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Geology of National Parks, 3D and Photographic Tours

Great Falls and Great Falls Lake
The undulating surface along the top of the cliff in this view reveals a series of channels where waterfalls once poured over the Dry Falls. Swirling currents at the base of the falls carved a basin that remains a natural lake at the base of the cliff. The Grand Coulee may have already been a south-draining stream before the Spokane Flood, but the shear volume of floodwaters flowing the drainage carved the unique landscape within the "coulee" (the name of a dry chasm originally formed by the great flood). The many lakes in the Grand Coulee are remnants of flooded basins eroded along the valley floor carved by the passage of floodwaters (Baker and others, 1987, Bretz, 1969).
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