Global Volcanism Program | Image GVP-07808
The steep-sided walls of the 1902 explosion crater at Santa María expose a sequence of alternating thin (1-10 m) light-colored lava flows and brownish-colored block-and-ash deposits. Growth of the composite cone involved the extrusion of basaltic-andesite lava flows, mostly from the summit vent. Andesitic lava, the most silicic of those forming the cone, caps the summit.
Photo by Bill Rose, 1974 (Michigan Technological University).