These blocky andesite lava flows from Trident Volcano were emplaced during an extended eruptive period between 1953 and the mid-1960's. Trident Volcano is composed of a cluster of andesite and dacite cones and is the only Katmai group volcano other than Katmai and Novarupta to have had historical activity. Photograph by T. Miller, U.S. Geological Survey, July, 1974.