Posted on 02/25/2008 2:36:06 AM PST by 2ndDivisionVet
Canadian geologists say they can shed light on how a vast lake, trapped under the ice sheet that once smothered much of North America, drained into the sea, an event that cooled Earth's climate for hundreds of years.
During the last ice age, the Laurentide Ice Sheet once covered most of Canada and parts of the northern United States with a frozen crust that in some places was three kilometres (two miles) thick.
As the temperature gradually rose some 10,000 years ago, the ice receded, gouging out the hollows that would be called the Great Lakes.
Beneath the ice's thinning surface, an extraordinary mass of water built up -- the glacial lake Agassiz-Ojibway, a body so vast that it covered parts of Manitoba, Saskatchewan, North Dakota, Ontario and Minnesota.
And then, around 8,200 years ago, Agassiz-Ojibway massively drained, sending a flow of water into the Hudson Strait and into the Labrador Sea that was 15 times greater than the present discharge of the Amazon River.
By some estimates, sea levels rose 14 metres (45 feet) as a result.
How the great flood was unleashed has been a matter of debate.
Some experts suggest an ice dam was smashed down, or the gushing water spewed out over the top of the icy lid.
Quebec researchers Patrick Lajeunesse and Guillaume Saint-Onge believe, though, that the outburst happened under the ice sheet, rather than above it or through it.
In a study appearing on Sunday in the journal Nature Geoscience, the pair describe how they criss-crossed Hudson Bay on a research vessel, using sonar to scan more than 10,500 kilometres (6,000 miles) to get a picture of the bay floor.
In the south of the bay, they found lines of deep waves in the sandy bed, stretching more than 900 kilometres (562 miles) in length and some 1.7 metres (5.5 feet) deep.
These are signs that the bay's floor, protected by the mighty lid of ice, was swept by a mighty current many years ago but has been still ever since, they say.
In the west of the bay, they found curious marks in the shape of parabolas twisting around to the northeast.
The arcs were chiselled as much as three metres (10 feet) into the sea bed and found at depths of between 80 and 205 metres (260 and 666 feet).
The duo believe that this part of the bay had icebergs that were swept by the massive current.
The bergs' jagged tips were trapped in the sea bed and acted like a pivot. As the icebergs swung around, other protruding tips ripped arc-like tracks on the bay floor.
Also presented as evidence are deep submarine channels and deposits of red sediment that stretch from land west of Hudson Bay right across the northwestern floor of the bay itself -- both point to a current that swept all before it.
"Laurentide ice was lifted buoyantly, enabling the flood to traverse southern Hudson Bay under the ice sheet," the study suggests.
Previous work suggests the flood was so huge that it affected climate around the world.
The influx of freshwater into the North Atlantic reduced ocean salinity so much that this braked the transport of heat flowing from the tropics to temperate regions.
Temperatures dropped by more than three degrees Celsius (5.4 degrees Fahrenheit) in Western Europe for 200-400 years -- a mini-Ice Age in itself.
How the great flood cooled the earth....
Water from the flood came from ice...
Article sounds like CNN wrote it...
Ping!
How on earth was that possible since SUV's were not invented yet?
Didn’t Fred Flintstone have an SUV? Or was that Mr. Slate?
I think it was char broiling those huge brontosaurus steaks...
Or it might have been this: http://www.youtube.com/watch?v=gDamNtQpu2w
Wooley mammoth farts.
When you cross it west to east, the change when you cross the ridge line that was the old lake shore is amazing. After miles and miles and miles of utterly flat terrain other then various creeks and rivers that dip below the flat surface, you claim this long ridge and the geology is just totally different.
Interesting to note, the Red River valley which lies just inside the Glacier Lake Agassiz shore line is some of the most fertile, deepest black soil farm land on earth.
All BS. The earth is only 6,000 years old.
And while all of this was happening thousands of years ago, an ancestor of Al Gore (named Al Grooora) was out telling everyone that if they did not break all their spears and bury their cooking oil that the earth was going to be jugded by the moon gods and fire would reign down on them. In spite of the cooling effect, Al Grooora was awarded the Neandrathal peace prize. He continued to spread his word whie riding on a massive chariot (whose 8 horses, BTW, pooped so much that entire villages had to be evacuated). 15 years later, after the earth had already dropped in temperature by 7 degrees the natives tried to find Al Grooora , but he fled to the equator, where he continued to preach his message on his fantastic 8 horse chariot. The end. (Now you know more about prhistoric history than all the PhDs in the world - combined).
Something I can’t get my head around is why they think the climate on the edge of the ice sheet - - especially when they talk about Eurasia - - was so dry. What the heck happened in the summer? The ice sheet would have melted some at the edges and refroze in the winter. And to get a layer of ice two miles thick, it would have had to snow....
A LOT.
The are lots of cold climates in the world today that are very dry.
Reasonably close to the right time for the Great Flood? Also about the right time for the English Channel to have been made?
LOL!
What I posted was pure guess but maybe the English channel too.
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