Cerro Escorial, a small andesitic-dacitic stratovolcano, has young-looking lava flows and a well-preserved crater. It is the youngest volcanic center of the NW-SE-trending Corrida de Cori range that marks the Chile/Argentina border. Escorial is located 4 km NE of an active sulfur mine in older, extensively hydrothermally altered rocks. Very youthful-looking lava flows extend westward 3-4 km over an ignimbrite deposit on the Chilean side. A 1-km-wide crater caps the summit. Escorial was considered by de Silva and Francis (1991) to be of probable Holocene age based on morphological evidence, but Richards and Villeneuve (2002) obtained an Ar/Ar age of about 0.342 million years on a lava flow. Most of the lava flows extend to the SW into Chile, but a few small lobes traveled NE on the Argentinian side of the volcano. De Silva (2007 pers. comm.) noted that the well-preserved summit crater postdates the lava flow and could be of Holocene age.