The Dalles Type of River Channel

Streams of large volume with high gradient, flowing over closely and vertically jointed rock, pluck rather than abrade. They erode rock basins in mid-channel without waterfalls or eddies. The channels are multiple and anastomose very irregularly. Flat-topped, vertically-walled rock islands are left among the channels. The type is the Dalles of Columbia River. Homology between the present Dalles channels and great areas of "scabland" on the Columbia Plateau north of Snake River is indicated. The "scablands" are the channels of enormous Pleistocene rivers across the plateau.