicknamed ‘plumerangs’, the evolution of such plumes represent a previously unappreciated health hazard.

Engaging with Science Policy

From Department of Earth Sciences. Published on Jun 09, 2017.

Victoria Honour, 2nd year PhD student, writes about her experiences as a Science Policy Intern at the House of Commons.

Earth Sciences win second place in the Workplace Travel Challenge

From Department of Earth Sciences. Published on May 04, 2017.

A team of nine people from Earth Sciences, took part in the Workplace Travel Challenge at the end of April 2017.

Jo Clegg wins competition with the most sustainable recipe

From Department of Earth Sciences. Published on May 04, 2017.

Earth Sciences' Jo Clegg wins a competition on sustainable food with the most sustainable recipe

Cambridge Earth Sciences top in the Complete University Guide

From Department of Earth Sciences. Published on Apr 27, 2017.

The Department of Earth Sciences is once again top amongst UK geology departments in the latest tables.

Opinion: Worthless mining waste could suck CO₂ out of the atmosphere and reverse emissions

By Anonymous from University of Cambridge - Department of Earth Sciences. Published on Apr 20, 2017.

The Paris Agreement commits nations to limiting global warming to less than 2˚C by the end of the century. However, it is becoming increasingly apparent that, to meet such a massive challenge, societies will need to do more than simply reduce and limit carbon emissions. It seems likely that large scale removal of greenhouse gases from the atmosphere may be called for: so-called “negative emissions”.

One possibility is to use waste material from mining to trap CO₂ into new minerals, locking it out of the atmosphere. The idea is to exploit and accelerate the same geological processes that have regulated Earth’s climate and surface environment over the 4.5 billion years of its existence.

Across the world, deep and open-pit mining operations have left behind huge piles of worthless rubble – the “overburden” of rock or soil that once lay above the useful coal or metal ore. Often, this rubble is stored in dumps alongside tiny fragments of mining waste – the “tailings” or “fines” left over after processing the ore. The fine-grained waste is particularly reactive, chemically, since more surface is exposed.

A lot of energy is spent on extracting and crushing all this waste. However, breaking rocks into smaller pieces exposes more fresh surfaces, which can react with CO₂. In this sense, energy used in mining could itself be harvested and used to reduce atmospheric carbon.

This is one of the four themes of a new £8.6m research programme launched by the UK’s Natural Environment Research Council, which will investigate new ways to reverse emissions and remove greenhouse gases from the atmosphere.

Spoil tips from current and historic mining operations, such as this gold mine in Kazakhstan, could provide new ways to draw CO₂ from the atmosphere. Photo Credit: Ainur Seitkan, Earth Sciences, University of Cambridge


The process we want to speed up is the “carbonate-silicate cycle”, also known as the slow carbon cycle. Natural silicate rocks like granite and basalt, common at Earth’s surface, play a key part in regulating carbon in the atmosphere and oceans by removing CO₂ from the atmosphere and turning it into carbonate rocks like chalk and limestone.

Atmospheric CO₂ and water can react with the silicate rocks to dissolve elements they contain like calcium and magnesium into the water, which also soaks up the CO₂ as bicarbonate. This weak solution is the natural river water that flows to the oceans, which hold more than 60 times more carbon than the atmosphere. It is here, in the oceans, that the calcium and bicarbonate can recombine, over millions of years, and crystallise as calcite or chalk, often instigated by marine organisms as they build their shells.

Today, rivers deliver hundreds of millions of tonnes of carbon each year into the oceans, but this is still around 30 times less than the rate of carbon emission into the atmosphere due to fossil fuel burning. Given immense geological time scales, these processes would return atmospheric CO₂ to its normal steady state. But we don’t have time: the blip in CO₂ emissions from industrialisation easily unbalances nature’s best efforts.

The natural process takes millions of years – but can we do it in decades? Scientists looking at accelerated mine waste dissolution will attempt to answer a number of pressing questions. The group at Cambridge which I lead will be investigating whether we can speed up the process of silicate minerals from pre-existing mine waste being dissolved into water. We may even be able to harness friendly microbes to enhance the reaction rates.

Another part of the same project, conducted by colleagues in Oxford, Southampton and Cardiff, will study how the calcium and magnesium released from the silicate mine waste can react back into minerals like calcite, to lock CO₂ back into solid minerals into the geological future.

Whether this can be done effectively without requiring further fossil fuel energy, and at a scale that is viable and effective, remains to be seen. But accelerating the reaction rates in mining wastes should help us move at least some way towards reaching our climate targets.

This article was originally published on The Conversation. Read the original article.

Could waste material from mining be used to trap COemissions? A new £8.6 million research programme will investigate the possibilities. Simon Redfern (Department of Earth Sciences) explains, in this article from The Conversation. 

Tagebau / Open cast mine

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Drones used to analyse ash clouds from Guatemalan volcano

By cjb250 from University of Cambridge - Department of Earth Sciences. Published on Apr 11, 2017.

During a ten-day research trip, the team carried out many proof-of-concept flights at the summits of both Volcán de Fuego and Volcán de Pacaya in Guatemala.  Using lightweight modern sensors they measured temperature, humidity and thermal data within the volcanic clouds and took images of multiple eruptions in real-time.

This is one of the first times that bespoke fixed-wing unmanned aerial vehicles (UAVs) have been used at a volcano such as Fuego, where the lack of close access to the summit vent has prevented robust gas measurements. Funding from the Cabot Institute has helped the team to develop technologies to enable this capability. The UAVs were successfully flown at distances of up to 8 km away, and at a height of over 3 km above the launch site.

The group plan to return to Guatemala later in the year with a wider range of sensors including a gas analyser, a four-stage filter pack; carbon stubs for ash sampling; thermal and visual cameras, and atmospheric sensors.

Dr Emma Liu, a volcanologist from the Department of Earth Sciences at Cambridge, said: “Drones offer an invaluable solution to the challenges of in-situ sampling and routine monitoring of volcanic emissions, particularly those where the near-vent region is prohibitively hazardous or inaccessible.

“These sensors not only help to understand emissions from volcanoes, they could also be used in the future to help alert local communities of impending eruptions – particularly if the flights can be automated.”

Dr Kieran Wood, Senior Research Associate in the Department of Aerospace Engineering at Bristol, added: “Even during this initial campaign we were able to meet significant science and engineering targets. For example, multiple imaging flights over several days captured the rapidly changing topography of Fuego’s summit. These showed that the volcano was erupting from not just one, but two active summit vents.”

Taking time out from their sample flights, the research group also used their aircraft to map the topology of a barranca and the volcanic deposits within it. These deposits were formed by a recent pyroclastic flow, a fast-moving cloud of superheated ash and gas, which travelled down the barranca from Fuego. The data captured will assist in modelling flow pathways and the potential impact of future volcanic eruptions on nearby settlements.

Dr Matt Watson, Reader in Natural Hazards in the School of Earth Sciences at Bristol, said: “This is exciting initial research for future investigations, and would not be possible without a very close collaboration between volcanology and engineering.”

Adapted from a press release by the University of Bristol.

A team of volcanologists and engineers from the Universities of Cambridge and Bristol has collected measurements from directly within volcanic clouds, together with visual and thermal images of inaccessible volcano peaks.

Volcán de Fuego

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Opinion: The rapidly populating coastal region from the Gulf to Pakistan faces a huge tsunami risk

By cjb250 from University of Cambridge - Department of Earth Sciences. Published on Apr 07, 2017.

 

That tsunamis can cause death and devastation has become painfully clear over the past two decades. On Boxing Day, 2004, a magnitude 9 earthquake off the coast of Sumatra caused waves several metres high to devastate the Indian Ocean – killing more than 230,000 people in 14 countries. In 2011, another magnitude 9 earthquake, this time off Japan, produced waves up to 20 metres in height, flooding the Fukushima nuclear reactor. It killed more than 15,000 people. The Conversation

A new study, published in Geophysical Journal International, by my colleagues and me suggests that a 1,000km long fault at the northern end of the Arabian Sea may pose a similar threat.

The Makran, as the southern coastal region of Iran and Pakistan is known, is a subduction zone. In such regions, one of the Earth’s tectonic plates is dragged beneath another, forming a giant fault known as a “megathrust”. As the plates move past each other, they can get stuck, causing stress to build up. At some point the stress becomes high enough that the megathrust breaks in an earthquake.

This was exactly what caused the Sumatra 2004 and Tohoku 2011 earthquakes. When a megathrust moves suddenly, the whole seafloor is offset and the water has to move out of the way over a huge area. This sets off waves with particular characteristics that can cross entire oceans: tsunamis. The phenomenon, along with their potentially large size, makes subduction zone earthquakes particularly dangerous.

The Makran region. Adapted from NASA photo.


But just because a part of a subduction zone produces earthquakes doesn’t mean that the whole megathrust can move in one go. We often see that stress builds up at different rates on different parts of the fault, with some parts sliding smoothly past each other. How much of a megathrust can move in one go is important because it determines the size of the resulting earthquake. The amount that the Makran megathrust can move in earthquakes has been a longstanding question, but the hostile climate and challenging politics of the region have made research there difficult.

We know that the eastern part of the Makran megathrust (in Pakistan) can produce large earthquakes. A magnitude 8.1 quake off the coast of western Pakistan in 1945 caused a tsunami which killed about 300 people along the coasts of Pakistan and Oman. There have been several smaller earthquakes on the megathrust since, including a magnitude 6 in February this year.

If the western part of the Makran (in Iran) also produces earthquakes – and the whole Makran megathrust were to move in one go – it could produce a magnitude 9 earthquake, similar to those in Sumatra and Tohoku.

However, we have never actually recorded a subduction earthquake in this part of Makran. In fact, there are only records of one candidate quake from 1483 – and the actual location of this is disputed. But it’s important to keep in mind that just because we haven’t seen an earthquake doesn’t mean that there couldn’t be one – particularly since the intervals between earthquakes are often hundreds or thousands of years. Historically, not many people have lived in the remote Iranian Makran, a desert which killed Alexander the Great’s army. So earthquakes might simply not have been documented.

GPS data

We used new data to look for tell-tale signs of a possible earthquake. Imagine a piece of paper on a table. If you hold one end and push the other end towards it, the paper crumples up and the distance between the two ends gets shorter. If you let go, the paper flattens out. The fixed end is like a megathrust which is stuck. Indeed, if the Arabian plate is stuck, and stress is building up, southern Iran will be squeezed and shortened. We can look for evidence of this shortening by using a more accurate version of the GPS systems found in smartphones. My coauthors from the National Cartographic Centre in Iran have set up a network of GPS stations to measure how fast different parts of Iran are moving relative to Arabia.

We found that the velocities fit with Iran being shortened near the coast, suggesting that stress is indeed building up – and meaning there could be a large subduction earthquake in the future. This fits with recent work looking at large boulders along the coast of Oman, thought to have been deposited by tsunamis. The locations of these boulders suggest that the tsunami which brought them there would need to have come from a subduction earthquake, either in western Makran or along the entire subduction zone – including Pakistan. These boulders were probably deposited in the last 5,000 years, but we can’t know for sure.

The 2004 Sumatra tsunami strikes Ao Nang, Thailand. David Rydevik/wikipedia, CC BY-SA


This is a hazard that people need to be aware of, particularly those living in coastal regions around the Arabian Sea. Rapid urbanisation along the Omani and Pakistani coasts in recent years has increased the population exposed to earthquakes and tsunamis in the Makran. Karachi, at the eastern end of the subduction zone, is now a megacity and home to around 25m people. Much of Muscat, the Omani capital, is less than 10 metres above sea level, making it vulnerable to tsunamis. The port of Gwadar in Pakistan, which was badly damaged in a 1945 earthquake, is also undergoing massive development.

To help protect these people, and make sure that they are properly prepared, we need to understand this hazard better. Education and early warning are both key – exercises testing the Indian Ocean Tsunami Warning System are a step in the right direction, especially if they engage the public.

At the moment, we can only say that a large earthquake in the Makran is consistent with the limited data which we have available. By continuing to work with scientists in Iran and Pakistan to make more measurements I hope that in the future we will have a much better idea of what to expect from this subduction zone.

Camilla Penney, PhD Candidate in Geophysics, University of Cambridge

This article was originally published on The Conversation. Read the original article.

In recent years, tsunamis have devastated coastal regions. Writing in The Conversation, Camilla Penney, PhD Candidate in Geophysics at University of Cambridge, looks at the risks faced by Gulf states and what can be done to mitigate them.

MUSCAT OMAN OCT 2010

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Opinion: Geologists unveil how Britain first separated from Europe – and it was catastrophic

By cjb250 from University of Cambridge - Department of Earth Sciences. Published on Apr 06, 2017.

As Brexit looms, Earth scientists have uncovered evidence of Britain’s original split from mainland Europe. Almost half a million years ago, according to new data, water suddenly started cascading over the narrow strip of land that joined England and France – putting pressure on a chalk bridge. The Conversation

Researchers show that, as a result, this ridge – a natural dam that separated the North Sea from the English Channel – was catastrophically ruptured hundreds of thousands of years later in a two-stage process, ultimately setting Britain’s insular environment in stone. Their results are reported in Nature Communications.

So where did all the water that caused this geological disaster come from? The scientists, from UK, Belgium and France, base their conclusions on a line of deep plunge pools (basins excavated by intense waterfalls) and a network of channels cut in the sea floor south-west of the ridge line. They deduce that these were first formed some 450,000 years ago as a lake of glacial melt water to the north-east in the North Sea basin (the depression where the north sea sits today, some of which was dry land back then) spilled over into what is today the English Channel.

Strait of Dover map. wikipedia, CC BY-SA


However, exactly why the glacial lake suddenly spilt over remains unknown. One possibility is that part of its ice sheet broke off, causing a surge that prompted the water to flow over. The 33km long land bridge at Dover Strait formed part of an icy landscape at the time. According to the researchers, it looked “more like the frozen tundra in Siberia than the green environment we know today”.

3D view of the seafloor in the 33km wide Dover Strait showing a prominent valley in the central part. Imperial College London/Professor Sanjeev Gupta and Dr Jenny Collier


The loose gravel that fills the seafloor plunge pools was first noticed 50 years ago. Indeed, the channel tunnel had to be rerouted to avoid them during its construction. There has long been speculation that they were associated with the remains of the land bridge that formed an ancient route between UK and Europe – and now we finally have some evidence to back this up.

The plunge pools themselves are huge, drilling down some 100 metres into the solid bedrock and measuring several kilometres across. The waterfalls that formed them are estimated to have been 100 metres high, as we know the land bridge stood high above the surrounding landscape.

Second sudden destruction

It seems Dover Strait may have gone through two breaches. The first one, about 450,000 years ago, was rather modest and formed a smaller channel than the one we see today. But the authors suggest that a second, more catastrophic breach subsequently occurred – possibly hundreds of thousands of year later, irrevocably separating Britain from Europe.

3D view of an ancient large waterfall in a valley in the central part of Dover Strait. A plunge pool lies at its base. Imperial College London/Professor Sanjeev Gupta and Dr Jenny Collier


This final collapse of the land bridge is marked out by a larger seafloor channel named the Lobourg Channel, which cuts through the earlier structures. This appears to have been carved by a major cataclysmic flood from the North Sea into the English Channel. The timings of the two-stage erosion, including the final destruction of the connecting bridge, are uncertain, but mollusc shells found either side of the breach indicate that it was complete at least 100,000 years ago.

The latest observations are the result of a broad marine geophysics campaign to tackle the problem. Ship-based seismic surveys of the floor of the English Channel have been combined with a type of sonar to provide an astoundingly detailed picture of the sea floor and its sub-surface. Uncertainty remains over the exact timings of each of the events, and researchers have set their sights on drilling into the sea floor to retrieve samples from the plunge pool sediments to determine their precise ages.

The erosion of the land bridge hundreds of thousands of years ago set Britain on its path to becoming an island nation. Subsequent changes in sea level at the end of that ancient ice age further confirmed its insularity, and Britain’s connection to mainland Europe was lost.

Simon Redfern, Professor in Earth Sciences, University of Cambridge

This article was originally published on The Conversation. Read the original article.

Brexit won't be the first time Britain has left Europe, says Simon Redfern, professor in Earth Sciences at University of Cambridge writing for The Conversation. Almost half a million years ago we experienced a catastrophic separation.

Dover White Cliffs

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The man who split the dinosaurs in two – Harry Govier Seeley

From Department of Earth Sciences. Published on Mar 23, 2017.

The talk was titled ‘On the Classification of the Fossil Animals Commonly Named Dinosaurs’ and it was given in 1887 by Harry Govier Seeley, Professor of Geology at King’s College, London. Seeley argued that the ‘terrible lizards’, which were becoming increasingly popular at the time, could be simply divided into two great groups – the Saurischia and the Ornithischia based on differences in their hip structure.

New study shakes the roots of the dinosaur family tree

By ps748 from University of Cambridge - Department of Earth Sciences. Published on Mar 22, 2017.

For 130 years palaeontologists have been working with a classification system in which dinosaur species have been placed in to two distinct categories: Ornithischia and Saurischia. But now, after careful analysis of dozens of fossil skeletons and tens of thousands of anatomical characters, the researchers have concluded that these long-accepted familial groupings may, in fact, be wrong and that the traditional names need to be completely altered.

The classification of dinosaurs dates back to Victorian times. Dinosaurs were first recognised as a unique group of fossil reptiles in 1842 as a result of the work of the anatomist, Professor Richard Owen (who later went on to found the Natural History Museum in London). Over subsequent decades, various species were named as more and more fossils were found and identified. During the latter half of the 19th century it was realised that dinosaurs were anatomically diverse and attempts were made to classify them into groups that shared particular features.

It was Harry Govier Seeley, a palaeontologist trained in Cambridge under the renowned geologist Adam Sedgwick, who determined that dinosaurs fell quite neatly into two distinct groupings, or clades; Saurischia or Ornithischia. This classification was based on the arrangement of the creatures’ hip bones and in particular whether they displayed a lizard-like pattern (Saurischia) or a bird-like one (Ornithischia).

As more dinosaurs were described it became clear that they belonged to three distinct lineages; Ornithischia, Sauropodomorpha and Theropoda. In 1887 Seeley placed the sauropodomorphs (which included the huge ‘classic’ dinosaurs such as Diplodocus and Brontosaurus) together with the  theropods (which included T. rex), in the Saurischia. The ornithischians and saurischians were at first thought to be unrelated, each having a different set of ancestors, but later study showed that they all evolved from a single common ancestor.   

This new analysis of dinosaurs and their near relatives, published today in the journal Nature, concludes that the ornithischians need to be grouped with the theropods, to the exclusion of the sauropodomorphs. It has long been known that birds (with their obviously ‘bird-like’ hips) evolved from theropod dinosaurs (with their lizard-like hips). However, the re-grouping of dinosaurs proposed in this study shows that both ornithischians AND theropods had the potential to evolve a bird-like hip arrangement- they just did so at different times in their history.

Lead author, Matthew Baron, says:

“When we started our analysis, we puzzled as to why some ancient ornithischians appeared anatomically similar to theropods. Our fresh study suggested that these two groups were indeed part of the same clade. This conclusion came as quite a shock since it ran counter to everything we’d learned.”

“The carnivorous theropods were more closely related to the herbivorous ornithischians and, what’s more, some animals, such as Diplodocus, would fall outside the traditional grouping that we called dinosaurs. This meant we would have to change the definition of the ‘dinosaur’ to make sure that, in the future, Diplodocus and its near relatives could still be classed as dinosaurs.”

The revised grouping of Ornithischia and Theropoda has been named the Ornithoscelida which revives a name originally coined by the evolutionary biologist, Thomas Henry Huxley in 1870. 

Co-author, Dr David Norman, of the University of Cambridge, says:

“The repercussions of this research are both surprising and profound. The bird-hipped dinosaurs, so often considered paradoxically named because they appeared to have nothing to do with bird origins, are now firmly attached to the ancestry of living birds.”

For 130 years palaeontologists have considered the phylogeny of the dinosaurs in a certain way. Our research indicates they need to look again at the creatures’ evolutionary history. This is simply science in action. You draw conclusions from one body of evidence and then new data or theories present themselves and you have to suddenly reconsider and adapt your thinking. All the major textbooks covering the topic of the evolution of the vertebrates will need to be re-written if our suggestion survives academic scrutiny.”

While analysing the dinosaur family trees the team arrived at another unexpected conclusion. For many years, it was thought that dinosaurs originated in the southern hemisphere on the ancient continent known as Gondwana. The oldest dinosaur fossils have been recovered from South America suggesting the earliest dinosaurs originated there. But as a result of a re-examination of key taxa it’s now thought they could just as easily have originated on the northern landmass known as Laurasia, though it must be remembered that the continents were much closer together at this time. 

Co-author, Prof Paul Barrett, of the Natural History Museum, says:

"This study radically redraws the dinosaur family tree, providing a new framework for unravelling the evolution of their key features, biology and distribution through time. If we're correct, it explains away many prior inconsistencies in our knowledge of dinosaur anatomy and relationships and it also highlights several new questions relating to the pace and geographical setting of dinosaur origins".

The research was funded through a Natural Environment Research Council (NERC) CASE studentship.

Matthew Baron et al: 'A new hypothesis of dinosaur relationships and early dinosaur evolution' Nature, 23 March 2017 

10.1038/nature21700

A short video guide has been prepared by the Natural History Museum to accompany this paper.

More than a century of theory about the evolutionary history of dinosaurs has been turned on its head following the publication of new research from scientists at the University of Cambridge and Natural History Museum in London. Their work suggests that the family groupings need to be rearranged, re-defined and re-named and also that dinosaurs may have originated in the northern hemisphere rather than the southern, as current thinking goes.

This conclusion came as quite a shock since it ran counter to everything we'd learned
Matthew Baron
Kulindadromeus, a small bipedal ornithischian dinosaur that is now part of the new grouping Ornithoscelida and identified as more obviously sharing an ancestry with living birds

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When did making mountains the modern way begin?

From Department of Earth Sciences. Published on Mar 14, 2017.

What with ‘tectonic shifts’ and ‘tectonic proportions’, the processes and terminology of Earth’s major structural change or tectonism have invaded everyday language. Now geological research is adding a new dimension – ‘changing tectonic regimes’, the US presidency comes to mind. So what is a ‘change in tectonic regime’?

Simple rule predicts when an ice age ends

From Department of Earth Sciences. Published on Feb 27, 2017.

A simple rule can accurately predict when Earth’s climate warms out of an ice age, according to a new study published in Nature. Researchers from UCL, University of Cambridge and University of Louvain have combined existing ideas to solve the problem of which solar energy peaks in the last 2.6 million years led to the melting of the ice sheets and the start of a warm period.

Fossil corset-animals (loriciferans) help solve Darwin’s dilemma

From Department of Earth Sciences. Published on Feb 13, 2017.

The living corset-animals (loriciferans) are a remarkable group of miniscule, seabed dwelling creatures, which were first found in the 1980s. Now, the discovery by palaeontologists Tom Harvey and Nick Butterfield of the loriciferans’ deep ancestry in 490 million year old Cambrian strata is helping to rewrite the story of the Cambrian explosion of life and resolve what is known as Darwin’s dilemma.

Earth Sciences students winning prizes

From Department of Earth Sciences. Published on Feb 13, 2017.

Congratulations to our students who have recently won prizes.

Tools of the Trade

From Department of Earth Sciences. Published on Feb 13, 2017.

A display showcasing a selection of the Sedgwick Museum’s unique historic collection of geological hammers.

The bicentenary of a pioneering account of the Geology of Cambridgeshire

From Department of Earth Sciences. Published on Feb 13, 2017.

The first account of the geology of Cambridgeshire was published 200 years ago. Written by the Reverend Professor John Hailstone FRS (1759-1847), the ‘Outline of the Geology of Cambridgeshire’ appeared in the third volume of the Transactions of the Geological Society of London.

Bag-like sea creature was humans’ oldest known ancestor

By tdk25 from University of Cambridge - Department of Earth Sciences. Published on Jan 30, 2017.

Researchers have identified traces of what they believe is the earliest known prehistoric ancestor of humans – a microscopic, bag-like sea creature, which lived about 540 million years ago.

Named Saccorhytus, after the sack-like features created by its elliptical body and large mouth, the species is new to science and was identified from microfossils found in China. It is thought to be the most primitive example of a so-called “deuterostome” – a broad biological category that encompasses a number of sub-groups, including the vertebrates.

If the conclusions of the study, published in the journal Nature, are correct, then Saccorhytus was the common ancestor of a huge range of species, and the earliest step yet discovered on the evolutionary path that eventually led to humans, hundreds of millions of years later.

Modern humans are, however, unlikely to perceive much by way of a family resemblance. Saccorhytus was about a millimetre in size, and probably lived between grains of sand on the seabed. Its features were spectacularly preserved in the fossil record – and intriguingly, the researchers were unable to find any evidence that the animal had an anus.

The study was carried out by an international team of academics, including researchers from the University of Cambridge in the UK and Northwest University in Xi’an China, with support from other colleagues at institutions in China and Germany.

Simon Conway Morris, Professor of Evolutionary Palaeobiology and a Fellow of St John’s College, University of Cambridge, said: “We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves. To the naked eye, the fossils we studied look like tiny black grains, but under the microscope the level of detail is jaw-dropping. All deuterostomes had a common ancestor, and we think that is what we are looking at here.”

Degan Shu, from Northwest University, added: “Our team has notched up some important discoveries in the past, including the earliest fish and a remarkable variety of other early deuterostomes. Saccorhytus now gives us remarkable insights into the very first stages of the evolution of a group that led to the fish, and ultimately, to us.”

 

 

Most other early deuterostome groups are from about 510 to 520 million years ago, when they had already begun to diversify into not just the vertebrates, but the sea squirts, echinoderms (animals such as starfish and sea urchins) and hemichordates (a group including things like acorn worms). This level of diversity has made it extremely difficult to work out what an earlier, common ancestor might have looked like.

The Saccorhytus microfossils were found in Shaanxi Province, in central China, and pre-date all other known deuterostomes. By isolating the fossils from the surrounding rock, and then studying them both under an electron microscope and using a CT scan, the team were able to build up a picture of how Saccorhytus might have looked and lived. This revealed features and characteristics consistent with current assumptions about primitive deuterostomes.

Dr Jian Han, of Northwest University, said: “We had to process enormous volumes of limestone – about three tonnes – to get to the fossils, but a steady stream of new finds allowed us to tackle some key questions: was this a very early echinoderm, or something even more primitive? The latter now seems to be the correct answer.”

In the early Cambrian period, the region would have been a shallow sea. Saccorhytus was so small that it probably lived in between individual grains of sediment on the sea bed.

The study suggests that its body was bilaterally symmetrical – a characteristic inherited by many of its descendants, including humans – and was covered with a thin, relatively flexible skin. This in turn suggests that it had some sort of musculature, leading the researchers to conclude that it could have made contractile movements, and got around by wriggling.

Perhaps its most striking feature, however, was its rather primitive means of eating food and then dispensing with the resulting waste. Saccorhytus had a large mouth, relative to the rest of its body, and probably ate by engulfing food particles, or even other creatures.

A crucial observation are small conical structures on its body. These may have allowed the water that it swallowed to escape and so were perhaps the evolutionary precursor of the gills we now see in fish. But the researchers were unable to find any evidence that the creature had an anus. “If that was the case, then any waste material would simply have been taken out back through the mouth, which from our perspective sounds rather unappealing,” Conway Morris said.

The findings also provide evidence in support of a theory explaining the long-standing mismatch between fossil evidence of prehistoric life, and the record provided by biomolecular data, known as the “molecular clock”.

Technically, it is possible to estimate roughly when species diverged by looking at differences in their genetic information. In principle, the longer two groups have evolved separately, the greater the biomolecular difference between them should be, and there are reasons to think this process is more or less clock-like.

Unfortunately, before a point corresponding roughly to the time at which Saccorhytus was wriggling in the mud, there are scarcely any fossils available to match the molecular clock’s predictions. Some researchers have theorised that this is because before a certain point, many of the creatures they are searching for were simply too small to leave much of a fossil record. The microscopic scale of Saccorhytus, combined with the fact that it is probably the most primitive deuterostome yet discovered, appears to back this up.

The findings are published in Nature. Reference: Jian Han, Simon Conway Morris, Qiang Ou, Degan Shu and Hai Huang. Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China). DOI: 10.1038/nature21072

Inset image: Photographs of the fossils show the spectacularly detailed levels of preservation which allowed researchers to identify and study the creature. Credit: Jian Han.

A tiny sea creature identified from fossils found in China may be the earliest known step on an evolutionary path that eventually led to the emergence of humans

We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves
Simon Conway Morris
Artist’s reconstruction of Saccorhytus coronarius, based on the original fossil finds. The actual creature was probably no more than a millimetre in size

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Antarctic Ice Sheet study reveals 8,000-year record of climate change

By sjr81 from University of Cambridge - Department of Earth Sciences. Published on Dec 12, 2016.

Results of the study, co-authored by Michael Weber, a paleoclimatologist and visiting scientist at the University of Cambridge, along with colleagues from the USA, New Zealand and Germany, are published this week in the journal Nature.

Global climate models that look at the last several thousand years have failed to account for the amount of climate variability captured in the paleoclimate record, according to lead author Pepijn Bakker, a climate modeller from the MARUM Center for Marine Environmental Studies at the University of Bremen in Germany.

The researchers first turned their attention to the Scotia Sea. “Most icebergs calving off the Antarctic Ice Sheet travel through this region because of the atmospheric and oceanic circulation,” explained Weber. “The icebergs contain gravel that drop into the sediment on the ocean floor – and analysis and dating of such deposits shows that for the last 8,000 years, there were centuries with more gravel and those with less.”

The research team’s hypothesis is that climate modellers have historically overlooked one crucial element in the overall climate system. They discovered that the centuries-long phases of enhanced and reduced Antarctic ice mass loss documented over the past 8,000 years have had a cascading effect on the entire climate system.

Using sophisticated computer modelling, the researchers traced the variability in iceberg calving (ice that breaks away from glaciers) to small changes in ocean temperatures.

“There is a natural variability in the deeper part of the ocean adjacent to the Antarctic Ice Sheet that causes small but significant changes in temperatures,” said co-author Andreas Schmittner, a climate modeller from Oregon State University. “When the ocean temperatures warm, it causes more direct melting of the ice sheet below the surface, and it increases the number of icebergs that calve off the ice sheet.”

Those two factors combine to provide an influx of fresh water into the Southern Ocean during these warm regimes, according to Peter Clark, a paleoclimatologist from Oregon State University, and co-author on the study.

“The introduction of that cold, fresh water lessens the salinity and cools the surface temperatures, at the same time, stratifying the layers of water,” he said. “The cold, fresh water freezes more easily, creating additional sea ice despite warmer temperatures that are down hundreds of meters below the surface.”

The discovery may help explain why sea ice is currently expanding in the Southern Ocean despite global warming, the researchers say.

“This response is well-known, but what is less-known is that the input of fresh water also leads to changes far away in the northern hemisphere, because it disrupts part of the global ocean circulation,” explained Nick Golledge from the University of Wellington, New Zealand, an ice-sheet modeller and study co-author. “Meltwater from the Antarctic won’t just raise global sea level, but might also amplify climate changes around the world. Some parts of the North Atlantic may end up with warmer temperatures as a consequence of part of Antarctica melting.”

Golledge used a computer model to simulate how the Antarctic Ice Sheet changed as it came out of the last ice age and into the present, warm period.

"The integration of data and models provides further evidence that the Antarctic Ice Sheet has experienced much greater natural variability in the past than previously anticipated,” added Weber. “We should therefore be concerned that it will possibly act very dynamically in the future, too, specifically when it comes to projecting future sea-level rise.”

Two years ago Weber led another study, also published in Nature, which found that the Antarctic Ice Sheet collapsed repeatedly and abruptly at the end of the Last Ice Age to 19,000 to 9,000 years ago. 

An international team of researchers has found that the Antarctic Ice Sheet plays a major role in regional and global climate variability – a discovery that may also help explain why sea ice in the Southern Hemisphere has been increasing despite the warming of the rest of the Earth.

The Antarctic Ice Sheet has experienced much greater natural variability in the past than previously anticipated.
Michael Weber
Iceberg in the Weddell Sea

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Curious Objects at the University Library

From Department of Earth Sciences. Published on Nov 07, 2016.

Curious Objects – an exhibition of ‘some unusual and unexpected items’ from the University Library’s collection runs from 3 Nov 2016 - 31 March 2017 at the Milstein Exhibition Centre, Cambridge University Library, West Road, Cambridge CB3 9DR. Free entry.

Graduate Research Opportunities

From Department of Earth Sciences. Published on Nov 02, 2016.

A full list of PhD topics for students hoping to start PhDs in 2017 with the Cambridge NERC DTP - Earth Sciences are now online.

International team head to Papua New Guinea to measure volcanic carbon degassing

From Department of Earth Sciences. Published on Sep 01, 2016.

An international team of scientists is traveling to the islands of Papua New Guinea this September to study degassing from active volcanoes in remote jungles there. Some of these volcanoes are among the most active on Earth, ejecting a significant proportion of global volcanic gases into the atmosphere.

Mistaken Point - Canada's 10th geological World Heritage Site

From Department of Earth Sciences. Published on Aug 02, 2016.

The ancient rugged coastline of Mistaken Point on Newfoundland’s Avalon Peninsula face the winds and waves of the Atlantic Ocean. It can be a difficult place to work, but nevertheless it has been a mecca for geologists for over several decades now.

An underestimated Kevan

From Department of Earth Sciences. Published on Jul 21, 2016.

Douglas Palmer on the Sedgwick Museum’s giant Pliosaurus cf. kevani in the latest edition of Geoscientist

Oesia – a new tube worm from deep Cambrian times

From Department of Earth Sciences. Published on Jul 21, 2016.

Collections up close, Sedgwick Museum of Earth Sciences

Professor Harry Elderfield tribute

From Department of Earth Sciences. Published on Jul 15, 2016.

Virtual Scilla Collection project

From Department of Earth Sciences. Published on Jul 12, 2016.

Fingerprinting rare earth elements from the air

From Department of Earth Sciences. Published on Jun 21, 2016.

Explosive Earth: Earthquakes and Eruptions in Iceland

From Department of Earth Sciences. Published on May 24, 2016.

Athena SWAN Bronze award

From Department of Earth Sciences. Published on May 03, 2016.

Bob Carter 1942-2016

From Department of Earth Sciences. Published on Mar 23, 2016.

Geophysical Research Letters, Volume 43, Issue 4

From Department of Earth Sciences. Published on Mar 17, 2016.

Shackleton's geologist - James Mann Wordie (1889-1962)

From Department of Earth Sciences. Published on Feb 16, 2016.