USGS Visual Identifier
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Geologic Unit: Chainman

Chainman Shale (CA*,NV*,UT*)
Chainman Formation (NV*)

Mississippian, Early*
Mississippian, Late*
Geologic Province:
Great Basin province*

Areal Extent:

Type Locality:
Not designated. Named from the Chainman mine, White Pine Co., NV (Spencer, 1917).
"Type locality": Ely district (Nolan and others, 1956).

(descending): Delle Phosphatic Member (NV*,UT*), Jensen Member (UT), Needle Siltstone Member (UT*), Scotty Wash Member (NV), Skunk Spring Limestone Bed (UT*), Willow Gap Member (UT).

Unit Name History:
Named (Spencer, 1917).
Areal limits (Nolan and others, 1956; Merriam and Hall, 1957; Hose and Repenning, 1959).
Revised (Langenheim and Tischler, 1960).
Areal limits (Brew, 1961).
Revised (Arnold and Sadlick, 1962; Sadlick, 1966).
Age modified (Brokaw, 1967).
Not used (Gordon and Poole, 1968).
Areal limits (Whitebread, 1969; Tschanz and Pampeyan, 1970).
Mapped (Nolan and others, 1971).
Redescribed (Brew and Gordon, 1971).
Not used (Dixon and others, 1972).
Age modified (Smith and Ketner, 1975).
Areal limits; Revised, divided into lower phosphatic member and Needle Siltstone Member (first used) (Sandberg and others, 1980; Sandberg and Gutschick, 1980).
Revised, divided into Delle Phosphatic Member (new) and Needle Siltstone Member (Sandberg and Gutschick, 1984).
Revised (Fraser and others, 1986).
Mapped 1:24k in Mountain Home Range, southwest UT (Hintze, 1986).
Mapped; Divided into (descending) Jensen Member, Willow Gap Limestone Member, Camp Canyon Member, Skunk Spring Limestone Bed or Member, Needle Siltstone Member, and Delle Phosphatic Member (Hintze and Best, 1987).
Areal limits (Day and others, 1987; Pampeyan and others, 1988; Jayko, 1990; Schneyer, 1990; Miller and others, 1990; Ketner and Ross, 1990; Ketner, 1990; Maldonado and Schmidt, 1991; Miller, 1993; Miller and others, 1993; Miller and Lush, 1994).

Note: If you need more information, please contact Nancy Stamm (
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" implies that a name has been abandoned or that it has fallen into disuse. Former usage and, if known, replacement name given in parentheses ().

Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
Database project personnel
Last modified: 15-Jan-2013