The Missoula Floods (also known as the Spokane Floods or the Bretz Floods) refer to the cataclysmic floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. The glacial flood events have been researched since the 1920s. These glacial lake outburst floods were the result of periodic sudden ruptures of the ice dam on the Clark Fork River that created Glacial Lake Missoula. After each ice dam rupture, the waters of the lake would rush down the Clark Fork and the Columbia River, inundating much of eastern Washington and the Willamette Valley in western Oregon. 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 an average of 55 years and that the floods occurred several times over the 2,000-year period between 15,000 and 13,000 years ago. U.S. Geological Survey hydrologist Jim O'Connor and Center of Environmental Studies (in Spain) scientist Gerard Benito have found evidence of at least twenty-five massive floods, the largest discharging ~10 cubic kilometers per hour.[2] Alternate estimates for the peak flow rate of the largest flood include 17 cubic kilometers per hour[3] and range up to 60 cubic kilometers per hour.[4] The maximum flow speed approached 36 meters/second (130 km/h or 80 mph).[
 
 
Copyright © 2006-17 Claud "Sonny" Rouch, all rights reserved. Website by OACYS Technology. Cover photo by Roberts Engineering.