Rex Trulove
Up here on top, there are three plaques. I took a picture of all three, but one of the pictures didn’t turn out. This is the first one, though. The plaque reads:
The Mad Rush to the Sea
Lake Missoula, which formed behind a glacial ice dam along the Clark Fork River about 15,000 years ago, would rise year after year until it finally became deep enough to float and break the ice. When it broke, the lake suddenly drained, dumping its water across eastern Washington and down the Columbia River to the Pacific Ocean. Because glaciers were still moving south out of Canada, new ice dams formed, and broke, time and again.
Between Plains and Thompson Falls, Highway 200 passes through 10 miles of nearly straight canyon. When the largest of the glacial lakes was draining, careful calculations estimate that the flow through this area was at least 9.5 cubic miles of water per hour. That is more than 10 times the combined flow of all the rivers in existence today.
When the lake drained, enormous volumes of water poured through three passes a few miles west of here. You can travel across miles of the giant ripples that formed under this tremendous flow along Highway 382 near the north end of Camas Prairie. These look just like sand ripples in a creek bed, except they are as much as 30 feet high and span 200 to 300 feet from crest to crest.
~David Alt, Author & Professor of Geology
