Interstate 70 east of Grand Junction runs through spectacular Glenwood Canyon. The highway is one of the most amazing pieces of engineering in the world. In places the road rests atop a long concrete wall, and the upper deck of the highway hangs over the lower deck.
In Glenwood Canyon we can see Paleozoic sedimentary rocks (younger than 550 million years) resting on top of Precambrian igneous and metamorphic rocks about 1.6 billion years old. A place where young rocks rest on much older rocks, with a long gap in geologic time missing, is called an unconformity. In the views below, the unconformity is marked by the band of trees about halfway up the cliffs.
The Colorado River cut this canyon within just the last couple of million years as mountain building raised the crust and the rive cut downward into it.
Created 25 November 2005, Last Update 14 December 2009
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