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How Earth’s earliest life overcame a genetic paradox

The unique temperature conditions of hydrothermal vents like this one could have favored the evolution of complex life. Credit : NOAA

On ancient Earth, the earliest life encountered a paradox. Chains of RNA—the ancestor of DNA—were floating around, haphazardly duplicating themselves. Scientists know that eventually, these RNA chains must have become longer and longer, setting the stage for the evolution of complex life forms like amoebas, worms, and eventually humans. But under all current models, shorter RNA molecules, having less material to copy, would have reproduced faster, favoring the evolution of primitive organisms over complex ones. Now, new research offers a potential solution: Longer RNA chains could have hidden out in porous rocks near volcanic sites such as hydrothermal ocean vents, where unique temperature conditions might have helped complex organisms evolve.

Hydrothermal vents are fissures in Earth’s crust that pump out superheated water. They would have been common on early Earth, which was more tectonically active than the planet is today, says Dieter Braun, an experimental biophysicist at Ludwig Maximilian University in Munich, Germany. The water in hydrothermal vents is particularly rich in nutrients, making them promising sites for the origin of life.

To figure out if hydrothermal vents could have given the evolution of complex life a boost, Braun and his colleagues examined the physics of a theoretical single pore in the rock surrounding a vent. The pore is open at the top and at the bottom and filled with a dilute solution of RNA molecules of various lengths. The solution on the hot side—the one closer to the stream of superheated water—would become less dense and rise up through the pore. Some of it would escape at the top, to be replenished by more nutrient-rich fluid entering at the bottom. The remainder would diffuse across to the cold side of the pore and drop back down. A complex physical effect called thermophoresis causes charged molecules in a solution to accumulate in colder water, and the longer chains, having more charge, would do this more often than shorter chains. Therefore, the shorter RNA chains would be more likely to escape out of the top of the pore, whereas the longer ones would stay trapped inside where, continually fed by nutrients, they could reproduce. Better still, Braun says, the continuous temperature cycling could actually help split the RNA double helix apart, making it easier for it to reproduce.

To test this elaborate hypothesis, Braun and his colleagues constructed a simulated piece of porous rock from a network of tiny glass capillary tubes heated on one side. They allowed dissolved fragments of DNA to be washed into the tubes from the bottom. Ideally, they would have used RNA, but Braun explains that there’s no good way to reproduce RNA in a lab, whereas it’s easy to reproduce DNA with a standard laboratory process called PCR. “All the thermophoresis and the characteristics of the trapping mechanism are the same for DNA and RNA,” he says. Once they let the experiment run, the researchers found that longer chains of DNA were more likely to accumulate inside the tubes than shorter chains were. As a result, the longer strands reproduced much better inside the pores and their populations grew, whereas the shorter strands were diluted so much that they went extinct, the team reports online today in Nature Chemistry.

It’s “nice chemistry,” says marine chemist Jeffrey Bada of the University of California (UC), San Diego, but he is not convinced that hydrothermal vents, or any other likely habitat on early Earth, could have provided the conditions created in the lab: “The processes outlined are not likely to take place on a significant scale on the Earth or elsewhere.” Biochemist Irene Chen of UC Santa Barbara disagrees and even thinks the research opens a door to studying environments beyond just volcanic ones. She suggests rock pores hotter on one side than the other could result from solar, as well as hydrothermal, heating, expanding the types of environments that could have favored the evolution of complex life. A physical environment that could plausibly have existed on the early Earth “actually selects for longer RNA sequences,” she says. “The extra length is basically room for biological creativity.”

Note : The above story is based on materials provided by American Association for the Advancement of Science. The original article was written by Tim Wogan.

Time lapse of Mexico volcano eruption

Dramatic time lapse video captured by local media showed the moment when Mexico’s Colima volcano, known locally as the ‘Fire Volcano’ erupted, sending a large plume of ash and gases into the air on Wednesday.

Video provided by AP

Geologists solve mystery of Tibetan mountains

In the most comprehensive study of its kind, University of Kansas geologists have unraveled one of the geologic mysteries of Tibet. The research, recently published online in Nature Geoscience, shows that it is the northward movement of India, thrusting under Tibet’s surface like a shovel pushing through a winter’s snow, that is causing the largest and thickest mountains on Earth to stretch in the east-west direction.

The paper is the work of Mike Taylor, associate professor of geology, and two of his former students, Richard Styron and Kurt Sundell. The lead author, Styron, now heads Earth Analysis, a consulting firm in Seattle.

“Understanding how north-trending rift valleys formed within the Tibetan plateau is something that has puzzled geoscientists for over three decades,” Taylor said. “I’ve sought the answer myself since I was a first-year graduate student 14 years ago. It’s been an extremely satisfying experience to be part of the group of KU geologists who have brought it all together.”

At 1,000 kilometers in width and 1,500 kilometers in east-west length, the Tibetan plateau is the largest continental mountain belt on Earth. The plateau is bordered to the south by the Himalayas, which include the Earth’s tallest mountains. Geoscientists have puzzled over the mechanism that created the two and how they began to stretch and move today, but many factors have hampered research, including the region’s remote location. To reach their research sites, KU geoscientists traveled to Lhasa, the capital of Tibet, then made a two-week drive by jeep farther into country’s interior.

The team studied the mechanism that formed and continues to mold the mountains by collecting and analyzing rock samples. Sometimes hiking nearly 14 miles across a single mountain range and back, they collected more than 60 samples from a long rift valley that cuts the Tibetan plateau and forms large mountains with extensive granite exposures.

Granite is an igneous rock that forms when magma cools and solidifies at relatively deep depths. By analyzing a common mineral found in granite called zircon, the team determined when the rock cooled, which allowed them to date when the formation of the mountains exhumed the zircon from the Earth’s hot interior and brought it to cooler regions near the planet’s surface.

The geoscientists found that the zircon samples began to cool about 15 million years ago, which is when Tibet began “stretching” in the east-west direction. By running thousands of computer models on their data, they discovered that the modern rift valley first formed in the south and then propagated northward, much like a zipper ripping open. The rate at which this massive zipper tore Tibet apart was 15 millimeters per year and continues today, a rate that is strikingly similar to the rate at which India is being shoved under the Himalayas. By comparing their work to previous geophysical studies of Tibet’s deep interior, the authors concluded that the acceleration of the rifting could be attributed to the insertion of India underneath the Tibetan plateau.

“The current elevation and the pattern of the rift valleys and mountains can be explained as Tibet’s response to the insertion of India,” Taylor said. “The whole process of mountain building is essentially driven by India’s northward motion.”

Taylor’s team is now focusing its research efforts on Nepal and the Andes. The National Science Foundation, American Chemical Society and the General Research Fund of the University of Kansas funded the Tibet project.

Reference:
“Accelerated extension of Tibet linked to the northward underthrusting of Indian crust.” Nature Geoscience (2015) DOI: 10.1038/ngeo2336

Note : The above story is based on materials provided by University of Kansas.

A 3-D view of the Greenland Ice Sheet opens window on ice history

This is a cross-section of the age of the Greenland Ice Sheet. Layers determined to be from the Holocene period, formed during the past 11,700 years, are shown in… view more Credit: NASA

Scientists using ice-penetrating radar data collected by NASA’s Operation IceBridge and earlier airborne campaigns have built the first comprehensive map of layers deep inside the Greenland Ice Sheet, opening a window on past climate conditions and the ice sheet’s potentially perilous future.

This new map allows scientists to determine the age of large swaths of the second largest mass of ice on Earth, an area containing enough water to raise ocean levels by about 20 feet.

“This new, huge data volume records how the ice sheet evolved and how it’s flowing today,” said Joe MacGregor, the study’s lead author, a glaciologist at The University of Texas at Austin Institute for Geophysics (UTIG), a unit of the Jackson School of Geosciences.

Greenland’s ice sheet has been losing mass during the past two decades, a phenomenon accelerated by warming temperatures. Scientists are studying ice from different climate periods in the past to better understand how the ice sheet might respond in the future.

Ice cores offer one way of studying the distant past. These cylinders of ice drilled from the ice sheet hold evidence of past snow accumulation and temperature and contain impurities such as dust and volcanic ash compacted over hundreds of thousands of years. These layers are visible in ice cores and can be detected with ice-penetrating radar.

Ice-penetrating radar works by sending radar signals into the ice and recording the strength and return time of reflected signals. From those signals, scientists can detect the ice surface, sub-ice bedrock and layers within the ice.

Researchers have developed 3-D maps of the age of the ice within the Greenland Ice Sheet. The new research will help scientists determine what may happen to the ice sheet as the climate changes.

New techniques used in this study allowed scientists to efficiently pick out these layers in radar data. Prior studies had mapped internal layers, but not at the scale made possible by these newer, faster methods.

Another major factor in this study was the scope of Operation IceBridge’s measurements across Greenland, which included flights that covered distances of tens of thousands of kilometers across the ice sheet.

“IceBridge surveyed previously unexplored parts of the Greenland Ice Sheet and did it using state-of-the-art CReSIS radars,” said study co-author Mark Fahnestock, an IceBridge science team member and glaciologist from the Geophysical Institute at the University of Alaska Fairbanks (UAF-GI).

CReSIS is the Center for Remote Sensing of Ice Sheets, a National Science Foundation science and technology center headquartered at the University of Kansas in Lawrence, Kansas.

IceBridge’s flight lines often intersect ice core sites where other scientists have analyzed the ice’s chemical composition to map and date layers in the ice. These core data provide a reference for radar measurements and provide a way to calculate how much ice from a given climate period exists across the ice sheet, something known as an age volume. Scientists are interested in knowing more about ice from the Eemian period, a time from 115,000 to 130,000 years ago that was about as warm as today. This new age volume provides the first data-driven estimate of where Eemian ice may remain.

Comparing this age volume to simple computer models helped the study’s team better understand the ice sheet’s history. Differences in the mapped and modeled age volumes point to past changes in ice flow or processes such as melting at the ice sheet’s base. This information will be helpful for evaluating the more sophisticated ice sheet models that are crucial for projecting Greenland’s future contribution to sea-level rise.

“Prior to this study, a good ice-sheet model was one that got its present thickness and surface speed right. Now, they’ll also be able to work on getting its history right, which is important because ice sheets have very long memories,” said MacGregor.

Video:

Reference :
This study was published online on Jan. 16, 2015, in Journal of Geophysical Research: Earth Surface. It was a collaboration among scientists at UTIG, UAF-GI, CReSIS and the Department of Earth System Science at the University of California, Irvine. It was supported by NASA’s Operation IceBridge and the National Science Foundation’s Arctic Natural Sciences.

For more information on Operation IceBridge, visit: http://www.nasa.gov/icebridge.

Note : The above story is based on materials provided by University of Texas at Austin.

Fossils survive volcanic eruption to tell us about the origin of the Canary Islands

El Hierro, the westernmost of the Canary Islands. Photograph: Eckhard Pecher

The most recent eruption on the Canary Islands – at El Hierro in 2011 – produced spectacularly enigmatic white ‘floating rocks’ that originated from the layers of oceanic sedimentary rock underneath the island. An international team of researchers, led from Uppsala University, use microscopic fossils found in the rocks to shed new light on the long-standing puzzle about the origin of the Canary Islands.

Despite being violently transported through the volcano, some of the rocks produced by the El Hierro eruption contain microscopic fossils of delicate single-celled marine organisms, making the survival of these fossils all the more extraordinary.

A new study published today in Scientific Reports, an open access journal of the Nature Publishing Group, by a team of scientists from the universities of Uppsala, Las Palmas de Gran Canaria, Lisbon, and the Research Council of Spain, uses these fossil time-travellers to date the sedimentary layers beneath El Hierro and, in turn, shed new light on the long-standing puzzle about the origin of the Canary Islands.

The origin and life cycle of oceanic volcanoes, such as the Canary Islands, has long been a source of debate among natural scientists. There are two competing models for the origin of the Canaries – one in which ocean floor fractures control the location of volcanic activity, and another in which an anomalously hot plume of molten rock from the Earth’s mantle feeds island growth from below.

A cornerstone of the debate concerns the validity of an age-progression along the island chain. A fixed mantle plume under the roughly eastwards moving African tectonic plate would cause the islands and the pre-volcanic ocean sediments underlying them to become progressively younger towards the westernmost island of El Hierro. The fracture model, in turn, would give rise to randomly distributed island ages.

‘Fossils and volcanoes are not usually compatible with each other, which is what makes these samples so special’, says Valentin Troll, professor at the Department of Earth Sciences at Uppsala University, who led the study that is now being published in Scientific Reports.

The study offers a unique perspective on the plume versus fracture model debate for the origin of the Canary Islands. The fossils are de facto witnesses of the pre-island environment. Researchers can now place constraints on the ages of the sedimentary strata present before island-building and, indeed, on the initiation of island-building itself. In combination with known sediment ages from the east of the archipelago, it is now clear that the oceanic sediments become younger towards the west of the island chain, thus verifying an age-progression among the islands. These findings are in strong agreement with the mantle plume model for the origin of the Canary Islands and thus contribute to our wider understanding of ocean island volcano genesis.

Reference:
Kirsten Zaczek, Valentin R. Troll, Mario Cachao, Jorge Ferreira, Frances M. Deegan, Juan Carlos Carracedo, Vicente Soler, Fiona C. Meade, Steffi Burchardt. Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands. Scientific Reports, 2015; 5: 7945 DOI: 10.1038/srep07945

Note : The above story is based on materials provided by Uppsala Universitet. The original article was written by Linda Koffmar.

New research re-creates planet formation, super-Earths and giant planets in the laboratory

New laser-driven shock compression experiments on stishovite, a high-density form of silica, provide thermodynamic and electrical conductivity data at unprecedented conditions and reveal the unusual properties of rocks deep inside large exoplanets and giant planets. Credit: Photo by E. Kowaluk, LLE

New laser-driven compression experiments reproduce the conditions deep inside exotic super-Earths and giant planet cores, and the conditions during the violent birth of Earth-like planets, documenting the material properties that determined planet formation and evolution processes.

The experiments, reported in the Jan. 23 edition of Science, reveal the unusual properties of silica — the key constituent of rock — under the extreme pressures and temperatures relevant to planetary formation and interior evolution.

Using laser-driven shock compression and ultrafast diagnostics, Lawrence Livermore National Laboratory (LLNL) physicist Marius Millot and colleagues from Bayreuth University (Germany), LLNL and the University of California, Berkeley were able to measure the melting temperature of silica at 500 GPa (5 million atmospheres), a pressure comparable to the core-mantle boundary pressure for a super-Earth planet (5 Earth masses), Uranus and Neptune. It also is the regime of giant impacts that characterize the final stages of planet formation.

“Deep inside planets, extreme density, pressure and temperature strongly modify the properties of the constituent materials,” Millot said. “How much heat solids can sustain before melting under pressure is key to determining a planet’s internal structure and evolution, and now we can measure it directly in the laboratory.”

In combination with prior melting measurements on other oxides and on iron, the new data indicate that mantle silicates and core metal have comparable melting temperatures above 300-500 GPa, suggesting that large rocky planets may commonly have long-lived oceans of magma — molten rock — at depth. Planetary magnetic fields can be formed in this liquid-rock layer.

“In addition, our research suggests that silica is likely solid inside Neptune, Uranus, Saturn and Jupiter cores, which sets new constraints on future improved models for the structure and evolution of these planets,” Millot said.

Those advances were made possible by a breakthrough in high-pressure crystal growth techniques at Bayreuth University in Germany. There, Natalia Dubrovinskaia and colleagues managed to synthesize millimeter-sized transparent polycrystals and single crystals of stishovite, a high-density form of silica (SiO2) usually found only in minute amounts near meteor-impact craters.

Those crystals allowed Millot and colleagues to conduct the first laser-driven shock compression study of stishovite using ultrafast optical pyrometry and velocimetry at the Omega Laser Facility at the University of Rochester’s Laboratory for Laser Energetics.

“Stishovite, being much denser than quartz or fused-silica, stays cooler under shock compression, and that allowed us to measure the melting temperature at a much higher pressure,” Millot said. “Dynamic compression of planetary-relevant materials is a very exciting field right now. Deep inside planets hydrogen is a metallic fluid, helium rains, fluid silica is a metal and water may be superionic.”

In fact, the recent discovery of more than 1,000 exoplanets orbiting other stars in our galaxy reveals the broad diversity of planetary systems, planet sizes and properties. It also sets a quest for habitable worlds hosting extraterrestrial life and shines new light on our own solar system. Using the ability to reproduce in the laboratory the extreme conditions deep inside giant planets, as well as during planet formation, Millot and colleagues plan to study the exotic behavior of the main planetary constituents using dynamic compression to contribute to a better understanding of the formation of the Earth and the origin of life.

Reference:
M. Millot, N. Dubrovinskaia, A.  ernok, S. Blaha, L. Dubrovinsky, D. G. Braun, P. M. Celliers, G. W. Collins, J. H. Eggert, R. Jeanloz. Shock compression of stishovite and melting of silica at planetary interior conditions. Science, 2015; 347 (6220): 418 DOI: 10.1126/science.1261507

Note: The above story is based on materials provided by DOE/Lawrence Livermore National Laboratory.

Early human ancestors used their hands like modern humans

Top row: First metacarpals of the thumb in (from left to right) a chimpanzee, fossil hominins Australopithecus africanus (StW 418) and two specimens belonging to either a robust australopiths or early Homo (SKX 5020 and SK 84), and a human. The bottom row shows 3D renderings from the microCT scans of the same specimens, showing a cross-section of the trabecular structure inside. Ma, million years ago. Credit: T.L. Kivell

New research suggests pre-Homo human ancestral species, such as Australopithecus africanus, used human-like hand postures much earlier than was previously thought.

Anthropologists from the University of Kent, working with researchers from University College London, the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany) and the Vienna University of Technology (Austria), have produced the first research findings to support archaeological evidence for stone tool use among fossil australopiths 3-2 million years ago.

The distinctly human ability for forceful precision (e.g. when turning a key) and power “squeeze” gripping (e.g. when using a hammer) is linked to two key evolutionary transitions in hand use: a reduction in arboreal climbing and the manufacture and use of stone tools. However, it is unclear when these locomotory and manipulative transitions occurred.

Dr Matthew Skinner, Senior Lecturer in Biological Anthropology and Dr Tracy Kivell, Reader in Biological Anthropology, both of Kent’s School of Anthropology and Conservation, used new techniques to reveal how fossil species were using their hands by examining the internal spongey structure of bone called trabeculae. Trabecular bone remodels quickly during life and can reflect the actual behaviour of individuals in their lifetime.

The researchers first examined the trabeculae of hand bones of humans and chimpanzees. They found clear differences between humans, who have a unique ability for forceful precision gripping between thumb and fingers, and chimpanzees, who cannot adopt human-like postures. This unique human pattern is present in known non-arboreal and stone tool-making fossil human species, such as Neanderthals.

The research, titled “Human-like hand use in Australopithecus africanus, shows that Australopithecus africanus,” a 3-2 million-year-old species from South Africa traditionally considered not to have engaged in habitual tool manufacture, has a human-like trabecular bone pattern in the bones of the thumb and palm (the metacarpals) consistent with forceful opposition of the thumb and fingers typically adopted during tool use.

These results support previously published archaeological evidence for stone tool use in australopiths and provide skeletal evidence that our early ancestors used human-like hand postures much earlier and more frequently than previously considered.

Reference:
M. M. Skinner, N. B. Stephens, Z. J. Tsegai, A. C. Foote, N. H. Nguyen, T. Gross, D. H. Pahr, J.-J. Hublin, T. L. Kivell. Human-like hand use in Australopithecus africanus. Science, 2015; 347 (6220): 395 DOI: 10.1126/science.1261735

Note: The above story is based on materials provided by University of Kent.

Doubt cast on global firestorm generated by dino-killing asteroid

Pioneering new research has debunked the theory that the asteroid that is thought to have led to the extinction of dinosaurs also caused vast global firestorms that ravaged planet Earth.

A team of researchers from the University of Exeter, University of Edinburgh and Imperial College London recreated the immense energy released from an extra-terrestrial collision with Earth that occurred around the time that dinosaurs became extinct. They found that the intense but short-lived heat near the impact site could not have ignited live plants, challenging the idea that the impact led to global firestorms.

These firestorms have previously been considered a major contender in the puzzle to find out what caused the mass extinction of life on Earth 65 million years ago.

The researchers found that close to the impact site, a 200 km wide crater in Mexico, the heat pulse — that would have lasted for less than a minute — was too short to ignite live plant material. However they discovered that the effects of the impact would have been felt as far away as New Zealand where the heat would have been less intense but longer lasting — heating the ground for about seven minutes — long enough to ignite live plant matter.

The experiments were carried out in the laboratory and showed that dry plant matter could ignite, but live plants including green pine branches, typically do not.

Dr Claire Belcher from the Earth System Science group in Geography at the University of Exeter said: “By combining computer simulations of the impact with methods from engineering we have been able to recreate the enormous heat of the impact in the laboratory. This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact. This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event.”

Plants and animals are generally resistant to localised fire events — animals can hide or hibernate and plants can re-colonise from other areas, implying that wildfires are unlikely to be directly capable of leading to the extinctions. If however some animal communities, particularly large animals, were unable to shelter from the heat, they may have suffered serious losses. It is unclear whether these would have been sufficient to lead to the extinction of species.

Dr Rory Hadden from the University of Edinburgh said: “This is a truly exciting piece of inter-disciplinary research. By working together engineers and geoscientists have tackled a complex, long-standing problem in a novel way. This has allowed a step forward in the debate surrounding the end Cretaceous impact and will help Geoscientists interpret the fossil record and evaluate potential future impacts. In addition, the methods we developed in the laboratory for this research have driven new developments in our current understanding of how materials behave in fires particularly at the wildland-urban-interface, meaning that we have been able to answer questions relating to both ancient mass extinctions at the same time as developing understanding of the impact of wildfires in urban areas today.”

The results of the study are published in the Journal of the Geological Society.

The research was supported by a European Research Council Starter Grant, a Marie Curie Career Integration Grant, the Leverhulme Trust, the EPSRC and the Austrian Science Fund.

Flaming ignition of dry plant material.

Reference:
Claire M. Belcher, Rory M. Hadden, Guillermo Rein, Joanna V. Morgan, Natalia Artemieva, and Tamara Goldin. An experimental assessment of the ignition of forest fuels by the thermal pulse generated by the Cretaceous–Palaeogene impact at Chicxulub. Journal of the Geological Society, January 22, 2015 DOI: 10.1144/jgs2014-082

Note : The above story is based on materials provided by University of Exeter.

Going with the flow

Sites where flow frequency and channel capacity effects reinforce and offset one another are indicated by filled and open circles, respectively. Red represents net increases and blue net decreases in flood hazard frequency. Credit : UCSB

Millions of Americans live in flood-prone areas. In 2012 alone, the cost of direct flood damage hit nearly half a billion dollars. However, because the factors contributing to flood risk are not fully understood, river basin management — and even the calculation of flood insurance premiums — may be misguided.

A new study by UC Santa Barbara’s Michael Singer and colleagues presents a paradigm shift in flood hazard analysis that could change the way such risk is assessed in the future. The results are published in the journal Geophysical Research Letters.

Existing analyses attribute flood hazard to how often high water flows occur. They don’t, however, take into account the ability of river channels to accommodate them. The researchers present a novel method that compares the effects of channel capacity and stream flow on flood hazard frequency. They also document how flood hazard has changed over time in more than 400 streams across the United States.

“Our results demonstrate that changes in river channel boundaries directly impact flood hazard trends across the U.S.,” said Singer, an associate researcher at UCSB’s Earth Research Institute. “We show that in order to accurately calculate flood hazard and insurance premiums for river basins, channel capacity needs to be considered jointly with stream flow.”

Lead author Louise Slater, a Ph.D. student at the University of St. Andrews in Scotland, gathered recently digitized U.S. Geological Survey (USGS) data. Using sophisticated filtering processes, she whittled down the original dataset of 11,000 stations to 401 that were well distributed across the country and developed a procedure for separating the effects of hydrology and geomorphology on flood hazard. On average, the study data spanned about 40 to 60 years for each location.

In order to find relative magnitudes of two data components — water quantity as well as channel size and condition — the researchers separated these factors and then investigated how they might interact with each other. Water quantity is also known as the flow frequency effect; channel size and conditions (morphology) is referred to as the channel capacity.

“If there’s more water coming from the watershed but the channel gets enlarged somehow, that would offset the increased water flow,” Singer explained. “These two factors potentially interacting could have no change or they could increase the amount of change in one direction or another.”

The findings revealed that important trends in channel morphology through time were three times more common than those related to water quantity, indicating that changes in the channel’s geometry tend to offset increases in water flow. “That raised alarm bells,” Singer said. “It suggests that a lot of areas that we might not have considered to have trends in flood risk actually do.”

For example, in the Pacific Northwest the increase in flood hazard is associated with the channel capacity effect because channels are filling in with sediment or vegetation that impede the flow of water. “The channel morphology has a big impact on flood hazard, making this an area where flood hazard has been underestimated,” Singer noted.

“The opposite is happening in the Mississippi River Valley,” he added. “This is an area where people might overestimate the impact of increased stream flow because the channels are adjusting to accommodate an accelerated hydrologic cycle.”

The study demonstrates that 10-year trends in channel capacity significantly impact long-term flooding frequency and that flood hazard is changing substantially at the majority of the sites studied. “Based on our analysis, we argue that in order to develop appropriate management strategies or to set flood insurance premiums for any location, you need to consider both the flow frequency and channel capacity effects of flood hazard,” Singer concluded.

Note : The above story is based on materials provided by University of California.

Two lakes beneath the ice in Greenland, gone within weeks

In April 2014, researchers flew over a site in southwest Greenland to find that a sub-glacial lake had drained away. This photo shows the crater left behind, as well as a deep crack in the ice. Credit: Photo by Stephen Price, Los Alamos National Laboratory, courtesy of The Ohio State University.

Researchers who are building the highest-resolution map of the Greenland Ice Sheet to date have made a surprising discovery: two lakes of meltwater that pooled beneath the ice and rapidly drained away.

One lake once held billions of gallons of water and emptied to form a mile-wide crater in just a few weeks. The other lake has filled and emptied twice in the last two years.

Researchers at The Ohio State University published findings on each lake separately: the first in the open-access journal The Cryosphere and the second in the journal Nature.

Ian Howat, associate professor of earth sciences at Ohio State, leads the team that discovered the cratered lake described in The Cryosphere. To him, the find adds to a growing body of evidence that meltwater has started overflowing the ice sheet’s natural plumbing system and is causing “blowouts” that simply drain lakes away.

“The fact that our lake appears to have been stable for at least several decades, and then drained in a matter of weeks — or less — after a few very hot summers, may signal a fundamental change happening in the ice sheet,” Howat said.

The two-mile-wide lake described in Nature was discovered by a team led by researcher Michael Willis of Cornell University. Michael Bevis, Ohio Eminent Scholar in Geodynamics and professor of earth sciences at Ohio State, is a co-author of the Nature paper, and he said that the repeated filling of that lake is worrisome.

Researchers at The Ohio State University were creating the highest-resolution maps of the Greenland Ice Sheet made to date, when they discovered a crater, shown here, which had once been the site of a sub-glacial lake. Image made by Ian Howat, using a Worldview image copyright DigitalGlobe Inc

Each time the lake fills, the meltwater carries stored heat, called latent heat, along with it, reducing the stiffness of the surrounding ice and making it more likely to flow out to sea, he said.

Bevis explained the long-term implications.

“If enough water is pouring down into the Greenland Ice Sheet for us to see the same sub-glacial lake empty and re-fill itself over and over, then there must be so much latent heat being released under the ice that we’d have to expect it to change the large-scale behavior of the ice sheet,” he said.

Howat’s team was first to detect the cratered lake described in The Cryosphere, on a spot about 50 kilometers (31 miles) inland from the southwest Greenland coast earlier in 2014. There, previous aerial and satellite imagery indicates that a sub-glacial lake pooled for more than 40 years. More recent images suggest that the lake likely emptied through a meltwater tunnel beneath the ice sheet some time in 2011.

The crater measures 2 kilometers (1.2 miles) across and around 70 meters (230 feet) deep. Researchers calculated that the lake that formed it likely contained some 6.7 billion gallons of water.

That’s not a large lake by most reckoning, but it’s roughly the same size as the combined reservoirs that supply water to the Columbus, Ohio metropolitan area’s 1.9 million residents. And it disappeared in a single season — remarkably quickly by geologic standards. Howat characterized the sudden drainage as “catastrophic.”

Researchers suspect that, as more meltwater reaches the base of the ice sheet, natural drainage tunnels along the Greenland coast are cutting further inland, Howat explained. The tunnels carry heat and water to areas that were once frozen to the bedrock, potentially causing the ice to melt faster.

“Some independent work says that the drainage system has recently expanded to about 50 kilometers inland of the ice edge, which is exactly where this lake is,” he added.

It’s possible that the lake was tapped by one of the invading tunnels. It’s also possible that thousands of such lakes dot the Greenland coast. They are hard to detect with radar, and researchers don’t know enough about why and how they form. In contrast to Antarctica, researchers know much less about what’s happening under the ice in Greenland.

“Until we get a good map of the bed topography where this lake was, we have no idea whatsoever how many lakes could be out there,” Howat said. “There may be something really weird in the bed in this particular spot that caused water to accumulate. But, if all you need is a bumpy surface a bit inland from the coast, then there could be thousands of little lakes.”

Howat and his team flew over the site in southwest Greenland in April 2014, after they realized that detection of the crater, nestled in the midst of a flat ice expanse, was not just an error in the high-resolution surface data they’ve been collecting. Using DigitalGlobe Inc.’s Worldview satellites, they’re assembling a Greenland ice map with 2-meter (approximately 6.5-feet) resolution.

Bevis and his colleagues discovered the lake described in Nature under similar circumstances in March 2013. They were gathering data to supplement their long-standing efforts to weigh the Greenland Ice Sheet with GPS and spotted the mitten-shaped lake by accident.

Using data from Worldview and NASA’s Operation IceBridge, the Cornell-led team calculated that the lake filled and emptied twice since 2012, at one point experiencing a sub-surface blowout that drove water from the lake at a volume of 215 cubic meters (nearly 57,000 gallons — close to the volume of a 30-foot-by-50-foot backyard swimming pool) every second.

Though researchers have long known of the existence of sub-glacial lakes, never before have they witnessed any draining away. The sudden discovery of two — one of which seems to be refilling and draining repeatedly — signals to Bevis that Greenland ice loss has likely reached a milestone.

“It’s pretty telling that these two lakes were discovered back to back,” he said. “We can actually see the meltwater pour down into these holes. We can actually watch these lakes drain out and fill up again in real time. With melting like that, even the deep interior of the ice sheet is going to change.”

Coauthors on the paper in The Cryosphere include Myoung-Jong Noh, a postdoctoral researcher, and Seongsu Jeong, a doctoral student, both of earth sciences at Ohio State; Claire Porter of the Polar Geospatial Center at the University of Minnesota; and Ben Smith of the Polar Science Center of the University of Washington.

Coauthors on the paper in Nature include Bradley Herried of the University of Minnesota and Robin Bell of Columbia University. Willis holds a joint appointment at the University of North Carolina, Chapel Hill.

These projects were funded by NASA and the National Science Foundation.

References:
Michael J. Willis, Bradley G. Herried, Michael G. Bevis, Robin E. Bell. Recharge of a subglacial lake by surface meltwater in northeast Greenland. Nature, 2015; DOI: 10.1038/nature14116

I. M. Howat, C. Porter, M. J. Noh, B. E. Smith, S. Jeong. Brief Communication: Sudden drainage of a subglacial lake beneath the Greenland Ice Sheet. The Cryosphere, 2015; 9 (1): 103 DOI: 10.5194/tc-9-103-2015

Note : The above story is based on materials provided by Ohio State University. The original article was written by Pam Frost Gorder.

Death of a dynamo: A hard drive from space

Hidden magnetic messages contained within ancient meteorites are providing a unique window into the processes that shaped our solar system, and may give a sneak preview of the fate of the Earth’s core as it continues to freeze.

The dying moments of an asteroid’s magnetic field have been successfully captured by researchers, in a study that offers a tantalising glimpse of what may happen to the Earth’s magnetic core billions of years from now.

Using a detailed imaging technique, the research team were able to read the magnetic memory contained in ancient meteorites, formed in the early solar system over 4.5 billion years ago. The readings taken from these tiny ‘space magnets’ may give a sneak preview of the fate of the Earth’s magnetic core as it continues to freeze. The findings are published today (22 January) in the journal Nature.

Using an intense beam of x-rays to image the nanoscale magnetisation of the meteoritic metal, researchers led by the University of Cambridge were able to capture the precise moment when the core of the meteorite’s parent asteroid froze, killing its magnetic field. These ‘nano-paleomagnetic’ measurements, the highest-resolution paleomagnetic measurements ever made, were performed at the BESSY II synchrotron in Berlin.

The researchers found that the magnetic fields generated by asteroids were much longer-lived than previously thought, lasting for as long as several hundred million years after the asteroid formed, and were created by a similar mechanism to the one that generates the Earth’s own magnetic field. The results help to answer many of the questions surrounding the longevity and stability of magnetic activity on small bodies, such as asteroids and moons.

“Observing magnetic fields is one of the few ways we can peek inside a planet,” said Dr Richard Harrison of Cambridge’s Department of Earth Sciences, who led the research. “It’s long been assumed that metal-rich meteorites have poor magnetic memories, since they are primarily composed of iron, which has a terrible memory — you wouldn’t ever make a hard drive out of iron, for instance. It was thought that the magnetic signals carried by metal-rich meteorites would have been written and rewritten many times during their lifetime, so no-one has ever bothered to study their magnetic properties in any detail.”

The particular meteorites used for this study are known as pallasites, which are primarily composed of iron and nickel, studded with gem-quality silicate crystals. Contained within these unassuming chunks of iron however, are tiny particles just 100 nanometres across — about one thousandth the width of a human hair — of a unique magnetic mineral called tetrataenite, which is magnetically much more stable than the rest of the meteorite, and holds within it a magnetic memory going back billions of years.

“We’re taking ancient magnetic field measurements in nanoscale materials to the highest ever resolution in order to piece together the magnetic history of asteroids — it’s like a cosmic archaeological mission,” said PhD student James Bryson, the paper’s lead author.

The researchers’ magnetic measurements, supported by computer simulations, demonstrate that the magnetic fields of these asteroids were created by compositional, rather than thermal, convection — meaning that the field was long-lasting, intense and widespread. The results change our perspective on the way magnetic fields were generated during the early life of the solar system.

These meteorites came from asteroids formed in the first few million years after the formation of the Solar System. At that time, planetary bodies were heated by radioactive decay to temperatures hot enough to cause them to melt and segregate into a liquid metal core surrounded by a rocky mantle. As their cores cooled and began to freeze, the swirling motions of liquid metal, driven by the expulsion of sulphur from the growing inner core, generated a magnetic field, just as the Earth does today.

“It’s funny that we study other bodies in order to learn more about the Earth,” said Bryson. “Since asteroids are much smaller than the Earth, they cooled much more quickly, so these processes occur on shorter timescales, enabling us to study the whole process of core solidification.”

Scientists now think that the Earth’s core only began to freeze relatively recently in geological terms, maybe less than a billion years ago. How this freezing has affected the Earth’s magnetic field is not known. “In our meteorites we’ve been able to capture both the beginning and the end of core freezing, which will help us understand how these processes affected the Earth in the past and provide a possible glimpse of what might happen in the future,” said Harrison.

However, the Earth’s core is freezing rather slowly. The solid inner core is getting bigger, and eventually the liquid outer core will disappear, killing the Earth’s magnetic field, which protects us from the Sun’s radiation. “There’s no need to panic just yet, however,” said Harrison. “The core won’t completely freeze for billions of years, and chances are, the Sun will get us first.”

The research was funded by the European Research Council (ERC) and the Natural Environment Research Council (NERC).

Reference:
James F. J. Bryson, Claire I. O. Nichols, Julia Herrero-Albillos, Florian Kronast, Takeshi Kasama, Hossein Alimadadi, Gerrit van der Laan, Francis Nimmo, Richard J. Harrison. Long-lived magnetism from solidification-driven convection on the pallasite parent body. Nature, 2015; 517 (7535): 472 DOI: 10.1038/nature14114

Note : The above story is based on materials provided by University of Cambridge.

Sequestration on shaky ground

A new study finds a natural impediment to the long-term sequestration of carbon dioxide. Credit: Christine Daniloff/MIT

Carbon sequestration promises to address greenhouse-gas emissions by capturing carbon dioxide from the atmosphere and injecting it deep below the Earth’s surface, where it would permanently solidify into rock. The U.S. Environmental Protection Agency estimates that current carbon-sequestration technologies may eliminate up to 90 percent of carbon dioxide emissions from coal-fired power plants.

While such technologies may successfully remove greenhouse gases from the atmosphere, researchers in the Department of Earth, Atmospheric and Planetary Sciences at MIT have found that once injected into the ground, less carbon dioxide is converted to rock than previously imagined.

The team studied the chemical reactions between carbon dioxide and its surroundings once the gas is injected into the Earth — finding that as carbon dioxide works its way underground, only a small fraction of the gas turns to rock. The remainder of the gas stays in a more tenuous form.

“If it turns into rock, it’s stable and will remain there permanently,” says postdoc Yossi Cohen. “However, if it stays in its gaseous or liquid phase, it remains mobile and it can possibly return back to the atmosphere.”

Cohen and Daniel Rothman, a professor of geophysics in MIT’s Department of Earth, Atmospheric, and Planetary Sciences, detail the results this week in the journal Proceedings of the Royal Society A.

Current geologic carbon-sequestration techniques aim to inject carbon dioxide into the subsurface some 7,000 feet below the Earth’s surface, a depth equivalent to more than five Empire State Buildings stacked end-to-end. At such depths, carbon dioxide may be stored in deep-saline aquifers: large pockets of brine that can chemically react with carbon dioxide to solidify the gas.

Cohen and Rothman sought to model the chemical reactions that take place after carbon dioxide is injected into a briny, rocky environment. When carbon dioxide is pumped into the ground, it rushes into open pockets within rock, displacing any existing fluid, such as brine. What remains are bubbles of carbon dioxide, along with carbon dioxide dissolved in water. The dissolved carbon dioxide takes the form of bicarbonate and carbonic acid, which create an acidic environment. To precipitate, or solidify into rock, carbon dioxide requires a basic environment, such as brine.

The researchers modeled the chemical reactions between two main regions: an acidic, low-pH region with a high concentration of carbon dioxide, and a higher-pH region filled with brine, or salty water. As each carbonate species reacts differently when diffusing or flowing through water, the researchers characterized each reaction, then worked each reaction into a reactive diffusion model — a simulation of chemical reactions as carbon dioxide flows through a briny, rocky environment.

When the team analyzed the chemical reactions between regions rich in carbon dioxide and regions of brine, they found that the carbon dioxide solidifies — but only at the interface. The reaction essentially creates a solid wall at the point where carbon dioxide meets brine, keeping the bulk of the carbon dioxide from reacting with the brine.

“This can basically close the channel, and no more material can move farther into the brine, because as soon as it touches the brine, it will become solid,” Cohen says. “The expectation was that most of the carbon dioxide would become solid mineral. Our work suggests that significantly less will precipitate.”

Cohen and Rothman point out that their theoretical predictions require experimental study to determine the magnitude of this effect.

“Experiments would help determine the kind of rock that would minimize this clogging phenomenon,” Cohen says. “There are many factors, such as the porosity and connectivity between pores in rocks, that will determine if and when carbon dioxide mineralizes. Our study reveals new features of this problem that may help identify the optimal geologic formations for long-term sequestration”

Note : The above story is based on materials provided by Massachusetts Institute of Technology. The original article was written by Jennifer Chu.

UNL drillers help make new Antarctic discoveries

WISSARD drillers set in place an ultraviolet light collar, used for purification, at the borehole site near the Whillans Ice Stream grounding zone in Antarctica. Credit: Frank Rack, UNL Science Management Office

Using a hot-water drill and an underwater robotic vehicle designed, built and operated by a University of Nebraska-Lincoln engineering team, scientists have made new discoveries about Antarctica’s geology and biology.

In addition to new observations about how Antarctica’s ice sheets are affected by rising temperatures, the expedition also uncovered a unique ecosystem of fish and invertebrates living in an estuary deep beneath the Antarctic ice.

“UNL team members once again demonstrated their engineering and operational expertise by providing clean access to a challenging, unexplored sub-ice environment,” said Frank Rack, executive director of the ANDRILL (Antarctic Drilling Project) Science Management Office and UNL’s principal investigator for the project.

The latest discoveries come in the final year of the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project. The project was delayed last year because of the U.S. federal government shutdown in October 2013, the start of Antarctica’s summer field research season. After they leave Antarctica at the end of January, most of the drillers will be laid off until a new research project and additional funding are identified.

Earlier this month, a National Science Foundation-funded team of researchers bored through nearly 740 meters of ice at a point where the Whillans Ice Stream oozes off the coastline of West Antarctica to feed into the Ross Ice Shelf, a slab of glacial ice the size of Texas that floats on the Ross Sea.

It was scientists’ first look at what’s known as the grounding zone, where the ice shelf meets the sea floor.

“This season we accessed another critical polar environment, which has never been directly sampled by scientists before: the grounding zone of the Antarctic ice sheet,” said Slawek Tulaczyk, a glaciologist from the University of California, Santa Cruz, and a chief scientist on the project.

Working around the clock, more than 40 scientists, technicians and camp staff from the WISSARD project gathered as many samples and as much data as they could while the borehole remained open.

On Jan. 16, eight days after piercing the ice, the UNL team deployed “Deep SCINI,” a remotely operated vehicle or ROV, to explore the marine cavity around the borehole.

The camera-equipped vehicle detected a variety of fish and invertebrates in an ecosystem that may provide new insights into how creatures survive and thrive in a brutally cold and dark environment.

It was the first deployment of Deep SCINI, a prototype ROV developed at UNL for combined ice and water depths of greater than 1,000 meters. It was built by Bob Zook, an ROV engineer recruited by UNL, and Justin Burnett, a UNL graduate student in mechanical engineering. UNL received grant funding from the NSF and NASA to develop Deep SCINI and other technology used in the expedition.

Other members of UNL’s team are: Dennis Duling, lead driller; Daren Blythe, Dar Gibson, Jeff Lemery, Graham Roberts and James Roth.

“This is the first time that Deep-SCINI ROV has been used in the field and it passed this test with flying colors,” Rack said, “collecting video of fish living under the ice shelf in this extremely hostile environment far from the front of the ice shelf.”

In previous expeditions, the UNL team drilled through the Ross Ice Shelf in 2010, discovering a previously unknown species of sea anemone that lives in the ice; and as part of the WISSARD project in 2012-13, used the hot water drill system to cleanly access a subglacial lake located about 60 miles inland from the grounding zone.

Rack and eight drillers were flown to the grounding zone site by ski-equipped LC-130 aircraft on Dec. 28. They needed time to get the drill ready for operation after it had been stored for two Antarctic winters on snow berms near Subglacial Lake Whillans, site of the 2012-13 project. A traverse team of tractors and drivers had moved the drill containers to the grounding zone and began setting up camp before the UNL team’s arrival. Among other things, the UNL drillers needed to reinstall and test sensors and network components that had been stored at McMurdo Station so they would not freeze.

Rack said the drill system works like an industrial-scale water-treatment plant on skis, which pumps filtered hot water at moderately high pressures of 500 to 800 pounds per square inch through a hose that is equipped with a weighted drill head and nozzle. It took about three days to drill through the ice, with the hose advancing slowly downward as the nozzle and drill head melted the ice.

Preliminary findings offer interesting clues about how climate change might affect Antarctic ice, according to a recent report on the expedition published by Scientific American. Ross Powell, a glaciologist from Northern Illinois University and WISSARD chief scientist, pointed to a layer of pebbles strewn on the bottom of the seawater cavity. They appear to have dropped from the ice as it melted and indicate a fairly recent change in the environment. They might help measure how fast the ice is melting and the stability of the ice shelf. A weakening or collapse of the Ross Ice Shelf would allow glaciers to flow more rapidly into the ocean, raising global sea level.

Reference:
Three papers describing the WISSARD hot water drill system were published in the journal Annals of Glaciology in December (www.igsoc.org/annals/55/68/published.html). More information about the WISSARD project can be found at www.wissard.org.

Note : The above story is based on materials provided by University of Nebraska-Lincoln.

Ash Spews From Mexico Volcano

The Colima volcano in Western Mexico spewed a column of ash thousands of metres into the air on Monday.

Video provided by AP

 

Paleontologist names a carnivorous reptile that preceded dinosaurs

Here is a representation of paleontologist Sterling Nesbitt’s latest addition to the paleontological vernacular: Nundasuchus, a 9-foot-long carnivorous reptile with steak knife-like teeth and bony plates on the back. Credit: Virginia Tech

Finding a new species of dinosaur is pretty rare. Getting a hand in the discovery and naming of one — that’s rarer still.

Or it would be for anyone other than 32-year-old Sterling Nesbitt, an assistant professor of geological sciences in the College of Science and the newest addition to Virginia Tech’s paleontology team.

Nesbitt has been responsible for naming more than half a dozen reptiles (including dinosaurs) in his young career.

His latest addition to the paleontological vernacular is Nundasuchus, (noon-dah-suh-kis) a 9-foot-long carnivorous reptile with steak knifelike teeth, bony plates on the back, and legs that lie under the body.

Nundasuchus is not a dinosaur, but one of the large reptiles that lived before dinosaurs took over the world.

“The full name is actually Nundasuchus songeaensis,” Nesbitt explained. “It’s Swahili mixed with Greek.”

The basic meaning of Nundasuchus, is “predator crocodile,” “Nunda” meaning predator in Swahili, and “suchus” a reference to a crocodile in Greek.

“The ‘songeaensis’ comes from the town, Songea, near where we found the bones,” Nesbitt said. “The reptile itself was heavy-bodied with limbs under its body like a dinosaur, or bird, but with bony plates on its back like a crocodilian.”

The new, albeit ancient, reptile, is featured online in the Journal of Vertebrate Paleontology.

“We discovered the partial skeleton in 2007 when I was a graduate student, but it took some years to piece the bones together as they were in thousands of pieces,” Nesbitt said.

Although a large number of skeleton bones were found, most of the skull was not recovered despite three trips to the site and more than 1,000 hours spent painstakingly piecing the bones back together and cleaning them.

Nundasuchus was found in southwestern Tanzania, while Nesbitt and a team of researchers were looking for prehistoric relatives of birds and crocodiles, but not really expecting to find something entirely new.

“There’s such a huge gap in our understanding around the time when the the common ancestor of birds and crocodilians was alive — there isn’t a lot out there in the fossil record from that part of the reptile family tree,” Nesbitt said. “This helps us fill in some gaps in reptile family tree, but we’re still studying it and figuring out the implications.”

The find itself was a bit of a “eureka moment” for the team. Nesbitt said he realized very quickly what he had found.

“Sometimes you know instantly if it’s new and within about 30 seconds of picking up this bone I knew it was a new species,” he said. “I had hoped to find a leg bone to identify it, and I thought, This is exactly why we’re here’ and I looked down and there were bones everywhere. It turns out I was standing on bones that had been weathering out of the rock for hundreds of years — and it was all one individual of a new species.”

Nesbitt says he has been very lucky to put himself in the right position for finding bones, but it also takes a lot of work doing research on what has been found in various locations through previous research; what type of animals were known to inhabit certain areas; and research into the geological maps of areas to determine the most likely places to find fossils.

Nesbitt has been involved in naming 17 different reptiles, dinosaurs, and dinosaur relatives in the last 10 years, including seven of which he discovered.

Reference:
Sterling J. Nesbitt, Christian A. Sidor, Kenneth D. Angielczyk, Roger M. H. Smith, Linda A. Tsuji. A new archosaur from the Manda beds (Anisian, Middle Triassic) of southern Tanzania and its implications for character state optimizations at Archosauria and Pseudosuchia. Journal of Vertebrate Paleontology, 2014; 34 (6): 1357 DOI: 10.1080/02724634.2014.859622

Note : The above story is based on materials provided by Virginia Tech.

Scientists drilling first deep ice core at the South Pole

Existing deep ice cores are shown by black dots. The South Pole core (red dot) will fill in the picture of Antarctic climate. The UW researchers were also part of a recent project to drill an ice core at the West Antarctic Ice Sheet divide (WD).

This winter, when many people’s imaginations were fixed on the North Pole, a small group of scientists has been working on the other side of the planet. In round-the-clock daylight and frigid temperatures, glaciologists have been drilling an ice core at the South Pole.

Drilling continues through the end of January for the first of two years of a joint project by the University of Washington and the University of California, Irvine. The National Science Foundation is funding the South Pole Ice Core Project to dig into climate history at the planet’s southernmost tip.

The 40,000-year record will be the first deep core from this region of Antarctica, and the first record longer than 3,000 years collected south of 82 degrees latitude.

“The cold temperatures in the ice, about -50 C, have caused some surprises with drilling since certain aspects of the drill perform differently even than during the test in Greenland at -30 C,” said T.J. Fudge, a UW postdoctoral researcher who is chief scientist for this month.

The location is just 2.7 km (1.7 miles) from the South Pole. Its thick, uncontaminated layers of ice will help answer questions about how Antarctic climate interacts with the rest of the world.

UW’s T.J. Fudge packages a freshly drilled section of ice core Jan. 2 at the South Pole research station. Murat Aydin

“South Pole is part of the East Antarctic Ice Sheet, yet is influenced by storms coming across the West Antarctic Ice Sheet,” Fudge said. “This core will help us figure out how the two sides of Antarctica communicate during climate changes in the past.”

The period between 40,000 years ago and 20,000 years ago includes sudden swings in temperature, and warming at the end of the last ice age.

Scientists were also attracted by cold conditions, even by polar standards.

“Most of the other places where we’ve worked the ice is -25 C to -30 C, and that’s too warm for rare organic molecules and other trace gases that people are interested in measuring,” said co-leader Eric Steig, a UW professor of Earth and space sciences.

“This is basically the coldest ice that we have drilled in,” said principal investigator Murat Aydin, a UC Irvine researcher who was chief scientist from setup of the field camp in early November through the end of December. “Everything is harder in the cold.”

All three scientists were part of a team that collected a more than 2-mile ice core from West Antarctica, a five-year effort that ended in 2011. Analysis of that ice is still ongoing at the UW, UC Irvine and many other labs around the country.

The new project at the South Pole is using a new intermediate-depth drill based on a Danish design, and a new drilling fluid. The team reached a depth of 1/2 kilometer (1/3 mile) on Jan. 14. Researchers hope to pass 700 meters by the end of this season and 1,500 meters (almost a mile down) by the end of next season.

“We’re not just trying to punch through the ice sheet, the most important objective is to bring up the highest-quality ice possible,” Aydin said.

After the core is drilled, three-foot sections will be flown to McMurdo Station and transferred to a ship. Scientists will then converge on Denver’s National Ice Core Laboratory this summer to process the samples and ship pieces to labs across the country.

In the UW’s IsoLab, Steig will analyze different types of oxygen molecules in the ice to determine the temperature. This will provide a record of climate changes for that region and help to evaluate the large-scale climate patterns across the Southern Hemisphere.

“The South Pole is one of the very few places in Antarctica that has not warmed up in the past 50 years,” Steig said. “That’s interesting, and needs to be better understood.”

The UC Irvine group will look at ultra-trace gases from air bubbles trapped in the ice. Aydin is interested in gases that are one in a billion to one in a trillion molecules in the atmosphere, but provide clues about the productivity of land-based plants and the extent of tropical wetlands during previous eras.

So far, looking at the core shows one layer of ash that the researchers think is tied to a volcanic eruption in the South Sandwich Islands.

“Otherwise, the core has been beautifully clear,” Fudge said.

Scientists work inside a field tent at about -20 C, the same temperature as the national ice core lab. Extra-curricular highlights of this year’s season included the Christmas Day round-the-world running race, and participating in the New Year’s annual marking of the South Pole.

Hear Fudge describe his work on a previous ice core:

Note : The above story is based on materials provided by University of Washington.

X-rays unlock secrets of ancient scrolls buried by volcano

Photograph of Herculaneum Papyrus scroll “PHerc.Paris.4” Length : 16cm Credit: D. Delattre © Bibliothèque de l’Institut de France

Scientists have succeeded in reading parts of an ancient scroll that was buried in a volcanic eruption almost 2,000 years ago, holding out the promise that the world’s oldest surviving library may one day reveal all of its secrets.

The scroll is among hundreds retrieved from the remains of a lavish villa at Herculaneum, which along with Pompeii was one of several Roman towns that were destroyed when Mt. Vesuvius erupted in A.D. 79.

Some of the texts from what is called the Villa of the Papyri have been deciphered since they were discovered in the 1750s. But many more remain a mystery to science because they were so badly damaged that unrolling the papyrus they were written on would have destroyed them completely.

“The papyri were completely covered in blazing-hot volcanic material,” said Vito Mocella, a theoretical scientist at the Institute of Microelectronics and Microsystems (CNR) in Naples who led the latest project.

Two words in a hidden layer of the fragment. In the top the sequence of Greek capital letters spells PIPTOIE (pi-iota-pi-tau- omicron-iota-epsilon); in the bottom the letter sequence of the next line, EIPOI (epsilon-iota-pi-omicron-iota) Credit: Mocella et al. Nature Communications

Previous attempts to peer inside the scrolls failed to yield any readable texts because the ink used in ancient times was made from a mixture of charcoal and gum. This makes it indistinguishable from the burned papyrus.

Mocella and his colleagues decided to try a method called X-ray phase contrast tomography that had previously been used to examine fossils without damaging them.

Phase contrast tomography takes advantage of subtle differences in the way radiation—such as X-rays—passes through different substances, in this case papyrus and ink.

Using lab time at the European Synchrotron Radiation Facility in Grenoble, France, the researchers found they were able to decipher several letters, proving that the method could be used to read what’s hidden inside the scrolls.

“Our goal was to show that the technique is sensitive to the writing,” said Mocella. In a further step, the scientists compared the handwriting to that of other texts, allowing them to conclude that it was likely the work of Philodemus, a poet and Epicurean philosopher who died about a century before the volcanic eruption.

The next challenge will be to automate the laborious process of scanning the charred lumps of papyrus and deciphering the texts inside them, so that some 700 further scrolls stored in Naples can be read, Mocella said.

Scholars studying the Herculaneum texts say the new technique, which was detailed in an article published Tuesday in the journal Nature Communications, may well mark a breakthrough for their efforts to unlock the ancient philosophical ideas hidden from view for almost two millennia.

“It’s a philosophical library of Epicurean texts from a time when this philosophy influenced the most important classical Latin authors, such as Virgil, Horace and Cicero,” said Juergen Hammerstaedt, a professor of Greek and Latin at the University of Cologne, Germany, who was not involved in the project.

“There needs to be much work before one can virtually unroll carbonized papyrus because one will have to develop a digital method that will allow us to follow the layers,” he said. “But in the 260 years of Herculaneum papyrology it is certainly a remarkable year.”

Reference:
Nature Communications, http://nature.com/articles/DOI: 10.1038/ncomms6895

Note : The above story is based on materials provided by The Associated Press.

Ocean floor dust gives new insight into supernovae

Dr Anton Wallner in the Nuclear Physics Department at ANU. Credit: Stuart Hay, ANU

Scientists plumbing the depths of the ocean have made a surprise finding that could change the way we understand supernovae, exploding stars way beyond our solar system.

They have analysed extraterrestrial dust thought to be from supernovae, that has settled on ocean floors to determine the amount of heavy elements created by the massive explosions.

“Small amounts of debris from these distant explosions fall on the earth as it travels through the galaxy,” said lead researcher Dr Anton Wallner, from the Research School of Physics and Engineering.

“We’ve analysed galactic dust from the last 25 million years that has settled on the ocean and found there is much less of the heavy elements such as plutonium and uranium than we expected.”

The findings are at odds with current theories of supernovae, in which some of the materials essential for human life, such as iron, potassium and iodine are created and distributed throughout space.

Supernovae also create lead, silver and gold, and heavier radioactive elements such as uranium and plutonium.

Dr Wallner’s team studied plutonium-244 which serves as a radioactive clock by the nature of its radioactive decay, with a half-life of 81 million years.

“Any plutonium-244 that existed when the earth formed from intergalactic gas and dust over four billion years ago has long since decayed,” Dr Wallner said.

“So any plutonium-244 that we find on earth must have been created in explosive events that have occurred more recently, in the last few hundred million years.”

The team analysed a 10 centimetre-thick sample of the earth’s crust, representing 25 million years of accretion, as well as deep-sea sediments collected from a very stable area at the bottom of the Pacific Ocean.

“We found 100 times less plutonium-244 than we expected,” Dr Wallner said.

“It seems that these heaviest elements may not be formed in standard supernovae after all. It may require rarer and more explosive events such as the merging of two neutron stars to make them.”

The fact that these heavy elements like plutonium were present, and uranium and thorium are still present on earth suggests that such an explosive event must have happened close to the earth around the time it formed, said Dr Wallner.

“Radioactive elements in our planet such as uranium and thorium provide much of the heat that drives continental movement, perhaps other planets don’t have the same heat engine inside them,” he said.

The research is published in Nature Communications.

Reference:
A. Wallner, T. Faestermann, J. Feige, C. Feldstein, K. Knie, G. Korschinek, W. Kutschera, A. Ofan, M. Paul, F. Quinto, G. Rugel, P. Steier. Abundance of live 244Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis. Nature Communications, 2015; 6: 5956 DOI: 10.1038/ncomms6956

Note : The above story is based on materials provided by Australian National University.

Geophysicists find the crusty culprits behind sudden tectonic plate movements

Image via Shutterstock

Yale-led research may have solved one of the biggest mysteries in geology — namely, why do tectonic plates beneath the Earth’s surface, which normally shift over the course of tens to hundreds of millions of years, sometimes move abruptly?

A new study published Jan. 19 in the journal Proceedings of the National Academy of Sciences says the answer comes down to two things: thick crustal plugs and weakened mineral grains. Those effects, acting together, may explain a range of relatively speedy moves among tectonic plates around the world, from Hawaii to East Timor.

Of course, in this case “speedy” still means a million years or longer.

“Our planet is probably most distinctly marked by the fact that it has plate tectonics,” said Yale geophysicist David Bercovici, lead author of the research. “Our work here looks at the evolution of plate tectonics. How and why do plates change directions over time?”

Traditionally, scientists believed that all tectonic plates are pulled by subducting slabs — which result from the colder, top boundary layer of the Earth’s rocky surface becoming heavy and sinking slowly into the deeper mantle. Yet that process does not account for sudden plate shifts. Such abrupt movement requires that slabs detach from their plates, but doing this quickly is difficult since the slabs should be too cold and stiff to detach.

According to the Yale study, there are additional factors at work. Thick crust from continents or oceanic plateaux is swept into the subduction zone, plugging it up and prompting the slab to break off. The detachment process is then accelerated when mineral grains in the necking slab start to shrink, causing the slab to weaken rapidly.

The result is tectonic plates that abruptly shift horizontally, or continents suddenly bobbing up.

“Understanding this helps us understand how the tectonic plates change through the Earth’s history,” Bercovici said. “It adds to our knowledge of the evolution of our planet, including its climate and biosphere.”

The study’s co-authors are Gerald Schubert of the University of California-Los Angeles and Yanick Ricard of the Université de Lyon in France.

Note : The above story is based on materials provided by Yale University. The original article was written by Jim Shelton.

Preserved fossil represents oldest record of parental care in group of prehistoric reptiles

Parental care reconstruction. Credit: Chuang Zhao

New research details how a preserved fossil found in China could be the oldest record of post-natal parental care from the Middle Jurassic.

The specimen, found by a farmer in China, is of an apparent family group with an adult, surrounded by six juveniles of the same species. Given that the smaller individuals are of similar sizes, the group interpreted this as indicating an adult with its offspring, apparently from the same clutch.

A fossil specimen discovered by a farmer in China represents the oldest record of post-natal parental care, dating back to the Middle Jurassic.

The tendency for adults to care for their offspring beyond birth is a key feature of the reproductive biology of living archosaurs — birds and crocodilians — with the latter protecting their young from potential predators and birds, not only providing protection but also provision of food.

This behaviour seems to have evolved numerous times in vertebrates, with evidence of a long evolutionary history in diapsids — a group of amniotes which developed holes in each side of the skull about 300 million years ago and from which all existing lizards, snakes and birds are descended

However, unequivocal evidence of post-natal parental care is extremely rare in the fossil record and is only reported for two types of dinosaurs and varanopid ‘pelycosaurs’ — a reptile which resembled a monitor lizard.

A new study by the Institute of Geology, Chinese Academy of Geological Sciences, Beijing; the University of Lincoln, UK; and Hokkaido University, Japan, presents new evidence of post-natal parental care in Philydrosauras, a choristodere from the Yixian Formation of western Liaoning Province, China. Choristoderes are a group of relatively small aquatic and semi-aquatic diapsid reptiles which emerged in the Middle Jurassic Period more than 160 million years ago.

The team reviewed the fossil record of reproduction in this group using exceptionally preserved skeletons of the aquatic choristoderan Philydrosauras. The specimen was donated to the Jinzhou Paleontological Museum in Jinzhou City four years ago by a local farmer who discovered the skeleton.

The skeletons are of an apparent family group with an adult, surrounded by six juveniles of the same species. Given that the smaller individuals are of similar sizes, the group interpreted this as indicating an adult with its offspring, apparently from the same clutch.

Dr Charles Deeming, from the School of Life Sciences, University of Lincoln, UK, said: “That Philydrosauras shows parental care of the young after hatching suggests protection by the adult, presumably against predators. Their relatively small size would have meant that choristoderes were probably exposed to high predation pressure and strategies, such as live birth, and post-natal parental care may have improved survival of the offspring. This specimen represents the oldest record of post-natal parental care in diapsids to our knowledge and is the latest in an increasingly detailed collection of choristoderes exhibiting different levels of reproduction and parental care.”

A test of whether post-natal parental care is an ancestral behaviour that has persisted in the evolutionary development of amniotes will depend on future fossil discoveries.

The study is published in Geosciences Journal.

Reference:
Junchang Lü, Yoshitsugu Kobayashi, D. Charles Deeming, Yongqing Liu. Post-natal parental care in a Cretaceous diapsid from northeastern China. Geosciences Journal, 2014; DOI: 10.1007/s12303-014-0047-1

Note : The above story is based on materials provided by University of Lincoln.

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