Channeled Scablands

The Channeled Scablands are a network of eroded basalt plateaus and coulees in eastern Washington, carved chiefly by repeated catastrophic Ice Age floods released from Glacial Lake Missoula.

Missoula floods: Catastrophic Ice Age floods that repeatedly swept across eastern Washington after Glacial Lake Missoula burst through its ice dam. These floods supplied the water and erosive force that carved most of the Scablands.
J Harlen Bretz: An American geologist who argued that catastrophic floods carved the Channeled Scablands. His field observations first connected the region’s channels, dry falls, and giant current marks to enormous floods.
Columbia River Basalt Group: A vast sequence of flood-basalt lava flows that erupted across the Pacific Northwest during the Miocene. The resistant basalt flows form the bedrock that floods cut into and across.
Grand Coulee: A major basalt canyon in central Washington, partly excavated by Ice Age floods. It records a principal route by which floodwater crossed the Columbia Plateau.
Outburst flood: A sudden, large release of water from a lake, glacier, or other natural reservoir. The Missoula floods are among the largest known examples of this geological process.
Glacial Lake Missoula: A large Ice Age lake in western Montana, impounded by the Purcell Lobe of the Cordilleran Ice Sheet. Its repeated drainage sent floodwaters westward across the Scablands.
Joseph T. Pardee: An American geologist who identified evidence for Glacial Lake Missoula and its catastrophic drainage. His work supplied a plausible source for the floods Bretz had inferred.
Basalt: A dark, fine-grained volcanic rock produced when low-viscosity lava cools at or near Earth’s surface. Flood erosion exposed and scoured the basalt bedrock underlying much of the Scablands.
Palouse Falls: A waterfall on the Palouse River in southeastern Washington, dropping into a steep-walled basalt canyon. The falls occupy a flood-carved canyon where the Palouse River was diverted from its former course.
Megaflood: An exceptionally large flood capable of reshaping landscapes on a regional scale. The Scablands made megafloods central to explanations of certain dramatic landforms.

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