Geology
The Missoula Floods that swept periodically across eastern Washington and across the Columbia River Plateau during the Pleistocene epoch carved out the Palouse River Canyon, which is 1,000 feet (300 m) deep in places.
The ancestral Palouse River flowed through the now-dry Washtucna Coulee directly into the Columbia River. The present-day canyon was created when the Missoula Floods overtopped the northern drainage divide of the ancestral Palouse River, diverting it to the current course to the Snake River by eroding a new, deeper channel.
The area is characterized by interconnected and hanging flood-created coulees, cataracts, plunge pools, kolk created potholes, rock benches, buttes and pinnacles typical of scablands.
Read more about this topic: Palouse River