Geology and Astronomy

(Oldest Fossil Rodents in South America Discovered; Find Is 10 Million Years Older and Confirms Animal From Africa)

In a literal walk through time along the Ucayali River near Contamana, Peru, a team of researchers found rodent fossils at least 41 million years old -- by far the oldest on the South American continent. The remains -- teeth -- showed these mouse- and rat-size animals are most closely related to African rodents, confirming the hypothesis that early rodents of South America had origins in Africa, said Darin Croft, an anatomy professor at the Case Western Reserve University School of Medicine and member of the research team.

This discovery supports the contention that rodents landed in the north and spread south. The rodents are from the suborder Caviomorpha, the group that includes living rodents such as guinea pigs, chinchillas, and New World porcupines. The fossils from this group are only about 32 million years old in central Chile and about 30 million years old in Patagonia, Argentina,. Taken all together, the pattern contradicts the theory of a northward expansion deduced from the fossil record 20 years ago. The findings, which describe three new species, are published online in Proceedings of the Royal Society B.This really pushes back the date of the first South American rodents," said Croft, a paleontologist who specializes in mammalian evolution.

Pierre-Olivier Antoine, a professor of paleontology in the Institute of Evolutionary Sciences at Montpellier University in southern France, asked Croft to join the team of scientists from France, Germany, Peru and Panama. Members first flew into the region in 2008, after reading Harvard Geology Professor Bernhard Kummel's 1948 description of the area. Kummel mentions fossils along the Ucayali, a major tributary of the Amazon, but the team found no evidence that anyone had investigated them.

During three trips from 2008 to 2010, Antoine's group found the fossils in a portion of the riverbank exposed when the water level is low. The geology along the river showed that layers of rock, including the fossil layer, had been pushed up in a rainbow-shaped fold, called an anticline. The layers that had once been above or below the fossils turned from horizontal to nearly vertical. Instead of digging down to the past, the scientists walked downstream from the fossil layer to go back in time, upstream to go forward in time.

A new geological study, being reported Thursday in the journal Nature, showed that tools from a site near Lake Turkana in Kenya were made about 1.76 million years ago, the earliest of their ilk found so far.

Previous dates were estimates ranging from 1.4 million to 1.6 million years ago.

Although no erectus fossils were found with the Turkana tools, a skull of that species was excavated last year in the same sediment level across the lake. This suggests that Homo erectus was responsible for these particular tools, which were made with what scientists refer to as Acheulean technology. The term connotes the type of oval and pear-shaped hand axes and other implements that were a specialty of early humans.

American researchers at the Lamont-Doherty Earth Observatory, part of Columbia University, established the age of the Turkana tools by dating the surrounding mudstone with a paleomagnetic technique. When layers of silt and clay hardened into stone, this preserved the orientation of Earth’s magnetic field at the time, and an analysis of the periodic polarity reversals and other records yielded the age of the site known as Kokiselei.

“I was taken aback when I realized that the geological data indicated it was the oldest Acheulean site in the world,” said the lead author of the report, Christopher J. Lepre, a researcher at Lamont-Doherty who also teaches geology at Rutgers University.

The assemblage of hand axes, picks and other cutting tools was collected, mostly in the 1990s, by French archaeologists led by Hélène Roche of the National Center for Scientific Research in France. Dr. Roche, a co-author of the paper, was steered to the site by Richard Leakey, the Kenyan fossil hunter who had discovered, just six miles away, the Turkana Boy, a young Homo erectus who lived about 1.5 million years ago and is the most complete early hominid skeleton found so far.

An team led by KU Leuven astronomer Leen Decin discovered not less than a dozen cold dust arcs around the giant star CW Leo.

The team used the sensitive PACS instrument on board the Herschel Space Observatory to detect for the first time arcs of dust far away from the star. CW Leo has expelled these shells of dust in different epochs in its life. The faintest shell we can see now was, according to the team, expelled about 16,000 years ago. In the meantime it has drifted away from the star over more than 7,000 billion kilometers.

Until recently, the environment of giant stars seemed homogeneous, but more and more observations indicate that this is not true," says Leen Decin. These new Herschel images confirm that in a stunning way. We have detected a dozen arcs, puffed out by the star in the course of its life. The faintest shell we found is already at a distance of 7,000 billion kilometers from the star.

The different shells were ejected by the star with intervals of 500 to 1,700 years. The astronomers in the team believe such shells, even fainter, are also present further out, up to the violent bow shock where the expelled material of the star collides with the interstellar medium. The oldest shells have probably disappeared in the bow shock already.

Our own Sun too will turn into a red giant star, about five billion years from now, when it will inflate and condensate dust in the outer, cooling layers of its atmosphere. The episodes in CW Leo's history help astronomers understand the future of our own Sun.

On Tuesday, August 23, just before 2:00pm, the earth moved in Virginia and most of the East Coast felt the quake.

Waves of excitement rippled through the Department of Geology and Astronomy as it became apparent what we were feeling was actually an earthquake, the largest that most of us have experienced! The epicenter of the magntiude 5.8 quake was located near the Spotsylvania Fault about 40 miles northwest of Richmond, in the central Virginia Seismic Zone. That area also experienced a magnitude 4.5 quake in 2003. A similar seismically active zone, the Lancaster Seismic Zone, is present in southeastern Pennsylvania. The largest recent earthquake in our area occurred in 1994 with magnitude 4.6, and was centered a few miles west of Reading.

External Links:
USGS information about the quake
A very informative blog from the American Geophysical Union
Watch the seismic waves travel across the continent thanks to Earthscope/USArray
Earthquakes in Pennsylvania (Pennsylvania Geological Survey)

 
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Natural gas companies have been placing enormous bets on the wells they are drilling, saying they will deliver big profits and provide a vast new source of energy for the United States.

But the gas may not be as easy and cheap to extract from shale formations deep underground as the companies are saying, according to hundreds of industry e-mails and internal documents and an analysis of data from thousands of wells.

In the e-mails, energy executives, industry lawyers, state geologists and market analysts voice skepticism about lofty forecasts and question whether companies are intentionally, and even illegally, overstating the productivity of their wells and the size of their reserves. Many of these e-mails also suggest a view that is in stark contrast to more bullish public comments made by the industry, in much the same way that insiders have raised doubts about previous financial bubbles.

“Money is pouring in” from investors even though shale gas is “inherently unprofitable,” an analyst from PNC Wealth Management, an investment company,  wrote to a contractor in a February e-mail. “Reminds you of dot-coms.”

“The word in the world of independents is that the shale plays are just giant Ponzi schemes and the economics just do not work,” an analyst from IHS Drilling Data, an energy research company,  wrote in an e-mail on Aug. 28, 2009.

Company data for more than 10,000 wells in three major shale gas formations raise further questions about the industry’s prospects. There is undoubtedly a vast amount of gas in the formations. The question remains how affordably it can be extracted.

  
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The data show that while there are some very active wells, they are often surrounded by vast zones of less-productive wells that in some cases cost more to drill and operate than the gas they produce is worth. Also, the amount of gas produced by many of the successful wells is falling much faster than initially predicted by energy companies, making it more difficult for them to turn a profit over the long run.