Description

From Wood and Kienle (1990) ^[1] : "Mount Drum, the westernmost volcano in the Wrangell volcanic field, was formed between ~0.65 and 0.24 Ma during at least two cycles of cone-building and ring-dome extrusion. The first cycle began with the construction of a cone consisting chiefly of andesite and dacite lava flows, breccias, lahars, and tuffs, and culminated with the emplacement of a series of rhyolite ring domes around the cone's southeast flank. The second cycle of activity, following without an apparent time break, continued to build the cone but with more dacitic flows and fewer pyroclastic and volcaniclastic deposits. This stage was followed by the emplacement of at least nine dacitic domes that lie on 270 degrees of arc, crudely defining a circle ~12-13 km in diameter centered approximately at the present summit of Mount Drum. The rhyodacite dome of Snider Peak and its massive dacite flows erupted late in the second cycle, probably marking the end of major constructive activity. Following the second cycle, paroxysmal explosive activity, probably from the central vent area, destroyed the south half of the stratovolcano and deposited ~7 cubic km of hot and cold avalanche debris over an area >200 square km."