Longs Peak, Colorado, USA
U.S. Geological Survey photo (fair use policy)
Longs Peak is in northern Colorado, part of Rocky Mountain National Park. This is its sheer east face, known to climbers as the Diamond, overlooking Chasm Lake. This face of the mountain is a cirque, a bowl in which a glacier once sat. Two other alpine glaciers advanced from valleys to the left of this picture and merged at Chasm Lake, feeding a major ice stream whose valley is now drained by Roaring Fork, on its way to the Gulf of Mexico via the Missouri and Mississippi Rivers. Over the long series of glaciations of the last 2 million years, this valley has been filled with ice many times.
Alpine glaciers erode their way headward, plucking rock off the cirque walls and depositing the pieces far downhill in stony heaps called moraines. Given enough time, they can grind a peak into a scoop-sided, faceted shape known as a horn. The Matterhorn of Switzerland is the best-known example.
This U.S. Geological Survey photo repeats a historical photo taken in 1916 from the same spot. The Survey's program of reoccupying photo sites of the first explorers has allowed us to document precisely how the Western landscape changes with time.
Gallery of Glacier and Ice Pictures
