Washington Geologic Wonders: Dry Falls was really flowing during the last Ice Age

Dry Falls
The Dry Falls formation in Grant County was created by massive flooding during the last Ice Age, 12,000-18,000 years ago. Photo: Rian Skov/DNR.

The majestic Dry Falls formation near Coulee City was created by the Missoula floods about 12,000-18,000 years ago during the last Ice Age. A cycle of damming and breaching of the ice surrounding Glacial Lake Missoula (a massive lake situated in current-day western Montana) produced numerous large floods. In their wake, the floods left the many large carved landforms (including Dry Falls) that we see today across parts of Montana, Idaho, Oregon, and Washington. The floods sculpted Dry Falls by cutting into the Columbia River Basalts rock formation. It is estimated that the volume of water coming over the falls during those Ice Age floods was about ten times greater than Niagara Falls.

This impressive spot is easy to visit and learn about, thanks to the Washington State Parks-maintained visitor center there. Dry Falls also is a principal stop along the proposed Ice Age Floods National Geologic Trail.

Learn more about the geology of Washington state by reading  Washington State Geology News, published by DNR’s Division of Geology and Earth Resources. Sign up for a free subscription

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