A catastrophic flood, probably exceeding 10 million cfs, was released down the Portneuf River at Red Rock Pass, Idaho, when ancient Lake Bonneville broke its natural dam in Wisconsin time. The flood entered the Snake River and overflowed banks at bends and constrictions, scoured deep channels (many of which are now abandoned), and left extensive high bars of sand, gravel, and boulders. The flood was at least 410 feet deep at Brownlee damsite near Homestead, Oregon.

First Page Preview

First page PDF preview
You do not currently have access to this article.