Glacial Lake Missoula - Definition and Overview

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 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. The height of the ice dam typically approached 2,000 feet, flooding the valleys of western Montana approximately 200 miles eastward.

The periodic rupturing of the ice dam resulted in the Missoula Floods, which swept across Eastern Washington and down the Columbia River Gorge approximately 40 times during a 2,000 year period.

See also

• List of prehistoric lakes

External links

• USGS Site on Glacial Lake Missoula (http://vulcan.wr.usgs.gov/Glossary/Glaciers/IceSheets/description_lake_missoula.html)