Steam rises in December 1980 from a cinder cone in Alaska's Okmok caldera. Known only as Cone A, it is one of numerous unnamed pyroclastic cones within the 10-km-wide caldera. Erosional furrows produce linear stripes on the flank of the cone. Eruptions from Cone A in 1945 and 1958 produced lava flows, which issued onto the caldera floor. Cone A erupted again six months after the date of this photo. The wall of Okmok caldera forms the skyline ridge.