Missoula floods
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The Missoula floods were a series of cataclysmic glacial lake outburst floods that swept periodically across the area that would become eastern Washington, northern Idaho and northern Oregon, and down
Glacial Lake Columbia (west) and Glacial Lake Missoula (east) are shown south of the Cordilleran ice sheet. The areas inundated in the Columbia and Missoula floods are shown in red.
Giant ripple marks at Markle Pass near Camas Hot Springs, Montana, U.S. View towards the northwest.
During the ice age floods, Dry Falls was under 300 feet (91 m) of water approaching at a speed of 65 miles per hour (105 km/h).
Glacial Lake Missoula high-water mark, 4,200 feet (1,280 m), near Missoula, MT
Grand Coulee
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Grand Coulee is an ancient river bed in the U.S. state of Washington. This National Natural Landmark stretches for about 60 miles southwest from Grand Coulee Dam to Soap Lake, being bisected by Dry Fa
Grand Coulee, below Dry Falls. The layering effect of periodic basalt lava flows is visible.
Looking northward in Grand Coulee
Steamboat Rock in the Grand Coulee
Part of the Grand Coulee has been dammed and filled with water as part of the Columbia Basin Project.