Carbonate Petrography

Carbonate petrography is the study of limestones, dolomites and associated deposits under optical or electron microscopes greatly enhances field studies or core observations and can provide a frame of reference for geochemical studies.

25 strangest Geologic Formations on Earth

The strangest formations on Earth.

What causes Earthquake?

Of these various reasons, faulting related to plate movements is by far the most significant. In other words, most earthquakes are due to slip on faults.

The Geologic Column

As stated earlier, no one locality on Earth provides a complete record of our planet’s history, because stratigraphic columns can contain unconformities. But by correlating rocks from locality to locality at millions of places around the world, geologists have pieced together a composite stratigraphic column, called the geologic column, that represents the entirety of Earth history.

Folds and Foliations

Geometry of Folds Imagine a carpet lying flat on the floor. Push on one end of the carpet, and it will wrinkle or contort into a series of wavelike curves. Stresses developed during mountain building can similarly warp or bend bedding and foliation (or other planar features) in rock. The result a curve in the shape of a rock layer is called a fold.

Friday, 29 April 2016

Ancient Fossil Forests Discovered in the Arctic

Ancient Fossil Forests Discovered in the Arctic



What did a portion of the main trees on Earth resemble? Earth researchers from Cardiff University diving around in Arctic Norway are surrounding an answer. Furthermore, that answer is: oddly well known. 

UK scientists have uncovered antiquated fossil forest, thought to be somewhat in charge of a stand out amongst the most dramatic moments in the Earth's atmosphere in the previous 400 million years. 

The fossil forest, with tree stumps saved set up, were found in Svalbard, a Norwegian archipelago arranged in the Arctic Ocean. They were recognized and portrayed by Dr Chris Berry of the School of Earth and Ocean Sciences. 

Prof John Marshall, of Southampton University, has precisely dated the forest to 380 million years. 

The forest became close to the equator amid the late Devonian period, and could give an understanding into the reason for a 15-fold diminishment in levels of carbon dioxide (CO2) in the air around that time. 

Current speculations propose that amid the Devonian period (420-360 million years back) there was an immense drop in the level of CO2 in the air, thought to be to a great extent created by an adjustment in vegetation from humble plants to the main substantial woods trees. 

Woods hauled CO2 out of the air through photosynthesis, the procedure by which plants make sustenance and tissues – and the arrangement of soils. 

Albeit at first the presence of extensive trees retained a greater amount of the sun's radiation, in the end temperatures on Earth additionally dropped drastically to levels fundamentally the same to those accomplished today due to the diminishment in barometrical CO2. 

In light of the high temperatures and vast measure of precipitation on the equator, it is likely that central forests contributed most to the draw down of CO2. Svalbard was situated on the equator around this time, before the tectonic plate floated north by around 80° to its flow position in the Arctic Ocean. 

"These fossil forests demonstrates to us what the vegetation and scene resembled on the equator 380 million years prior, as the main trees were starting to show up on the Earth," said Dr Berry. 

The group found that the woodlands in Svalbard were framed predominantly of lycopod trees, better known for developing a huge number of years after the fact in coal overwhelms that in the long run transformed into coal stores, for example, those in South Wales. They likewise found that the woodlands were to a great degree thick, with little crevices, around 20cm between each of the trees, which presumably came to around 4m high. 

"Amid the Devonian Period, it is broadly trusted that there was a colossal drop in the level of carbon dioxide in the climate, from 15 times the present add up to something drawing nearer current levels. 

"The development of tree-sized vegetation is the doubtlessly reason for this emotional drop in carbon dioxide in light of the fact that the plants were retaining carbon dioxide through photosynthesis to assemble their tissues, furthermore through the procedure of shaping soils."

Saturn's Crisscrossed Rings Hide Tiny Moon

Saturn's Criss-crossed Rings Hide Tiny Moon




It seems that whenever we look at a new picture of Saturn by NASA’s Cassini mission, there’s always something unique. And often, there’s hidden gem.

Captured on Feb. 11, this observation, at first, doesn't make a whole lot of sense. We already know that Saturn sports hundreds of distinct rings, but they all occupy the same plane. How did Cassini see rings that are criss-crossed?

Actually, this observation only shows one ring plane, but behind are the shadows of each ring being cast on Saturn’s upper atmosphere, creating the illusion there are 2 sets of rings.


At first glance, Saturn's rings appear to be intersecting themselves in an impossible way. In actuality, this view from NASA's Cassini spacecraft shows the rings in front of the planet, upon which the shadow of the rings is cast. And because rings like the A ring and Cassini Division, which appear in the foreground, are not entirely opaque, the disk of Saturn and those ring shadows can be seen directly through the rings themselves.


But while you digest the scene and work out which lines are rings and which are shadows, you’re probably overlooking tiny moon Pan, a 17 mile (or 28 kilometre) wide satellite occupying a gap in the rings (just below the middle of the photo).

Many of the gaps in Saturn’s rings possess small moons whose gravity keeps these rings clear of debris as they orbit. Pan occupies the famous Encke Gap, for example. Many other gaps, however, don’t appear to have moons, so their nature is a little more mysterious. Some theories on ring dynamics suggest some of these gaps may have formed through resonances with Saturn’s larger moons.


The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.



Regardless of how they were formed, Cassini continues to capture their beauty, constantly reaffirming Saturn as the jewel of the solar system.

Giant Sinkhole Eats Highway in Oregon

Giant Sinkhole Eats Highway in Oregon

This gigantic sinkhole opened after a heavy rainstorm along the Oregon coast.
The startling chasm, which started out less than a foot across in mid-December, suddenly turned into a monster 80 feet in diameter on Jan. 28, after an inch and a half of rain caused a culvert to fail and triggered a landslide nearby. The hole has closed down the stretch of U.S. 101 that runs through the unincorporated town of Harbor, just south of the city of Brookings, according to news reports.
Officials reportedly have estimated that it will take at least a week to repair the hole, which started in the parking lot of the Fireside Diner, and then grew to devour a big hunk of the highway. To further exacerbate the situation, a second, smaller sinkhole opened up in the middle of the road itself.
spectacular drone video of the damage, shot by local resident Kyle Rice, already has attracted nearly 200,000 views on YouTube. The hole also has attracted coverage from BBC News and Russia’s RT.com, where some readers used it as fodder for anti-American retorts and conspiracy theories. “Research shows US is one big sinkhole,” one wrote, while another suggested that it may have been caused by “hundreds of underground tunnels throughout America.”



The actual explanation is a bit less bizarre. According to the U.S. Geological Survey, sinkholes happen frequently where the rocks below the land surface are porous enough to be dissolved by groundwater circulating through them. 
Though USGS identifies Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania as the states where the most sinkhole damage occurs, Oregon also has a history of really big sinkholes. The big kahuna was a 50-foot-deep, 100-foot-long hole that appeared on Interstate 5 near Roseburg in November 1996, causing a pair of big rigs to plunge into it.

One of Titan's Strange Seas is Pure Methane

One of Titan's Strange Seas is Pure Methane

This image, taken by the Cassini spacecraft, shows the first flash of sunlight reflected off a hydrocarbon lake on Saturn’s moon Titan. The July 2009 image confirmed the presence of liquid in the moon’s northern hemisphere.

A new study of eight years of radar data collected by the Saturn-orbiting Cassini spacecraft shows that the planet’s largest moon, Titan, the only other body in the solar system besides Earth where liquids pool on the surface has a sea of pure methane.



Before Cassini, scientists had expected Titan’s seas to be dominated by ethane, since sunlight breaks apart methane and converts it into the more complex ethane hydrocarbon.

Instead, Alice Le Gall, a Cassini scientist at France’s LATMOS research laboratory, and colleagues discovered that Ligeia Mare, Titan’s second-largest sea, is almost pure methane.

Scientists suspect that methane rain may be regularly filling the sea, or that ethane is locked in the sea’s crust, or flowing into the adjacent sea, according to a press release about the study, which was published in the March 11 issue of Journal of Geophysical Research Planets.

The findings are based on radar observations made by Cassini between 2007 and 2015. Those measurements of heat given off by Ligeia Mare were combined with results of a 2013 experiment that bounced radar waves off the seafloor, which allowed scientists to estimate the sea’s depth.

Ligeia Mare, which turns out to be as deep as 525 feet, also likely sports a layer of organic-rich sludge on its floor, the scientists said.

“It’s a marvelous feat of exploration that we’re doing extraterrestrial oceanography on an alien moon,” Cassini scientist Steve Wall, with NASA’s Jet Propulsion Laboratory in Pasadena, Calif., noted in the press release.

Cassini, which has been studying the Saturn system for almost 12 years, has revealed that almost 2 percent of Titan’s 620,000 square miles of real estate are covered in liquid.

The moon has three large seas, all located in the northern polar region, that are surrounded by small lakes. So far, just one large lake has been found in Titan’s southern hemisphere.

Pregnant T. rex Found, May Contain DNA

Pregnant T. rex Found, May Contain DNA

This illustration shows a pregnant T. rex next to another female.
A pregnant Tyrannosaurus rex has been found, shedding light on the evolution of egg-laying as well as on gender differences in the dinosaur. The remains also could contain the holy grail of all dinosaur fossils: DNA.
"Yes, it's possible," Lindsay Zanno told Discovery News, referring to genetic material that may be present in this as well as similar dinosaur finds. "We have some evidence that fragments of DNA may be preserved in dinosaur fossils, but this remains to be tested further."
What has been confirmed so far is that the T. rex, which was found in Montana and dates to 68 million years ago, retained medullary bone that reveals the individual was pregnant. Medullary bone is only present in female living dinosaurs, i.e. birds, just before and during egg laying. It's this type of bone that could retain preserved DNA.
Zanno is an assistant research professor of biological sciences at North Carolina State University, where she is also head of the North Carolina Museum of Natural Sciences' Paleontology Research Lab and is curator of paleontology. She explained that medullary bone lines the marrow cavity of the long bones of birds.
"It's a special tissue that is built up as easily mobilized calcium storage just before egg laying," she said. "The outcome is that birds do not have to pull calcium from the main part of their bones in order to shell eggs, weakening their bones the way crocodiles do."
Crocodiles, she said, are the closest living relatives of dinosaurs.
"Medullary bone is thus present just before and during egg laying, but is entirely gone after the female has finished laying eggs," she said.
Early on, Mary Schweitzer suspected that medullary bone was present in the tyrannosaur remains, and was able to confirm her suspicions after she, Zanno and their team conducted a chemical analysis of the T. rex's femur.
The material, found to be consistent with known medullary tissues from ostriches and chickens, contained karatan sulfate, a substance not present in any other bone types.
"This analysis allows us to determine the gender of this fossil, and gives us a window into the evolution of egg laying in modern birds," Schweitzer said.
Credits: Discovery news

Homo naledi, new specie of Homo

Homo naledi, new specie of the genus Homo from the Dinaledi Chamber, South Africa

Dinaledi skeletal specimens.
A team of scientists have discovered Homo naledi which is a new specie of extinct homonin within Dinaledi chamber of the rising star cave system, Cradle of human kind, South Africa. The Dinaledi chamber is located approximately 30 meters underground, within the Rising Star cave system at about 26°1′13′′ S; 27°42′43′′ E. The system lies within the Malmani dolomites, approximately 800 meters southwest of the well-known site of Swartkrans in the Cradle of Humankind World Heritage Site, Gauteng Province, South Africa. Modern humans, or Homo sapiens, are now the only living species in their genus. But as recently as 100,000 years ago, there were several other species that belonged to the genus Homo. Together with modern humans, these extinct human species, our immediate ancestors and their close relatives, are collectively referred to as ‘hominins’. 
Fossil hominins were first recognized in the Dinaledi Chamber in the Rising Star cave system in October 2013. During a relatively short excavation, our team recovered an extensive collection of 1550 hominin specimens, representing nearly every element of the skeleton multiple times, including many complete elements and morphologically informative fragments, some in articulation, as well as smaller fragments many of which could be refit into more complete elements. The collection is a morphologically homogeneous sample that can be attributed to no previously-known hominin species. Here we describe this new species, Homo naledi. We have not defined H. naledi narrowly based on a single jaw or skull because the entire body of material has informed our understanding of its biology.
Now Berger et al. report the recent discovery of an extinct species from the genus Homo that was unearthed from deep underground in what has been named the Dinaledi Chamber, in the Rising Star cave system in South Africa. The species was named Homo naledi; ‘naledi’ means ‘star’ in Sotho (also called Sesotho), which is one of the languages spoken in South Africa.
The unearthed fossils were from at least 15 individuals and include multiple examples of most of the bones in the skeleton. Based on this wide range of specimens from a single site, Berger et al. describe Homo naledi as being similar in size and weight to a small modern human, with human-like hands and feet. Furthermore, while the skull had several unique features, it had a small braincase that was most similar in size to other early hominin species that lived between four million and two million years ago. Homo naledi's ribcage, shoulders and pelvis also more closely resembled those of earlier hominin species than those of modern humans.
The Homo naledi fossils are the largest collection of a single species of hominin that has been discovered in Africa so far and, in a related study, Dirks et al. describe the setting and context for these fossils. However, since the age of the fossils remains unclear, one of the next challenges will be to date the remains to provide more information about the early evolution of humans and their close relatives.

Saturday, 23 April 2016

The Pleistocene Ice Age

The Pleistocene Ice Age 

The Pleistocene Glaciers 

Today, most of the land surface in New York City lies hidden beneath concrete and steel, but in Central Park it’s still possible to see land in a seminatural state. If you stroll through the park, you’ll find that the top surfaces of outcrops are smooth and polished, and in places have been grooved and scratched. Here and there, glacial erratics rest on the bedrock. You are seeing evidence that an ice sheet once scraped along this now-urban ground. Geologists estimate that the ice sheet that overrode the New York City area may have been 250 m thick, enough to bury a 75-story building. 
The fact that glaciated landscapes still decorate the surface of the Earth means that the last ice age occurred fairly recently during Earth’s history. Otherwise, the landscape features would have been either eroded away or buried. The ice age responsible for the glaciated landscapes of North America, Europe, and Asia happened mostly during the Pleistocene Epoch, which began about 2.6 Ma, so as we’ve noted earlier, it is commonly known as the Pleistocene Ice Age. 

Pleistocene ice sheets of the northern hemisphere.

Tuesday, 12 April 2016

Thrust Faults: Forecasting megaquakes

Can slow creep along thrust faults help forecast  megaquakes?

Summary:

In Japan and areas like the Pacific Northwest where megathrust earthquakes are common, scientists may be able to better forecast large quakes based on periodic increases and decreases in the rate of slow, quiet slipping along the fault.

Diagram showing the edge of the continental plate on which the island of Japan sits (green). At the Japan Trench (right edge), the Pacific Plate (orange) pushes under the wedge-shaped Japanese plate, driving west and downward in quiet slips at a rate of about 8 cm/year. Some places (locked areas) get stuck, however, with small locked areas generating repeated small quakes and larger locked areas generating larger quakes. The new study found that an increase in the frequency of these small off-shore earthquakes presaged larger quakes, including the 2011 Tohoku-oki quake.Credit: Image courtesy of University of California, Berkeley


This hope comes from a new study by Japanese and UC Berkeley seismologists, looking at the more than 1,000-kilimeter-long fault off northeast Japan where the devastating 2011 Tohoku-oki earthquake originated, generating a tsunami that killed thousands. There, the Pacific Plate is trundling under the Japan plate, not only causing megaquakes like the magnitude 9 in 2011, but giving rise to a chain of Japanese volcanoes.
The scientists studied 28 years of earthquake measurements, looking at quakes of magnitude 2.5 or greater between 1984 and 2011. They discovered 1,515 locations off the coast of Japan where small repeating earthquakes happen -- 6,126 quakes in all.
According to co-author Robert Nadeau, a UC Berkeley seismologist and a fellow with the Berkeley Institute for Data Science (BIDS), an analysis of these quakes found that larger, more destructive earthquakes -- those of magnitude 5 or greater -- occurred much more frequently when the periodic slow-slip was fastest. This included the great Tohoku-oki earthquake, which also devastated a nuclear power plant and led to widespread radioactive contamination.
"The persistence of the periodic pattern over time may help us refine earthquake probabilities in the future by taking into account the times of expected slow-slip pulses," he said. "Right now, seismologists gives forecasts on a 30-year time frame and assume nothing is changing on a shorter time scale. Our study points out that things are changing, and in a periodic way. So it may be possible for scientists to give shorter time ranges of greater and lower probability for larger events to happen."
The research was led by Naoki Uchida, a seismologist at Tohoku University, and included UC Berkeley seismologist Roland Burgmann, professor of earth and planetary science. They published their findings in the Jan. 29 issue of Science.
Story Source:
The above post is reprinted from materials provided by University of California, Berkeley. The original item was written by Robert Sanders. Note: Materials may be edited for content and length.