From Wikipedia, the free encyclopedia.
The Missoula Floods refer to the floods that swept across Eastern Washington at the end of the last ice age, inundating the Columbia River Gorge and the Willamette Valley.
The floods were the result of the periodic catastrophic rupture of the ice dam in the Clark Fork River that created Glacial Lake Missoula. Each time the ice dam ruptured, the waters of the lake would rush down the Clark Fork and the Columbia River. After the rupture, the ice would reform, recreating Glacial Lake Missoula once again.
Geologists estimate that the cycle of flooding and reformation of the lake lasted on average of 55 years and that the floods occurred approximately 40 times over the 2,000 year period between 15,000 and 13,000 years ago.
The Missoula Floods are considered to be the primary reason for the agricultural richness of the Willamette Valley.
