Wednesday, March 11, 2009

The Columbia River Gorge

Ancient basalt flows

17-million years ago a series of rifts opened in Eastern Oregon and sent flood after flood of fast-flowing basalt lava cascading across the landscape, eventually burying the region beneath more than a mile of stone.

Later came epic floods of ice and water. During the last glacial period, an ice damn burst, emptying out a small inland sea that covered much of Montana. The result was a three-day deluge that began with a 300-foot tsunami sweeping across the plains of Washington and blasting out the Gorge.

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