(310) MISSISSIPPIAN MADISON LIMESTONE Uniform thin beds of (Total about 1,100 blue-gray limestone and feet, but only lower sparse very thin layers of 300 feet preserved in shale. Brachiopods, corals, this section) and other fossils abundant. (345) LATE AND DARBY FORMATION (About Thin beds of gray and buff MIDDLE DEVONIAN 350 feet) dolomite interbedded with layers of gray, yellow, and black shale. A few fossil brachiopods, corals, and bryozoans. (390) (425) LATE AND BIGHORN DOLOMITE (About Thick to very thin beds of MIDDLE 450 feet; Leigh blue-gray or brown dolomite, ORDOVICIAN Dolomite Member about white on weathered surfaces. 40 feet thick at top) A few broken fossil brachiopods, bryozoans, and horn corals. Thin beds of white fine-grained dolomite at top are the Leigh Member. (440) (500) LATE CAMBRIAN GALLATIN LIMESTONE (180 Blue-gray limestone mottled feet) with irregular rusty or yellow patches. Trilobites and brachiopods. (530) MIDDLE CAMBRIAN GROS VENTRE FORMATION PARK SHALE MEMBER Gray-green shale containing (220 feet) beds of platy limestone conglomerate. Trilobites, brachiopods, and fossil algal heads. DEATH CANYON Two thick beds of LIMESTONE MEMBER dark-blue-gray limestone (285 feet) separated by 15 to 20 feet of shale that locally contains abundant fossil brachiopods and trilobites. WOLSEY SHALE MEMBER Soft greenish-gray shale (100 feet) containing beds of purple and green sandstone near base. A few fossil brachiopods. FLATHEAD LIMESTONE (175 Brown, maroon, and white feet) sandstone, locally containing