WALLS OF WATER RAGE THROUGH THE COLUMBIA GORGE
Water volumes exceeded the capacity of the gorge near today's John Day Dam, creating another impoundment which backflooded into the Dalles and Umatilla basins. Surging water gouged the walls of the gorge to their modern near-vertical alignment, thereby creating the complex of waterfalls at the gorge's west end. Patches of scabland were created near the Dalles and extensive sand and gravel bars were dropped into the valleys of tributary streams.
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Basalt terraces at Rowena, shaped by the Ice Age Floods.