GeoSnaps - Image of the Day
Geologic snapshots capturing Arizona’s geologic setting and mining history with a picture of the day from 1 January through 31 December 2013.
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Sept. 3, 2012 | San Francisco Peaks | Coconino County, Arizona
The San Francisco Peaks north of Flagstaff are Arizona's highest mountain but used to be much higher before the stratovolcano collapsed. The gentle slopes at far right and far left project upward toward the center, giving an idea of how high this mountain used to be, estimated at about 15,300 feet above sea level. This is 800 feet higher than Mt. Whitney in California, meaning that Arizona used to have the tallest peak in the lower 48 states (obviously before there were any states). The age of the collapse is constrained between the youngest lavas on Mt. Humphries (the peak on the right), about 440,000 years ago, and another volcano that was erupted on top of the collapse (not visible), about 100,000 years ago. This unique view of the Peaks is taken from the north side and looks to the south.(Photo and caption by Wayne Ranney)