Map of Lake Missoula

ID: 4716 ~ Source: Lake Roosevelt National Recreation Area, National Parks Service
This file appears in: Carving the Columbia

The borders of Idaho, Washington, and Montana give a sense of how much land this ice-age lake covered. When the ice dams burst, the entire lake could flow into the Pacific in a matter of days.

This file appears in: Carving the Columbia

By Charlie Byers
Between 18,000 and 13,000 years ago, glaciers advanced and retreated over northern Washington. This ice formed a fragile dam on the Clark Fork River, which slowly filled with water, creating glacial Lake Missoula. The lake spanned hundreds of miles…