Andre
Aug17-04, 01:56 PM
Last decade ice core digging in the West Antlantic Ice Sheet (WAIS) gave a big surprise. Diatoms in the mud under the ice sheet revealed that there has been a sea bottom with a maximum age of some 500,000 years but possibly younger.
Pleistocene Collapse of the West Antarctic Ice Sheet
Reed P. Scherer, et al
Some glacial sediment samples recovered from beneath the West Antarctic ice sheet at ice stream B contain Quaternary diatoms and up to 108 atoms of beryllium-10 per gram. Other samples contain no Quaternary diatoms and only background levels of beryllium-10 (less than 106 atoms per gram). The occurrence of young diatoms and high concentrations of beryllium-10 beneath grounded ice indicates that the Ross Embayment was an open marine environment after a late Pleistocene collapse of the marine ice sheet.
Science, Vol 281, Issue 5373, 82-85 , 3 July 1998 (http://www.sciencemag.org/cgi/content/full/281/5373/82)
There was big commotion but apart from scary stories about sudden collapses of ice sheets the attention receded. Yet we are facing a formal "not understood" (science talk for mystery) phenonemon.
Guess what's under the Greenland ice sheet.
Grass and Trees! (http://www.eurekalert.org/pub_releases/2004-08/uoca-gic081304.php)
Greenland ice core project yields probable ancient plant remains
A team of international researchers working on the North Greenland Ice Core Project recently recovered what appear to be plant remnants nearly two miles below the surface between the bottom of the glacial ice and the bedrock.
Researchers from the project, known as NGRIP, said particles found in clumps of reddish material recovered from the frozen, muddy ice in late July look like pine needles, bark or blades of grass. Thought to date to several million years ago before the last ice age during the Pleistocene epoch smothered Greenland, the material will be analyzed in several laboratories, said researchers.
The suspected plant material under about 10,400 feet of ice indicates the Greenland Ice Sheet "formed very fast," said NGRIP project leader Dorthe Dahl-Jensen, a professor at the University of Copenhagen's Niels Bohr Institute. "There is a big possibility that this material is several million years old -- from a time when trees covered Greenland," she said.
"Several of the pieces look very much like blades of grass or pine needles," said University of Colorado at Boulder geological sciences Professor James White, a NGRIP principal investigator. "If confirmed, this will be the first organic material ever recovered from a deep ice-core drilling project," said White, also a fellow of CU-Boulder's Institute of Arctic and Alpine Research.
More here. (http://www.glaciology.gfy.ku.dk/ngrip/index_eng.htm)
I hope that they can date the sample roughly as carbon dating only goes to about 45,000 years. I think it will be a next surpsrise I doubt that these samples are older than half a million year.
Strange that millions of years is automatically assumed because of the "counter intuitive" estimate for younger years, although this would probably yield a world record. Mineralization (fossilization) of small objects can be done in weeks in the right circumstances. These samples seem not to be fossilized. (source (http://home.entouch.net/dmd/fossilization.htm) It's the question if sub freezing temperatures stop the process completely for millions of years.
It may be as young as the last interglacial, the Eemian, 130,000 years ago. Then it would be a nice smoking gun for my little pet idea.
Pleistocene Collapse of the West Antarctic Ice Sheet
Reed P. Scherer, et al
Some glacial sediment samples recovered from beneath the West Antarctic ice sheet at ice stream B contain Quaternary diatoms and up to 108 atoms of beryllium-10 per gram. Other samples contain no Quaternary diatoms and only background levels of beryllium-10 (less than 106 atoms per gram). The occurrence of young diatoms and high concentrations of beryllium-10 beneath grounded ice indicates that the Ross Embayment was an open marine environment after a late Pleistocene collapse of the marine ice sheet.
Science, Vol 281, Issue 5373, 82-85 , 3 July 1998 (http://www.sciencemag.org/cgi/content/full/281/5373/82)
There was big commotion but apart from scary stories about sudden collapses of ice sheets the attention receded. Yet we are facing a formal "not understood" (science talk for mystery) phenonemon.
Guess what's under the Greenland ice sheet.
Grass and Trees! (http://www.eurekalert.org/pub_releases/2004-08/uoca-gic081304.php)
Greenland ice core project yields probable ancient plant remains
A team of international researchers working on the North Greenland Ice Core Project recently recovered what appear to be plant remnants nearly two miles below the surface between the bottom of the glacial ice and the bedrock.
Researchers from the project, known as NGRIP, said particles found in clumps of reddish material recovered from the frozen, muddy ice in late July look like pine needles, bark or blades of grass. Thought to date to several million years ago before the last ice age during the Pleistocene epoch smothered Greenland, the material will be analyzed in several laboratories, said researchers.
The suspected plant material under about 10,400 feet of ice indicates the Greenland Ice Sheet "formed very fast," said NGRIP project leader Dorthe Dahl-Jensen, a professor at the University of Copenhagen's Niels Bohr Institute. "There is a big possibility that this material is several million years old -- from a time when trees covered Greenland," she said.
"Several of the pieces look very much like blades of grass or pine needles," said University of Colorado at Boulder geological sciences Professor James White, a NGRIP principal investigator. "If confirmed, this will be the first organic material ever recovered from a deep ice-core drilling project," said White, also a fellow of CU-Boulder's Institute of Arctic and Alpine Research.
More here. (http://www.glaciology.gfy.ku.dk/ngrip/index_eng.htm)
I hope that they can date the sample roughly as carbon dating only goes to about 45,000 years. I think it will be a next surpsrise I doubt that these samples are older than half a million year.
Strange that millions of years is automatically assumed because of the "counter intuitive" estimate for younger years, although this would probably yield a world record. Mineralization (fossilization) of small objects can be done in weeks in the right circumstances. These samples seem not to be fossilized. (source (http://home.entouch.net/dmd/fossilization.htm) It's the question if sub freezing temperatures stop the process completely for millions of years.
It may be as young as the last interglacial, the Eemian, 130,000 years ago. Then it would be a nice smoking gun for my little pet idea.