Arêtes are sharp mountain ridges, said to be “knife-edged,” formed by glacial erosion in two separate valleys eating into the rock that divides them. Snow that falls on the near side of this arête ultimately contributes to Margerie Glacier, the most visited glacier in the park, while on the far side it joins Johns Hopkins Glacier, which is, arguably, even more spectacular. As no doubt you can imagine, snow has a very difficult time clinging to mountain slopes so steep, and thus it frequently cascades down as avalanches, carving the corrugations that are so prominent in the lower right. This process is in no way limited to the wintertime as at these altitudes, snow is possible anytime of the year. Photographer: Richard Becker