From Miller et al (1998): "Redoubt Volcano is a steep-sided cone about 10 km in diameter at its base and with a volume of 30-35 cubic kilometers. The
volcano is composed of intercalated
pyroclastic deposits and
lava flows and rests on Mesozoic granitic rocks of the Alaska-Aleutian Range batholith (Till and others, 1993; 1994). It has been moderately dissected by the action of numerous alpine glaciers. A 1.8-km-wide, ice-filled summit
crater is breached on the north side by a northward-flowing glacier, informally known as the Drift Glacier, which spreads into a piedmont lobe in the upper Drift River Valley. The most recently active
vent is located on the north side of the crater at the head of the Drift glacier.
Holocene lahar deposits in the Crescent River and Drift River valleys extend downstream as far as Cook Inlet."