Volcán Cay, located east of Macá volcano and NW of the town of Puerto Aisén, is a basaltic and dacitic stratovolcano. An explosion crater is open to the east, and about a half dozen explosion craters and pyroclastic cones lie along a fissure trending SW of the summit. Another 10 basaltic pyroclastic cones are located along second parallel fissure 5 km to the SE that is part of the major regional Liquiñe-Ofqui fault zone. These cones were considered to be of Holocene age by González-Ferrán (1995), but Naranjo and Stern (2004) found no evidence for Holocene tephra deposits.