Notable geologic features which the trail passes include the Cow Creek scabland, the point at which the Palouse River departs its former course (captured by ice-age flood erosion), Washtucna Coulee (the abandoned course of the Palouse River scoured wide by the floods), Devil's Canyon (a dry, straight, 4 miles former flood channel which descends to the Snake River), giant current-created ripples formed by the flood currents in the low lands along the Snake River, and the Walker Bar, created by the outflow of the floods.