An aerial view of the Rocky Mountains, somewhere over Colorado, with a fresh snowfall. The Rocky Mountains took shape during a period of intense plate tectonic activity that formed much of the rugged landscape of the western United States. Three major mountain-building episodes reshaped the west from about 170 to 40 million years ago (Jurassic to Cenozoic Periods). The last mountain building event, the Laramide orogeny, (about 70-40 million years ago) the last of the three episodes, is responsible for raising the Rocky Mountains. Photo Credit: Alan Cressler (alan_cressler on Flickr)
U.S. Geological Survey,Inkey
CC BY 2.0
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