"At the upper ends of Denali’s glaciers are steep-walled semicircular basins called cirques. Cirques form from freeze-thaw cycles of meltwater in the rocks above the glacier, and by glacial erosion and mass wasting occurring under the glacier. As cirques on the opposite sides of a ridge are cut deeper into the divide, they form a narrow, sharp, serrated ridge called an arête. As the arête wears away from glacial ice breaking it down, the low point between cirques is called a col (or if it is large, a pass). Cols are saddle-shaped depressions in the ridge between cirques. A spire-like sharp peak, called a horn, is formed when cirques cut back into a mountaintop from three or four sides."

en.wikipedia.org/wiki/Denali_National_Park_and_Preserve

Talkeetna Air Taxi - Denali Flight and Glacier Landing

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