http://www.calgaryherald.com/entertainment/movie-guide/Missing+Canadian+flood+path+discovered/2751507/story.htmlThursday, April 01, 2010 7:53:22 AM
'Missing' Canadian flood path discovered
By Margaret Munro, Canwest News ServiceApril 1, 2010 2:07 AM
Scientists say they have uncovered the path of a colossal flood that swept across northern Canada 13,000 years ago, plunging the Northern Hemisphere into a prolonged cold snap.
A Canadian-British team reported it has found the "missing flood path" along the Mackenzie, Athabasca and Clearwater river systems that triggered the cooling event that is considered one of the most catastrophic geological events in recent Earth history. Scoured out valley bottoms, giant gravel bars and fields of boulders all point to a massive freshwater pulse from Lake Agassiz, a huge meltwater basin that formed at the end of the last ice age.
"You know something big happened when you look at the size of the boulders in that gravel," says geologist James Teller, of the University of Manitoba, pointing to rocks up to two metres across tossed around by the rushing water.
He is co-author of the report published today in the journal Nature that adds an intriguing chapter to the story of Lake Agassiz, which used to be the world's largest lake, covering a huge million-square-kilometre patch of what is now northern parts of Manitoba and Ontario. Teller says there were several huge floods from the lake as ice dams burst, culminating with one about 8,400 years ago that sent water pouring out through Hudson Bay, altering ocean currents and triggering a sea level rise.
Teller has speculated a giant pulse of water may even be linked to the flood behind the biblical story of Noah's Ark. He and his colleagues now say a much earlier outburst from Lake Agassiz 13,000 years ago appears to have had an even more dramatic impact on the global climate, triggering an abrupt and prolonged cold snap in the Northern Hemisphere.
Researchers have turned up "very persuasive dating evidence," Teller says, at the mouth of the Mackenzie River that drains into the Arctic Ocean. The huge gravel bars on the delta caught the eye of Julian Murton, of University of Sussex in England, while he was on a field trip to study permafrost.
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