The Ice Age Floods, which happened around 20,000 years ago, have intrigued geologists for over a century. J. Harlen Bretz, a geology professor at the University of Chicago, proposed a theory about these floods about 100 years ago. He suggested that these massive floods shaped the topography of eastern and central Washington, creating features like Grand Coulee and Dry Falls. This theory was initially controversial as it contradicted the conventional geological explanations.
Bretz had studied the geologic features left by glaciers in the Cascades and Puget Sound area. He had also researched the impact of floods caused by melting glaciers. However, he believed that the landscape in eastern and central Washington was the result of much larger floods. His idea of massive floods creating large coulees and leaving thick flood deposits was met with skepticism.
Bretz’s theory took years to be accepted by the scientific community. Today, the route of these massive floods is known as the Ice Age Floods National Geologic Trail. This trail starts in western Montana and northern Idaho, passes through Spokane County, and follows the Columbia River Gorge to the Pacific Ocean.