Posted on 09/11/2007 4:25:24 PM PDT by blam
Source: Geological Survey of Norway
Date: September 11, 2007
Studying Evidence From Ice Age Lakes
Science Daily — During the last Ice Age, the ice dammed enormous lakes in Russia. The drainage system was reversed several times and the rivers flowed southwards. A group of geologists is now investigating what took place when the ice melted and the lakes released huge volumes of fresh water into the Arctic Ocean.
”The ice-dammed lakes in Russia were larger than the largest lakes we know today,” Eiliv Larsen, a geologist at the Geological Survey of Norway (NGU), tells me. He is in charge of the important SciencePub International Polar Year project that is studying natural climate changes in the Arctic and the ways in which man has adapted to them.
Moving glaciers
”The entire drainage system in Russia has been reversed several times during the past 130 000 years. The heavy ice cap covering the land area in the north dammed up lakes and forced the large rivers, the Dvina, Mezen, Pechora and Vychegda, to flow southwards to the Caspian Sea, the Black Sea and on to the Mediterranean,” Eiliv Larsen continues.
However, the ice margin in the north shifted; the ice cap varied in extent, sometimes suddenly advancing eastwards, sometimes retreating. When the plug was released as the ice melted, the water poured from the huge lakes into the Kara Sea and the White Sea, causing the sea level to rise.
The sum total of all these dramatic changes greatly influenced the climate and the circulation in the seas in the Barents Region. SciencePub scientists are trying to find answers to where, when and how often this took place.
Digging down
”We drive vehicles and boats along the large valleys and rivers,” Maria Jensen, a group leader and geologist at NGU, tells me. “Where sediments are exposed along the coast and rivers, we study the sequence of their deposition. It’s here, in the transportation of clay, silt and sand out into the marine system, that we find evidence of the major events,” she points out.
In a cutting beside the River Vychegda, a few kilometres from the village of Ust Nem in the Komi Republic, geologists from Norway, Denmark, Russia and Germany are digging their way down through layers that were deposited during the last Ice Age.
Astrid Lyså, another NGU geologist, explains: ”We remove the outermost layer to get at undisturbed sediments. Then we clean the section, measure it, and photograph, draw and describe the structures in every single layer. We also take samples to date the beds using luminescence, a technique that reveals, for example, when a sand grain was last exposed to the light.”
Reading the history
By investigating a given section, geologists can, for instance, find out what types of deposits are present in the area. They may be moraine, peat, mire, or sediments deposited in the sea, rivers and ice-dammed lakes. The scientists can also find out in which environment these sediments were deposited; was it deep, still or shallow water, beneath the ice, or were the sediments deposited by the wind?
It is thus actually possible to read the history of an ice-dammed lake by studying the succession of layers dug out with a spade, a scraper, a knife and a trowel.
That is precisely what they are doing here at Ust Nem. There seems to have been two ice-dammed lakes here. The patterns of patches of coloured clay and the remains of crushed clay in the sediments suggest, for example, a strong increase in pore pressure and that this particular lake was tapped extremely rapidly.
A big jigsaw puzzle
The scientists are also investigating the landscape around the river, searching for old, dry valleys and small depressions that may explain the drainage system. After driving for just a couple of hours and walking a bit in the forest, they find small valleys which drained into the present course of the river.
The pieces in the jigsaw puzzle are thus gradually falling into place.
”When we fit everything together, we can see the details in and around the enormous lakes which the Russian rivers drained southwards on several occasions and at other times emptied into the Arctic Ocean when the ice melted,” Eiliv Larsen explains.
Note: This story has been adapted from a news release issued by Geological Survey of Norway.
GGG Ping?
Just curious, I’ve never seen any indication that Australia was ever affected by an ice age. But I don’t really know, one way or another. Anybody out there know anything?
The biggest difference was that you could have walked to what became Papua New Guinea and Tasmania.
Though I don’t hear anyone complaining about the global warming that wiped out all that land, and when sea levels rose about 300 feet.
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Thanks Blam. There was at least one event analogous to the glacial lake flood that produced the Channeled Scablands. |
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The entire drainage system in Russia has been reversed several times during the past 130 000 years.If so, then the living environment changed along with it, which means there were various ecosystems according to those reversals. There seems to have been a dramatic impact of the Western/Central Asian rivers and lakes and seas upon the flow of time and life around it. Mankind's journey would be much marked by these influences.
That said, those same reversals would have occurred throughout earth's long history. How did they impact the planet's life prior to man's arrival to Asia? For example, we laymen tend to think of the age of dinosaurs as static. Clearly the climate was not, so, neither was animal life.
Maria A. Jensen. Geological Survey of Norway. Conclusions….. So far. The fluvial sedimentary record from the Arkhangelsk Region
http://www.ngu.no/FileArchive/91/Jensen_presentasjon_maj2006.pdf
Maria A. Jensen. Geological Survey of Norway. Conclusions….. So far. The fluvial sedimentary record from the Arkhangelsk Region
http://www.ngu.no/FileArchive/91/Jensen_presentasjon_maj2006.pdf
A geologic study with major climatological implications. And there is no apparent effort on the part of the scientists to practice anything other than science.
One would think that everybody in Norway would be praying for evidence of 'global warming'...
They do this by driving around on the ground? Sounds as if they have never heard of LIDAR...
"The scientists are also investigating the landscape around the river, searching for old, dry valleys and small depressions that may explain the drainage system. After driving for just a couple of hours and walking a bit in the forest, they find small valleys which drained into the present course of the river."
If you look up the farthest reach of the ice sheets in the northern hemisphere during previous ice ages, they never got farther south than about 39 degrees north latitude. It just so happens that the southernmost point of Australia is also about 39 degrees from the equator. So if ice sheets were of equal extent in the southern hemisphere, they would not have covered any significant amount of land in Australia.
The past few million years were notable for the Quarternary ice age. There were many glacial and interglacial periods (over 20) during this time, the last glacial about 20,000 years ago. In Tasmania there is evidence of three different glaciations-the last glaciation, one sometime in the Quaternary, and one in the Tertiary. In mainland Australia, there is evidence of only the last glaciation, and the ice then covered only 25 square kilometres, in the vicinity of Mt Kosciuszko...
According to Wikipedia, Antarctica and Australia started separating 80 million years ago. I think when most people speak of ice ages they are referring to various cycles in the last few hundred thousand years, although apparently these are just parts of a an extended modern ice age that began 40 million years ago and which is still continuing.
‘most people’ NE ‘Lucius Cornelius Sulla’
I wonder if one of these reversals and consequent flooding along with catastrophic rain (for example from the explosion and dust of Mt. Mazama about 7600 years ago), could have caused the biblical flood story?
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