Laramie Formation

Weed, W.H., 1893, The Laramie and the overlying Livingston formation of Montana: U.S. Geological Survey Bulletin, 105, p. 10-41. Is a coal-bearing sandstone and shale formation about 1,000 ft thick mapped in southern and west part of area (geologic map), Park Co, MT, Montana folded belt province. Extends along flanks of Snowy Mountains, Bridger and Little Belt Ranges. Recognized as the chief coal-bearing formation in the entire Rocky Mountain region. Underlain by the massive sandstone assigned to the Fox Hills [sandstone] and revised at its upper contact in that it is overlain unconformably by the newly named Cretaceous Livingston formation. The upper contact marks an abrupt lithologic change. Has marine Cretaceous fossils. Sandstones of the Laramie are characteristically poorly cemented, generally massive and cross-bedded, consisting mainly of quartz, mica, and accessory minerals from Archean rocks; they do not contain volcanic rock fragments. Plant remains present in the gray shales. Measured section of lower part near Bowers mine. Willis, Bailey, 1902, Stratigraphy and structure, Lewis and Livingston ranges, Montana: Geological Society of America Bulletin, v. 13, p. 305-352. Laramie formation uppermost Upper Cretaceous formation in Bighorn Mountains thought to underlie the plains between the foothills of the Bighorns to the Black Hills in the Powder River basin and Williston basin. Laramie lies in a broad flat-bottomed basin with steep dips on the west slope of the Bighorn uplift. Thickness is thought to be several thousand feet. Laramie rocks are the lower parts of the sequence composed of sandstone, sandy shale, and shale with numerous lignite beds. Has a lower part of alternating shale and thin-bedded, rusty sandstone. Lower part in northern region has a conglomerate of flat pebbles derived from the Deadwood formation. Conglomerate recognized from west of Sheridan south to Crazywoman Creek. Schultz, A.R., 1920, Oil possibilities in and around Baxter basin, in the Rock Springs uplift, Sweetwater County, Wyoming: U.S. Geological Survey Bulletin, 702, 107 p. Mapped as "Laramie" formation on east flank of Rock Springs uplift, Sweetwater Co, WY, Greater Green River basin. Consists of sandstone, clay, and coal beds with massive basal bed of white and yellow sandstone with traces of conglomerate in places. Overlies Lewis shale; unconformably underlies post-"Laramie" formation rocks. Shown to be 1500 ft thick on stratigraphic chart. Cross sections. Late Cretaceous age. Pg. 65-86. Discussion of Cretaceous-Tertiary boundary in Denver basin, Colorado. Stratigraphic and paleontologic evidence show that Laramie formation, Arapahoe formation, and the Cretaceous parts of Denver formation and Dawson arkose comprise a unit correlative with Lance formation and its equivalents. Proposed herein that the Laramie be redefined to include all the Upper Cretaceous sequence between top of Fox Hills and base of the Paleocene in Denver basin; that term Arapahoe as Arapahoe conglomerate member be retained for the conglomerate immediately overlying present Laramie formation; that terms Denver formation and Dawson arkose be restricted to the Tertiary strata. The Laramie as expanded is equivalent to typical Lance formation and Hell Creek formation; to Medicine Bow formation plus basal part of Raton formation with the exception that both the Medicine Bow and Vermejo as now defined may include in their basal parts some strata that should be referred to Fox Hills sandstone. Laramie formation-Arapahoe formation contact in the Denver basin remains as defined by Emmons, Cross, and Eldridge in (1896). The contact is erosional separating clay of the Laramie from arkosic conglomerate of the Arapahoe. Mapped (geologic map) between Colorado Springs east to Black Squirrel Creek areas, and north of Matheson around mapped area to Ralston Creek area, CO in the Denver basin. Mapped locally at west edge of basin. Of Late Cretaceous age. Van Horn, Richard, 1957,