Lake Creek shale member of Pierre shale. Mostly dark-gray and black flaky shale; bentonite rare or absent; many limonite concretionary streaks and small soft limestone concretions; large tough limestone concretions very rare; poor cone-in-cone structure rarely developed; gypsum in places very abundant. Thickness 200+/- feet in outcrops in secs. 5 and 7, T. 13 S., R. 41 W., [Weskan NW 7.5-min quadrangle, Wallace County, northwestern Kansas]. Underlies Salt Grass shale member of Pierre and overlies Weskan shale member of Pierre. Differs from both Salt Grass and Weskan members by total absence or by great scarcity of the large limestone concretions that are so common in those members. [Age is Late Cretaceous.]
Named from Lake Creek, in northwestern part of Wallace Co., northwestern KS, along which the most extensive outcrops occur [Goodland 30- x 60-min quadrangle].

Source: US geologic names lexicon (USGS Bull. 896, p. 1134).

Is a member of Pierre Shale in Wallace Co, KS in Anadarko basin. Collections of the ammonite genus RHAEBOCERAS from upper part of member at USGS Mesozoic locality D618 about 18.5 km north-northeast of Sharon Springs in NE1/4, sec 31, T11S, R39W indicate an early Maestrichtian (Late Cretaceous) age.

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