Cerro Escorial (center horizon), viewed from the summit of Lastarria volcano, is a small andesitic-dacitic stratovolcano that straddles the Chile/Argentina border. Very youthful-looking lava flows of uncertain age are seen here extending 3-4 km SW-ward over an ignimbrite deposit on the Chilean side of the border. Cerro Escorial is located 4 km NE of an active sulfur mine in older, extensively hydrothermally altered rocks, some of which are seen in the middle ground. Photo by José Naranjo, 1983 (Servico Nacional de Geologica y Mineria).