Named as basal member of Great Blue limestone for abandoned Topliff quarries near Topliff Hill, Great Basin province. Type section measured on north side of Edwards Canyon, S1/2 SE1/4 sec 31, T8S, R3W and N1/2 NE1/4 sec 6, T9S, R3W, Tooele Co. Is 462 ft thick at type where it conformably overlies Humbug formation and conformably underlies Paymaster member (new) of Great Blue. Consists of dark gray, fine-grained to very fine grained limestone with one 1 ft thick olive green, fine-grained sandstone and one 14 ft thick medium-grained dolomite bed. The limestones are generally well-defined 6 in to 8 ft thick beds. Base placed at top of well-defined quartzite bed of Humbug. Top placed at base of first shale or quartzite above well-bedded limestone of Topliff. Black and brown chert present as nodules in the finer grained limestones. Forms ledgy outcrops. Of Late Mississippian age. Geologic map. Cross sections.

Source: GNU records (USGS DDS-6; Denver GNULEX).