The Great London [Search results for Geology] 

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]

Various specimens of Africa’s earliest coelacanth have been found in a 360 million year-old fossil estuary near Grahamstown, in South Africa’s Eastern Cape.

More than 30 complete specimens of the new fossil species, Serenichthys kowiensis, were collected from the famous Late Devonian aged Waterloo Farm locality, by palaeontologist Dr Robert Gess and described by him in collaboration with Professor Michael Coates of the University of Chicago.

Gess did the research whilst he was completing his PhD at the Evolutionary Studies Institute at the University of the Witwatersrand. An article describing the new species will be published in the in the prestigious Zoological Journal of the Linnean Society of London on Monday, 21 August.

“Remarkably, all of the delicate whole fish impressions represent juveniles. This suggests that Serenichthys was using a shallow, waterweed-filled embayment of the estuary as a nursery, as many fish do today,” says Gess.

The fossils come from black shales originally disturbed by road works at Waterloo Farm. These shales are the petrified compacted remains of mud, which was deposited in the quiet reaches of an estuary not unlike some of those along the Eastern Cape coast today.

“This earliest known record of a coelacanth nursery foreshadows a much younger counterpart, known from the 300 million year old Mazon Creek beds of Illinois in the United States,” says Gess.

“This glimpse into the early life history of ancient coelacanths raises further questions about the life history of the modern coelacanth, Latimeria, which is known to bear live young, but whether they, too, are clustered in nurseries remains unknown,” explains Coates.

360 million years ago, Africa was part of the southern supercontinent Gondwana, made up of Africa, India, Australia, Antarctica and South America. At that time, the rocks of Waterloo Farm were forming along the shores of the semi-enclosed Agulhas Sea, not far from the South Pole.

Gess originally identified coelacanth remains from the locality whilst carrying out excavations at Waterloo Farm in the mid-1990s under the supervision of Dr Norton Hiller, of the Rhodes University Geology Department. These fossils were not, however, well enough preserved to be reconstructed and described. His painstaking excavation of tons of shale salvaged during subsequent roadworks has now shed light on dozens more specimens, a few of which are preserved in exquisite detail.

These were prepared under a microscope and have allowed the species to be reconstructed in minute detail. They prove to be a new genus and species.

Coelacanths are believed to have arisen during the Devonian Period (about 419.2 ± 3.2 million years ago), however only five species of reconstructable Devonian coelacanths have previously been described, in addition to a number of very fragmentary remains. None of these came from Africa, but rather from North America, Europe, China and Australia. The new species gives important additional information on the early evolution of coelacanths.

“According to our evolutionary analysis (conducted by Gess and Coates), it is the Devonian species that most closely resembles the line leading to modern coelacanths,” says Gess.

The new species was discovered a mere 100km from the mouth of the Chalumna River, off which the type specimen of Latimeria chalumnae (the first discovered modern coelacanth) was caught in 1938.

Furthermore, the Geology Department at Rhodes, where Gess was based when he found his first fossil coelacanth, is on the site of the former Chemistry Department where Latimeria was first described. In keeping with the naming of its living relative (after an Eastern Cape river), the species name of the new fossil form, kowiensis, is after the Kowie River which rises among the hills where it was found, and the genus name, Serenichthys, honours Serena Gess, who provided land for the storage of more than 70 tons of black shale rescued from roadworks for ongoing research – in which all the new material was found.

All specimens have been deposited in the palaeontological collection of the Albany Natural History Museum, in Grahamstown, Eastern Cape Province, South Africa.

Source: University of the Witwatersrand [September 21, 2015]

Current rates of climate change could trigger instability in a major Antarctic glacier, ultimately leading to more than 2m of sea-level rise.

This is the conclusion of a new study looking at the future of Totten Glacier, a significant glacier in Antarctica. Totten Glacier drains one of the world's largest areas of ice, on the East Antarctic Ice Sheet (EAIS).

By studying the history of Totten's advances and retreats, researchers have discovered that if climate change continues unabated, the glacier could cross a critical threshold within the next century, entering an irreversible period of very rapid retreat.

This would cause it to withdraw up to 300 kilometres inland in the following centuries and release vast quantities of water, contributing up to 2.9 metres to global sea-level rise.

The EAIS is currently thought to be relatively stable in the face of global warming compared with the much smaller ice sheet in West Antarctica, but Totten Glacier is bucking the trend by losing substantial amounts of ice. The new research reveals that Totten Glacier may be even more vulnerable than previously thought.

The study, by scientists from Imperial College London and institutions in Australia, the US, and New Zealand is >published in Nature. Last year, the team discovered that there is currently warm water circulating underneath a floating portion of the glacier that is causing more melting than might have been expected.

Their new research looks at the underlying geology of the glacier and reveals that if it retreats another 100-150 km, its front will be sitting on an unstable bed and this could trigger a period of rapid retreat for the glacier. This would cause it to withdraw nearly 300 km inland from its current front at the coast.

Retreating the full 300 km inland may take several hundred years, according to co-author Professor Martin Siegert, Co-Director of the Grantham Institute at Imperial College London. However, once the glacier crosses the threshold into the unstable region, the melting will be unstoppable -- at least until it has retreated to the point where the geology becomes more stable again.

"The evidence coming together is painting a picture of East Antarctica being much more vulnerable to a warming environment than we thought," he said. "This is something we should worry about. Totten Glacier is losing ice now, and the warm ocean water that is causing this loss has the potential to also push the glacier back to an unstable place."

"Totten Glacier is only one outlet for the ice of the East Antarctic Ice Sheet, but it could have a huge impact. The East Antarctic Ice Sheet is by far the largest mass of ice on Earth, so any small changes have a big influence globally."

To uncover the history of Totten Glacier's movements, the team looked at the sedimentary rocks below the glacier using airborne geophysical surveys. From the geological record, influenced by the erosion by ice above, they were able to understand the history of the glacier stretching back millions of years.

They found that the glacier has retreated more quickly over certain 'unstable' regions in the past. Based on this evidence, the scientists believe that when the glacier hits these regions again we will see the same pattern of rapid retreat.

Author: Hayley Dunning. | Source: Imperial College London [May 18, 2016]

An unidentified fossilised bone in a museum has revealed the size of a fearsome abelisaur and may have solved a hundred-year old puzzle.

Alessandro Chiarenza, a PhD student from Imperial College London, last year stumbled across a fossilised femur bone, left forgotten in a drawer, during his visit to the Museum of Geology and Palaeontology in Palermo Italy. He and a colleague Andrea Cau, a researcher from the University of Bologna, got permission from the museum to analyse the femur. They discovered that the bone was from a dinosaur called abelisaur, which roamed the Earth around 95 million years ago during the late Cretaceous period.

Abelisauridae were a group of predatory, carnivorous dinosaurs, characterised by extremely small forelimbs, a short deep face, small razor sharp teeth, and powerful muscular hind limbs. Scientists suspect they were also covered in fluffy feathers. The abelisaur in today's study would have lived in North Africa, which at that time was a lush savannah criss-crossed by rivers and mangrove swamps. This ancient tropical world would have provided the abelisaur with an ideal habitat for hunting aquatic animals like turtles, crocodiles, large fish and other dinosaurs.

By studying the bone, the team deduced that this abelisaur may have been nine metres long and weighed between one and two tonnes, making it potentially one of the largest abelisaurs ever found. This is helping researchers to determine the maximum sizes that these dinosaurs may have reached during their peak.

Alfio Alessandro Chiarenza, co-author of the study from the Department of Earth Science and Engineering at Imperial, said: "Smaller abelisaur fossils have been previously found by palaeontologists, but this find shows how truly huge these flesh eating predators had become. Their appearance may have looked a bit odd as they were probably covered in feathers with tiny, useless forelimbs, but make no mistake they were fearsome killers in their time."

The fossil originated from a sedimentary outcrop in Morocco called the Kem Kem Beds, which are well known for the unusual abundance of giant predatory dinosaur fossils. This phenomenon is called Stromer's Riddle, in honour the German palaeontologist Ernst Stromer, who first identified this abundance in 1912. Since then scientists have been asking how abelisaurs and five other groupings of predatory dinosaurs could have co-existed in this region at the same time, without hunting each other into extinction.

Now the researchers in today's study suggest that these predatory dinosaur groups may not have co-existed so closely together. They believe that the harsh and changing geology of the region mixed the fossil fragment records together, destroying its chronological ordering in the Kem Kem beds, and giving the illusion that the abelisaurs and their predatory cousins shared the same terrain at the same time. Similar studies of fossil beds in nearby Tunisia, for example, show that creatures like abelisaurs were inland hunters, while other predators like the fish eating spinosaurs probably lived near mangroves and rivers.

Chiarenza added: "This fossil find, along with the accumulated wealth of previous studies, is helping to solve the question of whether abelisaurs may have co-existed with a range of other predators in the same region. Rather than sharing the same environment, which the jumbled up fossil records may be leading us to believe, we think these creatures probably lived far away from one another in different types of environments."

Fossilised femora are useful for palaeontologists to study because they can determine the overall size of the dinosaur. This is because femora are attached to the thigh and tail muscles and have scars, or bumps, which tell palaeontologists where the ligaments and muscles were attached to the bone and how big those muscles and ligaments would have been.

Andrea Cau, co-author from the University of Bologna, said: "While palaeontologists usually venture to remote and inaccessible locations, like the deserts of Mongolia or the Badlands of Montana, our study shows how museums still play an important role in preserving specimens of primary scientific value, in which sometimes the most unexpected surprises can be discovered. As Stephen Gould, an influential palaeontologist and evolutionary biologist, once said, sometimes the greatest discoveries are made in museum drawers."

The study is published in the journal Peer J. Chiarenza did the underpinning analysis with Cau while at the University of Bologna.

The next step will see the team looking for more complete remains from these predatory dinosaurs trying to better understand their environment and evolutionary history.

Author: Colin Smith | Source: Imperial College London [February 29, 2016]

An international team of scientists led by the University of Leicester has discovered a new species of fossil in England -- and identified it as an ancient parasitic intruder.

The fossil species found in 425-million year old rocks in Herefordshire, in the Welsh borderland, is described as 'exceptionally well preserved.' The specimens range from about 1 to 4 millimeters long.

The fossil species -- a 'tongue worm', which has a worm-like body and a head and two pairs of limbs -- is actually a parasite whose representatives today live internally in the respiratory system of a host, which it enters when it is eaten.

The new fossil, which was originally entirely soft-bodied, is the first fossil tongue worm species to be found associated with its host, which in this case is a species of ostracod -- a group of micro-arthropods (crabs, spiders and insects are also arthropods) with two shells that are joined at a hinge.

Professor David Siveter, of the Department of Geology at the University of Leicester made the discovery working alongside researchers from the Universities of Oxford, Imperial College London and Yale, USA. Their research is published in the journal Current Biology and was supported by The Natural Environmental Research Council, together with the Leverhulme Trust, the John Fell Oxford University Press (OUP) Research Fund and Yale Peabody Museum of Natural History.

Professor Siveter said: "This discovery is important not only because examples of parasites are exceptionally rare in the fossil record, but also because the possible host of fossil tongue worms -- and the origin of the lifestyle of tongue worms -- has been the subject of much debate.

"This discovery affirms that tongue worms were 'external' parasites on marine invertebrate animals at least 425 million years ago; it also suggests that tongue worms likely found their way into land-based environments and associated hosts in parallel with the movement of vertebrates onto the land by some 125 million years later."

Professor Siveter said tongue worms -- technically termed pentastomids -- are in fact not worms at all; they are an unusual group of tiny and widespread parasitic arthropods. Their fossils are exceptionally rare and until now are known only from a handful of isolated juvenile specimens.

Today they are known from about 140 species, nearly all of which are parasitic on vertebrate animals, particularly reptiles and including humans. Some of the fossil tongue worm specimens occur inside the shell, near the eggs of the ostracod; others are attached to the external surface of its shell, a unique position for any fossil or living tongue worm.

Professor Siveter added: "The tongue worm and its host lived in a sea that 425 million years ago -- during the Silurian period of geological time -- covered much of southern Britain, which was positioned then in warm southerly subtropical latitudes. The animals died and were preserved when a volcanic ash rained down upon them. The new species has been named Invavita piratica, which means an 'ancient intruder' and 'piracy', referring to its parasitic lifestyle in the sea."

The fossils have been reconstructed as virtual fossils by 3D computer modelling.

Source: University of Leicester [May 21, 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]

Planetary scientists have discovered pieces of opal in a meteorite found in Antarctica, a result that demonstrates that meteorites delivered water ice to asteroids early in the history of the solar system. Led by Professor Hilary Downes of Birkbeck College London, the team announce their results at the National Astronomy Meeting in Nottingham on Monday 27 June.

Opal, familiar on Earth as a precious stone used in jewellery, is made up of silica (the major component of sand) with up to 30% water in its structure, and has not yet been identified on the surface of any asteroid. Before the new work, opal had only once been found in a meteorite, as a handful of tiny crystals in a meteorite from Mars.

Downes and her team studied the meteorite, named EET 83309, an object made up of thousands and broken pieces of rock and minerals, meaning that it originally came from the broken up surface, or regolith, of an asteroid. Results from other teams show that while the meteorite was still part of the asteroid, it was exposed to radiation from the Sun, the so-called solar wind, and from other cosmic sources. Asteroids lack the protection of an atmosphere, so radiation hits their surfaces all the time.

EET 83309 has fragments of many other kinds of meteorite embedded in it, showing that there were many impacts on the surface of the parent asteroid, bringing pieces of rock from elsewhere in the solar system. Downes believes one of these impacts brought water ice to the surface of the asteroid, allowing the opal to form.

She comments: "The pieces of opal we have found are either broken fragments or they are replacing other minerals. Our evidence shows that the opal formed before the meteorite was blasted off from the surface of the parent asteroid and sent into space, eventually to land on Earth in Antarctica."

"This is more evidence that meteorites and asteroids can carry large amounts of water ice. Although we rightly worry about the consequences of the impact of large asteroid, billions of years ago they may have brought the water to the Earth and helped it become the world teeming with life that we live in today."

The team used different techniques to analyse the opal and check its composition. They see convincing evidence that it is extra-terrestrial in origin, and did not form while the meteorite was sitting in the Antarctic ice. For example, using the NanoSims instrument at the Open University, they can see that although the opal has interacted to some extent with water in the Antarctic, the isotopes (different forms of the same element) match the other minerals in the original meteorite.

Source: Royal Astronomical Society [June 28, 2016]

A new study presents evidence that the rise of atmospheric oxygenation did indeed occur 2.4-2.1 billion years ago. It also shows that biological usage of copper became prominent after the so called 'Great Oxidation Event.' An international team of researchers has recently published the study in the Proceedings of the National Academy of Sciences.

"Our findings make it possible to reconstruct nutrient content in early marine settings and demonstrate that the iron-rich content of the early oceans must have severely restricted the availability of nutrients important for life", says Dr Ernest Chi Fru of Stockholm University, who has led the research group.

The study suggests a gradual shift in mainly negative copper isotopic composition of marine carbon-rich sediments, beginning at 2.4 billion years ago (Ga), to permanently positive values after 2.3 Ga. The authors argue that the change reflects the drawn-out nature of the Great Oxidation Event (GOE), when atmospheric oxygen content went from virtually nothing, starting at 2.4 Ga, to peak at near present day levels by 2.3 Ga.

Fundamentally, the high iron content of the early oceans are suggested to have played a critical role in determining trace metal availability, whereby copper levels increased when decreasing marine iron content fell by about 1 000 times after the GOE. The research has been made by examining carbon-rich rocks deposited at the bottom of ancient oceans 2.66-2.1 billion years ago.

"The appearance of oxygen in the atmosphere is one of the most important changes in Earth's geological history that enabled the evolution of oxygen based life. Understanding the chemistry of the very early oceans and how nutrients were made available, guide our steps towards understanding the processes that govern our own evolution", says Dr Ernest Chi Fru of Stockholm University.

The study provides a tool for tracking how oxygen levels have fluctuated through Earth's history and the evolutionary changes that accompanied these fluctuations.

"Our study is highlighting how the isotopic ratios of copper can unlock the evolution of Earth's early oceans from being oxygen-poor to more like they are today. We now hope to apply this technique to understanding other major geological events in the Earth's history", says Professor Dominik Weiss, co-author from Imperial College London.

Source: Stockholm University [April 18, 2016]

Scientists working off west Africa in the Cape Verde Islands have found evidence that the sudden collapse of a volcano there tens of thousands of years ago generated an ocean tsunami that dwarfed anything ever seen by humans. The researchers say an 800-foot wave engulfed an island more than 30 miles away. The study could revive a simmering controversy over whether sudden giant collapses present a realistic hazard today around volcanic islands, or even along more distant continental coasts. The study appears today in the journal Science Advances.

"Our point is that flank collapses can happen extremely fast and catastrophically, and therefore are capable of triggering giant tsunamis," said lead author Ricardo Ramalho, who did the research as a postdoctoral associate at Columbia University's Lamont-Doherty Earth Observatory, where he is now an adjunct scientist. "They probably don't happen very often. But we need to take this into account when we think about the hazard potential of these kinds of volcanic features."

The apparent collapse occurred some 73,000 years ago at the Fogo volcano, one of the world's largest and most active island volcanoes. Nowadays, it towers 2,829 meters (9,300 feet) above sea level, and erupts about every 20 years, most recently last fall. Santiago Island, where the wave apparently hit, is now home to some 250,000 people.

There is no dispute that volcanic flanks present a hazard; at least eight smaller collapses have occurred in Alaska, Japan and elsewhere in the last several hundred years, and some have generated deadly tsunamis. But many scientists doubt whether big volcanoes can collapse with the suddenness that the new study suggests. Rather, they envision landslides coming in gradual stages, generating multiple, smaller tsunamis. A 2011 French study also looked at the Fogo collapse, suggesting that it took place somewhere between 124,000-65,000 years ago; but that study says it involved more than one landslide. The French researchers estimate that the resulting multiple waves would have reached only 45 feet--even at that, enough to do plenty of harm today.

A handful of previous other studies have proposed much larger prehistoric collapses and resulting megatsunamis, in the Hawaiian islands, at Italy's Mt. Etna, and the Indian Ocean's Reunion Island. But critics have said these examples are too few and the evidence too thin. The new study adds a new possible example; it says the estimated 160 cubic kilometers (40 cubic miles) of rock that Fogo lost during the collapse was dropped all at once, resulting in the 800-foot wave. By comparison, the biggest known recent tsunamis, which devastated the Indian Ocean's coasts in 2004 and eastern Japan in 2011, reached only about 100 feet. (Like most other well documented tsunamis, these were generated by movements of undersea earthquake faults--not volcanic collapses.)

Santiago Island lies 55 kilometers (34 miles) from Fogo. Several years ago, Ramalho and colleagues were working on Santiago when they spotted unusual boulders lying as far as 2,000 feet inland and nearly 650 feet above sea level. Some are as big as delivery vans, and they are utterly unlike the young volcanic terrain on which they lie. Rather, they match marine-type rocks that ring the island's shoreline: limestones, conglomerates and submarine basalts. Some weigh up to 770 tons. The only realistic explanation the scientists could come up with: A gigantic wave must have ripped them from the shoreline and lofted them up. They derived the size of the wave by calculating the energy it would have taken to accomplish this feat.

To date the event, in the lab Ramalho and Lamont-Doherty geochemist Gisela Winckler measured isotopes of the element helium embedded near the boulders' surfaces. Such isotopes change depending on how long a rock has been lying in the open, exposed to cosmic rays. The analyses centered around 73,000 years--well within the earlier French estimate of a smaller event. The analysis "provides the link between the collapse and impact, which you can make only if you have both dates," said Winckler.

Tsunami expert Bill McGuire, a professor emeritus at University College London who was not involved in the research, said the study "provides robust evidence of megatsunami formation [and] confirms that when volcanoes collapse, they can do so extremely rapidly." Based on his own work, McGuire s says that such megatsunamis probably come only once every 10,000 years. "Nonetheless," he said, "the scale of such events, as the Fogo study testifies, and their potentially devastating impact, makes them a clear and serious hazard in ocean basins that host active volcanoes."

Ramalho cautions that the study should not be taken as a red flag that another big collapse is imminent here or elsewhere. "It doesn't mean every collapse happens catastrophically," he said. "But it's maybe not as rare as we thought."

In the early 2000s, other researchers started publishing evidence that the Cape Verdes could generate large tsunamis. Others have argued that Spain's Canary Islands have already done so. Simon Day, a senior researcher at University College London has sparked repeated controversy by warning that any future eruption of the Canary Islands' active Cumbre Vieja volcano could set off a flank collapse that might form an initial wave 3,000 feet high. This, he says, could erase more than nearby islands. Such a wave might still be 300 feet high when it reached west Africa an hour or so later he says, and would still be 150 feet high along the coasts of North and South America. So far, such studies have raised mainly tsunamis of publicity, and vigorous objections from other scientists that such events are improbable. A 2013 study of deep-sea sediments by the United Kingdom's National Oceanography Centre suggests that the Canaries have probably mostly seen gradual collapses.

Part of the controversy hangs not only on the physics of the collapses themselves, but on how efficiently resulting waves could travel. In 1792, part of Japan's Mount Unzen collapsed, hitting a series of nearby bays with waves as high as 300 feet, and killing some 15,000 people. On July 9, 1958, an earthquake shook 90 million tons of rock into Alaska's isolated Lituya Bay; this created an astounding 1,724-foot-high wave, the largest ever recorded. Two fishermen who happened to be in their boat that day were carried clear over a nearby forest; miraculously, they survived.

These events, however, occurred in confined spaces. In the open ocean, waves created by landslides are generally thought to lose energy quickly, and thus to pose mainly a regional hazard. However, this is based largely on modeling, not real-world experience, so no one really knows how fast a killer wave might decay into a harmless ripple. In any case, most scientists are more concerned with tsunamis generated by undersea earthquakes, which are more common. When seabed faults slip, as they did in 2004 and 2011, they shove massive amounts of water upward. In deep water, this shows up as a mere swell at the surface; but when the swell reaches shallower coastal areas, its energy concentrates into in a smaller volume of water, and it rears up dramatically. The 2004 Indian Ocean earthquake and tsunami killed 230,000 people in 14 countries; the 2011 Tohoku event killed nearly 20,000 in Japan, and has caused a long-term nuclear disaster.

James Hunt, a tsunami expert at the United Kingdom's National Oceanography Centre who was not involved in the study, said the research makes it clear that "even modest landslides could produce high-amplitude anomalous tsunami waves on opposing island coastlines." The question, he said, "is whether these translate into hazardous events in the far field, which is debatable."

When Fogo erupted last year, Ramalho and other geologists rushed in to observe. Lava flows (since calmed down) displaced some 1,200 people, and destroyed buildings including a new volcano visitors' center. "Right now, people in Cape Verde have a lot more to worry about, like rebuilding their livelihoods after the last eruption," said Ramalho. "But Fogo may collapse again one day, so we need to be vigilant."

Source: The Earth Institute at Columbia University [October 02, 2015]

Analysis of the first fossil bee nest from the Plio-Pleistocene of South Africa suggests that the human ancestor Australopithecus africanus lived in a dry savannah environment, according a study published in the >open-access journal PLOS ONE by Jennifer Parker from University College London, United Kingdom, and colleagues.

Little paleoecological information is available for the site in South Africa where the first Au. africanus fossil—the 'Taung Child'—was discovered. However, insect-related fossils, abundant at the discovery site, can yield insights into the paleoenvironment. Bees, for example, tend to build characteristic nests in characteristic conditions. Parker and colleagues analyzed CT scans of a fossil bee nest that was discovered near the Taung Child site to determine its internal structure and thus the kinds of bees that built it.

The fossil nest was exceptionally well preserved, and the structure of its cells and tunnels suggested that it was made by a ground-nesting solitary bee. These bees typically nest on bare, light, dry soil that is exposed to the sun, which bolsters other recent evidence that Au. africanus lived in dry savannahs. Insect-related fossils are common but largely overlooked at sites where human ancestors lived, the researchers said, and their work underscores the contribution such fossils can make to understanding the environments where human ancestors lived.

"When Raymond Dart published his description of the 'Taung Child' in 1925 he profoundly changed our understanding of human evolution," says study co-author Philip Hopley. "In the 90 years following his discovery, attention of anthropologists has moved to other African sites and specimens, and research at Taung has been hampered by the complex geology and uncertain dating. New research at Taung is helping to reconstruct the environment in which this enigmatic little hominin lived and died."

Source: Public Library of Science [September 29, 2016]

Extensive systems of fossilised riverbeds have been discovered on an ancient region of the Martian surface, supporting the idea that the now cold and dry Red Planet had a warm and wet climate about 4 billion years ago, according to UCL-led research>.

The study, >published in Geology and funded by the Science & Technology Facilities Council and the UK Space Agency, identified over 17,000km of former river channels on a northern plain called Arabia Terra, providing further evidence of water once flowing on Mars.

"Climate models of early Mars predict rain in Arabia Terra and until now there was little geological evidence on the surface to support this theory. This led some to believe that Mars was never warm and wet but was a largely frozen planet, covered in ice-sheets and glaciers. We've now found evidence of extensive river systems in the area which supports the idea that Mars was warm and wet, providing a more favourable environment for life than a cold, dry planet," explained lead author, Joel Davis (UCL Earth Sciences).

Since the 1970s, scientists have identified valleys and channels on Mars which they think were carved out and eroded by rain and surface runoff, just like on Earth. Similar structures had not been seen on Arabia Terra until the team analysed high resolution imagery from NASA's Mars Reconnaissance Orbiter (MRO) spacecraft.

The new study examined images covering an area roughly the size of Brazil at a much higher resolution than was previously possible -- 6 metres per pixel compared to 100 metres per pixel. While a few valleys were identified, the team revealed the existence of many systems of fossilised riverbeds which are visible as inverted channels spread across the Arabia Terra plain.

The inverted channels are similar to those found elsewhere on Mars and Earth. They are made of sand and gravel deposited by a river and when the river becomes dry, the channels are left upstanding as the surrounding material erodes. On Earth, inverted channels often occur in dry, desert environments like Oman, Egypt, or Utah, where erosion rates are low -- in most other environments, the channels are worn away before they can become inverted.

"The networks of inverted channels in Arabia Terra are about 30m high and up to 1-2km wide, so we think they are probably the remains of giant rivers that flowed billions of years ago. Arabia Terra was essentially one massive flood plain bordering the highlands and lowlands of Mars. We think the rivers were active 3.9-3.7 billion years ago, but gradually dried up before being rapidly buried and protected for billions of years, potentially preserving any ancient biological material that might have been present," added Joel Davis.

"These ancient Martian flood plains would be great places to explore to search for evidence of past life. In fact, one of these inverted channels called Aram Dorsum is a candidate landing site for the European Space Agency's ExoMars Rover mission, which will launch in 2020," said Dr Matthew Balme, Senior Lecturer at The Open University and co-author of the study.

The researchers now plan on studying the inverted channels in greater detail, using higher-resolution data from MRO's HiRISE camera.

Source: University College London [August 23, 2016]

New research led by the University of Southampton shows Neanderthals kept coming back to a coastal cave site in Jersey from at least 180,000 years ago until around 40,000 years ago.

As part of a re-examination of La Cotte de St Brelade and its surrounding landscape, archaeologists from Southampton, together with experts from three other universities and the British Museum, have taken a fresh look at artefacts and mammoth bones originally excavated from within the site's granite cliffs in the 1970s. Their findings are published in the >journal Antiquity.

The researchers matched types of stone raw material used to make tools to detailed mapping of the geology of the sea bed, and studied in detail how they were made, carried and modified. This helped reconstruct a picture of what resources were available to Neanderthals over tens of thousands of years -- and where they were travelling from.

Lead author Dr Andy Shaw of the Centre for the Archaeology of Human Origins (CAHO) at the University of Southampton said: "La Cotte seems to have been a special place for Neanderthals. They kept making deliberate journeys to reach the site over many, many generations. We can use the stone tools they left behind to map how they were moving through landscapes, which are now beneath the English Channel. 180,000 years ago, as ice caps expanded and temperatures plummeted, they would have been exploiting a huge offshore area, inaccessible to us today."

Previous research focussed on particular levels in the site where mammoth bones are concentrated, but this new study took a longer-term perspective, looking at how Neanderthals used it and explored the surrounding landscape for over 100,000 years.

The team, including academics from the British Museum, University College London (UCL) and the University of Wales found that Neanderthals kept coming back to this particular place, despite globally significant changes in climate and landscape. During glacial phases (Ice Ages), they travelled to the site over cold, open landscapes, now submerged under the sea. They kept visiting as the climate warmed up and Jersey became a striking highpoint in a wide coastal plain connected to France.

Dr Beccy Scott of the British Museum added: "We're really interested in how this site became 'persistent' in the minds of early Neanderthals. You can almost see hints of early mapping in the way they are travelling to it again and again, or certainly an understanding of their geography. But specifically what drew them to Jersey so often is harder to tease out. It might have been that the whole Island was highly visible from a long way off -- like a waymarker -- or people might have remembered that shelter could be found there, and passed that knowledge on."

Paper author Dr Matt Pope, of the Institute of Archaeology at UCL, agrees: "La Cotte de St Brelade is probably the most important Neanderthal site in northern Europe and could be one of the last known places that Neanderthals survived in the region. It was certainly as important to them as it is to us, as we try and understand how they thrived and survived for 200,000 years.

"With new technology we have been able to reconstruct the environment of the La Cotte Neanderthals in a way earlier researchers couldn't. Our project has really put the Neanderthal back into the landscape, but emphasised how significant the changes in climate and landscape have been since then."

Project leader Professor Clive Gamble, of CAHO at the University of Southampton, comments: "Jersey is an island that endures, summed up by the granite cliffs of St Brelade's Bay. The elements which led to Neanderthals coming back for so many thousands of years shows how this persistence is deep rooted in Jersey's past. Our project has shown that more unites the past with the present than separates. We are not the only humans to have coped successfully with major environmental changes. Let's hope we are not the last."

The team's work was undertaken as part of the 'Crossing the Threshold' project led by Professor Clive Gamble and Dr John McNabb at the University of Southampton, together with UCL and the British Museum. The research was funded by the Arts and Humanities Research Council and looks at major changes in how early humans used places from 400,000 years ago.

Source: University of Southampton [December 12, 2016]

Magnetic nanovortices in magnetite minerals are reliable witnesses of the earth's history, as revealed by the first high-resolution studies of these structures undertaken by scientists from Germany and the United Kingdom. The magnetic structures are built during the cooling of molten rock and reflect the earth's magnetic field at the time of their formation. The vortices are unexpectedly resilient to temperature fluctuations, as electron holographic experiments in Julich have verified. These results are an important step in improving our understanding of the history of the earth's magnetic field, its core and plate tectonics.

The earth's magnetic field performs important functions: it protects us, for example, from charged particles from space and enables migratory birds, bees, and other animals to navigate. However, it is not stable, and constantly changes its intensity and state. Several times in the past it has even reversed its polarity -- the north and south poles have changed places.

Scientists in the area of paleomagnetism use magnetic minerals to investigate the history of the earth's magnetic field and its formation from molten metal flowing within the earth's core, the so-called geodynamo. Furthermore, the movement of continental plates can be monitored with the aid of such rocks.

In the course of millions of years, these minerals could often have been exposed to immense temperature fluctuations, due to extreme climate change or volcanic activity, for instance. How well do the magnetic structures survive such temperature fluctuations and how reliable is the information gained from them?

An international research team has now studied this question for the first time at ultra-high resolution on samples of magnetite, the mineral dominating the magnetic properties in the earth's crust.

"It is only in a small part of naturally occurring magnetite that magnetic structures known for being very stable with respect to temperature fluctuations are found," explains Dr. Trevor Almeida of Imperial College London. "Far more common are tiny magnetic vortices. Their stability could not be demonstrated until now."

Together with colleagues from Forschungszentrum Julich, the University of Edinburgh and the University of Nottingham, Almeida has studied the magnetic vortices in magnetite nanocrystals. As the structures are so tiny -- each grain is only about the size of a virus -- there is only one method with which the nanovortices can directly be observed while they are heated up and cooled down: "A special high-resolution electron microscope at the Ernst Ruska-Centre (ER-C) in Julich is capable of making magnetic fields on the nanoscale holographically visible," explains Almeida. "In this way, images of field lines are produced almost like using iron filings around a bar magnet to make its magnetic field visible, but with a resolution in the nanometre range."

The experiments in Julich showed that although the magnetic vortices alter in strength and direction when heated up, they go back to their original state as they cool down. "Therefore magnetite rocks, which carry signs of temperature fluctuations, are indeed a reliable source of information about the history of the earth," enthuses Almeida.

"Electron holography has made it possible for us to gain a completely new insight into the magnetic behaviour of magnetite," emphasized Prof. Rafal Dunin-Borkowski, Director at the ER-C and at the Peter Grunberg Institute in Julich.

As an expert in electron holography, he works with his Julich team on further improving the resolution of this technique and in providing German and international scientists the necessary infrastructure to perform this type of study.

"Weak magnetic fields in nanocrystals don't just play a role in paleomagnetism. In information technology, for instance, electron holograms can also be of use to help to push back the physical limits of data storage and processing."

The study has been published in Science Advances.

Source: Forschungszentrum Juelich [April 18, 2016]

Scientists have discovered an ancient animal that carried its young in capsules tethered to the parent's body like tiny, swirling kites. They're naming it after "The Kite Runner," the 2003 bestselling novel.

The miniscule creature, Aquilonifer spinosus, was an arthropod that lived about 430 million years ago. It grew to less than half an inch long, and there is only one known fossil of the animal, found in Herefordshire, England. Its name comes from "aquila," which means eagle or kite, and the suffix "fer," which means carry.

Researchers from Yale, Oxford, the University of Leicester, and Imperial College London described the new species in a paper published in the journal Proceedings of the National Academy of Sciences.

"Modern crustaceans employ a variety of strategies to protect their eggs and embryos from predators -- attaching them to the limbs, holding them under the carapace, or enclosing them within a special pouch until they are old enough to be released -- but this example is unique," said lead author Derek Briggs, Yale's G. Evelyn Hutchinson Professor of Geology and Geophysics and curator of invertebrate paleontology at the Yale Peabody Museum of Natural History. "Nothing is known today that attaches the young by threads to its upper surface."

The Kite Runner fossil shows 10 juveniles, at different stages of development, connected to the adult. The researchers interpret this to mean that the adult postponed molting until the juveniles were old enough to hatch; otherwise, the juveniles would have been cast aside with the shed exoskeleton.

The adult specimen's head is eyeless and covered by a shield-like structure, according to the researchers. It lived on the sea floor during the Silurian period with a variety of other animals including sponges, brachiopods, worms, snails and other mollusks, a sea spider, a horseshoe crab, various shrimp-like creatures, and a sea star. The juvenile pouches, attached to the adult by slender, flexible threads, look like flattened lemons.

Briggs said he and his colleagues considered the possibility that the juveniles were parasites feeding off a host, but decided it was unlikely because the attachment position would not be favorable for accessing nutrients.

"We have named it after the novel by Khalid Hosseini due to the fancied resemblance of the juveniles to kites," Briggs said. "As the parent moved around, the juveniles would have looked like decorations or kites attached to it. It shows that arthropods evolved a variety of brooding strategies beyond those around today -- perhaps this strategy was less successful and became extinct."

The researchers were able to describe Aquilonifer spinosus in detail thanks to a virtual reconstruction. They reconstructed the animal and the attached juveniles by stacking digital images of fossil surfaces revealed by grinding away the fossil in tiny increments.

Author: Jim Shelton | Source: Yale University [April 04, 2016]