to the most comprehensive and authoritative website on Glacial Lake Missoula and its role in the Ice Age Floods.
The site is sponsored by the Glacial Lake Missoula Chapter of the Ice Age Floods Institute, a nonprofit organization formed in 1995 which focuses on promoting public awareness and understanding of the formation of Glacial Lake Missoula and its impacts on what we see on the landscape around us today.
On this site you can learn about the great floods that shaped the Pacific Northwest, take a tour of local features created by the lake, learn about other points of interest in this area, and find out about other reliable sources of information on this topic.
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The Short Story
About 12,000 years ago, the valleys of western Montana lay beneath a lake nearly 2,000 feet deep. Glacial Lake Missoula formed as the Cordilleran Ice Sheet dammed the Clark Fork River just as it entered Idaho. The rising water behind the glacial dam weakened it until water burst through in a catastrophic flood that raced across Idaho, Oregon, and Washington toward the Pacific Ocean. Thundering waves and chunks of ice tore away soils and mountainsides, deposited giant ripple marks, created the scablands of eastern Washington and carved the Columbia River Gorge. Over the course of centuries, Glacial Lake Missoula filled and emptied in repeated cycles, leaving its story embedded in the land.