The sharp ridges to the right are the result of Pleistocene to Holocene glaciation of the volcano massif. Broad grassy foreground are Holocene andesite that reach the Bearing Sea. Fumarole vent at the summit of Makushin Volcano. Bright yellow sulfur deposits surround the vent. Pakushin, a flank vent of Makushin Volcano, is a cinder cone that was constructed during the Pleistocene.
Okmok caldera is visible in the distance.
View is from the east. A bubble bursts at a small, boiling hot springs on the flank of Makushin Volcano. Hot springs and fumaroles may form when groundwater is heated by a magmatic source. Layers of surge deposits blanket a bomb on the slopes of Sugarloaf, a flank vent of Makushin Volcano. Rock hammer is for scale.