Lake Viedma, approximately 50 miles (80 kilometers) long in extreme southwestern Argentina, is a major elongated trough lake formed from melting glacial ice. The lake is fed primarily by the Viedma Glacier at the western end of the lake. The Viedma Glacier measures 3 miles (5 kilometers) wide at its terminus at Lake Viedma. Medial moraines, appearing as dark linear strips in the glacier, were created when adjacent ice walls from different glaciers merged. Elevations within the snow-covered southern Andes Mountains range between 9000 and 11 000 feet (2740 and 3350 meters) above sea level. Numerous features associated with the glacial environment, including hanging valleys, tarns, cirques, horns, aretes, and U-shaped valleys, are visible in this near-vertical photograph. The brown landscape resulted from ice scouring, which left virtually no vegetation on the steep-walled valleys. The blue lake near the northern edge of the photograph is a small segment of Lake San Martin.