“…Member D contains several fine-grained biotitic dacitic welded tuff sheets, the "red liparite" of Lindgren. The tuffs resemble ash-flow tuffs of the lower unit of the Elkhorn Mountains Volcanics (Smedes, 1966 The unconformity at the base of member A is characterized by an abrupt and persistent change in mineral constituents. The beds below the unconformity, the Telegraph Creek Formation (upper part) or the Virgelle Sandstone Member, are composed of abundant quartz, some feldspar, and varying amounts of biotite, sphene, and magnetite in a calcite matrix, whereas the basal sandstones and mudstones of member A appear to be slightly reworked crystal tuffs with abundant plagioclase, minor quartz, moderate hornblende, and pyroxene in a clay-rich zeolite or calcite matrix.…”