Cataclysms on the Columbia A Layman's Guide to the Features Produced by the Catastrophic Bretz Floods in the Pacific Northwest

The Landscape Just what was the Pacific Northwest like 12 thousand years ago, after the last flood? As the melting ice fronts in the intermontane valleys of the Rocky Mountains retreated, lakes formed behind the terminal moraines, those piles of earth and rock debris that are deposited in front of an advancing glacier. The largest of these lakes is now know as Flathead Lake in Montana. Dozens of other lakes in the trenches became filled with glacial outwash, became swamps, and were eventually cut into by streams to form trenches along the valleys and new plains. In the Purcell Trench, lakes Coeur d'Alene, Pend Oreille and still farther north Kootenai Lake were larger than now; they since have been reduced in size by deltas where entering streams deposited their load.The once smooth rolling plains of loess-covered basalt on the Columbia Plateau were now deeply scarred into hundreds of miles of broad and narrow dry channels and deeper coulees. Their scabland bottoms were dotted with kolk lakes whose basins had been plucked out in the barren basalt, particularly in the Cheney-Palouse area in the east, and the Grand Coulee to the west . . .Allen, John Logan is the author of 'Cataclysms on the Columbia A Layman's Guide to the Features Produced by the Catastrophic Bretz Floods in the Pacific Northwest' with ISBN 9780881922158 and ISBN 0881922153.