All the rock debris shown in the foreground of this photo constitutes ground moraine. The material was formerly beneath Grinnell
Glacier. Debris in moraines ranges in size from fine silt, which you cannot see in this photo, to large boulders; thus, moraine
deposits are unsorted. The rock debris deposited by glaciers also tends to be angular. The sharp, angular
edges of the rocks are evident in the photo. Ground moraine is exposed as glaciers retreat. Grinnell Glacier is located off the
photo to the left. A large proglacial lake containing floating slabs of ice occupies the lower-middle portion of the photo.
Photo: R. Schukar. Used with permission.