 The volcano is about 3 @.@ 7 miles ( 6 @.@ 0 km ) in diameter at its base with a rough volume of 7 @.@ 2 to 8 @.@ 4 cu mi ( 30 – 35 km3 ) . The sides of the upper cone are relatively steep ( in comparison to volcanoes in general ) . Made up of pyroclastic flow deposits and lava flows , and resting on Mesozoic era rocks of the Aleutian Mountain Range batholith , the mountain has been somewhat weathered by movement of several glaciers that reside on it . The current main vent is on the north side of the crater by the head of the Drift glacier . Also present on the mountain are Holocene lahar deposits that extend as far as the Cook Inlet . This mountain has produced andesite , basalt and dacite , with relatively silicic andesite dominant in recent eruptions . 
