Epic Flood Cooled Our Planet Eons Ago
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 thick.
As the temperature gradually rose 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 14m 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.
