Wednesday, March 9, 2011

A Flood of Biblical Proportions in North America

The Middle East was not alone in having floods of Biblical proportions. Although there was probably no Noah in North America 13,000 years ago, we had several major floods that were probably even greater than that of Noah’s time. In my book, I mention a flood that occurred when an ice dam holding back the waters of Lake Missoula broke.            

 Between about 14,500 and 12,800 years ago, a large lake about the size of modern Lake Ontario and Lake Erie combined formed in northwestern Montana. The lake, Lake Missoula, was created by continental glaciation that had advanced southward cutting off the drainage of the Clark Fork River to the Pacific Ocean. Prior to the ice dam breaking, the water behind the dam is thought to have been about 2,000 feet deep. With that much water, the ice dam began to float resulting in its breaking up. As the dam broke, water rushed out of Lake Missoula and flooded the downstream areas of Idaho, Washington, and Oregon before draining down the Columbia River Valley to the ocean. In less than two days, the lake is thought to have drained. Following the flood, the ice sheet again advanced to the south, once again damming the Clark Fork River. The cycle of damming and catastrophic flooding is thought to have been repeated about 25 and perhaps as many as 89 times. Today giant ripples are still present in the valley floors and the ancient shorelines are visible in the surrounding hillsides. 

See  for more and, in particular, watch the video about the geology of the Lake Missoula area today.

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