Moraines at Lee Vining Canyon. This view of the Sierra Crest, looking to the southwest, shows several Pleistocene glacial moraines. This photo is taken from atop a lateral moraine that forms the north wall of the canyon, looking across at the lateral moraine that forms the south wall. These moraines were deposited during late Tahoe Stage glaciation, about 50,000 to 100,000 years ago. (Estimated dates for Sierra glaciation vary widely.) The glacier originated on the flanks of of Mt. Dana, the unglaciated peak on the right, and moved down the canyon to the left. The low mounds across the floor of the canyon in the lower left are the eroded remains of a recessional moraine left by the retreating glacier during the more recent Tioga Stage, which ended about 15,000 years ago. The small snow field on on the flank of Mt. Dana at the upper right is "Dana Glacier," all that remains of the river of ice that once filled this canyon. Inyo National Forest. Near Lee Vining, Mono Co., Calif.