It was more than 100 years later that this river figured in the explanation of geological events from a much earlier time. In the 1920's, J.Harlan Bretz began studying the geology of the Columbia River basin and attempting to account for its complex and unique landforms. After much field observation and thinking, he postulated the existence of a catastrophic flood, greater than any other ever known in the history of the world. An important observation which led to this conclusion was the enormous plunge pool below Palouse Falls. While a beautiful 180-foot drop, the Palouse Falls at its present size in no way explains this huge basin. Coupled with other evidence over a wide area, this led Bretz to explain the geology of the Columbia Basin through the agency of these great waters, now known in his honor as the Bretz Floods.
Today we visited Palouse Falls and saw how Bretz reached his conclusion. We also explored the lower river by Zodiac, near the site of Lewis and Clark's salmon trading almost exactly 195 years ago.
