Named as the upper member of Great Blue formation for Poker Knoll and adjoining hills north of Topliff Hill in S1/2 sec 33, T7S, R3W and NE1/4 sec 4 and W1/2 sec 3, T8S, R3W, Tooele Co, UT in Great Basin province, designated the type locality. Is poorly exposed. No measured section of type described. Lower contact with Chiulos member (new) of Great Blue placed at base of gray- to black-weathering silty limestone. Upper contact with Manning Canyon shale is transitional through 20 ft. Limestones of Poker Knoll are medium to fine grained, thin-bedded, weathering to platy chips, and are dark gray to tan. Much brown-weathering black chert is interlayered in beds 1-12 in thick. Some clay shales in middle of member. Thickness established as not less than 600 ft and more than 700 ft. Of Late Mississippian age. Geologic map. Cross sections.

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