Australia’s largest carnivorous dinosaur, dubbed “lightning claw” due to its terrifyingly large talons, has been identified from fossilised bones found in opal in the New South Wales outback.
The dinosaur would have been around 7m in length – larger than the Australovenator, a dinosaur found in Queensland that was previously thought to be Australia’s largest meat-eating ancient beast.
A 25cm claw, part of a forearm, a metatarsal, a rib and parts of a hip and lower leg were discovered by opal miners and handed over to researchers in 2005.
The remains, found near the NSW town of Lightning Ridge, have finally been identified as a new type of dinosaur by a team led by palaeontologist Dr Phil Bell, of the University of New England.
“When I first saw the bones I knew they were important and unique but it’s taken until now to do all our comparisons and find out this is a new dinosaur to science,” Bell told Guardian Australia.
“It was obviously a predator but the key thing about this guy is the giant claws on its hands. These claws compensate for a rather dainty skull and slender jaws, which are unlike the giant skull of a T-Rex, which had a bone crushing bite.
“This dinosaur probably ran down its prey and used its arms like grappling hooks. Its mouth was simply to tear off small pieces of meat.”
The remains studied by Bell are around 110m years old. It is thought the lightning claw dinosaur would have been extinct within three to four million years and did not survive to see the mass extinction of dinosaurs 65m years ago.
“We don’t know what else is out there, whether it faced competition or its environment changed,” Bell said. “It certainly would’ve been replaced by something equally fearsome and equally large, we just haven’t found it yet.”
Bell said Australia is something of an “enigma” to dinosaur-hunting palaeontologists. The continent is covered in rocks older than the time of the dinosaurs meaning there are few spots to find remains – Lightning Ridge is the only place in New South Wales where dinosaur fossils can be found.
“We get tantalising glimpses into ancient ecosystems but there’s certainly new discoveries to be found,” Bell said. “Having a big scary predator dinosaur on your desk is certainly quite nice.”
Reference:
A large-clawed theropod (Dinosauria: Tetanurae) from the Lower Cretaceous of Australia and the Gondwanan origin of megaraptorid theropods, Gondwana Research, Available online 5 September 2015. DOI: 10.1016/j.gr.2015.08.004
Note: The above post is reprinted from materials provided by Guardian News . The original article was written by Oliver Milman.
An explosion test conducted as part of the New England Detonation Experiment (NEDE). This shot was detonated using factory-made COMP B charges in dry boreholes in a granite quarry. Credit: Anastasia Stroujkova
After analyzing the seismic waves produced by small underground chemical explosions at a test site in Vermont, scientists say that some features of seismic waves could be affected by the amount of gas produced in the explosion.
This unexpected finding may have implications for how scientists use these types of chemical explosions to indirectly study the seismic signal of nuclear detonations. Researchers use chemical blasts to learn more about the specific seismic signatures produced by explosions—which differ from those produced by earthquakes—to help efforts to detect and trace nuclear test explosions under entities such as the Comprehensive Nuclear-Test-Ban Treaty.
Chemical explosions are only a proxy for nuclear explosions, however, and it is difficult to say how or if the results of the new study may apply to seismic monitoring of nuclear explosions, cautioned study author Anastasia Stroujkova of Weston Geophysical Corp.
In the study published online in the Bulletin of the Seismological Society of America, Stroujkova reports that characteristics of P waves produced by chemical explosions depend on the amount of gas by-products released in the rock cavity that is created by the blasts. P waves are the fast-moving seismic waves that push and pull through rock in the direction of the wave’s propagation, and are the first part of a seismic signature to reach a seismic monitoring station.
In particular, the lingering, non-condensable gas produced in the explosions seemed to affect the size of low frequency portion of P waves, which could be important for seismic monitoring, said Stroujkova. High frequency seismic waves weaken faster than low frequency waves, sometimes becoming lost among the background noise of other seismic signals before they can reach monitoring stations a thousand or more kilometers away, “while the low frequencies can be detected and analyzed further away from the sources,” she explained.
In nuclear explosions, the low frequency amplitude is also proportional to the yield, or amount of energy discharged by a detonation, Stroujkova noted, making it “an important observable characteristic of seismic waves.”
The amount of gas produced in the chemical explosions could affect the low frequency P waves in two possible ways, Stroujkova suggested. The expanding gas could contribute to an increase in the volume of the rock cavity produced by the explosion, or the gas may be fracturing the surrounding rock for a long time after the initial explosion. “More research is needed to better understand and clarify these possible effects,” she said.
The explosions studied by Stroujkova are part of the New England Damage Experiment (NEDE) in Vermont, conducted by Weston Geophysical Corp. in collaboration with New England Research, Inc. The main goal of the NEDE is to study seismic waves generated by explosives that differ in detonation power. In particular, the project has focused on the slower, shear or S waves, in which oscillations take place in the plane perpendicular to P waves.
The small explosions studied by Stroujkova were fueled by either an ammonium nitrate and fuel oil combination or Composition B, an explosive mix often used in artillery projectiles and land mines. The explosives were detonated in boreholes in the granite bedrock at depths ranging from about 11 to 13 meters (36 to 46 feet) deep. The explosions were performed by a team of professional blasters within a rock quarry. The explosions, designed to be fully contained underground, are smaller than the majority of the blasts used in quarry mining.
Video
An explosion test conducted as part of the New England Detonation Experiment (NEDE). This shot was detonated using factory-made COMP B charges in dry boreholes in a granite quarry.
Credit: Anastasia Stroujkova
The Cosgrove volcano track is shown. Credit: Drew Whitehouse, NCI National Facility VizLab
Scientists have discovered the world’s longest known chain of continental volcanoes, running 2,000 kilometres across Australia, from the Whitsundays in North Queensland to near Melbourne in central Victoria.
The volcanic chain was created over the past 33 million years, as Australia moved northwards over a hotspot in the Earth’s mantle, said leader of the research Dr Rhodri Davies from The Australian National University (ANU).
“We realised that the same hotspot had caused volcanoes in the Whitsundays and the central Victoria region, and also some rare features in New South Wales, roughly halfway between them,” said Dr Davies, from the ANU Research School of Earth Sciences.
“The track is nearly three times the length of the famous Yellowstone hotspot track on the North American continent,” said Dr Davies.
This kind of volcanic activity is surprising because it occurs away from tectonic plate boundaries, where most volcanoes are found. These hotspots are thought to form above mantle plumes, narrow upwellings of hot rock that originate at Earth’s core-mantle boundary almost 3,000 kilometres below the surface.
The study, published in Nature, found that sections of the track have no volcanic activity because the Australian continent is too thick to allow the hot rock in mantle plumes to rise close enough to the Earth’s surface for it to melt and form magma.
The research found that the plume created volcanic activity only where Earth’s solid outer layer, called the lithosphere, is thinner than 130 kilometres.
These new findings will help scientists to understand volcanism on other continents and from earlier periods in Earth’s history, said co-author Dr Nick Rawlinson, now at the University of Aberdeen’s School of Geosciences.
“Ultimately this new understanding may help us to reconstruct the past movements of continents from other hotspots,” he said.
The giveaway that the continent is just thin enough for melting to begin, such as in northern New South Wales, is the formation of an unusual mineral called leucitite.
Leucitite is found in low-volume magmas that are rich in elements such as potassium, uranium and thorium, said co-author Professor Ian Campbell from the ANU Research School of Earth Sciences.
“Now that we know there is a direct relationship between the volume and chemical composition of magma and the thickness of the continent, we can go back and interpret the geological record better,” Professor Campbell said.
The scientists have named the volcanic chain the Cosgrove hotspot track.
Dr Davies said the mantle plume that formed the Australian volcanoes is probably still in existence, under the sea a little to the northwest of Tasmania.
“There are observations of higher mantle temperatures and increased seismicity in this region,” he said.
Reference:
Lithospheric controls on magma composition along Earth’s longest continental hotspot track, Nature, DOI: 10.1038/nature14903
Darwinius is one of the best preserved early fossil primates known to exist. Credit: Jens L. Franzen et al: PLoS One; 10.1371/journal.pone.0005723
A famous fossil of an early primate shares more in common with modern lemurs based on how its teeth erupted, according to new model developed at U of T Scarborough.
The model, developed by PhD student Sergi López-Torres and Associate Professors Mary Silcox and Michael Schillaci, re-examined the interpretation of Darwinius, the best preserved fossil primate known to exist.
By looking at the sequence in which adult teeth come in — known as dental eruption — in primates, they found it had more in common with lemurs than squirrel monkeys, the model species used by the researchers who discovered Darwinius.
“Every species has a particular pattern by which their teeth come in and this allows us to estimate the age of fossils that died before their adult teeth could emerge,” says López-Torres. “It seems that the pattern of dental eruption for Darwinius is more similar to that of lemurs than to that of monkeys.”
Before looking at Darwinius, López-Torres did a large study of 97 living and fossil primates in order to get a clearer picture of how different species compare through patterns of dental development. He found that the three most primitive ancestors — the ancestor to lemurs and lorises, the ancestor to monkeys, apes, and tarsiers, and the ancestor to all primates — share the same eruption sequence with each other. That pattern shares some similarities with the dental eruption sequence found in Darwinius.
“The major difference is we found that anthropoids (ancestors to monkeys, apes and humans) are characterized by a late eruption of the third molar, which is something Darwinius clearly doesn’t show,” he says. “One idea that still stands links Darwinius to anthropoids, but since it doesn’t show this late eruption, it looks more like a modern lemur.”
Their model also suggests Darwinius was a little older at the time of death and would have weighed slightly less as an adult than the original estimates predicted.
The team that originally discovered Darwinius argued the 47-million-year-old fossil was more closely related to haplorrhines, the group that includes anthropoids (monkeys, apes, and humans) and tarsiers. Subsequent studies by the same group suggested Darwinius was specifically related to anthropoids, the primate lineage in which humans belong.
Other researchers argue that Darwinius is more likely a strepsirrhine, meaning it belongs to the opposite branch of the primate family tree, closer to lemurs and lorises.
“Our findings don’t entirely support the strepsirrhine hypothesis, but it’s certainly consistent with it,” says López-Torres. “We can say for certain it’s not consistent with the anthropoid hypothesis.”
While the new model proposes only a slight change in adult weight and age at death — 622-642g and 1.05-1.14 years compared to original estimates of 650-900g and 9-10 months — the findings are significant in terms of figuring out what Darwinius was actually like.
“It may seem trivial going from 9 or 10 months to a little over a year, but if you consider that, for example, some species of lemur can reproduce at a year old, this difference could mean a major change in what the life of this animal was like,” notes López-Torres.
“Our goal as palaeontologists is to bring these animals back to life. It’s the best preserved fossil primate. It even has stomach contents, so there’s a lot of potential for understanding its biology,” adds Silcox.
“We want to be able to answer broader evolutionary questions, but we also need to have a nuanced view of what this particular animal was like.”
The model is explained in a new research published online in the journal Royal Society Open Science.
Reference:
Jens L. Franzen, Philip D. Gingerich, Jörg Habersetzer, Jørn H. Hurum, Wighart von Koenigswald, B. Holly Smith. Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE, 2009; 4 (5): e5723 DOI: 10.1371/journal.pone.0005723
Illustration of impact resulting in unique double crater in Sweden. Credit: Don Dixon/Erik Sturkell/University of Gothenburg
Researchers at the University of Gothenburg have found traces of two enormous meteorite impacts in the Swedish county of Jämtland, a twin strike that occurred around 460 million years ago.
The researchers have discovered two craters in Jämtland. One is enormous, while the other is a tenth of the size of the first.
“The two meteorite impacts occurred at the same time, 458 million years ago, and formed these two craters,” says Erik Sturkell, Professor of Geophysics at the University of Gothenburg.
Erik Sturkell and his research colleagues found one of the craters 20 kilometres south of Östersund in Brunsflo. This is an enormous crater, with a diameter of 7.5 kilometres. The smaller crater is located 16 kilometres from there, and has a diameter of 700 metres.
An era of meteorites
The two meteorite impacts 458 million years ago were not the only ones to strike Earth at this time.
“Around 470 million years ago, two large asteroids collided in the asteroid belt between Mars and Jupiter, and many fragments were thrown off in new orbits. Many of these crashed on Earth, such as these two in Jämtland,” says Erik Sturkell.
Jämtland was under the sea at the time, with a water depth of 500 metres at the points where two meteorites simultaneously stuck. Double impacts like this are very unusual. This is the first double impact on Earth that has been conclusively proved.
“Information from drilling operations demonstrates that identical sequences are present in the two craters, and the sediment above the impact sequences is of the same age. In other words, these are simultaneous impacts,” says Erik Sturkell.
The water was forced away during the impact, and for a hundred seconds these enormous pits were completely dry.
“The water then rushed back in, bringing with it fragments from the meteorites mixed with material that had been ejected during the explosion and with the gigantic wave that tore away parts of the sea bed,” says Erik Sturkell.
Impacts at several locations in Sweden
Several meteorites have also been found on Kinnekulle.
“In the 1940s, an unusual-looking red limestone slab was found in a quarry. A few years later, researchers understood that there was a meteorite in the slab. Large meteors explode and disintegrate almost completely, while small meteors fall as rocks, such as in this limestone,” says Erik Sturkell.
Around 90 meteorites from meteorite impacts have been found on Kinnekulle over the past fifteen years.
“Small meteorites survive the fall, while large ones explode and disintegrate. In Jämtland we have only found minerals from the meteorites, small grains of chromite.
The fact that active quarrying is conducted on Kinnekulle is the reason why researchers have found meteorites there. And as a discovery was made as long ago as the 1940s, the individuals working in the quarry know what to look for.
So might it be possible to distinguish slabs in our limestone floors that might come from meteorites? “Technically speaking, yes, although there is probably not much chance, as the limestone slabs that come from meteors are often rather ugly and will probably have been discarded. But they do exist!”
This chart shows how Antarctic ice would be affected by different emissions scenarios. (GtC stands for gigatons of carbon.) Credit: Ken Caldeira and Ricarda Winkelmann
New work from an international team including Carnegie’s Ken Caldeira demonstrates that the planet’s remaining fossil fuel resources would be sufficient to melt nearly all of Antarctica if burned, leading to a 50- or 60-meter (160 to 200 foot) rise in sea level. Because so many major cities are at or near sea level, this would put many highly populated areas where more than a billion people live under water, including New York City and Washington, DC. It is published in Science Advances.
“Our findings show that if we do not want to melt Antarctica, we can’t keep taking fossil fuel carbon out of the ground and just dumping it into the atmosphere as CO2 like we’ve been doing,” Caldeira said. “Most previous studies of Antarctic have focused on loss of the West Antarctic Ice Sheet. Our study demonstrates that burning coal, oil, and gas also risks loss of the much larger East Antarctic Ice Sheet.”
Caldeira initiated this project with lead author Ricarda Winkelmann while she was a Visiting Investigator at the Carnegie Institution for Science. Winkelmann and co-author Anders Levermann are at the Postdam Institute for Climate Impact Research; co-author Andy Ridgwell is at the University of California Riverside.
Although Antarctica has already begun to lose ice, a complex array of factors will determine the ice sheet’s future, including greenhouse gas-caused atmospheric warming, additional oceanic warming perpetuated by the atmospheric warming, and the possible counteracting effects of additional snowfall.
“It is much easier to predict that an ice cube in a warming room is going to melt eventually than it is to say precisely how quickly it will vanish,” Winkelmann said, explaining all the contributing factors for which the team’s models had to account.
The team used modeling to study the ice sheet’s evolution over the next 10,000 years, because carbon persists in the atmosphere millennia after it is released. They found that the West Antarctic ice sheet becomes unstable if carbon emissions continue at current levels for 60 to 80 years, representing only 6 to 8 percent of the 10,000 billion tons of carbon that could be released if we use all accessible fossil fuels.
“The West Antarctic ice sheet may already have tipped into a state of unstoppable ice loss, whether as a result of human activity or not. But if we want to pass on cities like Tokyo, Hong Kong, Shanghai, Calcutta, Hamburg and New York as our future heritage, we need to avoid a tipping in East Antarctica,” Levermann said.
The team found that if global warming did not exceed the 2 degree Celsius target often cited by climate policymakers, Antarctic melting would cause sea levels to rise only a few meters and remain manageable. But greater warming could reshape the East and West ice sheets irreparably, with every additional tenth of a degree increasing the risk of total and irreversible Antarctic ice loss.
This is the first study to model the effects of unrestrained fossil-fuel burning on the entirety of the Antarctic ice sheet. The study does not predict greatly increased rates of ice loss for this century, but found that average rates of sea level rise over the next 1,000 years could be about 3 centimeters per year (more than 1 inch per year) leading to about 30 m (100 feet) of sea level rise by the end of this millennium. Over several thousand years, total sea level rise from all sources could reach up to 60 meters (200 feet).
“If we don’t stop dumping our waste CO2 into the sky, land that is now home to more than a billion people will one day be underwater,” Caldeira said.
Reference:
Ricarda Winkelmann, Anders Levermann, Andy Ridgwell, and Ken Caldeira. Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet. DOI: 10.1126/sciadv.1500589
Artistic depictions of Tokarahia kauaeroa (top centre, copyright: Chris Gaskin, University of Otago Geology Museum) and Waharoa ruwhenua (bottom centre, c Credit: Robert Boessenecker) with photographs of respective fossil skulls.
University of Otago palaeontology researchers are continuing to rewrite the history of New Zealand’s ancient whales by describing two further genera and three species of fossil baleen whales.
They have named these newly described filter-feeding baleen whale species Waharoa ruwhenua, Tokarahia kauaeroa and re-identified Tokarahia lophocephalus, a poorly known species discovered in the 1950s.
All are eomysticetids—a whale family occupying an important position in the evolutionary tree of cetaceans—and Tokarahia appears to be a transitional fossil between primitive toothed baleen whales and modern baleen whales.
These filter-feeding whales lived around 25-30 million years ago when the continent of Zealandia was reduced to low islands surrounded by extensive shallow seas. Their fossils were collected from rock formations in the South Island’s Waitaki river area.
The whales join two other eomysticetid species that recent Otago Geology PhD graduate Dr Robert Boessenecker and his supervisor Professor Ewan Fordyce have previously identified.
These five whale species are the only members of the Eomysticetidae family to have been identified in the Southern Hemisphere.
The pair’s latest findings appear in separate articles in the Zoological Journal of the Linnean Society and the journal PeerJ.
Specimens of Waharoa ruwhenua excavated by Professor Fordyce and other colleagues include an adult and juveniles, allowing insights into growth and feeding adaptations.
“The skulls of these three specimens were spectacularly preserved, revealing that eomysticetids had unusually long and delicate surfboard-like snouts, with blowholes placed far forward on the skull, and enormous attachment areas for jaw muscles,” Dr Boessenecker says.
The delicate nature of the jaws and skulls indicate that they were likely not “lunge feeders” like humpback whales, but were adapted for right whale-like skim feeding— “they would have been a sort of slow-cruising vacuum cleaner for krill,” he says.
The adult size of these whales is estimated to be between five and six metres long. The researchers say that the presence of a small juvenile indicates that the continental shelf waters of Zealandia were potentially a calving ground for baleen whales.
The researchers’ discovery and description of the Tokarahia kauaeroa and Tokarahia lophocephalus whales helps to fill in an important gap in the history of the evolution of primitive toothed whales into baleen whales.
Dr Boessenecker and Professor Fordyce found that Tokarahia kauaeroa had skeletal features falling between those of primitive “archaeocete” whales and modern baleen whales.
“This makes this whale a hallmark example of a ‘transitional fossil’,” Dr Boessenecker says.
The specimen of Tokarahia lophocephalus that Professor Fordyce and colleagues excavated preserves a single isolated peg-like tooth – suggesting that although these baleen whales were filter feeders, they still retained primitive teeth that had no role in feeding.
Isotopic analysis of bones indicated that Tokarahia was undergoing north-south migration within the southern ocean, likely on a yearly basis.
Dr Boessenecker says that taken together, these three new fossils considerably add to our knowledge of the New Zealand fossil record.
“More importantly though, they fill in major gaps of knowledge—anatomy, growth, paleoecology—in whale evolution between ‘toothy’ archaeocete ancestors and toothless modern species,” he says.
Professor Fordyce added that these “dawn” baleen whales probably ranged south into the richly productive waters of the Southern Ocean, newly developed after the last remnants of the Gondwana continents broke apart.
“These early baleen whales are ‘children of climate change’ since their history is linked closely to an Antarctic cooling pulse that led to the development of modern ocean circulation,” he says.
Some of the inner workings of Earth’s subduction zones and their “megathrust” faults are revealed in a paper published in the journal Science. U.S. Geological Survey scientist Jeanne Hardebeck calculated the frictional strength of subduction zone faults worldwide, and the stresses they are under. Stresses in subduction zones are found to be low, although the smaller amount of stress can still lead to a great earthquake.
Subduction zone megathrust faults produce most of the world’s largest earthquakes. The stresses are the forces acting on the subduction zone fault system, and are the forces that drive the earthquakes. Understanding these forces will allow scientists to better model the physical processes of subduction zones, and the results of these physical models may give us more insight into earthquake hazards.
“Even a ‘weak’ fault, meaning a fault with low frictional strength, can accumulate enough stress to produce a large earthquake. It may even be easier for a weak fault to produce a large earthquake, because once an earthquake starts, there aren’t as many strongly stuck patches of the fault that could stop the rupture,” explained lead author and USGS geophysicist Hardebeck.
Although the physical properties of these faults are difficult to observe and measure directly, their frictional strength can be estimated indirectly by calculating the directions and relative magnitudes of the stresses that act on them. The frictional strength of a fault determines how much stress it can take before it slips, creating an earthquake.
Evaluating the orientations of thousands of smaller earthquakes surrounding the megathrust fault, Hardebeck calculated the orientation of stress, and from that inferred that all of the faults comprising the subduction zone system have similar strength. Together with prior evidence showing that some subduction zone faults are “weak,” this implies that all of the faults are “weak,” and that subduction zones are “low-stress” environments.
A “strong” fault has the frictional strength equivalent to an artificial fault cut in a rock sample in the laboratory. However, the stress released in earthquakes is only about one tenth of the stress that a “strong” fault should be able to withstand. A “weak” fault, in contrast, has only the strength to hold about one earthquake’s worth of stress. A large earthquake on a “weak” fault releases most of the stress, and before the next large earthquake the stress is reloaded due to motion of Earth’s tectonic plates.
Reference:
Jeanne L. Hardebeck. Stress orientations in subduction zones and the strength of subduction megathrust faults. Science, September 2015 DOI: 10.1126/science.aac5625
An aerial photo shows the edge of the Holuhraun lava flow (blue line), where the lava went over a combination of sand and bedrock. Two types of lava appear on either side of the red line: smooth pahoehoe on the right and rubbly a’a on the left.
As volcanologists at Lamont-Doherty Earth Observatory, we love everything lava. Right now, we’re exploring how the structure of the surfaces lava flows over influences how it advances. Does it matter if the lava is flowing on loose sand or solid rocks? On a road or a grassy field or into a forest?
We headed to the “Volcanologists’ Disneyland”—also known as Iceland—to find out.
Our destination was one of the largest lava flows ever recorded in human history, the recent flow at Holuhraun. Because the flow is so large, it covers areas with varying ground characteristics: old flows, solid bedrock, subglacial sand, a pebble-covered river bank, a large river, and so on, making it a good site for studying lava-substrate interaction.
We joined a large group of other scientists (17 total, about half of them graduate students) collaborating on the study of the volcanic terrain, led by Professor Christopher Hamilton of the University of Arizona. These were mostly planetary scientists from NASA, the USGS, University of Arizona, Arizona State, University of South Florida and University of Western Ontario, all interested in looking at the Holuhraun flow because of its close resemblance to lava flows on other planets, particularly Mars.
The group brought different instruments to document various aspects of the flow: A LiDAR scanner was used to scan the topography of the main vent at very high resolution (millimeters). High-accuracy mobile GPS antennas were walked along the flow margins and across the flow interior to map them in <10 cm scale. A thermal camera recorded temperatures at cracks and hot springs. And the eyes, cameras and notebooks of all members recorded geomorphological observations of the flow’s characteristics such as roughness, vesicularity and flow type (e.g., a’a/pahoehoe).
Our main tool was an unmanned aerial vehicle (UAV), also known as a drone, that carries a camera. We call it Buzz. Every day in the field, Buzz took thousands of photos of the lava flows, looking particularly at the edges of the flow. We will use the photos to construct a three-dimensional digital topography map of the flow. Photos of the areas outside the flows will help us classify the substrate that the lava was flowing over.
The Holuhraun flow is located in a remote part of the Icelandic Highlands—between the volcanoes Askja and Bardarbunga, just north of the Vatnajokull ice cap. The latest eruption started in April 2014 and lasted until February 2015. Visiting the flow so quickly after the eruption ended required special research permits—the fresh lava is highly unstable and easily collapses when stepped on. The internal parts of the flow are still very hot, as evidenced by the constant fuming of water vapor from cracks in the flow’s crust.
The Holuhraun flow is unique in that the river that occupied the valley in which the flow traveled is still flowing underneath the lava. The water is heated by the lava and emerges at the front of the flow at temperatures exceeding 120 degrees Fahrenheit (50 degrees Celsius). While some parts of the river make for incredible bathing spots, others are dangerous to cross.
We noticed that the Holuhraun flow was confined by the river banks on one side but not on the other, and that the lava bulldozed into the unconsolidated sandy river bed. This sort of bulldozing and resistance to flow is never accounted for in lava flow models and may be important where lava is flowing over layers of sand or ash from a previous eruption.
Even in August, the team dealt with strong winds, pouring rain and chilly temperatures (30s to lower 50s Fahrenheit). On occasion, the daily forecast called for rain, sun, gusty winds and fog all at the same time. The changing weather conditions made it difficult to plan for flights, yet we still managed to pilot dozens of successful flights, and covered most of the flow front and margins.
The team plans to return to Iceland next year to look at changes in the flow and the areas around it. The map we create with this year’s data will serve as a baseline to measure the changes.
These are bone fragments of Homo neladi, a new species of hominin recently discovered in South Africa by a team of scientists including Anthropologist Charles Musiba of the University of Colorado Denver. Credit: Charles Musiba
An international team of scientists, including one from the University of Colorado Denver and another from the University of Colorado Anschutz Medical Campus in Aurora, announced the discovery Thursday of a new species of hominin, a small creature with a tiny brain that opens the door to a new way of thinking about our ancient ancestors.
The discovery of 15 individuals, consisting of 1,550 bones, represents the largest fossil hominin find on the African continent.
“We found adults and children in the cave who are members of genus Homo but very different from modern humans,” said CU Denver Associate Professor of Anthropology Charles Musiba, PhD, who took part in a press conference Thursday near the discovery inside the Rising Star Cave in the Cradle of Humankind World Heritage Site outside Johannesburg, South Africa. “They are very petite and have the brain size of chimpanzees. The only thing similar we know of are the so-called `hobbits’ of Flores Island in Indonesia.”
Homofloresiensis or Flores Man was discovered in 2003. Like this latest finding, it stood 3.5 five feet high and seems to have existed relatively recently though the exact age is unknown.
Caley Orr, PhD, an assistant professor of cell and developmental biology at the University of Colorado School of Medicine, analyzed the fossil hands.
“The hand has human-like features for manipulation of objects and curved fingers that are well adapted for climbing,” Orr said. “But its exact position on our family tree is still unknown.”
The new species has been dubbed Homonaledi after the cave where it was found — naledi means `star’ in the local South African language Sesotho.
One of the most intriguing aspects of the discovery is that the bodies appear to have been deposited in the cave intentionally. Scientists have long believed this sort of ritualized or repeated behavior was limited to humans.
The team of 35 to 40 scientists was led by Lee Berger, research professor in the Evolutionary Studies Institute at the University of Witwatersrand in South Africa. It was supported by the National Geographic Society and the National Research Foundation. The October issue of National Geographic magazine will feature the discovery as its cover story. It will also be the subject of a NOVA/National Geographic Special airing Sept. 16.
Getting inside the Dinaledi chamber of the remote cave system was difficult, requiring the help of six `underground astronauts,’ who squeezed through a 7-inch wide gap to reach the remains.
“The chamber has not given up all of its secrets,” said Berger, a National Geographic Explorer-in-Residence. “There are potentially hundreds if not thousands of remains of H. naledi still down there.”
The announcement coincides with the publication of two studies about the new species in the journal eLife, co-authored by Musiba and Orr.
In it, the researchers try to place Homonaledi in context with other species. Generally speaking, they say, there is an assumption that any new group of fossils must belong to an existing species.
But it’s not that simple here.
“Assigning these remains to any known species of Homo is problematic,” the study said. “While Homo(naledi) shares aspects of cranial and mandibular morphology with Homohabilis, Homorudolfensis, Homoerectus, MP Homo and Homosapiens, it differs from all of these taxa in its unique combination of derived cranial vault, maxillary, and mandibular morphology.”
The study suggests that Homonaledi most closely resembles Homoerectus with its small brain and body size. Yet it also resembles Australopithecus which highlights its own uniqueness.
Complicating matters is the fact that researchers still don’t know the exact age of the fossil site.
“If these fossils are late Pliocene or early Pleistocene, it is possible that this new species of small-brained, early Homorepresents an intermediate between Australopithecus and Homoerectus,” the study said.
That would also make the new species very old.
But if the fossils are more recent, they theorize, it raises the possibility that a small-brained Homolived in southern Africa at the same time as larger brained Homospecies were evolving.
“This raises many questions,” Musiba said. “How many species of human were there? Were their lines that simply extended outward and then disappeared? Did they co-exist with modern humans? Did they interbreed?”
Homonaledi has a chest similar to a chimpanzee and hands and feet proportionate with modern humans, though with curved fingers.
“They would have had great climbing ability,” said Musiba. “The oldest adults were about 45 and the youngest were infants.”
He described poring over the bones late at night as akin to `hitting the jackpot.’
“You just didn’t want to go home because it was so exciting,” he said. “I felt like a kid in a candy store.” The find represents another milestone in Musiba’s efforts to advance the understanding of our earliest human relatives.
As director of CU Denver’s Tanzania Field School, he takes groups of students each year to gain hands-on experience working in and around the famed Laetoli hominin footprints site and Olduvai Gorge where some of the oldest hominin remains have been found.
Not long ago, they discovered ancient footprints of lions, rhinos and antelopes near those of the early hominins.
And last year, Musiba was appointed to an international team of advisors dedicated to building a museum complex in Tanzania to showcase a collection of 70 hominin footprints, estimated at 3.6 million years old. They are considered the earliest example of bipedalism among hominins.
Musiba said the Rising Star expedition was notable for getting so many anthropologists to work together.
“Anthropology can be a cut-throat profession with all these scientists scrambling for limited resources,” he said. “To me one of the most exciting aspects of this research was the collaborative nature of it.”
Reference:
Paul HGM Dirks, Lee R Berger, Eric M Roberts, Jan D Kramers, John Hawks, Patrick S Randolph-Quinney, Marina Elliott, Charles M Musiba, Steven E Churchill, Darryl J de Ruiter, Peter Schmid, Lucinda R Backwell, Georgy A Belyanin, Pedro Boshoff, K Lindsay Hunter, Elen M Feuerriegel, Alia Gurtov, James du G Harrison, Rick Hunter, Ashley Kruger, Hannah Morris, Tebogo V Makhubela, Becca Peixotto, Steven Tucker. Geological and taphonomic context for the new hominin speciesHomo naledifrom the Dinaledi Chamber, South Africa. eLife, 2015; 4 DOI: 10.7554/eLife.09561
Microbes in Kabuno Bay metabolize iron and grow at rates high enough to indicate their ancient equivalents deposited some of the world’s largest sedimentary iron ore deposits. Credit: University of British Columbia
An isolated, iron-rich bay in the heart of East Africa is offering scientists a rare glimpse back into Earth’s primitive marine environment, and supports theories that tiny microbes created some of the world’s largest ore deposits billions of years ago.
According to University of British Columbia (UBC) research published this week in Scientific Reports, 30 per cent of the microbes in the Democratic Republic of the Congo’s Kabuno Bay grow by a type of photosynthesis that oxidizes (rusts) iron rather than converting water into oxygen like plants and algae.
“Kabuno Bay is a time machine back to Earth’s early history when iron-rich ocean chemistry prevailed,” said Marc Llirós of the University of Namur, first author of the paper.
“The bay is giving us real-world insight into how ancient varieties of photosynthesis may have supported Earth’s early life prior to the evolution of the oxygen producing photosynthesis that supports life today,” said UBC geomicrobiologist Sean Crowe, senior author of the study.
While iron-respiring bacteria were discovered in 1993, the new Scientific Reports study provides evidence that microorganisms could have been directly involved in depositing Earth’s oldest iron formations.
Before 2.3 billion years ago, there was little oxygen in the atmosphere but plenty of dissolved iron and many organisms like bacteria derived energy by metabolizing the metal. Many researchers believe iron-metabolizing microbes might have turned plentiful dissolved iron into minerals, which then settled out of seawater and deposited along the ocean floor.
The UBC study of the Kabuno Bay iron microbes supports that theory. The microbes metabolize iron and grow at rates high enough to indicate their ancient equivalents were capable of depositing some of the world’s largest sedimentary iron ore deposits, known as banded iron formations.
By oxidizing iron, these microorganisms likely helped shape the chemistry of Earth over billions of years, ultimately leading to the evolution of more complex life such as plants and animals.
Reference:
Marc Llirós, Tamara García–Armisen, François Darchambeau, Cédric Morana, Xavier Triadó–Margarit, Özgül Inceoğlu, Carles M. Borrego, Steven Bouillon, Pierre Servais, Alberto V. Borges, Jean–Pierre Descy, Don E. Canfield, Sean A. Crowe. Pelagic photoferrotrophy and iron cycling in a modern ferruginous basin. Scientific Reports, 2015; 5: 13803 DOI: 10.1038/srep13803
Mono-corer with the small section of core retrieved. Note the small weights to help penetrate the sediment, much less weight than is used on the Hudson River core pictured above. Credit: Bill Schmoker
Sediment coring the bottom of the world’s oceans is something that Lamont knows a lot about. Since 1947 Lamont has been actively collecting and archiving sediment from around the world. Currently our Core Repository contains sediment cores from every major ocean and sea in the world, some 18,700 cores! This is in large part due to Lamont’s first director, Maurice Ewing, who instilled a philosophy of “A core a day” for all ocean research vessels. Ewing firmly believing that if we had the sediment we would be able to piece together patterns and stories about our planet, so every day at noon, or thereabouts, the ship would collect a core.
Scientists from around the world have requested slivers of mud from the cores in the repository to unlock Earth’s mysteries and secrets. The cores in Lamont’s Core Repository are ‘no stranger’ to revealing stories of Earth systems, including those of climate cycles. Almost 40 years have passed since the groundbreaking work of the CLIMAP group that used the cores to connect the start of Earth’s glacial cycles to changes in eccentricity, precession and tilt. (Hayes, Imbrie and Shackleton, 1976) . Collecting sediment on this Arctic GEOTRACES cruise will help us understand more of the stories locked in the oceans.
The length of a core is dictated by the goal of the collection. Early Lamont cores were more about collecting just to gather the material because the ship was there. These early core were generally 6 to 9 meters long, although one incredibly long 28.2m core was collected from the Central Pacific! Locally cores have been collected on the Hudson River and local marshes that are closer to 1 or 2 meters in length.
For the sampling GEOTRACES is doing in the Arctic there is a specific goal of collecting just the top few dozen centimeters of sediment and the water just above it, yet at a depth of ~2200 meters. This will require a much different technique than what was used for the Central Pacific core!
The sediment in this region is soft, so the plan was to drop a small general-purpose device called a Mono-corer over the side of the ship with a few small weights on top to help drive the core tube in straight. The corer would hang below the bottom of the rosette of water samplers, far enough below that the rosette would remain ‘mud-free’ but still able to collect near bottom water samples. The mud in the mono-corer would be held in place by a spring-loaded door that snapped closed once the mud was inside and the tube began its return trip to the ship. All sounded good.
Although the plan was good, things don’t always go perfectly. Making sure the corer actually penetrated the sediment without tipping over or over-penetrating and compressing the top sediments proved challenging, as did ensuring the sample made it back to the ship intact. After several attempts a special ‘cone-of-silence’ (any Get Smart fans out there?) was rigged up by the two Lamonters, Tim and Marty Fleischer, to avoid interference with the communications that were connecting with the rosette altimeter, controlling the lowering of the device. The cone was installed and the speed of the core lowering was slowed. Success! ‘Houston we have mud!’
Note: The above post is reprinted from materials provided by Columbia University.
A map of seismic activity in the UK shows a dense cluster in Nottinghamshire Credit: British Geological Survey
Seismic activity across the UK has been analysed for the first time to set a national baseline for earthquakes caused by human activity ahead of any future decisions around fracking.
The study – published today in the academic journal Marine and Petroleum Geology – reveals that since 1999, an average of at least three onshore earthquakes a year with local magnitude greater than or equal to 1.5 were as a result of anthropogenic activity.
The research was carried out by ReFINE (Researching Fracking in Europe), an independent research consortium focusing on the issue of shale gas and oil exploitation using fracking methods.
Research lead Professor Richard Davies, of Newcastle University, said: “Earthquakes triggered or induced by humans are not a new concept for us here in the UK, but earthquakes related to fracking are.
“Understanding what the current situation is and setting a national baseline is imperative, otherwise how can we say with any confidence in the future what the impact of fracking has been nationwide?
“What this research shows is that in recent years, an average of at least three earthquakes a year, with local magnitudes greater than or equal to 1.5, are as a result of human activity. If widespread exploitation of the UK’s shale reservoirs is granted and numbers consistently rise then, in conjunction with local monitoring data, we should be able to confidently demonstrate a causal link.”
About the study:
The first human-induced earthquake in the UK probably occurred in 1755 due to the collapse of lead mines in Derbyshire. Data collected by the British Geological Survey between 1970 and 2012 shows there have been approximately 8,000 onshore recorded seismic events in the UK with a range of origins including mining, deep geothermal energy, industrial explosions, meteorological phenomena such as lightning strikes and natural causes.
Analysing the 1,769 seismic events over a forty year period that were above or equal to 1.5 in local magnitude – the minimum detectable threshold – the team of experts from Newcastle, Durham and Keele universities showed that at least 21% were related to human activity, at least 40% were naturally-occurring and 39% were ‘undefined’. “We have been careful only to include earthquakes where there has been a strongly indicated link to human activity,” explains Professor Davies. “Using historic data means that isn’t always possible so some man-made events remain undefined.”
The data shows a sharp decline in the number of earthquakes from the 1980s, mirroring the demise of the UK coal industry. From 1999 onwards, there has been an average of at least three earthquakes a year related to human activity, with an annual range between zero and eight.
Taking into account the undefined earthquakes, the author’s average would still be just 12, providing a useful baseline prior to any future widespread use of fracking for the exploitation of the UK’s shale reservoirs.
The link between coal mining and man-made seismicity has been known for the last 150 years and became particularly apparent when the British Geological Survey launched its National Seismic Monitoring system in the late 1960s.
This latest research suggests that by the mid-1980s, a third of all detected seismic events in the UK were coal mining related, with the majority occurring in Derbyshire, Nottinghamshire, Staffordshire and Yorkshire coalfields. The number of coal mining related earthquakes drops by more than 95% from 1991, correlating to the closure of the UK’s deep mines.
The first UK exploratory fracking operation at Preese Hall, Lancashire, in 2011 resulted in a 2.3 magnitude earthquake. Two months later, a second earthquake of 1.5 magnitude was recorded and operations were suspended.
“Historically, fracking-related earthquakes have been small but the UK is criss-crossed by faults – some of which may be critically stressed – and if triggered these could result in earthquakes that people can feel,” explains Professor Davies.
“Worldwide, the biggest published example of a fracking earthquake to date is 4.4 in magnitude, recorded in Canada last year, although an event of this size in the UK is highly unlikely.
“We are the first country in the world to analyse historical earthquakes to establish a baseline. Our research provides the UK with its first pre-fracking national baseline against which, allied to other data sets, we will be able to make informed decisions about shale exploitation and the impact it has, or hasn’t had, in the future.”
Reference:
“Anthropogenic earthquakes in the UK: a national baseline prior to shale exploitation.” Miles P Wilson, Richard J Davies, Gillian R Foulger, Bruce R Julian, Peter Styles, Jon G Gluyas and Sam Almond. Marine and Petroleum Geology. September 9, 2015.
Plate tectonic velocity for North America Credit: M. Kaban, GFZ
In the course of billions of years continents break up, drift apart, and are pushed back together again. The cores of continents are, however, geologically extremely stable and have survived up to 3.8 billions of years. These cores that are called cratons are the oldest known geological features of our planet. It was assumed that the cratons are stable because of their especially solid structure due to relatively low temperatures compared to the surrounding mantle.
A team of German-American scientists now discovered that these cratons that were assumed to be “as solid as a rock” are not that solid after all. The team leading by Dr. Mikhail Kaban from the GFZ German Research Centre for Geosciences now discovered that the craton below the North American continent is extremely deformed: its root is shifted relative to the center of the craton by 850 kilometers towards the west-southwest.
This fact is in contrast to the prevailing assumptions that these continental roots did not undergo substantial changes after their formation 2.5 to 3.8 billion years ago. The study that appears in the latest online publication of Nature Geoscience contradicts this traditional view. “We combined and analyzed several data sets from Earth’s gravity field, topography, seismology, and crustal structure and constructed a three dimensional density model of the composition of the lithosphere below North America,” explains GFZ scientist Mikhail Kaban. “It became apparent that the lower part of the cratonic root was shifted by about 850 kilometers.”
What caused the deformation of the stable and solid craton? A model of the flows in Earth’s mantle below North America, developed by the scientists, reveals that the mantle material below 200 kilometers flows westward at a velocity of about 4 millimeters per year. This is in concordance with the movement of the tectonic plate. Due to the basal drag of this flow the lower part of the cratonic lithosphere is shifted. “This indicates that the craton is not as solid and as insensitive to the mantle flow as was previously assumed,” Kaban completes. There is far more mechanical, chemical, and thermal interaction between the craton of billions of years in age and its surrounding in the upper mantle of Earth than previously thought.
Reference:
Mikhail K. Kaban, Walter D. Mooney, Alexey G. Petrunin. Cratonic root beneath North America shifted by basal drag from the convecting mantle. Nature Geoscience, 2015; DOI: 10.1038/NGEO2525
Brain endocast of the duck-billed dinosaur Arenysaurus, originally described in a preprint prior to formal publication. Despite this, the paleontological community did not collapse in upon itself. Credit: Cruzado-Caballero et al., 2015
The topic of preprints for paleontologists has gotten a nice flurry of discussion this week, thanks to a blog post by Liz Martin-Silverstone. Preprints, for those who are not familiar, are non-final and unpublished versions of a manuscript made available online prior to formal publication. The reasons to do so are many, including solicitation of comments from interested parties, establishing priority on a particular discovery, or providing a citeable unit for one’s colleagues. Of course, there are also some concerns, such as the wisdom of circulating potentially unreviewed materials, changes between manuscript submission and publication, possibility of ‘claim jumping’ (both by and against preprint authors), and more. All of these are discussed by Liz and the comment thread at her blog post, but something struck me during this discussion.
Namely, we’ve had the discussion before, concerning conferences, conference presentations, conference abstracts, and citation/discussion of these abstracts. Within paleontology, it is not uncommon to read and cite relevant conference abstracts if a more formal paper has not yet followed or will not follow. There is some debate about whether or not this is a good thing, but in my view it can be a helpful way to credit work when other types of citation are not possible. That’s not dissimilar from the situation for preprints.
So, I wanted to expand upon one particular thought I had:
Is posting a preprint substantively different from giving a conference presentation or publishing a conference abstract?
I would argue that no, it is not, in most respects. Let’s look at various concerns about preprints, to see how they compare with conference presentations and abstracts. (this list is quoted and paraphrased from Liz’s original post, so I will be brief)
Concerns About Preprints (Compared to Concerns About Conference Presentations and Abstracts)
Preprints: “Someone could steal my work.”
Yep, applies to conferences, too. Or any other time someone muses anything out loud or online.
Preprints: “But what about all the mistakes?”
Yep, applies to conference presentations and abstracts, too.
Preprints: “Why would a journal publish something already online?”
Reputable journals are generally OK with presenting something at a conference, with which there is an associated abstract. Preprints really shouldn’t be much different.
Preprints: “Why not just wait for the final paper instead of an unformatted manuscript?”
Let’s rephrase that: “Why not just wait for the final paper instead of presenting at a conference?” The way these questions are at odds with scientific discourse should be apparent.
Preprints: “[Work] in preprints is not peer-reviewed, or edited, and some people have concerns that any incorrect information will be propagated.”
Conference presentations and abstracts are unreviewed also, except at the most basic levels.
Preprints: “But how do I know what happened to the preprint afterwards?”
Conference abstract volumes are scattered with the bones of unfinished or unpublished projects. And in cases where something was eventually published, it is actually pretty easy to draw a link between the conference title, abstract, and the final paper. I have faith that my fellow scientists can do the same.
In other words, I see few essential differences between conference abstracts/presentations and preprints for unpublished papers. Both have their issues, but both also have (potential, and considerable) advantages. I worry that we are so concerned about possible (but rare) worst-case scenarios that little change happens within the profession.
Considering our field’s long history of conferences and conference abstract volumes touting unpublished work, are preprints really that radical of a step?
Scientists at the Senckenberg Research Institute in Frankfurt have described the world’s oldest fossil sea turtle known to date. The fossilized reptile is at least 120 million years old – which makes it about 25 million years older than the previously known oldest specimen. The almost completely preserved skeleton from the Cretaceous, with a length of nearly 2 meters, shows all of the characteristic traits of modern marine turtles. The study was published today in the scientific journal PaleoBios.
“Santanachelys gaffneyi is the oldest known sea turtle” – this sentence from the online encyclopedia Wikipedia is no longer up to date. “We described a fossil sea turtle from Colombia that is about 25 million years older,” rejoices Dr. Edwin Cadena, a scholar of the Alexander von Humboldt foundation at the Senckenberg Research Institute. Cadena made the unusual discovery together with his colleague from the US, J. Parham of California State University, Fullerton.
“The turtle described by us as Desmatochelys padillai sp. originates from Cretaceous sediments and is at least 120 million years old,” says Cadena. Sea turtles descended from terrestrial and freshwater turtles that arose approximately 230 million years ago. During the Cretaceous period, they split into land and sea dwellers. Fossil evidence from this time period is very sparse, however, and the exact time of the split is difficult to verify. “This lends a special importance to every fossil discovery that can contribute to clarifying the phylogeny of the sea turtles,” explains the turtle expert from Columbia.
The fossilized turtle shells and bones come from two sites near the community of Villa de Leyva in Colombia. The fossilized remains of the ancient reptiles were discovered and collected by hobby paleontologist Mary Luz Parra and her brothers Juan and Freddy Parra in the year 2007. Since then, they have been stored in the collections of the “Centro de Investigaciones Paleontológicas” in Villa Leyva and the “University of California Museum of Paleontology.”
Cadena and his colleague examined the almost complete skeleton, four additional skulls and two partially preserved shells, and they placed the fossils in the turtle group Chelonioidea, based on various morphological characteristics. Turtles in this group dwell in tropical and subtropical oceans; among their representatives are the modern Hawksbill Turtle and the Green Sea Turtle of turtle soup fame.
“Based on the animals’ morphology and the sediments they were found in, we are certain that we are indeed dealing with the oldest known fossil sea turtle,” adds Cadena in summary.
This aerial view shows the marine-terraced coastline of California north of Santa Cruz. Credit: Ramon Arrowsmith via Wikimedia Commons
For millions of years, the Pacific and North American plates have been sliding past — and crashing into — one another. This ongoing conflict creates uplift, the geological phenomenon that formed mountains along the west coast.
A new analysis by UC Santa Barbara earth scientist Alex Simms demonstrates that the Pacific coastlines of North America are not uplifting as rapidly as previously thought. The results appear in the journal Geological Society of America Bulletin.
“Current models overestimate uplift rates by an average of 40 percent,” said Simms, an associate professor in UCSB’s Department of Earth Science. “They do not take into account glacio-isostatic adjustment, the Earth’s response to the melting and growth of past ice sheets. Previous studies of the Pacific coast, including California, have ignored this when trying to use past sea levels to calculate uplift rates.”
Uplift is the vertical elevation of the Earth’s surface in response to plate tectonics.
Scientists determine uplift rates by measuring marine terraces — flat mesas that indicate where the ocean level used to be — and comparing their elevations to geologic records of sea-level change. However, traditionally used “global” sea-level records come from places like the Huon Peninsula of Papua New Guinea, far away from the ice sheets that once covered Canada. That’s a problem because the freezing of water into ice sheets and its subsequent thawing actually changed the shape of the Earth ever so slightly — and this deformation affects ocean levels.
According to Simms, the land responds the way a mattress does, indenting from weight and then relaxing back to its original shape. The Earth’s gravitation field also changes in response to the building up and melting of these ice sheets. These changes to the land and Earth’s gravity cause past sea levels to vary across the world. Most of this glacio-isostatic adjustment is not caused by current glacier melt but by the rebound of the Earth from the several-kilometer-thick ice sheets that covered much of Canada 20,000 years ago.
Simms and his colleagues compiled existing elevation measurement data from more than two dozen sites ranging from mid-Oregon to Baja California. They then recalculated uplift rates for each, applying a correction for glacio-isostatic adjustment.
Some areas are affected to a greater degree than others. The uplift rate for Punta Cabras in Baja California showed the largest difference: 72 percent lower than previous estimates. The rate for the San Diego area was reduced by 62 percent. For other areas, the rate changes were not as dramatic.
“Areas in Oregon are moving so fast that when you add the correction, the adjustment is much smaller: 10 to 20 percent,” Simms said. “If a site is going up 100 meters versus 90 meters, that’s not a big change. Here, sea level changed differently because of the distance from where these big ice sheets used to be.”
This study provides one of the first spatially corrected sea-level records for California. “A 2012 study looked at one spot with one model, but we looked at variation across the state,” Simms explained. “Now our data can be applied not only in California but along the Pacific coast of North America.”
Professor Tim Beach and Professor Sheryl Luzzader-Beach in the tropical lowlands of Central America. Credit: Image provided by Tim Beach, Department of Geography and the Environment
Evidence from the tropical lowlands of Central America reveals how Maya activity more than 2,000 years ago not only contributed to the decline of their environment but continues to influence today’s environmental conditions, according to researchers at The University of Texas at Austin.
Synthesizing old and new data, researchers were the first to show the full extent of the “Mayacene” as a microcosm of the early anthropocene — a period when human activity began greatly affecting environmental conditions.
“Most popular sources talk about the anthropocene and human impacts on climate since the industrial revolution, but we are looking at a deeper history,” said lead author Tim Beach, the C.B. Smith Sr. Centennial Professor of Geography and the Environment. “Though it has no doubt accelerated in the last century, humans’ impact on the environment has been going on a lot longer.”
By looking at Maya impacts on climate, vegetation, hydrology and lithosphere from 3,000 to 1,000 years ago, researchers propose that the Maya’s advanced urban and rural infrastructure altered ecosystems within globally important tropical forests.
The researchers identified six stratigraphic markers — or “golden spikes” — that indicate a time of large-scale change, including: “Maya clay” rocks; unique soil sequences; carbon isotope ratios; widespread chemical enrichment; building remains and landscape modifications; and signs of Maya-induced climate change.
“These spikes give us insight into how and why Mayas interacted with their environment, as well as the scope of their activity,” said Sheryl Luzzadder-Beach, co-author and chair of the Department of Geography and the Environment.
Maya clay and soil sequences indicated erosion, human land-use changes and periods of instability. Soil profiles near wetlands revealed heightened carbon isotope ratios due to agriculture and corn production; and researchers noted a three- to fourfold increase in phosphorus throughout Maya-age sediments.
However, the most visual indication of human impact was found in building material remains and landscape modifications. Researchers believe that these clues reveal how the Maya used water management to adapt to climate change.
“In studying the wetland systems, we were surprised to find a combination of human and natural contributions,” Luzzadder-Beach said. “Geochemical changes indicated that some wetlands were natural, while others were built landscapes used to grow crops away from the large population.”
The changes are both good and bad, researchers said.
“Historically, it’s common for people to talk about the bad that happened with past environmental changes, such as erosion and climate change from deforestation,” Beach said. “But we can learn a lot from how Maya altered their environment to create vast field systems to grow more crops and respond to rising sea levels.”
While some studies suggest that deforestation and other land use contributed to warming and drying of the regional climate by the Classic Period (1700-1100 years ago), many existing forests are still influenced by Maya activities, with many structures, terraces and wetlands still existing today, researchers said.
“This work speaks to the deep history and complexity of human interactions with nature, and in a part of the world where we still have little knowledge about the natural environment,” Beach said.
Reference:
Tim Beach, Sheryl Luzzadder-Beach, Duncan Cook, Nicholas Dunning, Douglas J. Kennett, Samantha Krause, Richard Terry, Debora Trein, Fred Valdez. Ancient Maya impacts on the Earth’s surface: An Early Anthropocene analog? Quaternary Science Reviews, 2015; 124: 1 DOI: 10.1016/j.quascirev.2015.05.028
It’s not a huge mystery why Los Angeles experiences earthquakes. The city sits near a boundary between two tectonic plates — they shift, we shake. But what about places that aren’t along tectonic plate boundaries?
For example, seismicity on the North American plate occurs as far afield as southern Missouri, where earthquakes between 1811 and 1812 estimated at around magnitude 7 caused the Mississippi River to flow backward for hours.
Until now, the cause of that seismicity has remained unclear.
While earthquakes along tectonic plate boundaries are caused by motion between the plates, earthquakes away from fault lines are primarily driven by motion beneath the plates, according to a new study published by USC scientist Thorsten Becker in Nature on Aug. 27.
Just beneath the Earth’s crust is a layer of hot, semi-liquid rock that is continually flowing — heating up and rising, then cooling and sinking. That convective process, interacting with the ever-changing motion of the plates at the surface, is driving intraplate seismicity and determining in large part where those earthquakes occur. To a lesser extent, the structure of the crust above also influences the location, according to their models.
“This will not be the last word on the origin of strange earthquakes. However, our work shows how imaging advances in seismology can be combined with mantle flow modeling to probe the links between seismicity and mantle convection,” said Becker, lead author of the study and professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences.
Becker and his team used an updated mantle flow model to study the motion beneath the mountain belt that cuts north to south through the interior of the Western United States.
The area is seismically active — the reason Yellowstone has geysers is that it sits atop a volcanic hotspot. Previously, scientists had suggested that the varying density of the plates was the main cause. (Imagine a mountain’s own weight causing it to want to flow apart and thin out.)
Instead, the team found that the small-scale convective currents beneath the plate correlated with seismic events above in a predictable way. They also tried using the varying plate density or “gravitational potential energy variations” to predict seismic events and found a much poorer correlation.
“This study shows a direct link between deep convection and shallow earthquakes that we didn’t anticipate, and it charts a course for improved seismic hazard mapping in plate interiors,” said Tony Lowry, co-author of the paper and associate professor of geophysics and geodynamics at Utah State University.
Reference:
Thorsten W. Becker, Anthony R. Lowry, Claudio Faccenna, Brandon Schmandt, Adrian Borsa & Chunquan Yu. Western US intermountain seismicity caused by changes in upper mantle flow. DOI:10.1038/nature14867
Kīlauea’s summit vent within Halema‘uma‘u Crater was more than 500 feet across in March 2013, five years after it opened. Credit: Tim Orr/U.S. Geological Survey
In 1980, Mount St. Helens erupted in Washington State, killing 57 people and destroying hundreds of homes. The area around the mountain became a wasteland: Roadways were swallowed and bridges damaged. Ash fell over 11 states.
Today, volcanoes rarely make the news in the United States, even though the western half of the country is dotted with volcanic systems that could unleash eruptions many times more powerful than the Mount St. Helens disaster.
“In contrast to events like hurricanes or earthquakes, volcanic unrest can last for long periods of time, and that’s one reason people stop paying attention to the hazards that are looming,” said volcanologist Greg Valentine, PhD, a University at Buffalo professor of geology and director of the Center for GeoHazards Studies in the UB College of Arts and Sciences.
To combat complacency and improve preparedness of communities near U.S. volcanoes, Valentine is heading a new research project that focuses on two locations: Kīlauea in the Hawaiian Islands, and the Long Valley caldera and volcanic field in eastern central California.
Kīlauea has been erupting continuously for more than 30 years and Long Valley — a “supervolcano” with a 20-mile-long caldera and huge explosive potential — has experienced unrest over the same period, with swarms of earthquakes rattling the area and volcanic gas rising up through the soil.
Valentine’s research, funded by a $2.9 million National Science Foundation grant, engages an interdisciplinary team to enhance disaster preparedness at both sites.
His team will advance scientific understanding of the volcanoes, studying Kīlauea’s subterranean plumbing and Long Valley’s eruptive history with the goal of refining forecasts that predict when an eruption may occur and where hazards, such as lava flows, hot gas and falling ash, could strike during such an event.
The project also will examine disaster preparedness, bringing in social scientists to assess how well communities around Kīlauea and Long Valley are prepared today and to identify better ways of communicating information on possible hazards to the public. Such steps are crucial given the danger the volcanoes pose.
Kīlauea’s ongoing eruption already has destroyed more than 200 structures, displaced families and threatened to cut off access to important roads.
The Long Valley system has the potential to release hundreds of cubic kilometers of ash in a single eruption. (For comparison, the Mount St. Helens disaster discharged about 1 cubic kilometer.)
“In some ways, the two locations we are studying are very different, but what they have in common is that they are experiencing prolonged periods of unrest,” Valentine said. “The extended period of activity can lead to complacency, where nothing dramatic is happening and stakeholders around a volcano lose sight of the real danger.
“We are engaging an interdisciplinary team to figure out how to improve resilience and preparedness in these situations where the risks are ongoing and the exact nature of the hazards that people are facing is uncertain.”
The research brings together geoscientists, engineers, statisticians and social scientists from UB, the University of Hawaii, Duke University, the University of Washington, the University of California, Berkeley, and Marquette University. The U.S. Geological Survey and Federal Emergency Management Agency also will be involved.
Note: The above post is reprinted from materials provided by University at Buffalo. The original item was written by Charlotte Hsu.
