Wagontire Mountain

An ash-flow tuff exposed over some 80 km2 of the southern slopes of Wagontire Mountain probably erupted from a vent on the mountain and another several km to the west. The flow varies from 2-40 m in thickness and has a volume of less than 1 km3. The flow is zoned resulting from different degrees of compaction and welding. The rock is essentially glassy with some phenocrysts of alkali feldspar, quartz, aegirine-augite, blue amphibole (?riebeckite) and magnetite. Possible aenigmatite is also present. Chemical analyses are available (Walker and Swanson, 1968, Table 1).