Wyoming G.T.N.P., near Amphitheatre Lake. On 13 July David Vetterlein (18), and Charles Sinclair (30), were glissading down a couloir leading to Amphitheatre Lake from the west. The snow was soft to a depth of about one foot. Vetterlein lost control of his glissade about halfway down and slid some 150 feet onto grass slopes where he sprained his ankle. He was left at Amphitheatre Lake with some food, water, and an old parka but had no other warm clothing. He was evacuated by horseback that evening.

Source: George Lowe, Park Ranger, G.T.N.P.

Analysis: This was Vetterlein’s first climb. He probably should have been roped or had more practice on simpler slopes. In more isolated mountains, this accident could have been more serious due to the lack of equipment.