Cloverly Formation

Lupton, C.T., 1916, Oil and gas near Basin, Big Horn County, Wyoming, IN Contributions to economic geology, 1915; Part 2, Mineral fuels: U.S. Geological Survey Bulletin, 621-L, p. L157-L190. table opp. p. 166, p. 167, 168. Cloverly formation. At type locality of Cloverly formation, near Cloverly, Wyoming, about 15 miles northeast of Basin, Bighorn County, Wyoming, the Cloverly formation, according to N.H. Darton (USGS Prof. Paper 51, p. 52, 1906), consists of 113 feet of strata, a detailed section of which is here given. Upper 20 feet (light-buff or tan-colored sandstone) of this formation constitutes Greybull sand, which carries oil and gas in Greybull field and water in Lamb anticline and Torchlight dome. The Greybull sand is overlain by Thermopolis shale (new). Age is Early Cretaceous. Report includes stratigraphic table. Source: US geologic names lexicon (USGS Bull. 896, p. 470); supplemental information from GNU records (USGS DDS-6; Denver GNULEX). Hewett, D.F., and Lupton, C.T., 1917, Anticlines in the southern part of the Big Horn basin, Wyoming; a preliminary report on the occurrence of oil: U.S. Geological Survey Bulletin, 656, 192 p., (incl. geologic map, scale 1:500,000) Lee, W.T., 1927, Correlation of geologic formations between east-central Colorado, central Wyoming, and southern Montana: U.S. Geological Survey Professional Paper, 149, 80 p. Pg. 64. Cloverly formation. Included the "rusty beds" in his Greybull sandstone member of Cloverly formation. Age is Early Cretaceous. Knappen, R.S., and Moulton, G.F., 1931, Geology and mineral resources of parts of Carbon, Big Horn, Yellowstone, and Stillwater Counties, Montana, IN Contributions to economic geology (short papers and preliminary reports), 1930; Part 2, Mineral fuels: U.S. Geological Survey Bulletin, 822-A, p. A1-A70. Pg. A23-A28. Cloverly formation. Included the "rusty beds" in Thermopolis shale [of Colorado age] and treated Greybull sandstone as top member of Cloverly formation. This is present approved definition of Cloverly formation. The Greybull sandstone is tentatively classified as Lower(?) Cretaceous. Hose, R.K., 1955, Geology of the Crazy Woman Creek area, Johnson County, Wyoming, IN Contributions to economic geology, 1955: U.S. Geological Survey Bulletin, 1027-B, p. B33-B118, (incl. geologic map, scale 1:48,000) Pg. B56-B57. Cloverly formation. In Johnson County, Wyoming, overlies Morrison formation and underlies Skull Creek shale. Thickness 135 to 165 feet. Age is Early Cretaceous. Report includes geologic map. Richards, P.W., 1955, Geology of the Bighorn Canyon-Hardin area, Montana and Wyoming: U.S. Geological Survey Bulletin, 1026, 93 p., (incl. geologic map, scale 1:62,500) Pg. 42-45. In Bighorn Canyon-Hardin area, Montana-Wyoming, formation is 300 to 400 feet thick, includes Pryor conglomerate member at base and Birdhead sandstone member at top. Overlies Morrison formation; underlies Thermopolis shale. Lupton (1916, USGS Bull. 621) called the 20 feet of sandstone at top of Darton's type Cloverly Greybull sandstone. This unit has been called member of Cloverly but not always top member. Overlying Greybull sandstone member in Bighorn basin is unit of shales and rusty-weathering sandstones which Darton called "rusty series" or "rusty beds." The "rusty beds" have been included in Thermopolis shale by some workers and in Greybull sandstone by other workers. If Cloverly formation from Birdhead sandstone down to the variegated beds is correlative with Darton's "rusty beds," then Cloverly in Bighorn Canyon-Hardin area, includes strata younger than type Cloverly. Inclusion of "rusty beds" in the Cloverly constitutes a redefinition of Cloverly as described by Darton. This redefinition is justifiable because Darton's upper unit of Cloverly, the Greybull sandstone member, is not readily separated in many localities from underlying "rusty beds." Top of Cloverly --if it is to occur at a lithologic break of considerable areal extent-- should be pla