Pg. 42 and passim. Glenn Creek shale member of Jefferson limestone. Recognized in northwestern Montana. Underlies Lake limestone and overlies White Ridge limestone; all members of Jefferson limestone. Thickest (66 feet) at type locality on White Ridge; thinnest (7 feet) in Nannie basin region. Type locality on south side of southwestern peak of White Ridge, [Slategoat Mountain 7.5-min quadrangle, Lewis and Clark County, northwestern Montana], where it consists of (descending): (1) 31 feet of dull- and brighter-red calcareous shale with several beds (up to 14 inches thick) of gray argillaceous limestone, and at top thinner bedded very argillaceous lavender-red limestone; (2) 20 feet of thin-bedded red clay shale with green-gray fissile shale in upper 2 feet; (3) 8 feet of dull-red thick-bedded calcareous shale and shaly argillaceous red-gray limestone. Named for Glenn Creek, [Saypo quadrangle, Lewis and Clark County, northwestern Montana], whose middle branch heads at eastern base of White Ridge. On Saypo topographic sheet the names Glenn Creek and Moose Creek have been interchanged. Age is Middle Devonian.

Source: US geologic names lexicon (USGS Bull. 896, p. 828-829).