The Great London:
Earth Science

Scientists studying the Chicxulub crater have shown how large asteroid impacts deform rocks in a way that may produce habitats for early life.

Around 65 million years ago a massive asteroid crashed into the Gulf of Mexico causing an impact so huge that the blast and subsequent knock-on effects wiped out around 75 per cent of all life on Earth, including most of the dinosaurs. This is known as the Chicxulub impact.

In April and May 2016, an international team of scientists undertook an offshore expedition and drilled into part of the Chicxulub impact crater. Their mission was to retrieve samples from the rocky inner ridges of the crater -- known as the 'peak ring' -- drilling 506 to 1335 metres below the modern day sea floor to understand more about the ancient cataclysmic event.

Now, the researchers have carried out the first analysis of the core samples. They found that the impact millions of years ago deformed the peak ring rocks in such a way that it made them more porous, and less dense, than any models had previously predicted.

Porous rocks provide niches for simple organisms to take hold, and there would also be nutrients available in the pores, from circulating water that would have been heated inside the Earth's crust. Early Earth was constantly bombarded by asteroids, and the team have inferred that this bombardment must have also created other rocks with similar physical properties. This may partly explain how life took hold on Earth.

The study, which is published today in the >journal Science, also confirmed a model for how peak rings were formed in the Chicxulub crater, and how peak rings may be formed in craters on other planetary bodies.

The team's new work has confirmed that the asteroid, which created the Chicxulub crater, hit the Earth's surface with such a force that it pushed rocks, which at that time were ten kilometres beneath the surface, farther downwards and then outwards. These rocks then moved inwards again towards the impact zone and then up to the surface, before collapsing downwards and outwards again to form the peak ring. In total they moved an approximate total distance of 30 kilometres in a matter of a few minutes.

Professor Joanna Morgan, lead author of the study from the Department of Earth Science and Engineering, said: "It is hard to believe that the same forces that destroyed the dinosaurs may have also played a part, much earlier on in Earth's history, in providing the first refuges for early life on the planet. We are hoping that further analyses of the core samples will provide more insights into how life can exist in these subterranean environments."

The next steps will see the team acquiring a suite of detailed measurements from the recovered core samples to refine their numerical simulations. Ultimately, the team are looking for evidence of modern and ancient life in the peak-ring rocks. They also want to learn more about the first sediments that were deposited on top of the peak ring, which could tell the researchers if they were deposited by a giant tsunami, and provide them with insights into how life recovered, and when life actually returned to this sterilised zone after the impact.

Source: Imperial College London [November 17, 2016]

A multidisciplinary research team including University of Granada (UGR) researchers has analyzed two sea bed loggings retrieved from the Alboran Sea's basin at very high resolution and reconstructed climate and oceanographic conditions over the last millennium, including the anthropogenic influence in the westernmost region of the Mediterranean Sea.

Global warming, climate change and their effects on health and safety are probably the worst threats in mankind's history. Recent reports from the Intergovernmental Panel on Climate Change (IPCC 2007, 2014) have accumulated scientific evidence that the observed rise in mean ground temperature all over the world from the beginning of the 20th century is probably due to anthropogenic influence.

Moreover, global mean concentration of carbon dioxide in the atmosphere has risen since the industrial revolution due to human activities. This concentration has surpassed that found in ice cores over the last 800 000 years. In January 2016, NASA and the U.S. National Oceanic and Atmospheric Administration (NOAA) revealed that global mean temperature in 2015 was the highest since 1880, when records began.

Reconstructions of the global ground temperature in the Northern Hemisphere over the last millennium show hotter conditions during the so called Medieval Climatic Anomaly (800-1300 A.C.) and cooler temperatures during the Little Ice Age (1300-1850 A.C.).

Natural climate variability

Climate models give us a coherent explanation of the progressive cooling over the last millennium due to a natural climate variability (solar cycle changes and volcanic eruptions). However, we can see that this global tendency has reverted during the 20th century. Climate models are not capable of simulating the fast warming observed during the last century without including human impact along with natural mechanisms of climate forcing.

With this in mind, a multidisciplinary team of researchers has conducted a study reconstructing climate and oceanographic conditions in the westernmost region of the Mediterranean Sea. For that purpose, they have used marine sediments retrieved from the Alboran Sea's basin.

As a semi-closed basin located in a latitude affected by several climate types, it's especially sensitive and vulnerable to anthropogenic and climate forcing. Several organic and inorganic geochemical indicators have been integrated in the model for this research, thus deducing climate variables such as sea surface temperature, humidity, changes in vegetation cover, changes in sea currents, and human impact.

These indicators have shown consistent climate signals in the two sea bed loggings—essentially hot and dry climate conditions during the Medieval Climatic Anomaly, which switched to mostly cold and wet conditions during the Little Ice Age. The industrial period showed wetter conditions than during the Little Ice Age, and the second half of the 20th century has been characterized by an increasing aridity.

Climate variability in the Mediterranean region seems to be driven by variations in solar irradiation and changes in the North Atlantic Oscillation (NAO) during the last millennium. The NAO alternates a positive phase with a negative one. The positive phase is characterized by western winds, which are more intense and move storms towards northern Europe, which resulted in dry winters in the Mediterranean region and the north of Africa during the Medieval Climatic Anomaly and the second half of the 20th century.

In contrast, the negative phase is associated with opposite conditions during the Little Ice Age and the industrial period. Our records show that during NAO prolonged negative phases (1450 and 1950 A.C.), there occurred a weakening of the thermohaline circulation and a reduction of "upwelling" events (emergence of colder, more nutrient-rich waters). Anthropogenic influence shows up in the unprecedented increase of temperature, progressive aridification and soil erosion, and an increase of polluting elements since the industrial period. On a broad scale, atmospheric circulation patterns, oceanic circulation patterns (the NAO and the Atlantic meridional overturning circulation), and variations in solar irradiance seem to have played a key role during the last millennium.

Results show that recent climate records in the westernmost region of the Mediterranean Sea are caused by natural forcing and anthropogenic influence. The main conclusions derived from this research have been published in a special volume of the >Journal of the Geological Society of London about climate change during the Holocene.

Source: University of Granada [October 12, 2016]

Molecular-based moisture indicators, remains of midges and climate simulations have provided climate scientists with the final piece to one of the most enduring puzzles of the last Ice Age.

For years, researchers have struggled to reconcile climate models of the Earth, 13,000 years ago, with the prevailing theory that a catastrophic freshwater flood from the melting North American ice sheets plunged the planet into a sudden and final cold snap, just before entering the present warm interglacial.

Now, an international team of scientists, led by Swedish researchers from Stockholm University and in partnership with UK researchers from the Natural History Museum (NHM) London, and Plymouth University, has found evidence in the sediments of an ancient Swedish lake that it was the melting of the Scandinavian ice sheet that provides the missing link to what occurred at the end of the last Ice Age. The study, published in Nature Communications, today, examined moisture and temperature records for the region and compared these with climate model simulations.

Francesco Muschitiello, a PhD researcher at Stockholm University and lead author of the study, said: "Moisture-sensitive molecules extracted from the lake's sediments show that climate conditions in Northern Europe became much drier around 13,000 years ago."

Steve Brooks, Researcher at the NHM, added: "The remains of midges, contained in the lake sediments, reveal a great deal about the past climate. The assemblage of species, when compared with modern records, enable us to track how, after an initial warming of up to 4° Centigrade at the end of the last Ice Age, summer temperatures plummeted by 5°C over the next 400 years."

Dr Nicola Whitehouse, Associate Professor in Physical Geography at Plymouth University, explained: "The onset of much drier, cooler summer temperatures, was probably a consequence of drier air masses driven by more persistent summer sea-ice in the Nordic Seas."

According to Francesco Muschitiello the observed colder and drier climate conditions were likely driven by increasingly stronger melting of the Scandinavian ice sheet in response to warming at the end of the last Ice Age; this led to an expansion of summer sea ice and to changes in sea-ice distribution in the eastern region of the North Atlantic, causing abrupt climate change. Francesco Muschitiello added: "The melting of the Scandinavian ice sheet is the missing link to understanding current inconsistencies between climate models and reconstructions, and our understanding of the response of the North Atlantic system to climate change."

Dr Francesco Pausata, postdoctoral researcher at Stockholm University, explained: "When forcing climate models with freshwater from the Scandinavian Ice Sheet, the associated climate shifts are consistent with our climate reconstructions."

The project leader, Professor Barbara Wohlfarth from Stockholm University, concluded: "The Scandinavian ice sheet definitely played a much more significant role in the onset of this final cold period than previously thought. Our teamwork highlights the importance of paleoclimate studies, not least in respect to the ongoing global warming debate."

Source: University of Plymouth [November 17, 2015]

Using the oldest fossil micrometeorites -- space dust -- ever found, Monash University-led research has made a surprising discovery about the chemistry of Earth's atmosphere 2.7 billion years ago.

The findings of a new study >published in the journal Nature -- led by Dr Andrew Tomkins and a team from the School of Earth, Atmosphere and Environment at Monash, along with scientists from the Australian Synchrotron and Imperial College, London -- challenge the accepted view that Earth's ancient atmosphere was oxygen-poor. The findings indicate instead that the ancient Earth's upper atmosphere contained about the same amount of oxygen as today, and that a methane haze layer separated this oxygen-rich upper layer from the oxygen-starved lower atmosphere.

Dr Tomkins explained how the team extracted micrometeorites from samples of ancient limestone collected in the Pilbara region in Western Australia and examined them at the Monash Centre for Electron Microscopy (MCEM) and the Australian Synchrotron.

"Using cutting-edge microscopes we found that most of the micrometeorites had once been particles of metallic iron -- common in meteorites -- that had been turned into iron oxide minerals in the upper atmosphere, indicating higher concentrations of oxygen than expected," Dr Tomkins said.

"This was an exciting result because it is the first time anyone has found a way to sample the chemistry of the ancient Earth's upper atmosphere," Dr Tomkins said.

Imperial College researcher Dr Matthew Genge -- an expert in modern cosmic dust -- performed calculations that showed oxygen concentrations in the upper atmosphere would need to be close to modern day levels to explain the observations.

"This was a surprise because it has been firmly established that the Earth's lower atmosphere was very poor in oxygen 2.7 billion years ago; how the upper atmosphere could contain so much oxygen before the appearance of photosynthetic organisms was a real puzzle," Dr Genge said.

Dr Tomkins explained that the new results suggest the Earth at this time may have had a layered atmosphere with little vertical mixing, and higher levels of oxygen in the upper atmosphere produced by the breakdown of CO 2 by ultraviolet light.

"A possible explanation for this layered atmosphere might have involved a methane haze layer at middle levels of the atmosphere. The methane in such a layer would absorb UV light, releasing heat and creating a warm zone in the atmosphere that would inhibit vertical mixing," Dr Tomkins said.

"It is incredible to think that by studying fossilised particles of space dust the width of a human hair, we can gain new insights into the chemical makeup of Earth's upper atmosphere, billions of years ago." Dr Tomkins said.

Dr Tomkins outlined next steps in the research.

"The next stage of our research will be to extract micrometeorites from a series of rocks covering over a billion years of Earth's history in order to learn more about changes in atmospheric chemistry and structure across geological time. We will focus particularly on the great oxidation event, which happened 2.4 billion years ago when there was a sudden jump in oxygen concentration in the lower atmosphere."

Source: Monash University [May 12, 2016]

A study, carried out by Professor Andrew C. Scott of the Department of Earth Sciences at Royal Holloway, University of London and Professor Sue Rimmer from Southern Illinois University, reveals widespread fire occurred on Earth more than 80 million years after plants first invaded the land.

The findings, published in the American Journal of Science, indicate that although plants were first detected on land more than 440 million years ago there is only scant evidence of fire at that time.

Professor Scott, said: "What surprised us was that many of these early extensive fires were surface fires burning the undergrowth, as we can see the anatomy of the plants being burned through scanning electron microscope studies of larger pieces of the fossil charcoal."

He added: "This may be because plants were small and were limited in their distribution but over the following 50 million years they diversified and spread across the globe and some of the plants were trees and could have provided a good fuel to burn. Extensive forest fires soon followed, however and we see widespread charcoal deposits throughout the Lower Carboniferous (Mississippian) Period 358-323 million years ago."

Professor Scott and Professor Rimmer made the discovery after analysing charcoal which was washed in to an ocean that lay across what is now part of present day North America.

The team believes that it was not fuel availability that prevented widespread fire, or climate, but that the atmospheric oxygen levels were too low. It had been suggested that only when oxygen levels rose to above 17% (it is 21% today) that widespread fires would be found. This new data suggests that it was at around 360 million years ago, in the latest Devonian Period, that this threshold was reached and probably never went below this level for the rest of geological history.

This time period defines a new phase of the evolution of Earth System and regular wildfire would have played an important role in the evolution of both animals and plants.

Source: University of Royal Holloway London [October 21, 2015]

Geologists have for the first time seen and documented the Banda Detachment fault in eastern Indonesia and worked out how it formed.

Lead researcher Dr Jonathan Pownall from The Australian National University (ANU) said the find will help researchers assess dangers of future tsunamis in the area, which is part of the Ring of Fire -- an area around the Pacific Ocean basin known for earthquakes and volcanic eruptions.

"The abyss has been known for 90 years but until now no one has been able to explain how it got so deep," Dr Pownall said.

"Our research found that a 7 km-deep abyss beneath the Banda Sea off eastern Indonesia was formed by extension along what might be Earth's largest-identified exposed fault plane."

By analysing high-resolution maps of the Banda Sea floor, geologists from ANU and Royal Holloway University of London found the rocks flooring the seas are cut by hundreds of straight parallel scars.

These wounds show that a piece of crust bigger than Belgium or Tasmania must have been ripped apart by 120 km of extension along a low-angle crack, or detachment fault, to form the present-day ocean-floor depression.

Dr Pownall said this fault, the Banda Detachment, represents a rip in the ocean floor exposed over 60,000 square kilometres.

"The discovery will help explain how one of Earth's deepest sea areas became so deep," he said.

Professor Gordon Lister also from the ANU Research School of Earth Sciences said this was the first time the fault has been seen and documented by researchers.

"We had made a good argument for the existence of this fault we named the Banda Detachment based on the bathymetry data and on knowledge of the regional geology," said Professor Lister.

Dr Pownall said he was on a boat journey in eastern Indonesia in July when he noticed the prominent landforms consistent with surface extensions of the fault line.

"I was stunned to see the hypothesised fault plane, this time not on a computer screen, but poking above the waves," said Dr Pownall.

He said rocks immediately below the fault include those brought up from the mantle.

"This demonstrates the extreme amount of extension that must have taken place as the oceanic crust was thinned, in some places to zero," he said.

Dr Pownall also said the discovery of the Banda Detachment fault would help assesses dangers of future tsunamis and earthquakes.

"In a region of extreme tsunami risk, knowledge of major faults such as the Banda Detachment, which could make big earthquakes when they slip, is fundamental to being able to properly assess tectonic hazards," he said.

The research has been published in the journal >Geology.

Source: Australian National University [November 28, 2016]

An international research team is formalizing plans to drill nearly 5,000 feet below the seabed to take core samples from the crater of the asteroid that wiped out the dinosaurs.

The group met last week in Merida, Mexico, a city within the nearly 125-mile-wide impact site, to explain the research plans and put out a call for scientists to join the expedition planned for spring 2016. The roughly $10 million in funding for the expedition has been approved and scheduled by the European Consortium for Ocean Research Drilling (ECORD) — part of the International Ocean Discovery Program (IODP) — and the International Continental Scientific Drilling Program (ICDP).

Dinosaurs and other reptiles ruled the planet for 135 million years. That all changed 65.5 million years ago when a 9-mile-wide asteroid slammed into the Earth, triggering a series of apocalyptic events that killed most large animals and plants, and wiped out the dinosaurs and large marine reptiles. The event set the stage for mammals — and eventually humans — to take over. Yet, we have few geologic samples of the now buried impact crater.

Sean Gulick, a researcher at The University of Texas at Austin Institute for Geophysics (UTIG), and a team of scientists from the U.K. and Mexico are working to change that. The team is planning to take the first offshore core samples from near the center of the impact crater, which is called Chicxulub after the seaside village on the Yucatán Peninsula near the crater’s center.

The team, led by Gulick and Joanna Morgan of Imperial College London, will be sampling the crater’s “peak ring” — an enigmatic ring of topographically elevated rocks that surrounds the crater’s center, rises above its floor and has been buried during the past 65.5 million years by sediments.

A peak ring is a feature that is present in all craters caused by large impacts on rocky planetoids. By sampling the Chicxulub peak ring and analyzing its key features, researchers hope to uncover the impact details that set in motion one of the planet’s most profound extinctions, while also shedding light on the mechanisms of large impacts on Earth and on other rocky planets.

“What are the peaks made of? And what can they tell us about the fundamental processes of impacts, which is this dominant planetary resurfacing phenomena?” said Gulick, who is also a research associate professor at the UT Jackson School of Geosciences. UTIG is a research unit of the Jackson School.

The researchers are also interested in examining traces of life that may have lived inside the peak ring’s rocks. Density readings of the rocks indicate that they probably are heavily broken and porous — features that may have served as protected microenvironments for exotic life that could have thrived in the hot, chemically enriched environment of the crater site after impact. Additionally, the earliest recovery of marine life should be recorded within the sediments that filled in the crater in the millions of years after the impact.

“The sediments that filled in the [crater] should have the record for organisms living on the sea floor and in the water that were there for the first recovery after the mass extinction event,” Gulick said. “The hope is we can watch life come back.”

The expedition will last for two months and involve penetrating nearly 5,000 feet beneath the seabed from an offshore platform. The core will be the first complete sample of the rock layers from near the crater’s center.

Once extracted, the core will be shipped to Germany and split in two. Half will be immediately analyzed by an international team of scientists from the U.S., U.K., Mexico and other nations, and half will be saved at a core repository at Texas A&M University for future research needs by the international community.

The team also includes researchers from the National Autonomous University of Mexico (UNAM) and Centro de Investigación Científica de Yucatán (CICY). Scientists interested in joining the mission must apply by May 8, 2015. For more information on the mission and the application process, see the European Consortium for Ocean Research Drilling’s call for applications.

Source: University of Texas at Austin [April 06, 2015]

It took 100 million years for oxygen levels in the oceans and atmosphere to increase to the level that allowed the explosion of animal life on Earth about 600 million years ago, according to a UCL-led study funded by the Natural Environment Research Council.

Before now it was not known how quickly Earth's oceans and atmosphere became oxygenated and if animal life expanded before or after oxygen levels rose. The new study, published today in Nature Communications, shows the increase began significantly earlier than previously thought and occurred in fits and starts spread over a vast period. It is therefore likely that early animal evolution was kick-started by increased amounts of oxygen, rather than a change in animal behaviour leading to oxygenation.

Lead researcher, Dr Philip Pogge von Strandmann (UCL Earth Sciences), said: "We want to find out how the evolution of life links to the evolution of our climate. The question on how strongly life has actively modified Earth's climate, and why the Earth has been habitable for so long is extremely important for understanding both the climate system, and why life is on Earth in the first place."

Researchers from UCL, Birkbeck, Bristol University, University of Washington, University of Leeds, Utah State University and University of Southern Denmark tracked what was happening with oxygen levels globally 770 - 520 million years ago (Ma) using new tracers in rocks across the US, Canada and China.

Samples of rocks that were laid down under the sea at different times were taken from different locations to piece together the global picture of the oxygen levels of Earth's oceans and atmosphere. By measuring selenium isotopes in the rocks, the team revealed that it took 100 million years for the amount of oxygen in the atmosphere to climb from less than 1% to over 10% of today's current level. This was arguably the most significant oxygenation event in Earth history because it ushered in an age of animal life that continues to this day.

Dr Pogge von Strandmann, said: "We took a new approach by using selenium isotope tracers to analyse marine shales which gave us more information about the gradual changes in oxygen levels than is possible using the more conventional techniques used previously. We were surprised to see how long it took Earth to produce oxygen and our findings dispel theories that it was a quick process caused by a change in animal behaviour."

During the period studied, three big 'snowball Earth' glaciations - Sturtian (~716Ma), Marinoan (~635Ma) and Gaskiers (~580Ma) - occurred whereby the Earth's land was covered in ice and most of the oceans were frozen from the poles to the tropics. During these periods, temperatures plummeted and rose again, causing glacial melting and an influx of nutrients into the ocean, which researchers think caused oxygen levels to rise deep in the oceans.

Increased nutrients means more ocean plankton, which will bury organic carbon in seafloor sediments when they die. Burying carbon results in oxygen increasing, dramatically changing conditions on Earth. Until now, oxygenation was thought to have occurred after the relatively small Gaskiers glaciation melted. The findings from this study pushes it much earlier, to the Marinoan glaciation, after which animals began to flourish in the improved conditions, leading to the first big expansion of animal life.

Co-author Prof. David Catling (University of Washington Earth and Space Sciences), added: "Oxygen was like a slow fuse to the explosion of animal life. Around 635 Ma, enough oxygen probably existed to support tiny sponges. Then, after 580 Ma, strange creatures shaped like pizzas lived on a lightly oxygenated seafloor. Fifty million years later, vertebrate ancestors were gliding through oxygen-rich seawater. Tracking how oxygen increased is the first step towards understanding why it took so long. Ultimately, a grasp of geologic controls on oxygen levels can help us understand whether animal-like life might exist or not on Earth-like planets elsewhere."

Source: University College London [December 17, 2015]

Scientists from the Department of Earth Sciences at Royal Holloway, University of London together with colleagues from the USA, Russia and China, have discovered that forest fires across the globe were more common between 300 and 250 million years ago than they are today. This is thought to be due to higher level of oxygen in the atmosphere at that time.

The study which was published in the journal Frontiers in Plant Science, found that peats that were to become coal contained high levels of charcoal that could only be explained by the high levels of fire activity.

The team used the data from charcoal in coal to propose that the development of fire systems through this interval was controlled predominantly by the elevated atmospheric oxygen concentration (p(O2)) that mass balance models predict prevailed. At higher levels of p(O2), increased fire activity would have rendered vegetation with high moisture contents more susceptible to ignition and would have facilitated continued combustion.

In the study they examine the environmental and ecological factors that would have impacted fire activity and conclude that of these factors p(O2) played the largest role in promoting fires in Late Paleozoic peat-forming environments and, by inference, ecosystems generally, when compared with their prevalence in the modern world.

Professor Andrew Scott, one of the lead authors, said: "High oxygen levels in the atmosphere at this time has been proposed for some time and may be why there were giant insects and arthropods at this time but our research indicates that there was a significant impact on the prevalence and scale of wildfires across the globe and this would have affected not only the ecology of the plants and animals but also their evolution."

Professor Scott and his colleagues and students at Royal Holloway have pioneered the study of fire in Earth's deep past. Professor Scott, added: "We have been able to show that wildfire was an important element in Earth System many hundreds of millions of years before the arrival of humans."

Source: University of Royal Holloway London [October 27, 2015]

The world's largest canyon may lie under the Antarctic ice sheet, according to analysis of satellite data by a team of scientists, led by Durham University.

Although the discovery needs to be confirmed by direct measurements, the previously unknown canyon system is thought to be over 1,000km long and in places as much as 1km deep, comparable in depth to the Grand Canyon in USA, but many times longer.

The canyon system is made up of a chain of winding and linear features buried under several kilometres of ice in one of the last unexplored regions of the Earth's land surface: Princess Elizabeth Land (PEL) in East Antarctica. Very few measurements of the ice thickness have been carried out in this particular area of the Antarctic, which has led to scientists dubbing it one of Antarctica's two 'Poles of Ignorance'.

The researchers believe that the landscape beneath the ice sheet has probably been carved out by water and is either so ancient that it was there before the ice sheet grew or it was created by water flowing and eroding beneath the ice.

Although not visible to the naked eye, the subglacial landscape can be identified in the surface of the ice sheet.

Faint traces of the canyons were observed using satellite imagery and small sections of the canyons were then found using radio-echo sounding data, whereby radio waves are sent through the ice to map the shape of the rock beneath it. These are very large features which appear to reach from the interior of Princess Elizabeth Land to the coast around the Vestfold Hills and the West Ice Shelf.

The canyons may be connected to a previously undiscovered subglacial lake as the ice surface above the lake shares characteristics with those of large subglacial lakes previously identified. The data suggests the area of the lake could cover up to 1250km², more than 80 times as big as Lake Windermere in the English Lake District.

An airborne survey taking targeted radio-echo sounding measurements over the whole buried landscape is now underway with the aim of unambiguously confirming the existence and size of the canyon and lake system, with results due later in 2016.

Lead researcher, Dr Stewart Jamieson, from the Department of Geography at Durham University in the UK, said: "Our analysis provides the first evidence that a huge canyon and a possible lake are present beneath the ice in Princess Elizabeth Land. It's astonishing to think that such large features could have avoided detection for so long.

"This is a region of the Earth that is bigger than the UK and yet we still know little about what lies beneath the ice. In fact, the bed of Antarctica is less well known than the surface of Mars. If we can gain better knowledge of the buried landscape we will be better equipped to understand how the ice sheet responds to changes in climate."

Co-Author Dr Neil Ross from Newcastle University in the UK, said: "Antarctic scientists have long recognised that because the way ice flows, the landscape beneath the ice sheet was subtly reflected in the topography of the ice sheet surface. Despite this, these vast deep canyons and potential large lake had been overlooked entirely.

"Our identification of this landscape has only been possible through the recent acquisition, compilation and open availability of satellite data by many different organisations (e.g. NASA, ESA and the US National Snow and Ice Data Center), to whom we are very grateful, and because of some serendipitous reconnaissance radio-echo sounding data acquired over the canyons by the ICECAP project during past Antarctic field seasons."

Co-Author Professor Martin Siegert, from the Grantham Institute at Imperial College London, UK, said: "Discovering a gigantic new chasm that dwarfs the Grand Canyon is a tantalising prospect. Geoscientists on Antarctica are carrying out experiments to confirm what we think we are seeing from the initial data, and we hope to announce our findings at a meeting of the ICECAP2 collaboration, at Imperial, later in 2016.

"Our international collaboration of US, UK, Indian, Australian and Chinese scientists are pushing back the frontiers of discovery on Antarctica like nowhere else on earth. But the stability of this understudied continent is threatened by global warming, so all the countries of the world now must rapidly reduce their greenhouse gas emissions and limit the damaging effects of climate change."

>The research is >published in >Geology>.

Source: Durham University [January 13, 2016]

Uplift associated with the Great Rift Valley of East Africa and the environmental changes it produced have puzzled scientists for decades because the timing and starting elevation have been poorly constrained.

Now paleontologists have tapped a fossil from the most precisely dated beaked whale in the world -- and the only stranded whale ever found so far inland on the African continent -- to pinpoint for the first time a date when East Africa's mysterious elevation began.

The 17 million-year-old fossil is from the beaked Ziphiidae whale family. It was discovered 740 kilometers inland at an elevation of 620 meters in modern Kenya's harsh desert region, said vertebrate paleontologist Louis L. Jacobs, Southern Methodist University, Dallas.

At the time the whale was alive, it would have been swimming far inland up a river with a low gradient ranging from 24 to 37 meters over more than 600 to 900 kilometers, said Jacobs, a co-author of the study.

The study, published in the Proceedings of the National Academy of Sciences, provides the first constraint on the start of uplift of East African terrain from near sea level.

"The whale was stranded up river at a time when east Africa was at sea level and was covered with forest and jungle," Jacobs said. "As that part of the continent rose up, that caused the climate to become drier and drier. So over millions of years, forest gave way to grasslands. Primates evolved to adapt to grasslands and dry country. And that's when -- in human evolution -- the primates started to walk upright."

Identified as a Turkana ziphiid, the whale would have lived in the open ocean, like its modern beaked cousins. Ziphiids, still one of the ocean's top predators, are the deepest diving air-breathing mammals alive, plunging to nearly 10,000 feet to feed, primarily on squid.

In contrast to most whale fossils, which have been discovered in marine rocks, Kenya's beached whale was found in river deposits, known as fluvial sediments, said Jacobs, a professor in the Roy M. Huffington Department of Earth Sciences of SMU's Dedman College of Humanities and Sciences. The ancient large Anza River flowed in a southeastward direction to the Indian Ocean. The whale, probably disoriented, swam into the river and could not change its course, continuing well inland.

"You don't usually find whales so far inland," Jacobs said. "Many of the known beaked whale fossils are dredged by fishermen from the bottom of the sea."

Determining ancient land elevation is very difficult, but the whale provides one near sea level.

"It's rare to get a paleo-elevation," Jacobs said, noting only one other in East Africa, determined from a lava flow.

Beaked whale fossil surfaced after going missing for more than 30 years

The beaked whale fossil was discovered in 1964 by J.G. Mead in what is now the Turkana region of northwest Kenya.

Mead, an undergraduate student at Yale University at the time, made a career at the Smithsonian Institution, from which he recently retired. Over the years, the Kenya whale fossil went missing in storage. Jacobs, who was at one time head of the Division of Paleontology for the National Museums of Kenya, spent 30 years trying to locate the fossil. His effort paid off in 2011, when he rediscovered it at Harvard University and returned it to the National Museums of Kenya.

The fossil is only a small portion of the whale, which Mead originally estimated was 7 meters long during its life. Mead unearthed the beak portion of the skull, 2.6 feet long and 1.8 feet wide, specifically the maxillae and premaxillae, the bones that form the upper jaw and palate.

The researchers reported their findings in "A 17 million-year-old whale constrains onset of uplift and climate change in East Africa" online at the PNAS web site.

Modern cases of stranded whales have been recorded in the Thames River in London, swimming up a gradient of 2 meters over 70 kilometers; the Columbia River in Washington state, a gradient of 6 meters over 161 kilometers; the Sacramento River in California, a gradient of 4 meters over 133 kilometers; and the Amazon River in Brazil, a gradient of 1 meter over 1,000 kilometers.

Source: Southern Methodist University [March 17, 2015]