First study of 'Golden Age' mandolins unlocks secrets of their beauty

Mandolins made by G. Filano 1765 (a), A. Vinaccia 1785 (b), G.B. Fabricatore 1789 (c) and G. Gagliano 1799 (d). Credit: Image courtesy of Springer Science+Business Media

Analyzing varnishes and decorations could provide a new way to identify mandolin "Old Masters."

Some of the most elaborately decorated instruments in history were produced in 18th century Naples. The materials for varnishes and decorations used by individual mandolin masters, honed for wealthy clients in the ancient city's labyrinthine artisan quarter, have been kept secret for over 200 years. Details are disclosed for the first time by Tommaso Rovetta from the Università degli Studi di Pavia and colleagues at the Laboratorio Arvedi Research Group in Springer's journal Applied Physics A -- Materials Science & Processing.

Italian conservation scientists studied ten instruments from some of the most important dynasties of the "Golden Age" of Neapolitan mandolins. Advanced high-resolution imaging techniques shed light on some of the most jealously guarded decorative secrets and could provide a new way to accurately identify mandolins from specific workshops.

The Neapolitan mandolin was set apart by the deeper bowl of its body, producing a more resonant sound heard in works by Beethoven and Verdi. The style was developed by the Vinaccia family and adopted by other leading luthiers such as the Filano, Fabricatore and Gagliano families.

The scientists obtained mandolins from each of these makers courtesy of the National Museum of Musical Instruments in Rome and a private collector. Given their rarity and excellent state of conservation, only microscopic samples could be analysed from already-damaged areas. Nevertheless, the team was able to see that different workshops used different techniques and materials to achieve the same aesthetic effect.

"For mandolins of unknown origin, our results could represent a new way to identify where they were made and therefore their historic and economic value," says Tommaso Rovetta.

In particular, the resin used between patterns of pearl, ivory, bone or possibly horn around the sound hole contain a mixture unique to each workshop. Shellac, a resin from the lac beetle popular today in nail varnish, seems to be the only substance which formed a common base to which pigments and minerals were added. In a 1796 Fabricatore, a mineral found only in the volcanic lavas of Mount Vesuvius was detected. The mixtures in Vinaccia instruments were particularly complex and the scientists were surprised to find the fossilised remains of diatoms, a type of algae.

"We assume there were intense exchanges of technical know-how between masters and their apprentices but, with no written records, this knowledge was taken to the grave," says Rovetta. "We hope the rediscovery of ancient recipes will provide inspiration to today's luthiers."

Source: Springer Science+Business Media

Oldest stone tool ever found in Turkey discovered

Stone tool approximately 1.2 million years old. Credit: Image courtesy of University of Royal Holloway London

Scientists have discovered the oldest recorded stone tool ever to be found in Turkey, revealing that humans passed through the gateway from Asia to Europe much earlier than previously thought, approximately 1.2 million years ago.

According to research published in the journal Quaternary Science Reviews, the chance find of a humanly-worked quartzite flake, in ancient deposits of the river Gediz, in western Turkey, provides a major new insight into when and how early humans dispersed out of Africa and Asia.

Researchers from Royal Holloway, University of London, together with an international team from the UK, Turkey and the Netherlands, used high-precision equipment to date the deposits of the ancient river meander, giving the first accurate timeframe for when humans occupied the area.

Professor Danielle Schreve, from the Department of Geography at Royal Holloway, said: "This discovery is critical for establishing the timing and route of early human dispersal into Europe. Our research suggests that the flake is the earliest securely-dated artefact from Turkey ever recorded and was dropped on the floodplain by an early hominin well over a million years ago."

The researchers used high-precision radioisotopic dating and palaeomagnetic measurements from lava flows, which both pre-date and post-date the meander, to establish that early humans were present in the area between approximately 1.24 million and 1.17 million years ago. Previously, the oldest hominin fossils in western Turkey were recovered in 2007 at Koçabas, but the dating of these and other stone tool finds were uncertain.

"The flake was an incredibly exciting find," Professor Schreve said. "I had been studying the sediments in the meander bend and my eye was drawn to a pinkish stone on the surface. When I turned it over for a better look, the features of a humanly-struck artefact were immediately apparent.

"By working together with geologists and dating specialists, we have been able to put a secure chronology to this find and shed new light on the behaviour of our most distant ancestors."

Source: University of Royal Holloway London

Reshaping the horse through millennia: Sequencing reveals genes selected by humans in domestication

A man catches domestic Mongolian horses with a lasso in Khomiin Tal, Mongolia. Credit: Copyright: Ludovic Orlando.

Whole genome sequencing of modern and ancient horses unveils the genes that have been selected by humans in the process of domestication through the latest 5,500 years, but also reveals the cost of this domestication. A new study led by the Centre for GeoGenetics at the University of Copenhagen, in collaboration with scientists from 11 international universities, reports that a significant part of the genetic variation in modern domesticated horses could be attributed to interbreeding with the descendants of a now extinct population of wild horses. This population was distinct from the only surviving wild horse population, that of the Przewalski's horses. The study has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).

The domestication of the horse some 5,500 years ago ultimately revolutionized human civilization and societies. Horses facilitated transportation as well as the circulation of ideas, languages and religions. Horses also revolutionized warfare with the advent of chariotry and mounted cavalry and beyond the battlefield horses greatly stimulated agriculture. However, the domestication of the horse and the subsequent encroachment of human civilization also resulted in the near extinction of wild horses.

The only surviving wild horse population, the Przewalski's horses from Mongolia, descends from mere 13 individuals, preserved only through a massive conservation effort. As a consequence of this massive loss of genetic diversity, the effects of horse domestication through times have been difficult to unravel on a molecular level. Says Dr. Ludovic Orlando, Associate Professor at the Centre for GeoGenetics, who led this work

"The classical way to evaluate the evolutionary impact of domestication consists of comparing the genetic information present amongst wild animals and their living domesticates. This approach is ill suited to horses as the only surviving population of wild horses has experienced a massive demographic decline in the 20th century. We therefore decided to sequence the genome of ancient horses that lived prior to domestication to directly assess how pre-domesticated horses looked like genetically."

Recent advances in ancient DNA research have opened the door for reconstructing the genomes of ancient individuals. In 2013, Ludovic Orlando and his team succeeded in decoding the genome of a ~700,000 year-old horse, which represents the oldest genome sequenced to date. This time, the researchers focused on much more recent horse specimens, dating from ~16,000 and ~43,000 years ago. These were carefully selected to unambiguously predate the beginning of domestication, some 5,500 years ago. The bone fossils were excavated in the Taymyr Peninsula, Russia, where arctic conditions favor the preservation of DNA.

The human reshaping of the horse

While the horse contributed to reshaping human civilization, humans in turn reshaped the horse to fit their diverse needs and the diverse environments they lived in. This transformation left specific signatures in the genomes of modern horses, which the ancient genomes helped reveal. The scientists were able to detect a set of 125 candidate genes involved in a wide range of physical and behavioral traits, by comparing the genomes of the two ancient horses with those of the Przewalski's horse and five breeds of domesticated horses. Says Dr. Dan Chang, post-doctoral researcher at the UCSC Paleogenomics Lab and co-leading author of the study:

"Our selection scans identified genes that were already known to evolve under strong selection in horses. This provided a nice validation of our approach."

Dr. Beth Shapiro, head of the UCSC Paleogenomics Lab continues: "We provide the most extensive list of gene candidates that have been favored by humans following the domestication of horses. This list is fascinating as it includes a number of genes involved in the development of muscle and bones. This probably reveals the genes that helped utilizing horses for transportation."

And Dr. Ludovic Orlando from the Centre for GeoGenetics at the University of Copenhagen concludes: "Perhaps even more exciting as it represents the hallmark of animal domestication, we identify genes controlling animal behavior and the response to fear. These genes could have been the key for turning wild animals into more docile domesticated forms."

The 'cost of domestication' in horses

However, the reshaping of the horse genome during their domestication also had significant negative impacts. This was apparent in the increasing levels of inbreeding found amongst domesticates, but also through an enhanced accumulation of deleterious mutations in their genomes relative to the ancient wild horses. This finding supports an earlier theory coined 'the cost of domestication', which predicted increasing genetic loads in domesticates compared to their wild ancestors. Says Professor Laurent Excoffier, University of Bern and group leader at the Swiss Institute for Bioinformatics:

"Domestication is generally associated with repeated demographic crashes. Yet, mutations that negatively impact genes are not eliminated by selection and can even increase in frequency when populations are small. Domestication thus generally comes at a cost, as deleterious mutations can accumulate in the genome. This had already been shown for rice and dogs. Horses now provide another example of this phenomenon."

This is something that was only detectable in the horse in comparison to the ancient genomes, as Przewalski's horses were found to show a proportion of deleterious mutations similar to domesticated horses. Says Hákon Jónsson, PhD-student at the Centre for GeoGenetics, co-leading author of the study: "The recent near extinction of the Przewalski's horse population resulted in the persistence of deleterious mutations in the population, following the same mechanism that once led to the accumulation of deleterious mutations in the genomes of domesticated horses. What is striking is that a similar order of magnitude 
was reached even though this occurred in a much shorter time scale than domestication."

An ancient contribution to the present

In addition, comparison of the ancient and modern genomes revealed that the ancient individuals contributed a significant amount of genetic variation to the modern population of domesticated horses, but not to the Przewalski's horses. This suggests that restocking from a wild population descendant from the ancient horses occurred during the domestication processes that ultimately led to the modern domesticated horses. Mikkel Schubert, PhD- student at the Centre for GeoGenetics, co-leading author of the study concludes:

"This confirms previous findings that wild horses were used to restock the population of domesticated horses during the domestication process. However, as we sequenced whole genomes, we can estimate how much of the modern horse genome has been contributed through this process. Our estimate suggests that at least 13%, and potentially up to as much as 60%, of the modern horse genome has been acquired by restocking from the extinct wild population. That we identified the population that contributed to this process demonstrates that it is possible to identify the ancestral genetic sources that ultimately gave rise to our domesticated horses."

Source: Faculty of Science - University of Copenhagen

Ancient Europeans intolerant to lactose for 5,000 years after they adopted agriculture

Milk

By analysing DNA extracted from the petrous bones of skulls of ancient Europeans, scientists have identified that these peoples remained intolerant to lactose (natural sugar in the milk of mammals) for 5,000 years after they adopted agricultural practices and 4,000 years after the onset of cheese-making among Central European Neolithic farmers.

The findings published online in the scientific journal Nature Communications (21 Oct) also suggest that major technological transitions in Central Europe between the Neolithic, Bronze Age and Iron Age were also associated with major changes in the genetics of these populations.

For the study, the international team of scientists examined nuclear ancient DNA extracted from thirteen individuals from burials from archaeological sites located in the Great Hungarian Plain, an area known to have been at the crossroads of major cultural transformations that shaped European prehistory. The skeletons sampled date from 5,700 BC (Early Neolithic) to 800 BC (Iron Age).

It took several years of experimentation with different bones of varying density and DNA preservation for the scientists to discover that the inner ear region of the petrous bone in the skull, which is the hardest bone and well protected from damage, is ideal for ancient DNA analysis in humans and any other mammals.

According to Professor Ron Pinhasi from the UCD Earth Institute and UCD School of Archaeology, University College Dublin, the joint senior author on the paper, "the high percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold. This gave us anywhere between 12% and almost 90% human DNA in our samples compared to somewhere between 0% and 20% obtained from teeth, fingers and rib bones."

For the first time, these exceptionally high percentage DNA yields from ancient remains made it possible for scientists to systematically analyse a series of skeletons from the same region and check for known genetic markers including lactose intolerance.

"Our findings show progression towards lighter skin pigmentation as hunter and gatherers and non-local farmers intermarried, but surprisingly no presence of increased lactose persistence or tolerance to lactose" adds Professor Pinhasi.

"This means that these ancient Europeans would have had domesticated animals like cows, goats and sheep, but they would not yet have genetically developed a tolerance for drinking large quantities of milk from mammals," he says.

According to Professor Dan Bradley from the Smurfit Institute of Genetics, Trinity College Dublin, co-senior author on the paper, "our results also imply that the great changes in prehistoric technology including the adoption of farming, followed by the first use of the hard metals, bronze and then iron, were each associated with the substantial influx of new people. We can no longer believe these fundamental innovations were simply absorbed by existing populations in a sort of cultural osmosis."

Source: University College Dublin

Hunter-gatherer past shows our fragile bones result from inactivity since invention of farming

Hunter-gatherer bone mass compared to agriculturalist bone mass. Credit: Timothy Ryan

New research across thousands of years of human evolution shows that our skeletons have become much lighter and more fragile since the invention of agriculture -- a result of our increasingly sedentary lifestyles as we shifted from foraging to farming.

The new study, published today in the journal PNAS, shows that, while human hunter-gatherers from around 7,000 years ago had bones comparable in strength to modern orangutans, farmers from the same area over 6,000 years later had significantly lighter and weaker bones that would have been more susceptible to breaking.

Bone mass was around 20% higher in the foragers -- the equivalent to what an average person would lose after three months of weightlessness in space.

After ruling out diet differences and changes in body size as possible causes, researchers have concluded that reductions in physical activity are the root cause of degradation in human bone strength across millennia. It is a trend that is reaching dangerous levels, they say, as people do less with their bodies today than ever before.

Researchers believe the findings support the idea that exercise rather than diet is the key to preventing heightened fracture risk and conditions such as osteoporosis in later life: more exercise in early life results in a higher peak of bone strength around the age of 30, meaning the inevitable weakening of bones with age is less detrimental.

There is, in fact, no anatomical reason why a person born today could not achieve the bone strength of an orangutan or early human forager, say researchers; but even the most physically active people alive are unlikely to be loading bones with enough frequent and intense stress to allow for the increased bone strength seen in the 'peak point' of traditional hunter-gatherers and non-human primate bones.

"Contemporary humans live in a cultural and technological milieu incompatible with our evolutionary adaptations. There's seven million years of hominid evolution geared towards action and physical activity for survival, but it's only in the last say 50 to 100 years that we've been so sedentary -- dangerously so," said co-author Dr Colin Shaw from the University of Cambridge's Phenotypic Adaptability, Variation and Evolution (PAVE) Research Group.

"Sitting in a car or in front of a desk is not what we have evolved to do."

The researchers x-rayed samples of human femur bones from the archaeological record, along with femora from other primate species, focusing on the inside of the femoral head: the ball at the top of the femur which fits into the pelvis to form the hip joint, one of the most load-bearing bone connections in the body.

Two types of tissue form bone: the cortical or 'hard' bone shell coating the outside, and the trabecular or 'spongy' bone: the honeycomb-like mesh encased within cortical shell that allows flexibility but is also vulnerable to fracture.

The researchers analysed the trabecular bone from the femoral head of four distinct archaeological human populations representing mobile hunter-gatherers and sedentary agriculturalists, all found in the same area of the US state of Illinois (and likely to be genetically similar as a consequence).

The trabecular structure is very similar in all populations, with one notable exception: within the mesh, hunter-gatherers have a much higher amount of actual bone relative to air.

"Trabecular bone has much greater plasticity than other bone, changing shape and direction depending on the loads imposed on it; it can change structure from being pin or rod-like to much thicker, almost plate-like. In the hunter-gatherer bones, everything was thickened," said Shaw.

This thickening is the result of constant loading on the bone from physical activity as hunter-gatherers roamed the landscape seeking sustenance. This fierce exertion would result in minor damage that caused the bone mesh to grow back ever stronger and thicker throughout life -- building to a 'peak point' of bone strength which counter-balanced the deterioration of bones with age.

Shaw believes there are valuable lessons to be learnt from the skeletons of our prehistoric predecessors. "You can absolutely morph even your bones so that they deal with stress and strain more effectively. Hip fractures, for example, don't have to happen simply because you get older if you build your bone strength up earlier in life, so that as you age it never drops below that level where fractures can easily occur."

Other theories for humans evolving a lighter, more fragile skeleton include changes in diet or selection for a more efficient, lighter skeleton, which was never reversed.

While the initial switch to farming did cause a dip in human health due to monoculture diets that lacked variety, the populations tested were unaffected by this window in history. "Of course we need a level of calcium to maintain bone heath, but beyond that level excess calcium isn't necessary," said Shaw.

The research also counters the theory that, at some point in human evolution, our bones just became lighter -- perhaps because there wasn't enough food to support a denser skeleton. "If that was true, human skeletons would be entirely distinct from other living primates. We've shown that hunter-gatherers fall right in line with primates of a similar body size. Modern human skeletons are not systemically fragile; we are not constrained by our anatomy."

"The fact is, we're human, we can be as strong as an orangutan -- we're just not, because we are not challenging our bones with enough loading, predisposing us to have weaker bones so that, as we age, situations arise where bones are breaking when, previously, they would not have" Shaw said.

While the 7,000-year-old foragers had vastly stronger bones than the 700-year-old farmers, Shaw says that neither competes with even earlier hominids from around 150,000 years ago. 

"Something is going on in the distant past to create bone strength that outguns anything in the last 10,000 years."

The next step for Shaw's research team will be to look at how different types of loading and mobility shape bodies and bones by cross-referencing archaeological records with testing on modern ultra-marathon runners, who cover punishing distances over a range of terrains -- from the Himalayas to the Namibian desert. He hopes this future work will provide insight into the kind of mobility that gave our ancient ancestors such powerful physical strength.

Source: University of Cambridge

Scientists find 240-million-year-old parasite that infected mammals' ancestor

Scott Gardner. Credit: Craig Chandler, University Communications.

An egg much smaller than a common grain of sand and found in a tiny piece of fossilized dung has helped scientists identify a pinworm that lived 240 million years ago.

It is believed to be the most ancient pinworm yet found in the fossil record.

The discovery confirms that herbivorous cynodonts -- the ancestors of mammals -- were infected with the parasitic nematodes. It also makes it even more likely that herbivorous dinosaurs carried pinworms.

Scott Gardner, a parasitologist and director of the Harold W. Manter Laboratory of Parasitology at the University of Nebraska-Lincoln, was among an international group of scientists who published the study in the journal Parasites & Vectors.

"This discovery represents a first for our team and I think it opens the door to finding additional parasites in other species of fossil organisms," he said.

The team found the pinworm egg in a coprolite -- fossilized feces -- collected in 2007 at an excavation site in Rio Grande do Sul state in southern Brazil.

The coprolite was collected at a site with abundant fossilized remains of cynodonts. Previously, an Ascarid-like egg -- resembling a species of nematode commonly found in modern-day mammals -- was found in the coprolite.

The pinworm egg, representing an undescribed or "new species," was named Paleoxyuriscockburni, in honor of Aidan Cockburn, founder of the Paleopathology Association.

The structure of the pinworm egg placed it in a biological group of parasites that occur in animals that ingest large amounts of plant material. Its presence helped scientists deduce which cynodont species, of several found at the collection site, most likely deposited the coprolite.

Since the field of paleoparasitology, or the study of ancient parasites, emerged in the early 20th century, scientists have identified parasites of both plants and animals that date back as far as 500 million years ago.

The study of parasites in ancient animals can help determine the age of fossilized organisms and help establish dates of origin and diversification for association between host species and parasites. Coprolites are a key part of the study, enabling a better understanding of the ecological relationships between hosts and parasites.

Other members of the team were Jean-Pierre Hugot of the National Museum of Natural History in Paris; Victor Borba, Juliana Dutra, Luiz Fernando Ferreira and Adauto Araujo of Oswaldo Cruz Foundation in Rio de Janeiro; Prisiclla Araujo and Daniela Leles of Fluminense Federal University in Rio de Janeiro; and Atila August Stock Da-Rosa of the Federal University of Santa Maria in Rio Grande do Sul.

Source: University of Nebraska-Lincoln

Kilauea, 1790 and today

The Island of Hawai'i, USA.

Scores of people were killed by an explosive eruption of Kīlauea Volcano, Hawai'i, in 1790. Research presented in GSA Bulletin by D.A. Swanson of the Hawaiian Volcano Observatory and colleagues suggests that most of the fatalities were caused by hot, rapidly moving surges of volcanic debris and steam that engulfed the victims. Deposits of such surges occur on the surface on the west summit area and cover an ash bed indented with human footprints.

The footprints, made by warriors and their families, appear along a major trail in use at the time. Today, the area is one of the most visited parts of Hawai'i Volcanoes National Park.
The explosive eruption resulted from the violent interaction of groundwater with hot rocks. Such explosive eruptions have happened frequently in Kīlauea's past and will probably occur in the future when the caldera collapses down to the water table, some 600 m (2000 ft) below the summit of the volcano.

The 1790 eruption of Kīlauea was explosive, and its major impacts were in the summit area of the volcano. The eruption taking place now at Kīlauea is effusive, says Swanson, producing a flow of lava that erupts without explosion. This flow is erupting from a site named Pu'u 'Ō'ō on the east rift zone, far from the summit area, and lava has to flow many kilometers (several miles) before reaching inhabited areas.

Explosive eruptions are very hazardous; the 1790 fatalities bear witness to this fact. Lava flows are not very hazardous to life but can be exceedingly destructive to property. Explosive eruptions are brief but terrifying. Lava flows often last for months or more and are captivating to the viewer. Kīlauea has both types of eruptions, but not at the same time.

Violent explosive eruptions from the summit of Kīlauea are geologically common. They are generally clustered into periods lasting a few centuries. It has been about 200 years since the most recent major explosion, which culminated about 300 years of frequent explosive eruptions. In the past 200 years, Kīlauea has produced many lava flows similar to the present one; small explosions took place in 1924 and, on an even smaller scale, during the past 6 years.

The general public is unaware of Kīlauea's explosive nature, because the volcano has erupted mainly lava flows in recent times. Kīlauea will almost certainly become explosive at some future time, producing conditions similar to those of 1790. However, according to Swanson, there is no reason to think that a period of violent eruptions will resume any time soon. The public can probably expect more lava flows in the near future, such as those of the past three decades from Pu'u 'Ō'ō.

Source: Geological Society of America

Protect the world's deltas, experts urge

A catastrophic landslide, one of the largest known on the surface of the Earth, took place within minutes in southwestern Utah more than 21 million years ago. Credit: Image courtesy of Kent State University

A catastrophic landslide, one of the largest known on the surface of the Earth, took place within minutes in southwestern Utah more than 21 million years ago, reports a Kent State University geologist in a paper published in the November issue of the journal Geology.

The Markagunt gravity slide, the size of three Ohio counties, is one of the two largest known continental landslides (larger slides exist on the ocean floors). David Hacker, Ph.D., associate professor of geology at Kent State University at Trumbull, and two colleagues discovered and mapped the scope of the Markagunt slide over the past two summers.

His colleagues and co-authors are Robert F. Biek of the Utah Geological Survey and Peter D. Rowley of Geologic Mapping Inc. of New Harmony, Utah.

Geologists had known about smaller portions of the Markagunt slide before the recent mapping showed its enormous extent. Hiking through the wilderness areas of the Dixie National Forest and Bureau of Land Management land, Hacker identified features showing that the Markagunt landslide was much bigger than previously known.

The landslide took place in an area between what is now Bryce Canyon National Park and the town of Beaver, Utah. It covered about 1,300 square miles, an area as big as Ohio's Cuyahoga, Portage and Summit counties combined.

Its rival in size, the "Heart Mountain slide," which took place around 50 million years ago in northwest Wyoming, was discovered in the 1940s and is a classic feature in geology textbooks.

The Markagunt could prove to be much larger than the Heart Mountain slide, once it is mapped in greater detail.

"Large-scale catastrophic collapses of volcanic fields such as these are rare but represent the largest known landslides on the surface of the Earth," the authors wrote. The length of the landslide -- over 55 miles -- also shows that it was as fast moving as it was massive, Hacker said.

Evidence showing that the slide was catastrophic -- occurring within minutes -- included the presence of pseudotachylytes, rocks that were melted into glass by the immense friction. Any animals living in its path would have been quickly overrun. Evidence of the slide is not readily apparent to visitors today. "Looking at it, you wouldn't even recognize it as a landslide," Hacker said.

But internal features of the slide, exposed in outcrops, yielded evidence such as jigsaw puzzle rock fractures and shear zones, along with the pseudotachylytes.

Hacker, who studies catastrophic geological events, said the slide originated when a volcanic field consisting of many strato-volcanoes, a type similar to Mount St. Helens in the Cascade Mountains, which erupted in 1980, collapsed and produced the massive landslide.

The collapse may have been caused by the vertical inflation of deeper magma chambers that fed the volcanoes. Hacker has spent many summers in Utah mapping geologic features of the Pine Valley Mountains south of the Markagunt where he has found evidence of similar, but smaller slides from magma intrusions called laccoliths.

What is learned about the mega-landslide could help geologists better understand these extreme types of events. The Markagunt and the Heart Mountain slides document for the first time how large portions of ancient volcanic fields have collapsed, Hacker said, representing "a new class of hazards in volcanic fields."

While the Markagunt landslide was a rare event, it shows the magnitude of what could happen in modern volcanic fields like the Cascades.

"We study events from the geologic past to better understand what could happen in the future," he said. The next steps in the research, conducted with his co-authors on the Geology paper, will be to continue mapping the slide, collect samples from the base for structural analysis and date the pseudotachylytes.

Hacker, who earned his Ph.D. in geology at Kent State, joined the faculty in 2000 after working for an environmental consulting company. He is co-author of the book Earth's Natural Hazards: Understanding Natural Disasters and Catastrophes, published in 2010.

Source:  Kent State University

Geologists discover ancient buried canyon in South Tibet

This photo shows the Yarlung Tsangpo Valley close to the Tsangpo Gorge, where it is rather narrow and underlain by only about 250 meters of sediments. The mountains in the upper left corner belong to the Namche Barwa massif. Previously, scientists had suspected that the debris deposited by a glacier in the foreground was responsible for the formation of the steep Tsangpo Gorge -- the new discoveries falsify this hypothesis. Credit: Ping Wang

A team of researchers from Caltech and the China Earthquake Administration has discovered an ancient, deep canyon buried along the Yarlung Tsangpo River in south Tibet, north of the eastern end of the Himalayas. The geologists say that the ancient canyon--thousands of feet deep in places--effectively rules out a popular model used to explain how the massive and picturesque gorges of the Himalayas became so steep, so fast.

"I was extremely surprised when my colleagues, Jing Liu-Zeng and Dirk Scherler, showed me the evidence for this canyon in southern Tibet," says Jean-Philippe Avouac, the Earle C. Anthony Professor of Geology at Caltech. "When I first saw the data, I said, 'Wow!' It was amazing to see that the river once cut quite deeply into the Tibetan Plateau because it does not today. That was a big discovery, in my opinion."

Geologists like Avouac and his colleagues, who are interested in tectonics--the study of the earth's surface and the way it changes--can use tools such as GPS and seismology to study crustal deformation that is taking place today. But if they are interested in studying changes that occurred millions of years ago, such tools are not useful because the activity has already happened. In those cases, rivers become a main source of information because they leave behind geomorphic signatures that geologists can interrogate to learn about the way those rivers once interacted with the land--helping them to pin down when the land changed and by how much, for example.

"In tectonics, we are always trying to use rivers to say something about uplift," Avouac says. 

"In this case, we used a paleocanyon that was carved by a river. It's a nice example where by recovering the geometry of the bottom of the canyon, we were able to say how much the range has moved up and when it started moving."

The team reports its findings in the current issue of Science.

Last year, civil engineers from the China Earthquake Administration collected cores by drilling into the valley floor at five locations along the Yarlung Tsangpo River. Shortly after, former Caltech graduate student Jing Liu-Zeng, who now works for that administration, returned to Caltech as a visiting associate and shared the core data with Avouac and Dirk Scherler, then a postdoc in Avouac's group. Scherler had previously worked in the far western Himalayas, where the Indus River has cut deeply into the Tibetan Plateau, and immediately recognized that the new data suggested the presence of a paleocanyon.

Liu-Zeng and Scherler analyzed the core data and found that at several locations there were sedimentary conglomerates, rounded gravel and larger rocks cemented together, that are associated with flowing rivers, until a depth of 800 meters or so, at which point the record clearly indicated bedrock. This suggested that the river once carved deeply into the plateau.

To establish when the river switched from incising bedrock to depositing sediments, they measured two isotopes, beryllium-10 and aluminum-26, in the lowest sediment layer. The isotopes are produced when rocks and sediment are exposed to cosmic rays at the surface and decay at different rates once buried, and so allowed the geologists to determine that the paleocanyon started to fill with sediment about 2.5 million years ago.

The researchers' reconstruction of the former valley floor showed that the slope of the river once increased gradually from the Gangetic Plain to the Tibetan Plateau, with no sudden changes, or knickpoints. Today, the river, like most others in the area, has a steep knickpoint where it meets the Himalayas, at a place known as the Namche Barwa massif. There, the uplift of the mountains is extremely rapid (on the order of 1 centimeter per year, whereas in other areas 5 millimeters per year is more typical) and the river drops by 2 kilometers in elevation as it flows through the famous Tsangpo Gorge, known by some as the Yarlung Tsangpo Grand Canyon because it is so deep and long.

Combining the depth and age of the paleocanyon with the geometry of the valley, the geologists surmised that the river existed in this location prior to about 3 million years ago, but at that time, it was not affected by the Himalayas. However, as the Indian and Eurasian plates continued to collide and the mountain range pushed northward, it began impinging on the river. Suddenly, about 2.5 million years ago, a rapidly uplifting section of the mountain range got in the river's way, damming it, and the canyon subsequently filled with sediment.

"This is the time when the Namche Barwa massif started to rise, and the gorge developed," says Scherler, one of two lead authors on the paper and now at the GFZ German Research Center for Geosciences in Potsdam, Germany.

That picture of the river and the Tibetan Plateau, which involves the river incising deeply into the plateau millions of years ago, differs quite a bit from the typically accepted geologic vision. Typically, geologists believe that when rivers start to incise into a plateau, they eat at the edges, slowly making their way into the plateau over time. However, the rivers flowing across the Himalayas all have strong knickpoints and have not incised much at all into the Tibetan Plateau. Therefore, the thought has been that the rapid uplift of the Himalayas has pushed the rivers back, effectively pinning them, so that they have not been able to make their way into the plateau. But that explanation does not work with the newly discovered paleocanyon.

The team's new hypothesis also rules out a model that has been around for about 15 years, called tectonic aneurysm, which suggests that the rapid uplift seen at the Namche Barwa massif was triggered by intense river incision. In tectonic aneurysm, a river cuts down through the earth's crust so fast that it causes the crust to heat up, making a nearby mountain range weaker and facilitating uplift.

The model is popular among geologists, and indeed Avouac himself published a modeling paper in 1996 that showed the viability of the mechanism. "But now we have discovered that the river was able to cut into the plateau way before the uplift happened," Avouac says, "and this shows that the tectonic aneurysm model was actually not at work here. The rapid uplift is not a response to river incision."

Source:  California Institute of Technology

Colorado's Front Range fire severity not much different than past

A new study indicates present-day forest fires on Colorado's Front Range are not significantly more intense than historical fires. Credit: Glenn Asakawa, University of Colorado

The perception that Colorado's Front Range wildfires are becoming increasingly severe does not hold much water scientifically, according to a massive new study led by the University of Colorado Boulder and Humboldt State University in Arcata, Calif.

The study authors, who looked at 1.3 million acres of ponderosa pine and mixed conifer forest from Teller County west of Colorado Springs through Larimer County west and north of Fort Collins, reconstructed the timing and severity of past fires using fire-scarred trees and tree-ring data going back to the 1600s. Only 16 percent of the study area showed a shift from historically low-severity fires to severe, potential crown fires that can jump from treetop to treetop.

The idea that modern fires are larger and more severe as a result of fire suppression that allowed forest fuels to build up in the past century is still prevalent among some, said CU-Boulder geography Professor Thomas Veblen, a study co-author. "The key point here is that modern fires in these Front Range forests are not radically different from the fire severity of the region prior to any effects of fire suppression," he said.

A paper on the subject was published Sept. 24 in the journal PLOS ONE. The study was led by Associate Professor Rosemary Sherriff of Humboldt State University and involved Research Scientist Tania Schoennagel of CU-Boulder's Institute of Arctic and Alpine Research, CU-Boulder doctoral student Meredith Gartner and Associate Professor Rutherford Platt of Gettysburg College in Gettysburg, Pa.

The study was funded by the National Science Foundation.

"The common assumption is that fires are now more severe and are killing higher percentages of trees," said Sherriff, who completed her doctorate at CU-Boulder under Veblen in 2004. "Our results show that this is not the case on the Front Range except for the lowest elevation forests and woodlands."

One important new finding comes from a comparison of nine large fires that have occurred on the Front Range since 2000 -- including the 2002 Hayman Fire southwest of Denver, the 2010 Fourmile Canyon Fire west of Boulder and the 2012 High Park Fire west of Fort Collins -- with historic fire effects in the region.

"It's true that the Colorado Front Range has experienced a number of large fires recently," said Schoennagel. "While more area has burned recently compared to prior decades -- with more homes coming into the line of fire -- the severity of recent fires is not unprecedented when we look at fire records going back before the 1900s."

In addition, tree-ring evidence from the new study shows there were several years on the Front Range since the 1650s when there were very large, severe fires. The authors looked at more than 1,200 fire-scarred tree samples and nearly 8,000 samples of tree ages at 232 forest sample sites from Teller County to Larimer County.

The study is one of the largest of its kind ever undertaken in the western United States. The team was especially interested in fire records before about 1920, when effective fire suppression in the West began in earnest.

"In relatively dry ponderosa pine forests of the West, a common assumption is that fires were relatively frequent and of low severity, and not lethal to most large trees, prior to fuel build-up in the 20th century," said Veblen. "But our study results showed that about 70 percent of the forest study area experienced a combination of moderate and high-severity fires in which large percentages of the mature trees were killed."

Along the Front Range, especially at higher elevations, homeowners and fire managers should expect a number of high-severity fires unrelated to any kind of fire suppression and fuel build-up, said Schoennagel. "This matters because high-severity fires are dangerous to people, kill more trees and are trickier and more expensive to suppress."

"Severe fires are not new to most forests in this region," said Sherriff. "What is new is the expanded wildland-urban interface hazard to people and property and the high cost of suppressing fires for society."

In addition, a warming Colorado climate -- 2 degrees Fahrenheit since 1977 -- has become a wild card regarding future Front Range fires, according to the team. While fires are dependent on ignition sources and can be dramatically influenced by high winds, the team expects to see a substantial increase in Front Range fire activity in the low and mid-elevations in the coming years as temperatures continue to warm, a result of rising greenhouses gases in Earth's atmosphere.

Source: University of Colorado at Boulder

Permafrost soil: Possible source of abrupt rise in greenhouse gases at end of last ice age

Pleistocene Ice Complex cliff: 35 meters high Pleistocene Ice Complex cliff at Sobo Sise Island (Lena Delta), Siberian Arctic. Credit: Alfred-Wegener-Institut / Thomas Opel

Scientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have identified a possible source of carbon dioxide (CO2) and other greenhouse gases that were abruptly released to the atmosphere in large quantities around 14,600 years ago. According to this new interpretation, the CO2 -- released during the onset of the Bølling/Allerød warm period -- presumably had their origin in thawing Arctic permafrost soil and amplified the initial warming through positive feedback. The study now appears online in the journal Nature Communications.

One of the most abrupt rises in the carbon dioxide concentration in the atmosphere at the end of the last ice age took place about 14,600 years ago. Ice core data show that the CO2 concentration at that time increased by more than 10 ppm (parts per million, unit of measure for the composition of gases) within 200 years. This CO2 increase, i.e. approx. 0.05 ppm per year, was significantly less than the current rise in atmospheric CO2 of 2-3 ppm in the last decade caused by fossil fuels. These data describe an abrupt change in the global carbon cycle during the transition from the last ice age to the present-day warm interglacial and allow conclusions to be drawn about similar processes that could play a role in the future.

To determine the origin of the greenhouse gas, a team around by the geoscientists and climate researchers Dr. Peter Köhler and Dr. Gregor Knorr from the Alfred Wegener Institute has carried out computer simulations focusing on the new interpretation of these CO2 data. These calculations were motivated by new radiocarbon data (14C) that provide information on the age of the CO2 released to the atmosphere. The age of the carbon then allows conclusions to be drawn about the carbon source.

"The virtual lack of radiocarbon in the CO2 that was released into the atmosphere shows us that the carbon must have been very old," says Köhler. The carbon therefore cannot be originated from the deep ocean, Köhler adds: "The carbon stored in the deep ocean has been subject to exchange with the atmosphere over a period of millennia. In the atmosphere 14C has its only source. It is produced through the impact of galactic cosmic rays on molecules in the atmosphere." However, radiocarbon is unstable and decays with a half-life of around 5,700 years. The atmospheric data of CO2 and 14C can only be explained if a carbon source is assumed that contains virtually no 14C any more -- thus the greenhouse gases must have had another source than the deep ocean.

Permafrost soil contains, to some extent, very old organic material, which is released in the form of the greenhouse gases CO2 and methane when the soil thaws. Permafrost soil thus might be a possible source of old carbon. The thawing of Arctic permafrost soil might have been caused by a sudden resumption of large-scale Atlantic heat transport in the ocean that initiated the Bølling/Allerød warm period in the high northern hemisphere.

The scientists were able to estimate the amount of the carbon dioxide released to the atmosphere by applying a computer model that simulates the global carbon cycle. The simulation results indicate that the input of more than half a gigaton of carbon per year (1 gigaton = 1 petagram) over a period of two centuries is necessary to explain the observed data. This corresponds to a total amount of more than 100 gigatons of carbon. Present-day anthropogenic CO2 emissions due to fossil fuels, at approx. ten gigatons of carbon a year, are greater than the release rates of this natural process by a factor of at least ten.

According to the study, the proposed thawing of large areas of permafrost, followed by the rise in greenhouse gases, occurred at the same time as the warming in the northern hemisphere at the beginning of the Bølling warm period. The released greenhouse gases may amplify the initial warming through feedback effects.

A similar effect is also predicted for the future in the current IPCC report. Warming in Siberia, for instance, is already leading to thawing of permafrost soil: outgassing of CO2 and methane takes place. The same processes observed today -- and are expected to an even greater extent in the coming decades -- presumably occurred in a similar manner 14,600 years ago. "However, the state of the climate on Earth today has already been changed by anthropogenically emitted greenhouse gases. Future CO2 release due to the proposed thawing of permafrost will be substantially less than the input due to fossil fuels. However, these emissions from permafrost soil are additional greenhouse gas sources that further amplify the anthropogenically induced effect," says Köhler.

Source:  Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research

Emergence of modern sea ice in Arctic Ocean, 2.6 million years ago

Field Work in the Arctic sea ice. Credit: Thomas A. Brown and Simon T. Belt

"We have not seen an ice free period in the Arctic Ocean for 2,6 million years. However, we may see it in our lifetime." says marine geologist Jochen Knies. In an international collaborative project, Knies has studied the historic emergence of the ice in the Arctic Ocean. The results are published in Nature Communications.

The extent of sea ice cover in Arctic was much less than it is today between four and five million years ago. The maximum winter extent did not reaching its current location until around 2.6 million years ago. This new knowledge can now be used to improve future climate models.

"We have not seen an ice free period in the Arctic Ocean for 2,6 million years. However, we may see it in our lifetime. The new IPCC report shows that the expanse of the Arctic ice cover has been quickly shrinking since the 70-ies, with 2012 being the year of the sea ice minimum," Jochen Knies.

He is marine geologist at the Geological Survey of Norway (NGU) and Centre for Arctic Gas Hydrate, Climate and Environment, UiT The Arctic Univeristy of Norway.

In an international collaborative project, Jochen Knies has studied the trend in the sea ice extent in the Arctic Ocean from 5.3 to 2.6 million years ago. That was the last time Earth experienced a long period with a climate that, on average, was warm before cold ice ages began to alternate with mild interglacials.

Fossils reveal past sea ice extent

"When we studied molecules from certain plant fossils preserved in sediments at the bottom of the ocean, we found that large expanses of the Arctic Ocean were free of sea ice until four million years ago," Knies tells us.

"Later, the sea ice gradually expanded from the very high Arctic before reaching, for the first time, what we now see as the boundary of the winter ice around 2.6 million years ago ," says Jochen Knies, who is also attached to CAGE, the Centre for Arctic Gas Hydrate, 

Environment and Climate at the University of Tromsø, the Arctic University of Norway.

Arctic Ocean likely to be completely free of sea ice

The research is of great interest on the international stage because present-day global warming is strongly tied to a shrinking ice cover in the Arctic Ocean. By the end of the present century, the Arctic Ocean seems likely to be completely free of sea ice, especially in summer.

This may have major significance for the entire planet 's climate system. Polar oceans , their temperature and salinity, are important drivers for world ocean circulation that distributes heat in the oceans. It also affects the heat distribution in the atmosphere. Trying to anticipate future changes in this finely tuned system, is a priority for climate researchers. For that they use climate modeling , which relies on good data.

"Our results can be used as a tool in climate modelling to show us what kind of climate we can expect at the turn of the next century. There is no doubt that this will be one of many tools the UN Climate Panel will make use of, too. The extent of the ice in the Arctic has always been very uncertain but, through this work, we show how the sea ice in the Arctic Ocean developed before all the land-based ice masses in the Northern Hemisphere were established," Jochen Knies explains.

Seabed samples from Spitsbergen

A deep well into the ocean floor northwest of Spitsbergen was the basis for this research. It was drilled as part of the International Ocean Drilling Programme, (IODP), to determine the age of the ocean-floor sediments in the area. Then, by analysing the sediments for chemical fossils made by certain microscopic plants that live in sea ice and the surrounding oceans, Knies and his co-workers were able to fingerprint the environmental conditions as they changed through time.

"One thing these layers of sediment enable us to do is to "read" when the sea ice reached that precise point," Jochen Knies tells us.

The scientists believe that the growth of sea ice until 2.6 million years ago was partly due to the considerable exhumation of the land masses in the circum-Arctic that occurred during this period. "Significant changes in altitudes above sea level in several parts of the Arctic, including Svalbard and Greenland, with build-up of ice on land, stimulated the distribution of the sea ice," Jochen Knies says.

"In addition, the opening of the Bering Strait between America and Russia and the closure of the Panama Cannel in central America at the same time resulted in a huge supply of fresh water to the Arctic, which also led to the formation of more sea ice in the Arctic Ocean," Jochen Knies adds.

All the large ice sheets in the Northern Hemisphere existed around 2.6 million years ago.

Scientists at Norwegian Geological Survey (NGU), CAGE, UiT The Arctic University of Norway,University of Plymouth, Universitat Autònoma de Barcelona, Stellenbosch University in South Africa and Institució Catalana de Recerca i Estudis Avançats in Barcelona have collaborated in this work.

Source:  University of Tromso (Universitetet i Tromsø - UiT)

Ancient creature discovered in the depths of the Arctic Ocean

This image shows the new species of bivalve mollusk was recently described and named Wallerconcha sarae. Credit: Paul Valentich-Scott; CC-BY 4.0

In the depths of the Arctic Ocean, buried deep in the sediment, an ancient creature waited for over a million years to be discovered. Paul Valentich-Scott, from the Santa Barbara Museum of Natural History (California), and three scientists from the United States Geological Survey (USGS, Menlo Park, California), Charles L. Powell, Brian D. Edwards, and Thomas D. Lorenson were up to the challenge. Each with different expertise, they were able to collect, analyze, and identify a new genus and new species of bivalve mollusk.

The path to discovery is seldom simple or easy. This discovery is no exception. Brian Edwards was the chief scientist on a joint US-Canadian ice breaker expedition aboard the US Coast Guard Cutter Healy in the summer of 2010. The primary purpose of the expedition was to map the Arctic seafloor and the sediments beneath. Dr. Edwards took deep sediment core samples to further understand the geology of the region including the unusual seafloor mound where these samples were collected. In several of these cores he uncovered bivalve seashells buried nearly 15 feet (4.5 m) below the seafloor surface.

Upon returning to his USGS laboratory in Menlo Park, California, Brian worked with Tom Lorenson on sampling the cores and extracting the shells. The recovered shells were then taken to USGS paleontologist Chuck Powell, for identification. While Chuck was able to ascertain the higher level classification of the clam shells (Family Thyasiridae), he was unable to determine the genus or species. Chuck contacted Paul Valentich-Scott, a clam specialist from the Santa Barbara Museum of Natural History in California.

When examining these ancient shell specimens, Paul was fairly certain that they were new to science. The hunt to validate the potential new species was on. Paul contacted a number of thyasirid bivalve specialists around the world and all gave it a thumbs up as a new species. Further, several scientists felt it also might be a new genus (the level above species).

'It is always exciting when you are the first person to be looking at a new creature' declared Valentich-Scott. 'While I have been fortunate to discover and describe many new species in my career, it is always exhilarating at the outset.'

Then the painstaking work began. Paul contacted museums around the globe and requested to borrow specimens that were potentially related to the new species. While he found many species that shared some characteristics, none matched the new Arctic specimens.

The four scientists have been writing up their findings for the past two years and now the work has been published in the international science journal ZooKeys.

The new genus and species is named after two individuals. The genus is named in honor of Dr. Thomas R. Waller a prominent paleontologist at the Smithsonian Institution. The suffix "concha" meaning shell, is combined to create the name Wallerconcha. The new species is named after Sara Powell the daughter of co-author Chuck Powell. Chuck was quick to mention "I want to name new species after all of my children."

While many of the specimens collected were definitely fossils, the scientists can't discount the new animal might still be alive today. One of the team members, Tom Lorenson, summarized it this way 'The likely collection of living specimens of this species awaits expeditions to come.' Who knows what other new creatures might be found in those expeditions?

Soure: Pensoft Publishers