Speleotherms from Soreq Cave. Credit: Eelco Rohling
An international team of scientists has found a dramatic ice sheet collapse at the end of the ice age before last caused widespread climate changes and led to a peak in the sea level well above its present height.
The team found the events 135,000 years ago caused the planet to warm in a different way to the end of the most recent ice age about 20,000 to 10,000 years ago.
The findings will help scientists understand the processes that control Earth’s dramatic climate changes, said the leader of the study, Dr Gianluca Marino of the Research School of Earth Sciences.
“We knew the sea level had overshot its present levels during the last interglacial period, but did not know why. Now we for the first time can explain the processes that caused the sea levels to exceed the present levels,” said Dr Marino.
“Ice-age cycles may superficially look similar to one another, but there are important differences in the relationships between melting of continental ice sheets and global climate changes.”
The team, which includes researchers from ANU as well as the Universities of Southampton and Swansea in the UK, has published their findings in Nature.
At the end of an ice age the continental ice sheets, ocean, and atmosphere change rapidly. Scientists have previously only been able to reconstruct in detail the changes at the end of the last ice age.
“We have compared the fluctuations at the end of an earlier ice age, and we found that the patterns were different,” said co-author Professor Eelco Rohling, from both ANU and the University of Southampton.
“At the end of the older ice age, 135,000 years ago, we found that a dramatic collapse of the Northern Hemisphere ice sheets into the North Atlantic Ocean suppressed the ocean circulation and caused cooling in the North Atlantic.”
“North Atlantic cooling was counterbalanced by Southern Ocean warming that then destabilised Antarctic land ice, causing a continuation of melting that eventually drove sea level rise to several meters above the present,” he said.
This is very different from the end of the last ice age, said Dr Marino.
“The northern hemisphere ice-sheet collapse and climate change did not occur at the same time, and that caused much less warming in Antarctica,” he said.
The team used precisely-dated cave records and marine sediments from the Mediterranean region to reconstruct the sequence of changes in all critical climate parameters.
Reference:
Bipolar seesaw control on last interglacial sea level, Nature, DOI: 10.1038/nature14499
This is a schematic of the influence of oxygen concentrations on global climate. Credit: Chris Poulsen, University of Michigan
Variations in the amount of oxygen in Earth’s atmosphere significantly altered global climate throughout the planet’s history. Efforts to reconstruct past climates must include this previously overlooked factor, a new University of Michigan-led study concludes.
Oxygen currently comprises about 21 percent of Earth’s atmosphere by volume but has varied between 10 percent and 35 percent over the past 541 million years.
In periods when oxygen levels declined, the resulting drop in atmospheric density led to increased surface evaporation, which in turn led to precipitation increases and warmer temperatures, according to University of Michigan paleoclimatologist Christopher Poulsen.
“The connection between oxygen levels and climate has never been considered. It turns out that it’s an important factor over geological timescales,” said Poulsen, a professor in the Department of Earth and Environmental Sciences. While not as critical to climate as levels of heat-trapping carbon dioxide gas, oxygen plays a key role, he said.
“Oxygen concentration can help explain features in the paleoclimate record not accounted for by variations in carbon dioxide levels, and it must considered if we are to fully understand past climates,” Poulsen said. “However, variations in oxygen levels are not an important factor in present-day climate change.”
The study is scheduled for online publication in the journal Science on June 11.
Throughout Earth’s history, oxygen levels repeatedly rose and fell. Removing oxygen molecules thins the atmosphere, increasing the likelihood that incoming sunlight will make it to the surface without getting scattered away.
More sunlight means more evaporation from the surface, which leads to higher humidity levels and increased precipitation. As humidity levels rise, temperatures also increase because water vapor is a potent heat-trapping “greenhouse” gas.
Adding oxygen molecules has the opposite effect: a thicker atmosphere, more scattering of incoming sunlight, reduced surface evaporation, and less heat trapped by water vapor.
In their Science paper, Poulsen and two colleagues quantify the effect of changing oxygen levels on climate using an atmospheric global climate model to account for changes in atmospheric density, mass and molecular weights.
The team’s computer simulations focused on the mid-Cretaceous, a period characterized by high atmospheric carbon dioxide levels and the warmest conditions of the last 100 million years. Specifically, they focused on Cenomanian Age, from 100.5 million years ago to 93.9 million years ago.
They developed a series of simulations in which oxygen levels varied from a low of 5 percent to a high of 35 percent. They found that decreased oxygen levels led to substantial increases in global precipitation rates and temperature.
Changing oxygen concentrations could help explain features of the paleoclimate record not accounted for by variations in carbon dioxide levels, such as warm polar temperatures and unexpectedly high precipitation rates in some periods, the researchers conclude.
Though previously unappreciated for its influence on climate, changing atmospheric oxygen levels have long been recognized for shaping the course of life on Earth. Billions of years ago, for example, photosynthesizing cyanobacteria in the oceans released massive amounts of oxygen that eventually made it possible for animals to colonize the land.
Reference:
Christopher J. Poulsen, Clay Tabor, Joseph D. White. Long-term climate forcing by atmospheric oxygen concentrations. Science, 2015 DOI: 10.1126/science.1260670
Did dinosaurs roam the Grand Canyon? Well, the answer depends on whom you talk to. And how old they believe the majestic canyon to be.
Although it might be fun to imagine scientists and researchers arguing about whether giant reptiles were hanging around Arizona’s most famous landmark 65 million years ago, this isn’t a debate about dinosaur territories. It’s a question of when the deep walls of the Grand Canyon were eroded by the snaking Colorado River.
Recently two different groups published papers that suggested the Grand Canyon started forming more than 6 million years ago. One group said the canyon had eroded to nearly its current form by 70 million years ago, and another said it started eroding 17 million years ago. These papers have caused several groups to take a closer look at both old and new data sets – including researchers from Arizona State University.
“We are confident the western canyon is younger than 6 million years and is certainly younger than 18 million years,” said Andrew Darling, a graduate student in ASU’s School of Earth and Space Exploration. The research is published online June 10 in the journal Geosphere.
The problem with the assertion is that studying the age of the Grand Canyon isn’t easy.
Measuring time can be tricky when everything you’re studying is eroding away. And the whole region has been eroding for a long time, so not much is left of the landscape that was there when the Grand Canyon started forming. Yet, most people think the Grand Canyon is young – around 6 million years old based on what is preserved.
While many different detective methods exist to gauge the canyon’s age, Darling and his adviser, Kelin Whipple, a professor in ASU’s School of Earth and Space Exploration, decided to see whether the shape of the landscape could be used to infer the timing of canyon incision in a different way.
They analyzed the shape of the land and an understanding about how landforms change, plus comparisons to other thoroughly dated features in the region – like the Grand Wash Fault and the cliff-band along it.
As Darling put together computer analyses of the landscape, he and Whipple noticed the cliffs that make the edge of the Colorado Plateau (the Grand Wash Cliffs) look different than the cliffs that make the Grand Canyon. The Grand Canyon cliffs are steeper. Looking more closely, the tributary streams that pour into the Colorado River are also steeper than those in the Grand Wash Cliffs.
Many other researchers have shown the fault that formed the Grand Wash Cliffs experienced most of its movement in a long period of fault slip between 18 million and 12 million years ago. The west side of the fault has slipped downward a few kilometers, making a hole for sediment eroding from the Grand Wash Cliffs to pile into. As erosion occurs, steep cliffs become more gradual slopes and rivers flatten out over time. But the western Grand Canyon has steeper cliffs and steeper tributary rivers than those along the Grand Wash Cliffs.
“We think this means that the western Grand Canyon is younger and started eroding more recently and at a higher rate than the area of the Grand Wash Cliffs,” Darling explained.
In both landscapes, the amount of erosion measured vertically is about the same: but the time taken to do that erosion is different and hence the erosion rates are different.
Using this inference, they evaluated the three previous hypotheses for the age of incision of Western Grand Canyon: 70 million years ago, 17 million years ago or about 6 million years ago.
“Since the canyon seems to be younger than the fault slip, only the most recent 6-million-year-old incision idea is supported by the topographic and erosion rate data,” Darling said.
Which, if Darling is correct, means we have an answer to our question: “There’s no way dinosaurs overlapped with what we call the Grand Canyon.”
One of the cichlid fish from Guatemala, Thorichthys meeki, collected by LSU Curator of Ichthyology Prosanta Chakrabarty for the study that refuted the date in which the Isthmus of Panama was formed. Credit: Courtesy of Prosanta Chakrabarty, LSU
A long-standing fact widely accepted among the scientific community has been recently refuted, which now has major implications on our understanding of how Earth has evolved.
Until recently, most geologists had determined the land connecting North and South America, the Isthmus of Panama, had formed 3.5 million years ago. But new data shows that this geological event, which dramatically changed the world, occurred much earlier. In a comprehensive biological study, researchers have confirmed this new information by showing that plants and animals had been migrating between the continents nearly 30 million years earlier.
‘This means the best-dated geological event we ever had is wrong,’ said Prosanta Chakrabarty, LSU associate professor in the Department of Biological Sciences and Curator of Ichthyology at the LSU Museum of Natural Science. His research on the evolution of freshwater and marine organisms in Central America was part of the study with colleagues at the Smithsonian Tropical Research Institute, American Museum of Natural History and the University of Gothenburg, which included living and extinct mammals, birds, plants, fish and invertebrate animals published by the Proceedings of the National Academy of Sciences.
The researchers found large pulses of movement among these plants and animals between North and South America from 41 million, 23 million and eight million years ago. These coordinated spikes in migration imply that geological changes in Central America, such as landmass formation and new freshwater corridors, were aiding migration for many kinds of plants and animals.
‘Before, South America was thought of as an island with no communication until 3.5 million years, so the only way to explain such high biodiversity was to say that it accumulated extremely fast. Now, with a longer history, we know that processes and patterns took a lot of time to form,’ said Christine Bacon, lead author of the study and associate researcher at the University of Gothenburg. ‘Our results change our understanding of the biodiversity and climate, both at the regional and global levels.’
Even after the reported geological closure, geminate marine species, those close relatives found on opposite sides of the narrow isthmus, also provide evidence that this landmass between North and South America is more like a sponge where organisms can periodically pass rather than a solid barrier. The current expansion of the Panama Canal has yielded new fossils that have informed these observations.
‘Now we know that the closure of the Isthmus of Panama, which is supposed to be one of the biggest deals in geology, is just one part of a really complicated puzzle of how the continents came together,’ Chakrabarty said.
He and colleagues at LSU mapped the evolution of two major families of fishes in Central America — cichlids, which include many aquarium fish, and poeciliids, which include guppies and swordtails. They collected samples of fishes from every country in Central America and sequenced the DNA to determine the genetic relationship between species. Matching the skeletal structure of fish found in the fossil record, they calibrated the DNA-based evolutionary tree and determined the age of each species.
Because freshwater fish can only migrate when a new passage way opens to a river or lake, there must have been dry land with freshwater running through it, Chakrabarty said. Therefore, their arrival in Central America signifies early geological changes.
‘The cool thing is there are so many freshwater fish species that are essentially stuck in one place until the land changes, so they can tell us about the history of the Earth,’ he said.
The formation of the Isthmus of Panama had large-scale effects on the planet. It divided the Atlantic and Pacific oceans, thus changing sea levels and ocean currents. This affected global temperatures possibly causing periods of glaciation.
‘The geology of this whole region is so complicated, and it’s amazing to me that the biology can inform us of that,’ he said.
Chakrabarty has been conducting research on Central American freshwater fish for about 15 years. He has received more than $1 million in National Science Foundation funding for this work. He and his lab have collected fish species from every country in Central America and have expanded the specimen collection at LSU to South America, the Greater Antilles and much of Asia. He is currently researching the evolution and migration of freshwater fish between South America, Central America and the Greater Antilles that may have began 50 to 60 million years ago.
Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) maps of modeled mineralogy (olivine in red; mafic glass in green; pyroxene in blue) projected over Context Camera (CTX) imagery. Credit: Geology (Geological Society of America) and Kevin M. Cannon and John F. Mustard, Brown University, Providence, Rhode Island, USA.
Quenched glasses formed by asteroid impacts can encapsulate and preserve biological material for millions of years on Earth, and can also serve as a substrate for microbial life. These impact glasses are thus an important target to search for signs of ancient life on Mars, but until now they have not been definitively detected on the martian surface.
In this study, Kevin Cannon and John Mustard used orbital remotely sensed data to investigate spectral signatures of geologic units on Mars that were formed during impacts (impactites).
Using spectral mixture modeling, they found that glass is in fact present in these units, mixed with other minerals like olivine and pyroxene. This modeling approach allows for the identification glass signatures that are not otherwise obvious when glass is present in a mixture.
The glass-rich impactites Cannon and Mustard have identified have been preserved on billion-year timescales, old enough to date back to more clement surface conditions on Mars. Their preservation is likely due to the current cold and dry surface environment; therefore, fossilization in glass, as proposed previously, seems to be a promising target to search for possible ancient martian biological activity.
Reference:
Preserved glass-rich impactites on Mars
Kevin M. Cannon and John F. Mustard, Brown University, Providence, Rhode Island, USA. Published online ahead of print on 5 June 2015; DOI: 10.1130/G36953.1
A zoom-in of potential red blood cells inside a fossil fragment that has been sliced open with a focused ion beam. Credit: Image courtesy of Imperial College London
Scientists have found remnants that have some similarities to red blood cells and collagen fibres in fragments of dinosaur fossils.
The team from Imperial College London have detected what look like soft tissue remnants in the fragments of 75 million year old dinosaur fossils even though the fossils are poorly preserved. Scientists have previously only found soft tissue in dinosaur fossils that have been exceptionally well preserved, which are very rare and far fewer in number.
The researchers suggest their study, published today in Nature Communications, may cause palaeontologists to rethink how fossils are preserved, and may be the first step towards a better understanding of the biology of dinosaurs and the relationships between different species.
In the study, the team analysed eight fossil fragments that have for more than a century been in the Natural History Museum’s Sternberg and Cutler collections.
The researchers examined part of a fossilised dinosaur claw and identified tiny structures that look ovoid and with an inner denser core. These could potentially be red blood cells although the researchers caution that further evidence would be needed to confirm that the structures do not have another origin. The hope is that if red blood cells can be found in fossilised dinosaur fragments, this could help scientists to understand when dinosaurs evolved a warm blooded, bird-like metabolism.
In one dinosaur fossil fragment, the team also found structures that looked fibrous and had a banded structure similar to the banding that can be seen in modern day collagen fibres. The structure of collagen varies between different animal groups, providing a type of fingerprint to link related creatures. Further evidence would be needed to definitively conclude that the structures found originate from a preservation of collagen. If verified, the identification of collagen-like structures could in the future provide a new independent line of evidence to show how various dinosaur groups are related to each other.
Study author Dr Sergio Bertazzo, a Junior Research Fellow from the Department of Materials at Imperial College London, said: “We still need to do more research to confirm what it is that we are imaging in these dinosaur bone fragments, but the ancient tissue structures we have analysed have some similarities to red blood cells and collagen fibres. If we can confirm that our initial observations are correct, then this could yield fresh insights into how these creatures once lived and evolved.”
Study author Dr Susannah Maidment, a Junior Research Fellow from the Department of Earth Science and Engineering at Imperial College London, added: “Our study is helping us to see that preserved soft tissue may be more widespread in dinosaur fossils than we originally thought. Although remnants of soft tissues have previously been discovered in rare, exceptionally preserved fossils, what is particularly exciting about our study is that we have discovered structures reminiscent of blood cells and collagen fibres in scrappy, poorly preserved fossils. This suggests that this sort of soft tissue preservation might be widespread in fossils. Early indications suggest that these poorly preserved fossils may be useful pieces in the dinosaur jigsaw puzzle to help us to understand in more detail how dinosaurs evolved into being warm blooded creatures, and how different dinosaur species were related.”
To carry out their study the team used a range of techniques. The first involved the use of a scanning electron microscopy device to observe the structure, composition and location of the soft tissue inside the dinosaur fossil fragments. The team then used a focused ion beam to slice into the samples and observe the internal structure of the fossils. They also examined the fossils using a transmission electron microscope to detect the fibrous structures.
Birds are the distant relatives of dinosaurs, so the researchers used an ion mass spectrometer device to compare their ancient soft tissue to a blood sample taken from an Emu. This enabled them to compare and contrast the samples and see that their fossils had some similarities in the organic signatures to the blood cells present in the emu blood sample.
The next step will see the team carrying out more research to confirm that the structures that they’ve observed are found in a wider range of fossil samples and also to understand how widespread this sort of soft tissue preservation might be in dinosaur fossils, how far back this type of preservation could go in the fossil records and the reasons why it may have occurred.
Reference:
Sergio Bertazzo, Susannah C. R. Maidment, Charalambos Kallepitis, Sarah Fearn, Molly M. Stevens and Hai-nan Xie. Fibres and cellular structures preserved in 75-million–year-old dinosaur specimens. Nature Communications, 2015 DOI: 10.1038/ncomms8352
Undated picture released by the journal Nature on June 5, 2015 shows density-dependent colour scanning electron micrographs of samples extracted from ribs of an indeterminate dinosaur, displaying mineralized fibres
Scientists said Tuesday they have discovered what appear to be red blood cells and collagen fibres in dinosaur bones, a find that may boost prospects of prising organic remains from a much wider range of fossils.
Using molecular microscopy, a British team analysed eight bone fragments from dinosaurs that lived some 75 million years ago, in the Cretaceous period.
The fossils were so poorly conserved that it was impossible to tell precisely what type of animal some of them came from, study co-author Sergio Bertazzo from Imperial College London told AFP.
The samples included the claw of a meat-eating dinosaur, a few toe bones from a ceratopsid (a group that included the horned Triceratops) and a duck-billed hadrosaur, and rib fragments from an unknown species.
All the bones are from the Dinosaur Park Formation in Alberta, Canada, and have been in the Natural History Museum in London since they were collected about 100 years ago.
“What we found are structures that could be original red blood cells from the dinosaur specimens and also other structures that could be the original collagen fibres,” Bertazzo said by email.
Other researchers have previously found remnants of organic material in dinosaur bones, but in exceptionally well-preserved fossils—which are few and far between.
“Therefore we indicate that the likelihood of finding organic material in fossils is much higher than previously thought, at least at the microscopic scale,” said Bertazzo.
It had long been thought that protein molecules cannot survive for longer than four million years.
Bertazzo and a team used a special microscope which uses a beam of heavy atoms to make infinitely small cuts in a sample at the nanometric scale (a nanometre is a billionth of a metre).
“The same microscope also has a robotic arm with a micro needle that can be used to pick up and move things inside the microscope,” explained Bertazzo.
“So, combining the beam and the needle, we could cut small bits of the fossils and perform an analysis to check for any fragment of amino acids.”
The team had set out to analyse gaps left in bone by decomposed organic material, instead finding structures that appear to be red blood cells, and fibres similar to collagen, a protein which makes up the bulk of connective tissues in animals.
“Totally blown away!” is how Bertazzo described the team’s breakthrough, while cautioning that further evidence is needed to confirm the nature of the structures.
“This was absolutely not what we were expecting to find at all. It actually took quite a while for us to be convinced of what we saw.”
The team compared their ancient soft tissue to an Emu blood sample, and intriguingly found “similarities”.
Dinosaurs are distant ancestors of modern-day birds, and scientists are hoping this type of research will reveal how, and when, a cold-blooded lizard gave rise to warm-blooded birds with a fast metabolism.
In vertebrate animals, the smaller the blood cell, the higher the metabolic rate, said Bertazzo.
“If we can find blood cells in lots of different dinosaurs, the range in size might provide an independent line of evidence for when dinosaurs became warm-blooded,” he said.
The main breakthrough of the research is to show that this type of soft tissue preservation is likely much more common than once thought, and Bertazzo said he “cannot even begin to speculate about what can be found in future.”
As for the possibility of one day discovering DNA, however, “many more studies should be done before we are even able to say if it is possible or not”.
Video
Scanning electron micrographs and 3D reconstructions from
serial sections of erythrocyte-like structures. Credit: Bertazzo et al., Nature Communications
Note : The above story is based on materials provided by AFP.
An artist’s rendering of the dinosaur Dreadnoughtus. Credit: Jennifer Hall
Scientists at the University of Liverpool have shown that the most complete giant sauropod dinosaur skeleton, Dreadnoughtus, discovered by palaeontologists in South America in 2014, was not as large as previously thought.
Found in Patagonia, the huge fossil had almost all of the major bones intact, allowing scientists to confidently estimate its overall size – measuring in at 26 metres long.
Preserved in rock, it is thought that the animal was close to maturity but not fully grown when it died, and may have grown to be even larger. The long-necked, plant-eating dinosaur was the biggest to ever walk the earth.
To estimate the mass of Dreadnoughtus scientists originally used a scaling equation that predicts body mass based on the size of thigh and arm bones. This method produced a range of estimates with the average being a colossal 60 tonnes.
Scientists at the University of Liverpool, in collaboration with researchers from Liverpool John Moores University, the University of Manchester, and Imperial College, re-evaluated this estimate after it became clear that other sauropod dinosaurs, only marginally smaller than the giant, weighed considerably less than 60 tonnes.
The team used a three-dimensional skeletal modelling technique to examine body mass more directly. This method involves mathematically reconstructing a ’skin’ volume around bones of Dreadnoughtus on a computer and then expanding that skin outline to account for muscle, fat and other tissues.
The size of expanded skin outline is based on similar data from living animals. By exploring a range of expansions the team could more accurately predict how heavy Dreadnoughtus could realistically have been.
Digital modelling
The team found that the mass of the Dreadnoughtus was more likely to be between 30 and 40 tonnes, considerably less than originally thought.
Dr Karl Bates, from the University’s Institute of Ageing and Chronic Disease, explains: “Estimating the body mass of an extinct animal from approximately 77 million years ago of this size from only its fossilised bones is extremely challenging and relies on the availability of certain data from living animals and modelling techniques.
“The original method used to calculate the mass of the animal is a common one and has been used successfully on many specimens. The highest estimates produced for this particular giant, however, didn’t quite match up.
“Using digital modelling and a dataset that took in species, alive and dead, we were able to see that the creature couldn’t be as large as originally estimated.”
“Our analysis suggests that only the lower estimates produced by previous methods are plausible. Estimates of 60 tonnes and above do not fit with our current understanding of the mass characteristics of living land animals.”
It is unclear how accurate previous predictions on the scale of these creatures have been, but future studies of living animals and developments in modelling techniques could help build a more fulsome picture of the size and lifestyles of the dinosaurs.
The research is published in the Royal Society journal Biology Letters.
Reference:
Karl T. Bates, Peter L. Falkingham, Sophie Macaulay, Charlotte Brassey, Susannah C. R. Maidment. Downsizing a giant: re-evaluating Dreadnoughtus body mass. DOI: 10.1098/rsbl.2015.0215
The discovery of a new fundamental rock property will improve estimates of underground resources, such as hydrocarbons and drinking water, as well as CO₂ storage reservoir capacity.
The revelation that electricity can flow more easily through sedimentary rocks in the vertical, rather than horizontal, direction is contrary to established scientific wisdom. This finding will improve the interpretation of geological fluid flow from geophysical surveys.
Fluids and electrical currents can flow through sedimentary rock via a network of gaps in between the sediment grains, called pores. Because gravity applies a vertical force, when sediments are compacted into sandstone the horizontal pathways in the pore network become more compressed and contorted than their vertical counterparts. These differences mean that it is easier for fluids and electrical current to flow through the less contorted and compressed vertical pathways. Prior to this study it was thought the horizontal layering of sediments and the horizontal alignment of sedimentary grains would cause electricity to flow more easily in the horizontal direction.
This discovery, made by scientists at the National Oceanography Centre (NOC), was published in the journal Geophysical Prospecting in November. Earlier this week this study was awarded the EAGE’s Loránd Eötvös prize for the ‘best research paper in 2014’ due to its ground breaking nature.
Lead author, Laurence North from the NOC, explained “It was the development of world leading technology at the NOC that allowed us to make this discovery. There have been a number of studies that showed similar effects, yet scientists dismissed their own findings as experimental error. However, because the unique electrical resistivity measurement system and processing software that I developed at the NOC is so accurate, I knew that the data must be the result of a ‘real’ rock property. Explaining the result, however, took a real lightbulb moment”.
Co-author Angus Best, Head of Marine Geoscience at the NOC, added “because this is the discovery of a fundamental rock property, it will be extremely useful for sub-seafloor fluid flow research in general, as well as for commercial applications.
We are very pleased to receive this prestigious award from the European Association of Geoscientists and Engineers, which gives wider recognition of the world-leading rock physics research we have been conducting at the NOC.
We are already using the results and related novel technology to advance sub-seafloor fluid flow studies of Arctic methane hydrate dissociation and geological CO₂ storage, as well as engaging with hydrocarbon industry partners.”
Seismologists studying the recent dramatic upswing in earthquakes triggered by human activity want to clear up a few common misconceptions about the trend.
There is increasing evidence that these earthquakes are caused by injecting fluids from oil and gas operations deep into the earth. These human-caused earthquakes are sometimes called “induced earthquakes.”
A Seismological Research Letters focus section to be published online June 10 addresses some common misconceptions about induced seismicity—the biggest of which is that it is primarily related to oil and gas recovery by hydraulic fracturing or “fracking.” The focus section will appear in the July/August print issue.
Guest editor Justin Rubinstein, a scientist with the U.S. Geological Survey, explains that most of the induced earthquakes felt in the United States are from the disposal of large amounts of wastewater from oil and gas production. The majority of this wastewater is ancient ocean brine that was trapped in rock layers along with gas and oil deposits. Only a small percentage of induced seismicity comes from fracking processes that inject liquid into the ground to break up rock layers to free oil and gas for recovery.
Wastewater disposal from oil and gas operations has increased in the U.S. in the past decade, especially in states like Oklahoma where the amount of wastewater disposal doubled between 1999 and 2013.
“Wastewater disposal is expanding and waste fluids are being injected into new locations. There have been changes in production practices as well, so in some areas there is much more wastewater that needs to be disposed,” Rubinstein noted.
Not all fluid injection causes earthquakes that can be detected or felt, Rubinstein added. Only a few dozen of the tens of thousands of wastewater disposal, enhanced oil recovery and hydraulic fracture wells in the U.S. have been linked to induced earthquakes that can be felt.
The central United States has experienced a surge in seismicity in the past six years, rising from an average of 24 earthquakes magnitude 3.0 or larger per year between 1973 and 2008 to an average of 193 earthquakes of this size every year between 2009 and 2014, with 688 occurring in 2014 alone.
Researchers are also tracking induced earthquakes in Canada, and the current batch of studies suggests that fracking might be more significant than wastewater disposal for causing earthquakes in that country, according to focus section co-editor David Eaton of the University of Calgary.
“There appear to be interregional differences between the U.S. and Canada,” he noted, “but it’s too early to say yet whether those reflect operational differences in the geological site conditions, or if it simply reflects the focus of studies that have been completed to date.”
As research continues in both countries, experts are recommending a more proactive approach to the risks of induced seismicity. A focus section article by Randi Jean Walters and colleagues at Stanford University outlines a possible workflow to reduce pre and post-injection risks at oil and gas sites. The workflow would incorporate seismic monitoring, a thorough understanding of a region’s past and present geology and detailed information on the industrial methods used in an oil and gas operation. Perhaps most important, they write, an ongoing risk assessment would take into account what sorts of resources—from buildings to natural settings—would be affected by seismic activity, and what kinds of seismic activity the surrounding population is willing to tolerate.
Another focus section paper by James Dieterich and colleagues at the University of California, Riverside explores the mechanics of induced seismicity. Their study uses an earthquake simulation program called RSQSim to explore how simple faults with various levels of pre-existing stress respond to fluid injection. Their model is able to reproduce many of the observed characteristics of induced seismicity and relate them to physical quantities such as injection duration and injected volumes. If the simulator can model more complex situations in future trials, it may offer guidance on managing the seismic risks at injection sites and estimating the probabilities of inducing earthquakes.
Other articles in the issue investigate characteristics of induced earthquakes that have been proposed to be different in natural and induced earthquakes, including their ground shaking and faulting styles.
A new dinosaur cousin of Tyrannosaurus rex has been found in Wales, the first meat-eating dinosaur ever found in the country.
The fossilised skeleton of a theropod dinosaur, including razor sharp teeth, and claws, was discovered on a beach near Penarth in the Vale of Glamorgan. It was analysed by experts from The University of Manchester, University of Portsmouth and the National Museum Wales. This new dinosaur was a distant cousin of Tyrannosaurus rex and lived at the very earliest part of the Jurassic Period, 201 million years ago, possibly making it the oldest Jurassic dinosaur in the world.
The discovery was made by two brothers, Nick and Rob Hanigan while fossil hunting along the Lavernock beach in the Vale of Glamorgan after storms in spring 2014. After a cliff fall on the beach, they spotted several loose blocks containing part of the skeleton of a small dinosaur.
The fossilised bones were found spread across five slabs of rock and although some were preserved together in the correct position, others were scattered and separated by the actions of scavenging fish and sea-urchins. The specimen was preserved with the fossilised remains of these sea-urchins.
Dr John Nudds, senior lecturer in palaeontology at The University of Manchester said: “It is very rare to find this type of dinosaur at all and never before in Wales. In fact it is only the second dinosaur ever found in Wales. Theropods were vicious hunters who would prey on others. They were evolving rapidly at the start of the Jurassic period, but are only known from a few specimens worldwide. So this is a very exciting finding that could tell us a lot about how these species were evolving.”
It is thought that the fossil was from a juvenile animal as some of its bones are not yet fully formed. Research is still underway, with a scientific paper in progress which will reveal the name of this new species. The fossil will be donated to the National Museum Wales.
Dr David Martill, reader in palaeobiology at University of Portsmouth said: “The new dinosaur was brought to my attention last year and I went up to Lancashire to see the specimen. There, laid out on the table, was the most beautiful little theropod dinosaur ever found in Europe. Although the bones were scattered on a few slabs of limestone, they were in excellent condition, and much of the skull appeared to be there. The teeth were small, but needle sharp, slightly curved and with the most wonderful steak-knife serrations on their edges.
“I then went to visit the discovery site, which showed that the dinosaur came from strata deposited exactly at the end of the Triassic and the start of the Jurassic. I now had the job to determine if this was a Triassic or Jurassic dinosaur. That took a lot of effort, but we are now convinced it is the first ever Jurassic dinosaur.”
The Welsh dinosaur was a small, slim, agile dinosaur, probably only about 50cm tall, which had a long tail to help it balance. It lived at the time when south Wales was a coastal region, offering a warm climate. It had lots of small, blade-like, sharp, serrated teeth suggesting that it would have eaten insects, small mammals and other reptiles.
The dinosaur also probably had a fuzzy coating of simple proto-feathers, as did many theropod dinosaurs, and this would have been used for insulation and possibly display purposes. It may also have had simple quill-like structures for defence.
The rocks that contain the dinosaur fossil date back to a time immediately after the start of the Jurassic period, 201.3 million years ago. At that time, the dinosaurs were just starting to diversify and the Welsh specimen is almost certainly the earliest Jurassic dinosaur in the world. It is related to Coelophysis that lived approximately 203 to 196 million years ago in what is now the southwestern part of the United States of America. It also could be said to be a distant cousin of the much later Tyrannosaurus rex.
Nick Hanigan said: “This is a once in a lifetime find – preparing the skull and to seeing the teeth of a theropod for the first time in 200 million years was absolutely fantastic – you just can’t beat that sort of thing!”
The hip and vertebrae of the Welsh theropod
Just one of the five blocks of stone containing the skeleton fossil‘Hand’ and claw bones uncovered by the Hanigan brothersOne of the Welsh theropod’s fossilised claws
Tübingen scientists reconstruct the DNA of the Megaloceros from findings in caves in the Swabian Alb and discover possible causes for its later extinction.
The mass extinction at the end of the last Ice Age led to the disappearance of many animal species including the mammoth, the woolly rhinoceros, cave bears and the Megaloceros, also known as the giant deer or Irish elk, which could weigh as much as 1.5 tons. Scientists still do not fully know the precise reasons for the extinction of many species; it probably took place due to a combination of climate change and hunting by humans. However, some species of animals survived the end of the last glacial period somewhat longer than others.
They include the giant deer, which populated huge areas of Eurasia during the Ice Age. These animals were still present in parts of north-western Europe after the Ice Age, before they finally disappeared about 7,000 years ago. Scientists at the University of Tübingen have now managed to isolate mitochondrial genomes (mtDNA) from deer bones found in the Swabian Alb that are 12,000 years old which sheds light on how prevalent these animals were in southern Germany.
The deer bones that have been examined were retrieved during excavations in the Hohle Fels and Hohlenstein-Stadel caves in the Swabian Alb. It was generally accepted that the giant deer had become extinct in this region and in the whole of Central Europe after the climax of the last Ice Age 20,000 years ago. Scientists initially believed that the findings were elk bones, as elks were widespread in southern Germany at that time. The reconstruction of the mtDNA by Johannes Krause and his team from the Institute for Archaeological Sciences in Tuebingen and the subsequent genetic analysis of the DNA have demonstrated, however, that the findings were bones from Megaloceros giganteus, the giant deer. “It’s not easy to distinguish between an elk and a giant deer using the morphology of small bone fragments. There could be many more bones, which we previously attributed to the elk, but which really come from giant deer,” says Johannes Krause.
Studies in the past did not provide any clear results about which of today’s deer are the closest relatives of the giant deer either. The Tübingen scientists compiled a dataset from the mtDNA of 44 modern deer species and the two giant deer individuals dating from the late Ice Age in order to reconstruct a family tree. It emerged that the fallow deer is the closest living relative of the giant deer. This species originated in the Middle East and was introduced to Europe for hunting purposes in the 17th century. “It was speculated on the basis of the physical size that the red deer was most closely related to the giant deer; but we can clearly reject this hypothesis with our study,” says Alexander Immel, a member of Krause’s team.
The scientists also examined stable isotopes of the collagen, a structural protein, which forms an essential part of the bones. They compared the carbon-13 and nitrogen-15 values in the giant deer bones from the Swabian Alb caves with those of red deer, other giant deer and reindeer, which were living at the beginning and the end of the last glacial period. “Prior to the last Ice Age, there was a clear distinction in the isotope values for all three species; after this period, there is a clear overlap — and this suggests that the habitat of deer species had shrunk or there was and overlap in the diets of the different deer species,” says Dorothée Drucker from the Biogeology department, who examined the collagen.
The scientists believe that giant deers had to share their habitat and their food with other species of deer after the last Ice Age. In addition the antlers of the giant deer, which measured up to 3.40 meters across, were little suited to life in Europe, which was increasingly becoming forested. The competition with other species and additional hunting by humans likely affected the giant deer and finally led to the extinction of these imposing animals.
Reference:
Alexander Immel, Dorothée G. Drucker, Marion Bonazzi, Tina K. Jahnke, Susanne C. Münzel, Verena J. Schuenemann, Alexander Herbig, Claus-Joachim Kind, Johannes Krause. Mitochondrial Genomes of Giant Deers Suggest their Late Survival in Central Europe. Scientific Reports, 2015; 5: 10853 DOI: 10.1038/srep10853
Vent fluid samples were collected using titanium isobaric gas-tight (IGT) samplers deployed by the remotely operated vehicle Jason aboard the R/V Atlantis in January 2012. The IGTs, unique instruments developed by Jeff Seewald and a team of WHOI engineers, are designed to maintain the sample fluid at the high pressure at which it was drawn. Credit: Chris German, WHOI/NASA, NSF/ROV Jason/Woods Hole Oceanographic Institution
In 2009, scientists from Woods Hole Oceanographic Institution embarked on a NASA-funded mission to the Mid-Cayman Rise in the Caribbean, in search of a type of deep-sea hot-spring or hydrothermal vent that they believed held clues to the search for life on other planets.
They were looking for a site with a venting process that produces a lot of hydrogen because of the potential it holds for the chemical, or abiotic, creation of organic molecules like methane — possible precursors to the prebiotic compounds from which life on Earth emerged.
For more than a decade, the scientific community has postulated that in such an environment, methane and other organic compounds could be spontaneously produced by chemical reactions between hydrogen from the vent fluid and carbon dioxide (CO2). The theory made perfect sense, but showing that it happened in nature was challenging.
Now we know why: an analysis of the vent fluid chemistry proves that for some organic compounds, it doesn’t happen that way.
New research by geochemists at Woods Hole Oceanographic Institution, published June 8 in the Proceedings of the National Academy of Sciences, is the first to show that methane formation does not occur during the relatively quick fluid circulation process, despite extraordinarily high hydrogen contents in the waters. While the methane in the Von Damm vent system they studied was produced through chemical reactions (abiotically), it was produced on geologic time scales deep beneath the seafloor and independent of the venting process. Their research further reveals that another organic abiotic compound is formed during the vent circulation process at adjacent lower temperature, higher pH vents, but reaction rates are too slow to completely reduce the carbon all the way to methane.
“We’ve really improved our understanding of the origin of abiotic hydrocarbons in all ridge-crest hydrothermal systems by identifying specifically where carbon is being transformed within the vent fluid circulation pathway,” said Jill McDermott, lead author of the study and a recent graduate of the MIT/WHOI Joint Program in Oceanography. “We also have a much better sense of how quickly these reactions are occurring in natural systems — some take thousands of years, while others only take hours to days.”
Methane and other organic compounds in natural waters can originate from three types of sources: living organisms, decomposition of living or dead biomass, and ‘abiotic’ formation via purely chemical processes with no participation from living organisms.
Finding out how methane and other organic species are formed in deep-sea hydrothermal systems is compelling because these compounds support modern day life, providing energy for microbial communities in the deep biosphere, and because of the potential role of abiotically-formed organic compounds in the origin of life.
The study, whose authors also include WHOI geochemists Jeffrey Seewald, Christopher German, and Sean Sylva, indicates that methane at the Von Damm vent field was created by a reaction between CO2 and water trapped for thousands of years within cooling volcanic rocks deep within Earth’s crust. Many vent sites are tectonically active, and when tectonic shifts occur, the rocks beneath the sea floor can crack, allowing seawater to penetrate and leach methane from within the rocks. Eventually that methane is carried up to the seafloor by the circulating vent water. While this concept had previously been theorized, this paper is the first to demonstrate its importance in nature.
How the researchers determined this was a neat trick, involving balancing the vent site’s CO2 budget by measuring the amount of CO2 in seawater in the vent fluid; analyzing the isotopic makeup of the CO2; and radiocarbon dating the CO2. The results of the analysis showed there has been no CO2 added, and no CO2 removed, and therefore it could not have been used to form methane.
An examination of the methane showed it was “radiocarbon dead.” That meant it was older than 50,000 years and carried no modern signature, indicating the methane came from ancient geologic sources.
“We were able to use enough different but complementary lines of evidence to show that the methane formation here is a purely chemical process, and that it happens in the absence of life,” said McDermott.
But why wasn’t the CO2 at this site reacting with the hydrogen to create methane? That question led to an equally fascinating discovery: a reaction between CO2 and hydrogen was occurring, but it wasn’t proceeding fast enough or progressing far enough to create methane.
Instead CO2 and hydrogen combined to create an “intermediate” compound called formate — an important “pre-biotic” organic compound.
The team discovered the formate when analyzing the vent fluids at cooler off-shoot vent sites at the Von Damm site and found it had less CO2 than it should have. That meant the CO2 must have been reacting to form something else. They determined the formate concentration in those fluids, and, said McDermott, “it turns out the amount of formate species that was formed in each one of these fluids, perfectly matches the amount of CO2 that was lost. It’s so rare that you can actually close the budget, and figure out where all the carbon has gone.” The amount of formate present also matched the amount predicted by thermodynamic models.
“This is an excellent example where hypotheses developed over the years from laboratory experiments and theoretical models could be tested and verified in nature,” said co-author Seewald.
Intermediate species like formate have a lot of energy available. They’re also a good energy source for microbes.
In fact, formate may be used by modern day microbes to generate methane in the subsurface biosphere. Formate may also have served as the first step toward forming reduced carbon compounds that were central to primitive biochemical pathways on early Earth.
“A particularly exciting aspect of this study is that our newest discoveries here on Earth provide a compelling ‘real-world’ example of just how pre-biotic chemistry could also arise elsewhere,” said co-author German.
Reference:
Jill M. McDermott, Jeffrey S. Seewald, Christopher R. German, and Sean P. Sylva. Pathways for abiotic organic synthesis at submarine hydrothermal fields. PNAS, June 8, 2015 DOI: 10.1073/pnas.1506295112
An eruption of the Calbuco Volcano in southern Chile. A team of astronomers led by the UW’s Amit Misra used data from volcanic eruptions on Earth to predict what an Earth-like exoplanet might look like during such eruptions. Credit: Wikimedia commons
Planets with volcanic activity are considered better candidates for life than worlds without such heated internal goings-on.
Now, graduate students at the University of Washington have found a way to detect volcanic activity in the atmospheres of exoplanets, or those outside our solar system, when they transit, or pass in front of their host stars.
Their findings, published in the June issue of the journal Astrobiology, could aid the process of choosing worlds to study for possible life and even one day help determine not only that a world is habitable, but in fact inhabited.
Volcanism is a key element in planetary habitability. That’s because volcanic outgassing helps a planet maintain moderate, life-inviting temperatures, regulating the atmosphere by cycling gases such as carbon dioxide between the atmosphere and the mantle.
Lead author Amit Misra, who has since graduated with a doctorate, said the project started in a UW astrobiology graduate seminar when a professor asked how one might detect plate tectonics—the grinding together and apart of huge slabs of a planet’s surface—on faraway worlds.
Plate tectonics is considered an aid to the origin of life because it allows for the recycling of materials from the atmosphere to the planetary interior. Some scientists have even proposed that life on Earth began at sites created by tectonic plates.
The students studied various models trying to predict whether an exoplanet might have plate tectonics, but found little in scientific literature on how to directly detect tectonic plates. So they started brainstorming.
“I came up with the idea of looking at explosive volcanic eruptions as a proxy, or stand-in, for plate tectonics,” Misra said. “I had done some work modeling aerosols produced by volcanic eruptions for other projects, so I started looking into how we might detect an eruption and what it would tell us.”
So the team used data from volcanic eruptions on Earth to predict what an Earth-like exoplanet might look like during such eruptions. The thinking, Misra said, was that explosive volcanic eruptions usually happen at the edges of tectonic plates, making them a good proxy indeed.
Gases released from smaller, nonexplosive volcanic eruptions tend to return quickly to the planet’s surface. Explosive eruptions, however, can send volcanic gases up into the stratosphere, where they “greatly affect the spectrum of the planet,” Misra said. The optical signature of the gases might be detectable by powerful telescopes such as the James Webb Space Telescope, scheduled for launch in 2018.
Co-authors are Joshua Krissansen-Totton, Matthew Koehler and Steven Sholes, all graduate students in the UW’s Department of Earth and Space Sciences and affiliated with the UW astrobiology program.
But while the connection between volcanic eruptions and tectonic plates is true on Earth, Misra said the team cannot say with certainty that the same is true throughout the cosmos. Still, he said, “An explosive eruption can probably be tied to volcanism if false positives such as dust storms can be ruled out.”
“These long-lasting, high-up aerosols can have a huge signal for an exoplanet, which is the key result for the paper,” Misra said. “What this means is that if we can detect a volcanic eruption on a planet, and if it meets other criteria like being in the habitable zone, that planet should move up our list of potential targets to search for life.”
The work may also someday help astronomers infer that a planet not only might have life, but actually does. Misra explained that while oxygen is thought an indicator of life, it’s also possible for oxygen to be produced abiotically, or by something other than biology.
Volcanism, Misra said, may help distinguish between oxygen that is produced by life or other planetary processes by helping astronomers better understand the planet’s environment.
“Volcanic gases often react with and destroy oxygen, and a detection of both oxygen and volcanism suggests that there is a source of oxygen in the planetary environment, which could be life,” Misra said.
The research was done through the Virtual Planetary Laboratory, a UW-based interdisciplinary research group, and funded through the NASA Astrobiology Institute.
Reference:
Misra Amit, Krissansen-Totton Joshua, Koehler Matthew C., and Sholes Steven. Transient Sulfate Aerosols as a Signature of Exoplanet Volcanism . DOI:10.1089/ast.2014.1204.
Beneath long-term work to rebuild sandbars in the Grand Canyon lies a legacy of river-running data collection that tells the story of Northern Arizona University researchers, highlighting their persistence and innovations.
A new USGS article in the online journal Eos touts the promising outcomes of controlled floods on the Colorado River, conclusions that rely in part on more than 25 years of measurements collected under difficult conditions and with changing technology.
“It’s a tough place to do research,” said Joe Hazel, research associate at NAU. “You would be hard pressed to find anywhere else in the world where a continuous monitoring record of environmental change was made with direct measurements in a remote river setting.”
At stake is a river ecosystem that has been as challenging to understand as to manage over decades of manipulation since the completion of Glen Canyon Dam. The issue of sandbar deposition and erosion, and the ability to determine just how much sand is in the water and where it comes from, has evolved along with attitudes about how the river should be managed.
“Trying to figure out how much sand is in the system and when to do floods has been the driving force behind our work,” Hazel said. “We tell the managers when the sandbars have eroded to a certain condition or level.”
Hazel and research associate Matt Kaplinski have embarked on nearly 100 river trips since 1989, when they became involved in NAU research that had been ongoing for a decade under pioneering researcher Stan Beus, now NAU regents’ professor emeritus of geology. Beus was instrumental in NAU’s securing of a grant from the Bureau of Reclamation to operate a sandbar monitoring program. Upon Beus’ retirement, Rod Parnell, NAU professor of earth science and environmental sustainability, assumed the title of principal investigator.
“That first year we ran 20 river trips,” Hazel said. The federal government’s continued interest in river monitoring—especially during high-flow experiments in 1996 and 2008—led NAU to produce a trove of information, some of it through methods that have not changed much over the decades, but that has also inspired cutting-edge innovations.
A painstaking process of producing handwritten coordinates from theodolites, measurement devices that have long been the mainstay of surveying, eventually was made easier through digital data collectors. But even then, in what Hazel called “the old days,” river levels would need to be lowered in order to expose sandbars for measurement.
Because 85 percent or more of the sediment is under water, Kaplinski led the development of a multibeam bathymetric system that used sonar to measure submerged sandbars.
“That’s really sophisticated and expensive equipment, and had never before been retrofitted to be used in a canyon setting,” Hazel said, pointing out that the technology is similar to what is being used in the search for missing Malaysian Airlines Flight 370.
Still, collecting the data entails mastering difficult conditions. Using rafts powered by outboard motors, researchers guide equipment worth hundreds of thousands of dollars through rapids, trying not to capsize or slam into a rock.
One payoff of all that work is an approach that appears to endorse continued high-flow experiments as a way to build sandbars over time. Their presence contributes to a downstream ecosystem, which lies within the Glen Canyon Recreation Area and Grand Canyon National Park, considered a World Heritage Site.
“It’s cool that Glen Canyon Dam is now being partially managed to benefit downstream resources instead of just generating hydro power and for water storage,” Hazel said.
And now, after a long and “painful migration process,” the decades of NAU data are available online for anyone to see. What had been relegated to notebooks and outdated floppy disks stored in an old metal cabinet, and generations of incompatible software, is now part of an interactive online database. Researchers around the world can benefit from the findings.
“This is leaving our legacy,” Hazel said. “Now all this data is being served to the public.”
A satellite image of Alaska shows alluvial fans created by melting glaciers draining into the Copper River. Credit: NASA
Over geologic time, the work of rain and other processes that chemically dissolve rocks into constituent molecules that wash out to sea can diminish mountains and reshape continents.
Scientists are interested in the rates of these chemical weathering processes because they have big implications for the planet’s carbon cycle, which shuttles carbon dioxide between land, sea, and air and influences global temperatures.
A new study, published online on June 8 in the journal Nature Geoscience, by a team of scientists from Stanford and Germany’s GFZ Research Center for Geosciences reveals that, contrary to expectations, weathering rates over the past 2 million years do not appear to have varied significantly between glacial and interglacial periods.
Scientists expect weathering rates to slow down during Earth’s ice ages because temperatures were lower, and as a consequence much of the water that might fall as rain is trapped as ice in glaciers blanketing Europe and North America.
“If you look at how these attributes of climate control weathering rates today, you would expect that weathering and sedimentation rates can vary widely between glacial to interglacial times,” said study author Friedhelm von Blanckenburg, a geochemist at the German Research Centre for Geosciences GFZ Potsdam.
For example, North America’s Sierra Nevada mountain range is pockmarked by U-shaped valleys that were carved out by ice sheets during their relentless march southward in glacial times. When temperatures warmed, the ice sheets retreated, exposing pulverized rocks in the crater that could be easily weathered and transported out to sea by rivers and streams. Even in regions not covered by glaciers, scientists know that rainfall changed between glacial and interglacial times. Studies of now-dry lakebeds that once dotted the western U.S. and cone-shaped sedimentation deposits, called alluvial fans, from ancient rivers suggest water flow varied widely as temperature and rainfall patterns waxed and waned between ice ages and the warmer periods that followed.
But all of these lines of evidence testified only to local variations of weathering and sedimentation rates. “If you want to know the global weathering rate,” von Blanckenburg said, “you have to go to the oceans, where local variations rates are averaged out.”
von Blanckenburg and his colleague, Julien Bouchez, a research scientist at the Global Institue of Physics in Paris, turned to a geochemical technique that compares the concentration of two forms, or isotopes, of the element beryllium (Be). 9Be is found naturally in silicate rocks on Earth; 10Be is a radioactive cosmogenic isotope produced by the collision of cosmic rays with nitrogen and oxygen molecules in the atmosphere.
“Because 10Be rains down onto Earth’s continents and oceans at more or less a constant rate, it’s like a clock that can be used to time processes,” von Blanckenburg said. “9Be, on the other hand, can be used to calculate how much dissolved rock has washed into the oceans from rivers.”
By determining the ratio of 10Be to 9Be in marine sediment layers, von Blanckenburg was able to reconstruct the weathering flux for nearly the entire Quaternary Period, a timespan encompassing 2.6 million years. To his surprise, he found that there was little change between glacial and interglacial periods.
To understand why, von Blanckenburg teamed up with Stanford researchers Kate Maher, an assistant professor of geological sciences, and graduate student Daniel Ibarra, who specialize in using computer models to understand how the flow of water controls weathering. Maher and Ibarra compiled data about river-to-ocean flow from an ensemble of climate models and calculated the average discharge from rivers at different latitudes during glacial and interglacial times.
The Stanford scientists reached the same conclusion that von Blanckenburg and Bouchez did using their beryllium ratio observations. “Our results suggested that globally the aggregate change in discharge from all the rivers was effectively zero between the glacial and interglacial times. That was surprising,” Maher said.
The models offered a likely explanation for this: they showed that while the change in water discharge for rivers at higher latitudes in the northern hemisphere could vary wildly between glacial and interglacial times, the flux for rivers in the tropics-which remained temperate even during ice ages-did not change by more than a few percent.
“The tropics account for more than half of the river runoff globally, so they strongly moderate chemical weathering fluxes during global shifts in climate,” Ibarra said. “Because weathering helps balance the global carbon cycle, that means the tropical weathering is a primary driver of atmospheric CO2 levels over very long time scales.”
Reference:
Stable runoff and weathering fluxes into the oceans over Quaternary climate cycles, Nature Geoscience, DOI: 10.1038/ngeo2452
Note : The above story is based on materials provided by Stanford University.
From left: These diamonds display high, moderate and low brightness under fluorescent light. Credit: Eric Welch/GIA
If you’ve ever wondered why your diamond looks different in sunlight versus candlelight or daylight versus office lights, it’s because the cut of your diamond responds differently depending on the light and the environment you are in. How – and where – you look at your diamond can greatly change its appearance.
Al Gilbertson, a GIA researcher, says if you think of a diamond like “a series of mirrors reflecting its environment,” it can help you understand how light and location can change the way your diamond appears. When you look at your diamond, you are also seeing a reflection of the surrounding environment, including yourself.
“Often times, the dark parts of the pattern you see in a diamond are a reflection of your face, or the camera – if you’re looking at a photograph,” Gilbertson says. “You can test this yourself. Hold the diamond at arm’s length and look at how bright it is and how the pattern of dark and light appears. Now, gradually bring it closer to your eye. By the time it gets very close, the area of dark pattern in the diamond has grown and is much more prominent.”
“This all means that in every different location you look at your diamond, this ‘series of mirrors’ is reflecting not only the environment, but also you. How close you hold it, and the environment you are in, affects the pattern you see.”
When it comes to the 4Cs of GIA’s Diamond Grading System – color, clarity, cut and carat weight – cut is often the least understood because there are so many components considered in the cut grade. The first three – brightness, fire and scintillation – describe the diamond’s appearance. The remaining four components – weight ratio, durability, polish and symmetry – describe the design and craftsmanship.
Each cut grade – excellent, very good, good, fair and poor – represents a range of proportion sets and diamond appearances. There is no single set that defines a well-cut round brilliant diamond – many different proportions can produce attractive diamonds, which should be bright, fiery, sparkling and have a pleasing overall appearance, especially when the pattern of bright and dark areas is viewed face up, Gilbertson says.
GIA’s Diamond Cut Grading System for standard round brilliant diamonds in the D-to-Z color scale and the Flawless-to-I3 clarity range provides an objective assessment of a diamond’s overall cut quality.
GIA studied diamond cut for decades and analyzed tens of thousands of proportion sets before the system was introduced in 2005. It had to be scientific, but also practical and applicable to the jewelry industry and public. There were more than 70,000 observations of 2,300 diamonds in studies conducted across all sectors of the jewelry industry – diamond manufacturers, dealers, retailers and potential customers.
Diamonds graded in GIA’s laboratories are examined in standardized and calibrated environments – scales for carat weight, optical measuring equipment for all of the diamond’s proportions, light for color grading and 10X loupes for clarity, polish and symmetry help ensure consistency and objective grading.
Most people won’t ever see the diamond in a laboratory, so what type of lighting is best when purchasing a diamond? Gilbertson encourages you to look at the diamond in the type of lighting you will most typically wear it.
GIA’s Cut Grade System offers a description based on research and what most people prefer. But Gilbertson likes to remind people that diamonds are more than that.
“Diamonds and jewelry are very personal,” he says. “People buy jewelry for themselves or receive it as a gift for a specific reason, often to celebrate a special occasion. Choose what you like and what looks best in your opinion. Then, enjoy the adventure of learning all the different appearances your diamond can have.”
(A) Triceratops skeleton. (B) Transverse view of a dentary (lower jaw) tooth family in this dinosaur whose functional teeth wore to vertical slicing faces. (C) Naturally worn slicing teeth in the lower jaw showing the wear-induced bowing out of the central regions of the occlusal faces of the teeth (arrow) to form fuller-like implements. Credit: Bill Lax/Florida State University
When it comes to the three-horned dinosaur called the Triceratops, science is showing the ancient creatures might have been a little more complex than we thought.
In fact, their teeth were far more intricate than any reptile or mammal living today.
Biological Science Professor Gregory Erickson and a multiuniversity team composed of engineers and paleontologists content that the Triceratops developed teeth that could finely slice through dense material giving them a richer and more varied diet than modern-day reptiles.
Erickson and the team outlined the findings of their study in the journal Science Advances.
Today, reptilian teeth are constructed in such a way that they are used mostly for seizing food — whether plant or animal — and then crushing it. The teeth do not occlude — or come together — like those of mammals. In essence, they can’t chew. The teeth of most herbivorous mammals self wear with use to create complex file surfaces for mincing plants.
“It’s just been assumed that dinosaurs didn’t do things like mammals, but in some ways, they’re actually more complex,” Erickson said.
Erickson, who has been studying the evolution of dinosaurs for years, became interested in looking at dinosaurs’ teeth several years ago and suspected that they had some unique properties. But, the technology to really discover what they were capable of did not exist.
Fast-forward a few years and engineer Brandon Krick entered the picture.
Krick is an assistant professor of mechanical engineering at Lehigh University and specializes in a relatively new area of materials science called tribology. Tribology is the science of how surfaces of materials interact while in motion.
The two of them, accompanied by scientists at University of Florida, University of Pennsylvania and the American Museum of Natural History, set out to find out what exactly these teeth were made of and how they worked.
Erickson had access to the teeth of Triceratops from museum specimens collected around North America. So, he began by cutting up a bunch of teeth to get a look at the interior.
He discovered that Triceratopsteeth were made of five layers of tissue. In contrast, herbivorous horse and bison teeth, once considered the most complex ever to evolve, have four layers of tissue. Crocodiles and other reptiles have just two.
“Each of those tissues does something,” Erickson said. “They’re not just there for looks.”
While Erickson examined the tissue, he also sent samples to Krick to determine what each did and how they worked in concert to allow these animals to slice plants. Krick was able to mimic how plants moved across the teeth by scratching the teeth and measuring the tissue wear rates.
What Krick and his team of engineers, including Lehigh graduate student Mike Sidebottom, found was that the material properties of the teeth were remarkably preserved in 66 million year old teeth.
“If you took these dinosaurs’ teeth and put them in a cow for example, they would work,” Erickson said.
A sophisticated three-dimensional model was developed to show how each tissue wore with use in a strategic manner to create a complex surface with a fuller (a recessed area in the middle, much like those seen in fighting knives and swords) on each tooth. This served to reduce friction during biting and promote efficient feeding.
The 3D wear model developed for this project is inspiring new engineering techniques that can be used for industrial and commercial applications.
“Paleontologists challenged us with an interesting engineering problem, and now, we have a wear model that can be used to design material systems with optimized wear properties and surface features for many applications,” Krick said.
The question that remains is how prevalent complex dental structure was among dinosaurs and other reptiles. Krick and Erickson intend to explore this further by examining other reptilian dental records and structures.
This work was funded by the National Science Foundation.
Video
Reference:
Gregory M. Erickson, Mark A. Sidebottom, David I. Kay, Kevin T. Turner, Nathan Ip, Mark A. Norell, W. Gregory Sawyer, Brandon A. Krick. Wear biomechanics in the slicing dentition of the giant horned dinosaur Triceratops. Science Advances, 05 Jun 2015 DOI: 10.1126/sciadv.1500055
Snapshot of a rogue event in multifilament dynamics recorded in a xenon cell at 60 times the critical power for filamentation. The optical fluence is plotted as a function of position on the optical detector. Credit: MBI
A comparative analysis of rogue waves in different physical systems comes to the surprising conclusion that these rare events are not completely unpredictable.
Metereological events often prove to be rather unpredictable, i.e., the “storm of the century” may well prove to be surpassed by yet another storm just in the subsequent year. From an insurance point of view, resulting damage often proves to be be well beyond any statistical prediction. Such phenomena generally underlie extreme value statistics, featuring a prevalent appearance of extreme events and contrasting long-term observations of rather normal events in the respective system. Rogue waves, also known as freak waves, are yet another example for such dynamics. While being extremely rare events, their appearance may cause considerable damage to the hull of ships.
The precise origin of rogue waves is still disputed. Moreover, it is unclear whether rogue waves can be predicted. Maybe, it is possible to issue a last-instant warning from observations of recorded wave heights? Do characteristic patterns exist that herald the impact of such a rogue wave? Unfortunately, there are only a few recordings of such ocean freak waves. Consequently, it may well take many more decades to answer those questions based on oceanic observations only. Nevertheless equivalent physical systems exist, which allow an exploration of this aspect at a substantially more solid statistical basis.
This is the point where the work of Simon Birkholz and coworkers sets in. Based on a statistical analysis of data in three different physical systems, the group conducted a detailed analysis on the predictability and determinism in the respective system. This analysis included original data of the famous New Year’s Wave, which hit the Draupner platform on January 1, 1995 as well as results of the Jalali group at the University of California at Los Angeles (UCLA), and finally data in a multifilament scenario measured at the Max-Born-Institut in Berlin. Â In the multifilament system, one can directly observe the rogue waves as short light flashes in the intensity profile. The wave height of the ocean system corresponds to light intensity in the optical systems.
The surprising result of this comparative analysis is that rogue events appear to be very much predictable in certain system, yet are completely stochastic and therefore unpredictable in others. In other words, rogue wave statistics does not enable any conclusion on predictability and determinism in the system. It is simply not true that rogue events per se appear out of nowhere and disappear without a trace. Ocean waves play a particular role here. Other than previously assumed, they are not completely stochastic. Therefore it is not true that they “appear out of nowhere and leave without a trace,” which has often been claimed to be a characteristic feature of ocean rogue waves. Nevertheless, practical predictions are still far away and may only enable a last-second warning of these “monsters of the deep.”
Reference:
Simon Birkholz, Carsten Brée, Ayhan Demircan, and Günter Steinmeyer. Predictability of Rogue Events. Physical Review Letters, June 2015 DOI: 10.1103/PhysRevLett.114.213901
An artistic life reconstruction of the new horned dinosaur Regaliceratops peterhewsi in the palaeoenvironment of the Late Cretaceous of Alberta, Canada. Credit: Art by Julius T. Csotonyi. Courtesy of Royal Tyrrell Museum, Drumheller, Alberta.
About 10 years ago, Peter Hews stumbled across some bones sticking out of a cliff along the Oldman River in southeastern Alberta, Canada. Now, scientists describe in the Cell Press journal Current Biology on June 4 that those bones belonged to a nearly intact skull of a very unusual horned dinosaur–a close relative of the familiar Triceratops that had been unknown to science until now.
“The specimen comes from a geographic region of Alberta where we have not found horned dinosaurs before, so from the onset we knew it was important,” says Dr. Caleb Brown of the Royal Tyrrell Museum of Palaeontology in Alberta, Canada. “However, it was not until the specimen was being slowly prepared from the rocks in the laboratory that the full anatomy was uncovered, and the bizarre suite of characters revealed. Once it was prepared it was obviously a new species, and an unexpected one at that. Many horned-dinosaur researchers who visited the museum did a double take when they first saw it in the laboratory.”
Brown likes to say, only partly in jest, that the uniqueness of this specimen was so obvious that you could tell it was a new species from 100 meters away.
What made this new horned dinosaur distinctive was the size and shape of its facial horns and the shield-like frill at the back of the skull. This new species is similar in many respects to Triceratops, except that its nose horn is taller and the two horns over its eyes are “almost comically small.” But the new dinosaur’s most distinctive feature is that frill, including what Brown describes as a halo of large, pentagonal plates radiating outward, as well as a central spike. “The combined result looks like a crown,” he says.
Brown and study co-author Donald Henderson named the new dinosaur Regaliceratops peterhewsi, a reference to its crown-like frill and to the man who first found and reported it to the museum. Despite the formal name, the scientists say they’ve taken to calling this dinosaur by the nickname “Hellboy.”
While this new dinosaur is intriguing in its own right, Brown and Henderson say what’s most significant are the implications for the evolution of dinosaurs’ horned ornamentation. It’s long been known that horned dinosaurs fall into one of two groups: the Chasmosaurines, with a small horn over the nose, larger horns over the eyes, and a long frill, and the Centrosaurines, characterized by a large horn over the nose, small horns over the eyes, and a short frill.
“This new species is a Chasmosaurine, but it has ornamentation more similar to Centrosaurines,” Brown says. “It also comes from a time period following the extinction of the Centrosaurines.”
Taken together, he says, that makes this the first example of evolutionary convergence in horned dinosaurs, meaning that these two groups independently evolved similar features.
The researchers say they hope to uncover more Regaliceratops peterhewsi specimens. They’ll also be working on digital reconstructions of the skull, noting that, though intact, the fossil has been deformed after 70 million years in the Rocky Mountain foothills.
“This discovery also suggests that there are likely more horned dinosaurs out there that we just have not found yet, so we will also be looking for other new species,” Brown says.
Reference:
Current Biology, Brown et al.: “A New Horned Dinosaur Reveals Convergent Evolution in Cranial Ornamentation in Ceratopsidae” DOI: 10.1016/j.cub.2015.04.041
Note : The above story is based on materials provided by Cell Press.
