From Hildreth and others (1999): "Alagogshak volcano, a newly recognized volcanic-front stratovolcano on the Alaska Peninsula rangecrest, 15 km southwest of Katmai Pass, produced 10-18 km3 of andesite-dacite eruptive products during several episodes of activity in the middle and late Pleistocene. From a central vent marked by hydrothermal alteration and remnants of a cratered fragmental cone on the present-day drainage divide, glacially incised stacks of lava flows (57-66 percent SiO,) dip radially and extend 6-10 km in most directions. Lava flows that make up four ridge-capping outliers well west of the volcano may also have erupted there. The medium-K calcalkaline Alagogshak eruptive suite is compositionally varied, probably reflecting independent evolution of different magma batches supplied in several episodes spread intermittently over at least 600,000 years."
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