Geology of the Okanogan Highlands 2012 - Stop 6

Stop 6: Curlew Lake State Park 

Curlew Lake is in a valley formed by erosion at the base of a continental glacier, known as the Cordilleran Ice Sheet. The ice sheet originated in the mountains of western Canada and covered a large part of northwestern North America, reaching a maximum extent about 20,000 years ago, and then melting away by approximately 10,000 years ago. Glaciers consist of moving, flowing ice, which over this valley may have been the better part of a mile thick. The hills on the far side of the lake are long ridges that are streamlined in a north-south direction, sculpted by the south-flowing glacier that covered this entire landscape. The valley of Curlew Lake was a pre-existing stream valley, which had its drainage altered and divided as a result of the glaciation. Sanpoil Lake and Curlew Lake are in the same valley, with less than 3 miles between them. Sanpoil Lake drains south into the Columbia River. On the other hand, Curlew Creek, the outlet stream of Curlew Lake, drains north into the Kettle River. This is an example of what is called a deranged stream drainage system, a common effect of recent glaciation.

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