The Channeled Scablands are a relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods within the southeastern part of Washington state. The Channeled Scablands were scoured by more than 40 cataclysmic floods during the Last Glacial Maximum and innumerable older cataclysmic floods over the last two million years. These floods were periodically unleashed whenever a large glacial lake broke through its ice dam and swept across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch. The last of the cataclysmic floods occurred between 18,200 and 14,000 years ago.
Drumheller Channels
View downstream of Park Lake Side Canyon, one of the channels which fed floodwaters to Grand Coulee
Coulee, or coulée is a term applied rather loosely to different landforms, all of which refer to a kind of valley or drainage zone. The word coulee comes from the Canadian French coulée, from French couler 'to flow'.
This side canyon of Grand Coulee in Washington was carved by the Missoula floods.
A view through a coulee in Alberta, with steep but lower sides, and water in the bottom.
Drumheller Channels in the Columbia Basin of Washington
A view upward into a coulee in the Oldman River valley in Lethbridge, Alberta