Porcupine Mountains Escarpment

March 24, 2006

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Provided and copyright by: James Dake
Summary authors & editors: James Dake

This photo was taken from the Escarpment trail at Porcupine Mountains Wilderness State Park in Michigan's Upper Peninsula. The escarpment seen on the left was formed by the Keweenawan lava flows in the Late Precambrian. It's composed of a tilted layer of basalt, with sandstone beneath it. The escarpment formed because the basalt that caps the ridge is more resistant than the underlying sandstone. Down in the right corner, you can see talus accumulated from broken rock. Across Lake Superior, and the Lake Superior Syncline, is Isle Royale National Park, which shares this same geology. In the distance is the Lake of the Clouds, which is over a mile long (1.6 km) and only 15 feet deep (4.5 m). Photo taken on August 22, 2005.

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