Glacial Lake Missoula

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Glacial Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago. The lake measured about and contained about of water, half the volume of Lake Michigan.

The lake was the result of an ice dam on the Clark Fork River caused by the southern encroachment of a finger of the Cordilleran Ice Sheet into the Idaho Panhandle (at the present day location of Lake Pend Oreille). The height of the ice dam typically approached , flooding the valleys of western Montana approximately eastward. It was the largest ice-dammed lake known to have occurred.

The periodic rupturing of the ice dam resulted in the Missoula Floods--cataclysmic floods that swept across Eastern Washington and down the Columbia River Gorge approximately 40 times during a 2,000 year period. The cumulative effect of the floods was to excavate of loess, sediment and basalt from the channeled scablands of eastern Washington and to transport it downstream. These floods are noteworthy for producing canyons and other large geologic features through cataclysms rather than through gradual processes.

See also

• Missoula Floods
• Glacial lake outburst flood
• List of prehistoric lakes

Cited references

External links

• USGS Site on Glacial Lake Missoula
• PBS's NOVA (TV series): Mystery of the Megaflood for information on the Missoula Floods
• The Seattle Times' Pacific NW magazine - "Trailing an Apocalypse" - 30-Sep-2007

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Last updated on Saturday January 19, 2008 at 19:29:37 PST (GMT -0800)
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