Erosion Atop Babcock Bench

December 20, 2018

BruceB_babcock2 (1)

Photographer: Bruce Bjornstad 
Summary Author: Bruce Bjornstad 

Shown above is a fine example of bizarre erosion by Ice Age floods as observed atop Babcock Bench, near Trinidad, Washington. This chaotically eroded surface (top of Grande Ronde Basalt) is perched high above, and immediately adjacent to, the Columbia River. Highly turbulent mega-floods, up to 700 ft (213 m) deep, scoured into this basalt surface, preferentially eroding out areas of weaker rock. The flood(s) responsible for the erosion occurred earlier in the last glacial cycle (18-19 thousand years ago) before the Okanogan Ice Lobe advanced to block the Columbia River upstream. For scale, note the 5-10 ft (1.5-3 m) wide jeep trail at upper right. Photo taken on October 3, 2017.