Volcanoes can be formed by plumes of magma originating in this layer of the Earth below the crust
... To produce basaltic 
magmas by melting of the basaltic oceanic crust would require... [DOC] [TLE] Earth Explainer: The volcano basics - Science News for Students [PAR] Oct 1, 2014 ... A volcano is a spot in Earth's crust where molten rock, volcanic ash and certain 
types of gases escape from an ... Volcanoes can form on land or below the sea.