July 10, 2009 10:00 AM PDT
Inferno Cone at Craters of the Moon in Idaho. "Cinder cones form when gas-rich volcanic froth erupts high into the air and then piles into a mound," according to the National Park Service. But those who climb Inferno Cone may find themselves disappointed because they can't find the source of the eruption. "These cinders were actually blown by the wind, and possibly squirted in this direction, from a vent far below."
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Photo by Daniel Terdiman/CNET
