A caravan moves across the Lee Adoyta region in the Ledi-Geraru project area near the early Homo site. The hills behind the camels expose sediments that are younger than 2.67 million year old, providing a minimum age for the LD 350-1 mandible. Credit: Erin DiMaggio, Penn State
The earliest known record of the genus Homo — the human genus — represented by a lower jaw with teeth, recently found in the Afar region of Ethiopia, dates to between 2.8 and 2.75 million years ago, according to an international team of geoscientists and anthropologists. They also dated other fossils to between 2.84 and 2.58 million years ago, which helped reconstruct the environment in which the individual lived.
“The record of hominin evolution between 3 and 2.5 million years ago is poorly documented in surface outcrops, particularly in Afar, Ethiopia,” said Erin N. DiMaggio, research associate in the department of geosciences, Penn State.
Hominins are the group of primates that include Homo sapiens — humans — and their ancestors. The term is used for the branch of the human evolutionary line that exists after the split from chimpanzees.
Directly dating fossils this old is impossible, so geologists use a variety of methods to date the layers of rock in which the fossils are found. The researchers dated the recently discovered Ledi-Geraru fossil mandible, known by its catalog number LD 350-1, by dating various layers of volcanic ash or tuff using argon40 argon39 dating, a method that measures the different isotopes of argon and determines the age of the eruption that created the sample. They present their results in today’s (Mar. 4) online issue of Science Express.
“We are confident in the age of LD 350-1,” said DiMaggio, lead author on the paper. “We used multiple dating methods including radiometric analysis of volcanic ash layers, and all show that the hominin fossil is 2.8 to 2.75 million years old.”
The area of Ethiopia where LD 350-1 was found is part of the East African Rift System, an area that undergoes tectonic extension, which enabled the 2.8 million-year-old rocks to be deposited and then exposed through erosion, according to DiMaggio. In most areas in Afar, Ethiopia, rocks dating to 3 to 2.5 million years ago are incomplete or have eroded away, so dating those layers and the fossils they held is impossible. In the Ledi-Geraru area, these layers of rocks are exposed because the area is broken by faults that occurred after the sedimentary rocks were deposited.
By dating volcanic ash layers below the fossils and then above the fossils, geologists can determine the youngest and oldest dates when the animal that became the fossil could have lived.
Other fossils found in this area include those of prehistoric antelope, water dependent grazers, prehistoric elephants, a type of hippopotamus and crocodiles and fish. These fossils fall within the 2.84 to 2.54 million years ago time range. Kaye E. Reed, University Professor, Institute of Human Origins, Arizona State University, analyzed the fossil assemblage to try to learn about the ecological community in which the LD 350-1 early Homo lived.
The fossils suggest that the area was a more open habitat of mixed grasslands and shrub lands with a gallery forest — trees lining rivers or wetlands. The landscape was probably similar to African locations like the Serengeti Plains or the Kalahari. Some researchers suggest that global climate change intensifying roughly 2.8 million years ago resulted in African climate variability and aridity and this spurred evolutionary changes in many mammal lines.
“We can see the 2.8 million-year-old aridity signal in the Ledi-Geraru faunal community,” said Reed. “But it’s still too soon to say that this means climate change is responsible for the origin of Homo. We need a larger sample of hominin fossils and that’s why we continue to come to the Ledi-Geraru area to search.”
Volcano Villarrica in southern Chile erupted in the early hours of Tuesday “Mar-3-2015”, sending ash and lava high into the sky, and forcing the evacuation of nearby communities.
The notorious San Andreas Fault runs virtually the entire length of California. Credit: Courtesy of US Geological Survey
U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) is reporting the successful study of stress fields along the San Andreas fault at the microscopic scale, the scale at which earthquake-triggering stresses originate.
Working with a powerful microfocused X-ray beam at Berkeley Lab’s Advanced Light Source (ALS), a DOE Office of Science User Facility, researchers applied Laue X-ray microdiffraction, a technique commonly used to map stresses in electronic chips and other microscopic materials, to study a rock sample extracted from the San Andreas Fault Observatory at Depth (SAFOD). The results could one day lead to a better understanding of earthquake events.
“Stresses released during an earthquake are related to the strength of rocks and thus in turn to the rupture mechanism,” says Martin Kunz, a beamline scientist with the ALS’s Experimental Systems Group. “We found that the distribution of stresses in our sample were very heterogeneous at the micron scale and much higher than what has been reported with macroscopic approximations. This suggests there are different processes at work at the microscopic and macroscopic scales.”
Kunz is one of the co-authors of a paper describing this research in the journal Geology. The paper is titled “Residual stress preserved in quartz from the San Andreas Fault Observatory at Depth.” Co-authors are Kai Chen, Nobumichi Tamura and Hans-Rudolf Wenk.
Most earthquakes occur when stress that builds up in rocks along active faults, such as the San Andreas, is suddenly released, sending out seismic waves that make the ground shake. The pent- up stress results from the friction caused by tectonic forces that push two plates of rock against one another.
“In an effort to better understand earthquake mechanisms, several deep drilling projects have been undertaken to retrieve material from seismically active zones of major faults such as SAFOD,” says co-author Wenk, a geology professor with the University of California (UC) Berkeley’s Department of Earth and Planetary Science and the leading scientist of this study. “These drill-core samples can be studied in the laboratory for direct information about physical and chemical processes that occur at depth within a seismically active zone. The data can then be compared with information about seismicity to advance our understanding of the mechanisms of brittle failure in the Earth’s crust from microscopic to macroscopic scales.”
Kunz, Wenk and their colleagues measured remnant or “fossilized” stress fields in fractured quartz crystals from a sample taken out of a borehole in the San Andreas Fault near Parkfield, California at a depth of 2.7 kilometers. The measurements were made using X-ray Laue microdiffraction, a technique that can determine elastic deformation with a high degree of accuracy. Since minerals get deformed by the tectonic forces that act on them during earthquakes, measuring elastic deformation reveals how much stress acted on the minerals during the quake.
“Laue microdiffraction has been around for quite some time and has been exploited by the materials science community to quantify elastic and plastic deformation in metals and ceramics, but has been so far only scarcely applied to geological samples,” says co-author Tamura, a staff scientist with the ALS’s Experimental Systems Group who spearheads the Laue diffraction program at the ALS.
Using ALS beamline 12.3.2, researchers carried out an X-ray microdiffraction study on quartz grains from the San Andreas Fault Observatory at Depth and found a heterogeneous distribution of stress.
The measurements were obtained at ALS beamline 12.3.2, a hard (high-energy) X-ray diffraction beamline specialized for Laue X-ray microdiffraction.
“ALS Beamline 12.3.2 is one of just a few synchrotron-based X-ray beamlines in the world that can be used to measure residual stresses using Laue micro diffraction,” Tamura says.
In their analysis, the Berkeley researchers found that while some of the areas within individual quartz fragments showed no elastic deformation, others were subjected to stresses in excess of 200 million pascals (about 30,000 psi). This is much higher than the tens of millions of pascals of stress reported in previous indirect strength measurements of SAFOD rocks.
“Although there are a variety of possible origins of the measured stresses, we think these measured stresses are records of seismic events shocking the rock,” says co-author Chen of China’s Xi’an Jiantong University. It is the only mechanism consistent with the geological setting and microscopic observations of the rock.”
The authors believe their Laue X-ray microdiffraction technique has great potential for measuring the magnitude and orientation of residual stresses in rocks, and that with this technique quartz can serve as “paleo-piezometer” for a variety of geological settings and different rock types.
“Understanding the stress fields under which different types of rock fail will help us better understand what triggers earthquakes,” says Kunz. “Our study could mark the beginning of a whole new era of quantifying the forces that shape the Earth.”
Reference:
K. Chen, M. Kunz, N. Tamura, H.-R. Wenk. Residual stress preserved in quartz from the San Andreas Fault Observatory at Depth. Geology, 2015; 43 (3): 219 DOI: 10.1130/G36443.1
Round diatoms (Di) in close proximity to methane-oxidizing bacteria (fluorescent green). Combination of fluorescence microscopy and X-ray spectroscopic mapping of silica. (Source: Eawag / MPI-Bremen)
Methane emissions are strongly reduced in lakes with anoxic bottom waters. But here — contrary to what has previously been assumed — methane removal is not due to archaea or anaerobic bacteria. A new study on Lake Cadagno in Canton Ticino shows that the microorganisms responsible are aerobic proteobacteria. The oxygen they require is produced in situ by photosynthetic algae.
In contrast to oceans, freshwater lakes — and tropical reservoirs — are significant sources of methane emissions. Methane, a greenhouse gas, arises from the degradation of organic material settling on the bottom. Although lakes occupy a much smaller proportion of Earth’s surface than oceans, they account for a much larger proportion of methane emissions. Well-mixed lakes, in turn, are the main contributors, while emissions from seasonally or permanently stratified lakes with anoxic bottom waters are greatly reduced. It has been assumed to date that the methane-removing processes occurring in such lakes are the same as those in marine systems. But a new study carried out on Lake Cadagno (Canton Ticino) by researchers from Eawag and the Max Planck Institute for Marine Microbiology (Bremen, Germany) shows that this is not the case.
Typical profiles of oxygen and methane concentrations in Lake Cadagno. Methane consumption occurs in a relatively thin water layer at a depth of 10–13 metres. (Data: Eawag / MPI-Bremen)
The scientists demonstrated that methane is almost completely consumed in the anoxic waters of Lake Cadagno, but they did not detect any known anaerobic methane-oxidizing bacteria — or archaea, which are responsible for marine methane oxidation. Instead, water samples collected from a depth of around 12 metres were found to contain abundant aerobic proteobacteria — up to 240,000 cells per millilitre.
“We wondered, of course, how these aerobic bacteria can survive in anoxic waters,” says first author Jana Milucka of the Max Planck Institute for Marine Microbiology. To answer this question, the behaviour of the bacteria was investigated in laboratory experiments: methane oxidation was found to be stimulated only when oxygen was added to the samples incubated in vitro, or when they were exposed to light. The scientists concluded that the oxygen required by the bacteria is produced by photosynthesis in neighbouring diatoms. Analysis by fluorescence microscopy showed that methane-oxidizing bacteria belonging to the family Methylococcaceae occur in close proximity to diatoms and can thus utilize the oxygen they generate .
Thanks to the combined activity of bacteria and diatoms, methane is thus consumed in the lake rather than being released into the atmosphere. This type of methane removal has not previously been described in freshwater systems. Project leader Carsten Schubert of Eawag comments: “For lakes with anoxic layers, and also for certain marine zones, it looks as if the textbooks will have to be rewritten.” Aerobic methane-oxidizing bacteria may play a significant role wherever sufficient light penetrates to anoxic water layers; according to Schubert, this is the case in most Swiss lakes. Similar observations have already been made in Lake Rotsee near Lucerne, in studies not yet published. Research will now focus on deeper lakes, where initial investigations suggest that different processes occur.
Reference:
Jana Milucka, Mathias Kirf, Lu Lu, Andreas Krupke, Phyllis Lam, Sten Littmann, Marcel MM Kuypers, Carsten J Schubert. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters. The ISME Journal, 2015; DOI: 10.1038/ismej.2015.12
Banded Iron Formation at Fortescue Falls, Karijini National Park. Credit: Graeme Churchard
A UWA geologist has proposed a hypothesis which threatens to overturn conventional notions of the way Banded Ironstone Formations (BIF) first evolved.
BIF is a sedimentary rock with stripes of iron and silica which is well known to geologists and rock collectors.
While it is generally accepted that BIF formed when dissolved iron oxidised and settled to the bottoms of early seas, geologist Desmond Lascelles says this would have been impossible as iron is only soluble in acid.
“Ferrous iron is not soluble in sea water,” he says.
“It only occurs as colloidal ferric iron or ferrous iron in sea water which precipitates out, but you can’t end up with sufficient iron in solution to form a banded iron formation.”
As none of these compounds are water soluble, Dr Lascelles says the ocean cannot form a large reservoir of iron.
He says silica, which forms the lighter bands in BIF, is similarly insoluble.
While it initially mixes with water it precipitates out as it ages so large quantities never occur in solution.
Instead, he says, the iron and silica compounds came from hydrothermal vents on the ocean floor known as “black smokers”.
Build-up happens around vents
The “smoke” is the precipitated iron oxides and iron silicates that end up as a mound around the vent.
Dr Lascelles says water currents redistribute these mounds and the particles settle elsewhere as layers of mud that harden to become banded ironstone.
Known BIF deposits are at least 1.8 billion years old, which is 600 million years after the “great oxidation event” when green plants first oxygenated the atmosphere and ocean.
Younger BIF has not been found, supporting the conventional notion that newly-oxygenated seas quickly lost their reservoir of dissolved iron, which literally rusted forming most of the world’s BIF within a relatively short period.
However, Dr Lascelles says the apparent increase in the amount of BIF in the Paleoproterozoic era (2,500 to 1,600 million years ago) had nothing to do with oxygen in the atmosphere.
Instead he attributes it to the introduction of plate tectonics and the movement of continents, after stable continents first formed.
Dr Lascelles says younger BIF forms on the ocean floor but the tectonic plates supporting it are then subducted under the continents.
According to his model, banded ironstone has been forming throughout history and new deposits may still be occurring, under suitable conditions, from hydrothermal vents deep beneath the ocean.
Reference:
Lascelles, D: Plate tectonics caused the demise of banded iron formations in Applied Earth Science DOI 10.1179/1743275814Y.0000000043
This image shows locations of the mainshock (red dot), aftershocks, surface ruptures (red lines), and locations of permanent (unfilled triangles) and temporary (filled triangles) seismic stations. Credit: Seismological Research Letters
SAN FRANCISCO–An analysis of buildings tagged red and yellow by structural engineers after the August 2014 earthquake in Napa links pre-1950 buildings and the underlying sedimentary basin to the greatest shaking damage, according to one of six reports on the Napa quake published in the March/April issue of Seismological Research Letters (SRL).
“This data should spur people to retrofit older homes,” said John Boatwright, a geophysicist with the U.S. Geological Survey (USGS) in Menlo Park and the lead author of a study that analyzed buildings tagged by the City of Napa.
The South Napa earthquake was the largest earthquake to strike the greater San Francisco Bay Area since the magnitude 6.9 Loma Prieta earthquake in 1989, damaging residential and commercial buildings from Brown’s Valley through historic downtown Napa.
“The larger faults, like the San Andreas and Hayward faults, get the public’s attention, but lesser known faults, like the West Napa fault, can cause extensive damage. Unreinforced brick masonry and stone buildings have been shown to be especially vulnerable to earthquakes,” said Erol Kalkan, a research structural engineer at USGS and guest editor of the SRL special issue, which features six technical reports that cover different aspects of the magnitude 6.0 South Napa earthquake on August 24, 2014.
This image shows red and yellow tags plotted on the street grid and topography of Napa. Credit: Seismological Research Letters
The South Napa earthquake occurred on the West Napa Fault system, a recognized but poorly studied fault lying between the longer Rodgers Creek and Green Valley faults, and caused strong ground motions, as detailed in the paper by Tom Brocher et al. The mapped surface rupture was unusually large for a moderate quake, extending nearly eight miles from Cuttings Wharf in the south to just west of Alston Park in the north.
An extensive sedimentary basin underlies much of Napa Valley, including the City of Napa. The basin, which may be as much as 2 km deep beneath the city, appears to have amplified the ground motion. A close look at the damaged buildings within the city revealed a clear pattern.
“Usually I look to certain factors that influence ground motion at a specific site – proximity to the fault rupture, directivity of the rupture process and the geology underneath the site,” said Boatwright. “The source distance and the direction of rupture did not strongly condition the shaking damage in Napa.”
Boatwright et al., analyzed data provided by structural engineers who inspected and tagged damaged buildings after the earthquake. The 165 red tags (prohibited access) and 1,707 yellow tags (restricted access) stretched across the city but were primarily concentrated within the residential section that lies between State Route 29 and the Napa River, including the historic downtown area.
When comparing the distribution of red and yellow-tagged buildings to the underlying sedimentary basin, to the pre-1950 development of Napa and to the recent alluvial geology of Napa Valley, the most severe damage correlates to the age of the buildings–pre-1950 construction–and their location within the basin. Less damaged areas to the east and west of central Napa lie outside of the sedimentary basin, and the moderately damaged neighborhoods to the north lie inside the basin but are of more recent construction.
Although the city’s buildings suffered extensive damage, there were few reports of ground failure, such as liquefaction and landslides. Brocher et al. suggest the timing of the earthquake near the end of the dry season, the three-year long drought and resulting low water table inhibited the liquefaction of the top layers of sandy deposits, sparing the area greater damage.
This is a secondary electron image showing a glass spherule formed in high-voltage flashover experiments to examine the effect of ash contamination on electrical insulators. Photo by Kimberly Genareau. Credit: Kimberly Genareau, Genareau et al., Geology, Geological Society of America.
In their open-access paper for Geology, Kimberly Genareau and colleagues propose, for the first time, a mechanism for the generation of glass spherules in geologic deposits through the occurrence of volcanic lightning. The existence of fulgurites — glassy products formed in rocks and sediments struck by cloud-to-ground lightning — provide direct evidence that geologic materials can be melted via natural lightning occurrence.
Lightning-induced volcanic spherules (LIVS) form in the atmosphere from the physical transformation of volcanic ash particles into spheres of glass due to the high heat generated by lightning discharge. Examples of these textures were discovered in deposits from two volcanic eruptions where lightning was extensively documented: The 23 March 2009 eruption of Mount Redoubt, Alaska, USA, and the April-May 2010 eruption of Eyjafjallajökull, Iceland.
In some cases, the individual spherules are smooth, while in other instances the surfaces are interrupted by holes or cracks that appear to result from outward expansion of the spherule interior. Analogue laboratory experiments, examining the flashover mechanism across high voltage insulators contaminated by volcanic ash, confirm that glass spherules can be formed from the high heat generated by electrical discharge.
Reference:
Lightning-induced volcanic spherules
Kimberly Genareau et al., University of Alabama, Tuscaloosa, Alabama, USA. Published online ahead of print on 27 Feb. 2015; http://dx.doi.org/10.1130/G36255.1. This article is OPEN ACCESS online.
Villarrica volcano in southern Chile began erupting early Tuesday forcing the evacuation of some 3,000 people in nearby villages, the government said. VIDEOGRAPHIC
The Z machine is in Albuquerque, N.M., and is part of the Pulsed Power Program, which started at Sandia National Laboratories in the 1960s. Pulsed power concentrates electrical energy and turns it into short pulses of enormous power, which are then used to generate X-rays and gamma rays. Credit: Randy Montoya
Recreating the violent conditions of Earth’s formation, scientists are learning more about how iron vaporizes and how this iron rain affected the formation of Earth and Moon. The study is published March 2 in Nature Geoscience.
“We care about when iron vaporizes because it is critical to learning how Earth’s core grew,” said co-author Sarah Stewart, UC Davis professor of Earth and Planetary Sciences.
Shock and release
Scientists from Lawrence Livermore National Laboratory, Sandia National Laboratory, Harvard University and UC Davis used one of the world’s most powerful radiation sources, the Sandia National Laboratories Z-machine, to recreate conditions that led to Earth’s formation. They subjected iron samples to high shock pressures in the machine, slamming aluminum plates into iron samples at extremely high speeds. They developed a new shock-wave technique to determine the critical impact conditions needed to vaporize the iron.
The researchers found that the shock pressure required to vaporize iron is much lower than expected, which means more iron was vaporized during Earth’s formation than previously thought.
Iron rain
Lead author Richard Kraus, formerly a graduate student under Stewart at Harvard, is now a research scientist at Lawrence Livermore National Laboratory. He said the results may shift how planetary scientists think about the processes and timing of Earth’s core formation.
“Rather than the iron in the colliding objects sinking down directly to the Earth’s growing core, the iron is vaporized and spread over the surface within a vapor plume,” said Kraus. “This means that the iron can mix much more easily with Earth’s mantle.”
After cooling, the vapor would have condensed into an iron rain that mixed into Earth’s still-molten mantle.
To the moon
This process may also explain why the Moon, which is thought to have formed by this time, lacks iron-rich material despite being exposed to similarly violent collisions. The authors suggest the Moon’s reduced gravity could have prevented it from retaining most of the vaporized iron.
Reference:
Richard G. Kraus, Seth Root, Raymond W. Lemke, Sarah T. Stewart, Stein B. Jacobsen, Thomas R. Mattsson. Impact vaporization of planetesimal cores in the late stages of planet formation. Nature Geoscience, 2015; DOI: 10.1038/ngeo2369
Aerial view of Kilauea volcano. Credit: Flickr user exfordy
Step away from the villages and idyllic beaches of Hawaii, and you may think you’ve been transported to the moon. Walking along the lava flows of the Kilauea volcano, the landscape changes from a lush tropical paradise to one that’s bleak and desolate, the ground gray and rippled with hardened lava.
That’s how Christelle Wauthier, assistant professor in the Department of Geosciences and the Institute for CyberScience at Penn State, describes it, anyway.
Wauthier has been studying Kilauea volcano for several years and is getting ready to start a new project at Penn State—one using a radar imaging technique that researchers call interferometric synthetic aperture radar (InSAR) to try to peer below its surface and learn more about why the volcano is so volatile.
Kilauea is the most active of the five volcanoes that make up the island of Hawaii. It’s been erupting continuously since 1983, so far spewing 3.5 cubic kilometers of lava onto the surrounding landscape. The lava usually flows southward, but last year an eruption started creeping east toward the nearby village of Pahoa.
The flow was inconsistent—advancing anywhere from 10 yards to one-quarter mile a day—but it was enough to cause evacuations and lots of anxiety for the residents of the small village.
Wauthier says the volcano’s recent brush with the island’s inhabitants reinforced the importance of studying not just what’s happening on the surface of the volcano, but also what’s going on below.
“The volcano has been erupting for 31 years, so obviously there’s a lot of magma coming from below,” said Wauthier. “There’s lots of magma moving up and out, so one of the questions we’re asking is where are all these magma sources and how do they relate to each other?”
One of the keys to answering this question is found in the deformations happening on the surface of Kilauea. While a deformation is simply a change on the volcano’s exterior, what it implies goes much deeper—there has to be something below the surface causing the change. And without X-ray glasses to diagnose what’s happening, Wauthier uses InSAR to try to piece together what might be going on.
“InSAR is a remote-sensing technique that combines radar data taken from satellites to create images that show subtle movements in the ground’s surface,” said Wauthier. “In this case, the movements we’re studying are deformations on Kilauea.”
To begin the process, Wauthier gathers satellite data from archived databases. She looks for information about changes in elevation from before and after a “natural hazard event”—an eruption or earthquake, for example. Wauthier then uses this data to create two images: one from before the natural hazard event and one from after. This shows how the event changed the ground’s surface.
The two pictures can then be combined to create a single, much more comprehensive InSAR image called an interferogram, which uses color to represent movement.
Wauthier says that while InSAR images can certainly be created from two images, she also uses a time-series approach called Multi-Temporal (MT)-InSAR when enough radar images are available. This technique uses multiple images instead of two.
“This approach is much more accurate, but it also requires much more data and computing power,” Wauthier said. “The powerful computer clusters and IT facilities available through the Institute for CyberScience here at Penn State are tremendously helpful by providing the necessary computing power and efficiency.”
After Wauthier creates the InSAR images, she can begin to use them to predict what might be happening underneath Kilauea. She uses an approach called inverse modeling to estimate what caused the deformation.
“Basically, we use what’s happening on the surface of the volcano to find a ‘best fit model’ for what’s happening underground,” said Wauthier. “For example, if we know the ground rose here but sank over there, we’ll come up with a best guess for the type of magma process—like a magma reservoir or intrusion—that’s below.”
But magma processes aren’t the only things that could be affecting Kilauea’s volatility. The southern flank of the volcano is moving away from the island, and Wauthier says this could also be influencing the volcano’s magma plumbing system and activity.
Wauthier says that although the flank is slipping seaward at an average speed of 6 to 10 centimeters a year, earthquakes in the past have caused more drastic movement and have even generated tsunamis.
Remote-sensing technologies like InSAR are important because they allow researchers like Wauthier to do important research without physically being on location. (Although when you’re studying the Hawaiian landscape, you might want to be.)
Wauthier says she would like to return to Hawaii one day, but in the meantime, she hopes the project will help uncover information that could help the people of Hawaii as well as other scientists at the U.S. Geological Society Hawaiian Volcano Observatory. Having a better understanding of Kilauea would help researchers better grasp the behavior of other ocean islands volcanoes.
“Ideally, we’d like to get a much better picture of the underground magma systems and how they interact with the flank slip,” she said. “The flank instabilities can cause earthquakes and tsunamis, so we’d like to be able to understand and forecast those better. Hopefully, the more we know about these natural hazards, the more we can help people anticipate and mitigate their risks.”
Tracy J. Thomson stands next to a block with numerous swim tracks in Capitol Reef National Park, Utah. Credit: Tracy Thomson.
A type of vertebrate trace fossil gaining recognition in the field of paleontology is that made by various tetrapods (four-footed land-living vertebrates) as they traveled through water under buoyant or semibuoyant conditions.
Called fossil “swim tracks,” they occur in high numbers in deposits from the Early Triassic, the Triassic being a geologic period (250 to 200 million years ago) that lies between the Permian and Jurassic. Major extinction events mark the start and end of the Triassic.
While it is known that tetrapods made the tracks, what is less clear is just why the tracks are so abundant and well preserved.
Paleontologists at the University of California, Riverside have now determined that a unique combination of factors in Early Triassic delta systems resulted in the production and unusually widespread preservation of the swim tracks: delayed ecologic recovery, depositional environments, and tetrapod swimming behavior.
“Given their great abundance in Lower Triassic strata, swim tracks have the potential to provide a wealth of information regarding environmental exploitation by reptiles during this critical time in their evolution following the end-Permian mass extinction,” said Mary L. Droser, a professor of paleontology in the Department of Earth Sciences, who led the research. “They also provide important data for our interpretation of Early Triassic sedimentological and stratigraphic processes. The Early Triassic period follows the largest mass extinction event in Earth’s history. The fossil record shows that a prolonged period of delayed ecologic recovery persisted throughout the Early Triassic.”
She explained that the fossil swim tracks are important and unique records of the aquatic behaviors and locomotion mechanics of tetrapods, and reveal a hidden biodiversity. They also constitute an excellent natural laboratory for investigating the paleoenvironmental and paleoecological conditions associated with their production and preservation.
Droser and Tracy J. Thomson, her former graduate student, surveyed the temporal distribution of the swim tracks seen in fossils in Utah, and report online this month, ahead of print, in the journal Geology that it is not the tetrapod swimming behavior alone, but the prevalence of unbioturbated substrates resulting from the unique combination of ecological and environmental conditions during the Early Triassic that led to the abundant production and preservation of swim tracks.
They identify three interacting factors that composed a “Goldilocks” effect in promoting the production and preservation of Lower Triassic swim tracks. These factors were (1) ecological, i.e., delayed ecologic recovery resulting in the lack of well-mixed sediment, (2) paleoenvironmental, i.e., depositional environments that promoted the production of firmground substrates, and (3) behavioral, i.e., the presence of tetrapods capable of aquatic locomotion such as swimming or bottom walking.
“During the Early Triassic, sediment mixing by animals living within the substrate was minimal,” said Thomson, the first author of the research paper who is now pursuing a doctoral degree at UC Davis. “This strongly contributed to the widespread production of firm-ground substrates that are ideal for recording and preserving trace fossils like swim tracks.”
Thomson explained that the end-Permian mass extinction event resulted in ecologic restructuring of both the marine and terrestrial realms. Bioturbation was suppressed, resulting in no extensively mixed sediment layer, thereby allowing fine-grained, low-water-content firmgrounds to develop near the sediment-water interface.
“Early Triassic deltas and their paleoenvironments were favorable habitats for functionally amphibious reptiles,” Droser said. “There were few animals living in the sediment mixing it up after the extinction, and so the muds became firm and cohesive providing ideal conditions for preservation. Periodic flooding supplied coarser grained material, enhancing swim track preservation.”
Reference:
T. J. Thomson, M. L. Droser. Swimming reptiles make their mark in the Early Triassic: Delayed ecologic recovery increased the preservation potential of vertebrate swim tracks. Geology, 2015; 43 (3): 215 DOI: 10.1130/G36332.1
New landslide maps have been developed that will help the Oregon Department of Transportation determine which coastal roads and bridges in Oregon are most likely to be usable following a major subduction zone earthquake that is expected in the future of the Pacific Northwest.
The maps were created by Oregon State University and the Oregon Department of Geology and Mineral Industries, or DOGAMI, as part of a research project for ODOT. They outline the landslide risks following a large earthquake on the Cascadia Subduction Zone.
The mapping is part of ongoing ODOT efforts to preserve the critical transportation routes that will facilitate response and recovery.
“Landslides are a natural part of both the Oregon Coast Range and Cascade Range, but it’s expected there will be a significant number of them that are seismically induced from a major earthquake,” said Michael Olsen, an assistant professor in the OSU School of Civil and Construction Engineering. “A massive earthquake can put extraordinary additional strain on unstable slopes that already are prone to landslides.”
Landslides are already a serious geologic hazard for western Oregon. But during an earthquake, lateral ground forces can be as high as half the force of gravity.
The Coast Range is of special concern, officials say, because it will be the closest part of the state to the actual subduction zone earthquake, and will experience the greatest shaking and ground movement. The research identified some of the most vulnerable landslide areas in Oregon as parts of the Coast Range between Tillamook and Astoria, and from Cape Blanco south to the California border – in each case, from the coast to about 30 miles inland.
“Major landslides have been identified by DOGAMI throughout western Oregon using high-resolution lidar mapping,” Olsen said. “Some experts believe that a number of these landslides date back to the last subduction zone earthquake in Oregon, in 1700. Coast Range slopes that are filled with weak layers of sedimentary rock are particularly vulnerable, and many areas are already on the verge of failure.”
According to the new map, the highway corridors to the coast that will face comparatively less risk from landslides will be Oregon Highway 36 from near Eugene to Florence; Oregon Highway 38 from near Cottage Grove to Reedsport; Oregon Highway 18 from Salem to Lincoln City; and large portions of U.S. Highway 30 from Portland to Astoria. However, landslides or other damages could occur on any road to the coast or in the Cascade Range due to the anticipated high levels of ground shaking.
The new research, along with other considerations, will help ODOT and other officials determine which areas merit the most investment in coming years as part of long-term planning for the expected earthquake. Given the high potential for damage and minimal resources available for mitigation, experts may choose to focus their efforts on highway corridors that are expected to receive less damage from the earthquake, Olsen said.
The research reflected in the new map considered such factors as slope, direction of ground movement, soil type, vegetation, distance to rivers, roads and fault locations, peak ground acceleration, peak ground velocity, annual precipitation averages, and other factors.
ODOT, Oregon State and DOGAMI have been state leaders in research on risks posed by the Cascadia Subduction Zone, earthquake and tsunami impacts, and initiatives to help the state prepare for a future disaster that scientists say is a certainty.
Officials said it’s important to consider not just the damage to structures that can occur as a result of an earthquake, but also landslide and transportation issues.
“ODOT recognizes the potential not only for casualties due to landslides during and after an earthquake, but also for the likelihood of isolating whole segments of the state’s population,” one ODOT official said. “Thousands of people in the coastal communities would be stranded and cut off from rescue, relief and recovery that would arrive by surface transport.”
ODOT recently completed a seismic vulnerability assessment and selected lifeline corridor routes to prioritize following an earthquake. ODOT also maintains an unstable slopes program, evaluating the frequency of rockfalls and landslides affecting highway corridors.
DOGAMI recently released another open file report as part of the Oregon Resilience Plan, which evaluated multiple potential hazards resulting from a Cascadia subduction zone earthquake, including landslides, liquefaction, and tsunamis.
Some recent efforts at OSU have also focused on understanding the different concerns raised by a subduction zone earthquake compared to the type of strike-slip faults more common in California, on which many seismic plans are based. Subduction earthquakes tend to be larger, affect a wider area and last longer.
Reference:
DOGAMI Open-File Report O-15-01, “Landslide Susceptibility Analysis of Lifeline Routes in the Oregon Coast Range,” by Rubini Mahalingam; Michael J. Olsen; Mahyar Sharifi-Mood; and Daniel T. Gillins, Oregon State University School of Civil and Construction Engineering.
ODOT Research Report SPR-740, “Impacts of Potential Seismic Landslides on Lifeline Corridors,” by Michael J. Olsen; Scott A. Ashford; Rubini Mahalingam; Mahyar Sharifi-Mood; Matt O’Banion and Daniel T. Gillins, Oregon State University School of Civil and Construction Engineering. Download the report: http://1.usa.gov/18352DF
Colima Volcano, one of Mexico’s most active, is at it again. The Operational Land Imager (OLI) on Landsat 8 captured this natural-color view of an ash plume from Colima on February 8, 2015.
Prior to this image on February 5, ash was reported to have reached an altitude of 7.9 kilometers (26,000 feet). The occurrence of lava-block avalanches decreased by late February, but residents were still warned to remain at least 5 kilometers away from the volcano.
Video of the eruption that includes footage of the eruption from February 4-9, 2015, can be viewed here.
References and Related Reading
Global Volcanism Program, Smithsonian Institution (2015) Colima. Accessed February 23, 2015.
The Telegraph (2015, February 12) Watch: Moment Colima volcano erupts in Mexico. Accessed February 23, 2015.
This model is a life reconstruction of the head of Gnatusuchus pebasensis, a 13-million-year-old, short-faced crocodile with globular teeth that was thought to use its snout to “shovel” mud bottoms, digging for clams and other mollusks. Model by Kevin Montalbán-Rivera. Credit: Copyright Aldo Benites-Palomino
Thirteen million years ago, as many as seven different species of crocodiles hunted in the swampy waters of what is now northeastern Peru, new research shows. This hyperdiverse assemblage, revealed through more than a decade of work in Amazon bone beds, contains the largest number of crocodile species co-existing in one place at any time in Earth’s history, likely due to an abundant food source that forms only a small part of modern crocodile diets: mollusks like clams and snails. The work, published today in the journal Proceedings of the Royal Society B, helps fill in gaps in understanding the history of the Amazon’s remarkably rich biodiversity.
“The modern Amazon River basin contains the world’s richest biota, but the origins of this extraordinary diversity are really poorly understood,” said John Flynn, Frick Curator of Fossil Mammals at the American Museum of Natural History and an author on the paper. “Because it’s a vast rain forest today, our exposure to rocks–and therefore, also to the fossils those rocks may preserve–is extremely limited. So anytime you get a special window like these fossilized “mega-wetland” deposits, with so many new and peculiar species, it can provide novel insights into ancient ecosystems. And what we’ve found isn’t necessarily what you would expect.”
Before the Amazon basin had its river, which formed about 10.5 million years ago, it contained a massive wetland system, filled with lakes, embayments, swamps, and rivers that drained northward toward the Caribbean, instead of today’s pattern of eastward river flow to the Atlantic Ocean. Knowing the kind of life that existed at that time is crucial to understanding the history and origins of modern Amazonian biodiversity. But although invertebrates like mollusks and crustaceans are abundant in Amazonian fossil deposits, evidence of vertebrates other than fish have been very rare.
Since 2002, Flynn has been co-leading prospecting and excavating expeditions with colleagues at fossil outcrops of the Pebas Formation in northeastern Peru. These outcrops have preserved life from the Miocene, including the seven species of crocodiles discussed in Proceedings B. Three of the species are entirely new to science, the strangest of which is Gnatusuchus pebasensis, a short-faced caiman with globular teeth that is thought to have used its snout to “shovel” mud bottoms, digging for clams and other mollusks. The new work suggests that the rise of Gnatusuchus and other “durophagous,” or shell-crunching, crocodiles is correlated with a peak in mollusk diversity and numbers, which disappeared when the mega-wetlands transformed into the modern Amazon River drainage system.
“When we analyzed Gnatusuchus bones and realized that it was probably a head-burrowing and shoveling caiman preying on mollusks living in muddy river and swamp bottoms, we knew it was a milestone for understanding proto-Amazonian wetland feeding dynamics,” said Rodolfo Salas-Gismondi, lead author of the paper and a graduate student at the University of Montpellier, in France, as well as researcher and chief of the paleontology department at the National University of San Marcos’ Museum of Natural History in Lima, Peru.
Besides the blunt-snouted crocodiles like Gnatusuchus, the researchers also recovered the first unambiguous fossil representative of the living smooth-fronted caiman Paleosuchus, which has a longer and higher snout shape suitable for catching a variety of prey, like fish and other active swimming vertebrates.
“We uncovered this special moment in time when the ancient mega-wetland ecosystem reached its peak in size and complexity, just before its demise and the start of the modern Amazon River system,” Salas-Gismondi said. “At this moment, most known caiman groups co-existed: ancient lineages bearing unusual blunt snouts and globular teeth along with those more generalized feeders representing the beginning of what was to come.”
The new research suggests that with the inception of the Amazon River System, mollusk populations declined and durophagous crocodile species went extinct as caimans with a broader palate diversified into the generalist feeders that dominate modern Amazonian ecosystems. Today, six species of caimans live in the whole Amazon basin, although only three ever co-exist in the same area and they rarely share the same habitats. This is in large contrast to their ancient relatives, the seven diverse species that lived together in the same place and time.
Reference:
Rodolfo Salas-Gismondi, John J. Flynn, Patrice Baby, Julia V. Tejada-Lara, Frank P. Wesselingh, Pierre-Olivier Antoine. A Miocene hyperdiverse crocodylian community reveals peculiar trophic dynamics in proto-Amazonian mega-wetlands. Proc. R. Soc. B, 2015 DOI: 10.1098/rspb.2014.2490
Fossil calibrations for select groups: Here is a look at the way the new fossil calibration database will help to tell evolutionary time. Credit: The Bruce Museum, Greenwich, CT
Have you ever wondered exactly when a certain group of plants or animals first evolved? This week a groundbreaking new resource for scientists will go live, and it is designed to help answer just those kinds of questions. TheFossil Calibration Database, a free, open-access resource that stores carefully vetted fossil data, is the result of years of work from a worldwide team led by Dr. Daniel Ksepka, Curator of Science at the Bruce Museum in Greenwich, and Dr. James Parham, Curator at the John D. Cooper Archaeological and Paleontological Center in Orange County, California, funded through the National Evolutionary Synthesis Center (NESCent).
“Fossils provide the critical age data we need to unlock the timing of major evolutionary events,” says Dr. Ksepka. “This new resource will provide the crucial fossil data needed to calibrate ‘molecular clocks’ which can reveal the ages of plant and animal groups that lack good fossil records. When did groups like songbirds, flowering plants, or sea turtles evolve? What natural events were occurring that may have had an impact? Precisely tuning the molecular clock with fossils is the best way we have to tell evolutionary time.”
More than twenty paleontologists, molecular biologists, and computer programmers from five different countries contributed to the design and implementation of this new database. The Fossil Calibrations Database webpage launches on Tuesday February 24th, and a series of five peer-reviewed papers and an editorial on the topic will appear in the scientific journal Palaeontologia Electronica, describing the endeavor. Dr. Ksepka is the author of one of the papers and co-author of the editorial.
“This exciting field of study, known as ‘divergence dating,’ is important for understanding the origin and evolution of biodiversity, but has been hindered by the improper use of data from the fossil record,” says Dr. Parham. “The Fossil Calibration Database addresses this issue by providing molecular biologists with paleontologist-approved data for organisms across the Tree of Life.”
The Tree of Life? “Think of it as a family tree of all species,” explains Dr. Ksepka.
Note: The above story is based on materials provided by Bruce Museum.
University of Florida paleontologist Jason Bourque reconstructs the 56-million-year-old shell of a newly described genus and species of ancient tropical turtle in his lab on Feb. 9, 2015. The fossil turtle gives clues to how today’s species might react to warming habitats. Credit: Photo by Jeff Gage/Florida Museum of Natural History
Tropical turtle fossils discovered in Wyoming by University of Florida scientists reveal that when Earth got warmer, prehistoric turtles headed north. But if today’s turtles try the same technique to cope with warming habitats, they might run into trouble.
While the fossil turtle and its kin could move northward with higher temperatures, human pressures and habitat loss could prevent a modern-day migration, leading to the extinction of some modern species.
The newly discovered genus and species, Gomphochelys (pronounced gom-fo-keel-eez) nanus — provides a clue to how animals might respond to future climate change, said Jason Bourque, a paleontologist at the Florida Museum of Natural History at UF and the lead author of the study, which appears online this week in the Journal of Vertebrate Paleontology.
The wayfaring turtle was among the species that researchers believe migrated 500-600 miles north 56 million years ago, during a temperature peak known as the Paleocene-Eocene Thermal Maximum. Lasting about 200,000 years, the temperature peak resulted in significant movement and diversification of plants and animals.
“We knew that some plants and lizards migrated north when the climate warmed, but this is the first evidence that turtles did the same,” Bourque said. “If global warming continues on its current track, some turtles could once again migrate northward, while others would need to adapt to warmer temperatures or go extinct.”
The new turtle is an ancestor of the endangered Central American river turtle and other warm-adapted turtles in Belize, Guatemala and southern Mexico. These modern turtles, however, could face significant roadblocks on a journey north, since much of the natural habitat of these species is in jeopardy, said co-author Jonathan Bloch, a Florida Museum curator of vertebrate paleontology.
“If you look at the waterways that turtles would have to use to get from one place to another, it might not be as easy as it once was,” Bloch said. “Even if the natural response of turtles is to disperse northward, they have fewer places to go and fewer routes available.”
To put the new turtle in evolutionary context, the researchers examined hundreds of specimens from museum collections around the country, including turtles collected during the 1800s housed at the Smithsonian Institution. Co-author Patricia Holroyd, a vertebrate paleontologist at the University of California, Berkeley, said the fossil history of the modern relatives of the new species shows they could be much more wide-ranging, if it were not for their restricted habitats.
The Central American river turtle is one of the most endangered turtles in the world, threatened by habitat loss and its exploitation as a human food source, Holroyd said. “This is an example of a turtle that could expand its range and probably would with additional warming, but — and that’s a big but — that’s only going to happen if there are still habitats for it,” she said.
References:
Jason R. Bourque, Blaine W. Schubert. Fossil musk turtles (Kinosternidae,Sternotherus) from the late Miocene–early Pliocene (Hemphillian) of Tennessee and Florida. Journal of Vertebrate Paleontology, 2015; 35 (1): e885441 DOI: 10.1080/02724634.2014.885441
Jason R. Bourque, J. Howard Hutchison, Patricia A. Holroyd, Jonathan I. Bloch. A new dermatemydid (Testudines, Kinosternoidea) from the Paleocene-Eocene Thermal Maximum, Willwood Formation, southeastern Bighorn Basin, Wyoming. Journal of Vertebrate Paleontology, 2015; e905481 DOI: 10.1080/02724634.2014.905481
Note: The above story is based on materials provided by University of Florida. The original article was written by Stephenie Livingston.
A French-Kenyan research team has just described a new fossil ancestor of today’s hippo family. This discovery bridges a gap in the fossil record separating these animals from their closest modern-day cousins, the cetaceans. It also shows that some 35 million years ago, the ancestors of hippos were among the first large mammals to colonize the African continent, long before those of any of the large carnivores, giraffes or bovines. This work, co-signed by researchers of the Institut des sciences de l’évolution de Montpellier (CNRS/Université de Montpellier/IRD/EPHE) and Institut de paléoprimatologie et paléontologie humaine : évolution et paléo-environnements (CNRS/Université de Poitiers) is published in the journal Nature Communications.
The ancestry of hippopotamuses is somewhat of an enigma. For a long time, paleontologists thought these semi-aquatic animals, with their unusual morphology (canines and incisors with continual growth, primitive skull and trifoliate tooth-wear pattern), to be related to the Suidae family, which includes pigs and peccaries. But in the 1990s and 2000s, DNA comparisons showed that the hippo’s closest living relatives were the cetaceans (whales, dolphins, etc.), which disagreed with most paleontological interpretations. Moreover, the lack of fossils significantly hindered attempts to uncover the truth about hippo evolution.
New paleontological work by a group of French and Kenyan researchers has now revealed that hippos are not related to suoids but instead descend from another, now extinct, group. The new fossils studied have made it possible to build the first evolutionary scenario that is compatible with both genetic and paleontological data. By analyzing a half-jaw and several teeth discovered at Lokone (in the Lake Turkana basin, Kenya), the French-Kenyan team described a new fossil species (belonging to a new genus (2)), dating back to about 28 million years. They named it Epirigenys lokonensis, from the word “Epiri” which means hippo in the Turkana language and the site of discovery, Lokone.
By comparing the characteristics of fossil teeth with those of ruminants, suoids, hippos and fossil anthracotheres (an extinct family of ungulates), the scientists reconstructed the relationships between these groups. The results show that Epirigenys forms a kind of evolutionary transition between the oldest known hippo in the fossil record (about 20 million years ago) and an anthracothere lineage. This position in the tree of life is compatible with the genetic data, confirming that the cetaceans are the hippos’ closest living cousins.
This kind of discovery may one day enable scientists to draw a picture of the common ancestor of cetaceans and hippos. Indeed, analysis of Epirigenys (28 million years old) has linked today’s hippos to a lineage of anthracotheres, the oldest of which date back about 40 million years. However, until now, the earliest known ancestor of the hippos was about 20 million years old, while the first fossils of cetaceans are 53 million years old. The time gap between today’s hippos and the oldest cetaceans is thereby filled by nearly 75% according to the present scenario.
Furthermore, this discovery shows the whole history of the African fauna in a new light. Africa was an isolated continent from about 110 to 18 million years ago. Most of the iconic African fauna (lions, leopards, rhinos, buffaloes, giraffes, zebras, etc.) are relatively recent arrivals on the continent (they have been there less than 20 million years). Until now, the same was believed to be true of hippos, but the discovery of Epirigenys demonstrates that their anthracothere ancestors migrated from Asia to Africa some 35 million years ago.
Reference:
Fabrice Lihoreau, Jean-Renaud Boisserie, Fredrick Kyalo Manthi, Stéphane Ducrocq. Hippos stem from the longest sequence of terrestrial cetartiodactyl evolution in Africa. Nature Communications, 2015; 6: 6264 DOI: 10.1038/ncomms7264
Geysers like Old Faithful in Yellowstone National Park erupt periodically because of loops or side-chambers in their underground plumbing, according to recent studies by volcanologists at the University of California, Berkeley.
The key to geysers, said Michael Manga, a UC Berkeley professor of earth and planetary science, is an underground bend or loop that traps steam and then bubbles it out slowly to heat the water column above until it is just short of boiling. Eventually, the steam bubbles trigger sudden boiling from the top of the column, releasing pressure on the water below and allowing it to boil as well. The column essentially boils from the top downward, spewing water and steam hundreds of feet into the air.
“Most geysers appear to have a bubble trap accumulating the steam injected from below, and the release of the steam from the trap gets the geyser ready to erupt,” Manga said. “You can see the water column warming up and warming up until enough water reaches the boiling point that, once the top layer begins to boil, the boiling becomes self-perpetuating.”
The new understanding of geyser mechanics comes from Manga’s studies over the past few years of geysers in Chile and Yellowstone, as well as from an experimental geyser he and his students built in their lab. Made of glass with a bend or loop, it erupts periodically, though, surprisingly, not as regularly as a real geyser they studied in the Atacama desert of Chile, dubbed El Jefe. Over six days of observation, El Jefe erupted every 132 seconds, plus or minus two seconds.
“At many geysers it looks like there is some cavity that is stuck off on the side where steam is accumulating,” Manga explained. “So we said, ‘Let’s put in a cavity and watch how the bubble trap generates eruptions.’ It allows us to get both small eruptions and big eruptions in the lab.”
Manga and his colleagues, including first author Carolina Munoz-Saez, a UC Berkeley graduate student from Chile, report their findings on the Chilean geysers in the February 2015 issue of the Journal of Volcanology and Geothermal Research. A description of the laboratory geyser appeared in the September 2014 issue of the same journal.
Balance of pressure and temperature
Fewer than 1,000 geysers exist around the world — half of them in Yellowstone — and all are located in active or formerly active volcanic areas. Water from the surface trickles downward and gets heated by hot magma, eventually, perhaps decades later, rising back to the surface in the form of hot springs, mud pots and geysers.
Why geysers erupt periodically, some with a regularity you can set a clock by, has piqued the interest of many scientists, but German chemist Robert Bunsen was the first to make pressure and temperature measurements inside a geyser — the Great Geysir in Iceland, after which geysers are named — in 1846. Based on these measurements, he proposed that eruptions start when water starts to boil at the surface, reducing pressure within the superheated water column and allowing boiling to propagate downward from the surface. Pressurized water boils at a higher temperature, so reducing the pressure on overheated water allows it to boil.
Since then, Manga said, a few researchers have stuck video cameras into geysers and seen features that suggest there are underwater chambers or loops that trap steam bubbles. Manga’s measurements in Yellowstone and Chile link the temperature and pressure changes down the water column with the underground plumbing to explain the periodic eruptions.
Geysers key to understanding volcanoes
Manga studies geysers to gain insight into volcanic eruptions, which bear many similarities to geysers but are much harder to study. Manga and his students feed temperature and pressure sensors as deep as 30 feet into geysers — something impossible to do with a volcano — and correlate these with above-ground measurements from seismic sensors and tiltmeters to deduce the sequence of underground events leading to an eruption. They have also been able to submerge video cameras as deep as six feet into geysers to view the submerged conduits and chambers below. He hopes to be able to extrapolate his findings to volcanoes, deducing the internal mechanics from exterior seismic and gravity measurements.
But geysers are fascinating in themselves, he said.
“One of our goals is to figure out why geysers exist — why don’t you just get a hot spring — and what is it that controls how a geyser erupts, including weather and earthquakes,” he said.
In this month’s publication, Manga and his students report on El Jefe (“the chief”), a geyser located at an elevation of about 14,000 feet in the El Tatio geyser field in Chile, where water boils at 86 degrees Celsius (187 degrees Fahrenheit) instead of 100 (212 degrees F). In 2012, they recorded internal and external data during 3,600 eruptions over six days. They compared these to above-ground measurements at Lone Star and other geysers in Yellowstone. Invasive measurements are forbidden in the park.
They concluded that Bunsen was essentially correct — boiling starts at the top of the superheated water column and propagates downward — but also that it’s the escaped bubbles from trapped steam in the rock conduits below the geyser that heat the water column to the boiling point. As the entire water column boils out of the ground, more than half the volume of stuff emerging is steam, though most of the mass is liquid water, they found. The plume seen from afar is mostly steam condensing into water droplets in the air, Manga said.
Preplay
In places like Yellowstone, the bubbles that slowly escape from the underground loop cause mini-eruptions called preplay leading up to the major eruption. Eruptions stop when the water column in the geyser cools below the boiling point, and the process repeats. All these underground processes seem to be affected only by the heat source deep below the geyser, because they could find no evidence that the surface temperature affected eruptions.
Manga plans to continue his Yellowstone and Chilean studies — his next trip to Yellowstone is in the fall — to gather more data to help explain the periods of geysers and better understand below-ground processes.
Co-authors with Manga and Munoz-Saez on the February paper are Shaul Hurwitz of the U.S. Geological Survey in Menlo Park, California; Maxwell Rudolph of Portland State University in Oregon; Atsuko Namiki of Hiroshima University in Japan; and professor emeritus Chi-Yuen Wang of UC Berkeley.
The September 2014 paper was co-authored by UC Berkeley undergraduates Esther Adelstein, Aaron Tran, Carolina Muñoz-Saez and researcher Alexander Shteinberg.
The work is supported by the National Science Foundation and the CONICYT program to support Berkeley-Chile collaborations, which is administered by UC Berkeley’s Center for Latin American Studies.
Video:
Volcanologist Michael Manga and student Esther Adelstein use a laboratory geyser they built to explain how geysers like Old Faithful work. (Video by Roxanne Makasdjian and Phil Ebiner, with geyser footage by Eric King and Kristen Fauria)
Reference:
Carolina Munoz-Saez, Michael Manga, Shaul Hurwitz, Maxwell L. Rudolph, Atsuko Namiki, Chi-Yuen Wang. Dynamics within geyser conduits, and sensitivity to environmental perturbations: Insights from a periodic geyser in the El Tatio geyser field, Atacama Desert, Chile. Journal of Volcanology and Geothermal Research, 2015; 292: 41 DOI: 10.1016/j.jvolgeores.2015.01.002
Geographic Resources Analysis Support System, commonly referred to as GRASS GIS, is a Geographic Information System (GIS) used for data management, image processing, graphics production, spatial modelling, and visualization of many types of data. It is Free (Libre) Software/Open Source released under GNU General Public License (GPL) >= V2. GRASS GIS is an official project of the Open Source Geospatial Foundation.
Originally developed by the U.S. Army Construction Engineering Research Laboratories (USA-CERL, 1982-1995, see history of GRASS 1.0-4.2 and 5beta), a branch of the US Army Corp of Engineers, as a tool for land management and environmental planning by the military, GRASS GIS has evolved into a powerful utility with a wide range of applications in many different areas of applications and scientific research. GRASS is currently used in academic and commercial settings around the world, as well as many governmental agencies including NASA, NOAA, USDA, DLR, CSIRO, the National Park Service, the U.S. Census Bureau, USGS, and many environmental consulting companies.
The GRASS Development Team has grown into a multi-national team consisting of developers at numerous locations.
In September 2006, the GRASS Project Steering Commitee was formed which is responsible for the overall management of the project. The PSC is especially responsible for granting SVN write access.
General GRASS GIS Features
GRASS GIS contains over 350 modules to render maps and images on monitor and paper; manipulate raster, and vector data including vector networks; process multispectral image data; and create, manage, and store spatial data. GRASS GIS offers both an intuitive graphical user interface as well as command line syntax for ease of operations. GRASS GIS can interface with printers, plotters, digitizers, and databases to develop new data as well as manage existing data.
GRASS GIS and support for teams
GRASS GIS supports workgroups through its LOCATION/MAPSET concept which can be set up to share data and the GRASS installation itself over NFS (Network File System) or CIFS. Keeping LOCATIONs with their underlying MAPSETs on a central server, a team can simultaneously work in the same project database.
GRASS GIS capabilities
Raster analysis: Automatic rasterline and area to vector conversion, Buffering of line structures, Cell and profile dataquery, Colortable modifications, Conversion to vector and point data format, Correlation / covariance analysis, Expert system analysis , Map algebra (map calculator), Interpolation for missing values, Neighbourhood matrix analysis, Raster overlay with or without weight, Reclassification of cell labels, Resampling (resolution), Rescaling of cell values, Statistical cell analysis, Surface generation from vector lines
3D-Raster (voxel) analysis: 3D data import and export, 3D masks, 3D map algebra, 3D interpolation (IDW, Regularised Splines with Tension), 3D Visualization (isosurfaces), Interface to Paraview and POVray visualization tools
Vector analysis: Contour generation from raster surfaces (IDW, Splines algorithm), Conversion to raster and point data format, Digitizing (scanned raster image) with mouse, Reclassification of vector labels, Superpositioning of vector layers
Point data analysis: Delaunay triangulation, Surface interpolation from spot heights, Thiessen polygons, Topographic analysis (curvature, slope, aspect), LiDAR
Image processing: Support for aerial and UAV images, satellite data (optical, radar, thermal), Canonical component analysis (CCA), Color composite generation, Edge detection, Frequency filtering (Fourier, convolution matrices), Fourier and inverse fourier transformation, Histogram stretching, IHS transformation to RGB, Image rectification (affine and polynomial transformations on raster and vector targets), Ortho photo rectification, Principal component analysis (PCA), Radiometric corrections (Fourier), Resampling, Resolution enhancement (with RGB/IHS), RGB to IHS transformation, Texture oriented classification (sequential maximum a posteriori classification), Shape detection, Supervised classification (training areas, maximum likelihood classification), Unsupervised classification (minimum distance clustering, maximum likelihood classification)
DTM-Analysis: Contour generation, Cost / path analysis, Slope / aspect analysis, Surface generation from spot heigths or contours
Geocoding: Geocoding of raster and vector maps including (LiDAR) point clouds
Visualization: 3D surfaces with 3D query (NVIZ), Color assignments, Histogram presentation, Map overlay, Point data maps, Raster maps, Vector maps, Zoom / unzoom -function
Map creation: Image maps, Postscript maps, HTML maps
The GRASS GIS 6 release introduced a new topological 2D/3D vector engine and support for vector network analysis. Attributes are managed in a SQL-based DBMS (PostgreSQL, mySQL, SQLite, ODBC, …), by default in DBF format. A new display manager has been implemented. The NVIZ visualization tool was enhanced to display 3D vector data and voxel volumes. Messages are partially translated (i18N) with support for FreeType fonts, including multibyte Asian characters. New LOCATIONs can be auto-generated eg. by EPSG code number using a location wizard. GRASS GIS is integrated with GDAL/OGR libraries to support an extensive range of raster and vector formats, including OGC-conformal Simple Features.
About GRASS GIS 7
GRASS GIS 7 is under development with a first releases in preparation (snapshots are already available). It offers large data support, an improved topological 2D/3D vector engine and much improved vector network analysis. Attributes are managed by default in SQLite format. The display manager has been improved for usability. The NVIZ visualization tool was completely rewritten. Image processing has also been improved. See more details at New Features.
Inoceramus, genus of extinct pelecypods (clams) found as fossils in Jurassic to Cretaceous rocks (laid down between 199.6 million and 65.5 million years ago). Especially important and widespread in Cretaceous rocks, Inoceramus had a distinctive shell; it is large, thick, and wrinkled in a concentric fashion, making identification relatively simple. The many pits at the dorsal region were the anchoring points for the ligaments that closed the shell.
Inoceramids: Some species of clams (bivalves) grew to giant size in the late Cretaceous, attaining diameters of four feet or more. In cross section, these shells are composed of prismatic (calcitic) crystals. The inner, nacreous (Mother of Pearl) layer of the shell (composed of aragonite) was usually dissolved during fossilization and the outer portion is usually covered with colonies of oysters and other invertebrates. Pearls are occasionally found pressed into the Inoceramid shell. According to Sowerby 1823, Inoceramus means “fibrous shell,” describing the prisms that are visible on the edge of shell fragments.
Inoceramus cuvieri was the first species of Inoceramus that was formally described by Sowerby (1814). Several species are found in the Late Cretaceous rocks of Kansas. At times in the Western Interior Sea, they provided shelter for various small fishes and at least one species of eel. They also produced pearls.
Inoceramid shells were discovered in Great Britain and France in the late 1700s and early 1800s, but they were seldom found complete. Europe in the James Parkinson (1811b) wrote one of the first descriptions of inoceramid shell fragments, in this case Inoceramus cuvieri from the English chalk:
“Fragments of thick shell of a fibrous structure: The doubts expressed respecting the nature of this shell, and the observations made with regard to it, offer another strong point of agreement between the shells of the two strata. The shell here alluded to is most probably that represented Org. Rem. vol. III. pl. V.-fig. 3; the structure of which agrees exactly with that mentioned as found in the French stratum of- chalk. That shell is however described as being of a tubular form; it is therefore right to observe, that fossil that represented Org. Rem. vol. III. pl. V.-fig. 3; the structure of which agrees exactly with that mentioned as found in the French stratum of- chalk. That shell is however described as being of a tubular form; it is therefore right to observe, that fossil pinnae do sometimes possess this peculiar structure.”
The clam had a thick shell paved with “prisms” of calcite deposited perpendicular to the surface, which gave it a pearly luster in life. Most species have prominent growth lines which appear as raised semicircles concentric to the growing edge of the shell. Paleontologists suggest that the giant size of some species was an adaptation for life in the murky bottom waters, with a correspondingly large gill area that would have allowed the animal to survive in oxygen-deficient waters.
Distribution
Species of Inoceramus had a worldwide distribution during the Cretaceous period. Many examples are found in the Pierre Shale of the Western Interior Seaway in North America. Inoceramus can also be found abundantly in the Cretaceous Gault Clay that underlies London. Other locations for this fossil include Vancouver Island, British Columbia, Canada; Texas, Tennessee, Kansas, California and Alaska, USA; Spain, France, and Germany.
