Tropic Shale

Usage of Geologic Unit Name:
Tropic Shale (UT*)
Cretaceous, Late*
Cenomanian, late*
Turonian, early*
Turonian, middle*
Geologic Province:
Paradox basin*
Plateau sedimentary province*
Areal Extent:
Type Locality:
Not designated. Named for excellent exposures around the town of Tropic, Garfield Co., UT (Gregory and Moore, 1931).

Unit Name History:
Named (Gregory and Moore, 1931). Revised (Peterson, 1969). Biostratigraphic dating (Cobban, 1988a). Age modified; Biostratigraphic dating (Cobban, 1988b).


Gregory, H.E. and Moore, R.C., 1931, The Kaiparowits region, a geographic and geologic reconnaissance of parts of Utah and Arizona: U.S. Geological Survey Professional Paper, 164, 161 p.

Peterson, Fred, 1969, Four new members of the Upper Cretaceous Straight Cliffs Formation in the southeastern Kaiparowits region, Kane County, Utah, IN Contributions to stratigraphy, 1968: U.S. Geological Survey Bulletin, 1274-J, p. J1-J28.

Cobban, W.A., 1988, Tarrantoceras Stephenson and related ammonoid genera from Cenomanian (Upper Cretaceous) rocks in Texas and the Western Interior of the United States: U.S. Geological Survey Professional Paper, 1473, 51 p.

Cobban, W.A., 1988, The Upper Cretaceous ammonite Watinoceras Warren in the Western Interior of the United States, IN Contributions to paleontology: U.S. Geological Survey Bulletin, 1788, 15 p.

Gillette, David D., and Albright, L Barry, 2003, Further discoveries of Cenomanian-Turonian (early Late Cretaceous) plesiosaurs from the Tropic Shale, southern Utah: Journal of Vertebrate Paleontology, v. 23, no. 3, Supplement, p. 55.

Gillette, David D., Hayden, Martha C., and Titus, Alan L., 1999, Occurrence and biostratigraphic framework of a plesiosaur from the Upper Cretaceous Tropic Shale of southwestern Utah: In, Vertebrate paleontology in Utah: Gillette, David D., ed., Utah Geological Survey, Miscellaneous Publication, v. 99-1, p. 269-273.

Leithold, Elana L., 1994, Fine-grained sediment transport and accumulation on a Cretaceous prodelta; the Tropic Shale of southern Utah: American Association of Petroleum Geologists and Society of Economic Paleontologists and Mineralogists,
Annual Meeting Abstracts, v. 1994, p. 195.

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Last modified: 1/7/2011