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CORSET SPRING SHALE

Type Section Information

The Corset Spring Shale was named for exposures at and near Corset Spring, in T.12 N., R. 69 E., in the southern portion of the Snake Range (Drewes and Palmer, 1957).

Geologic Age

The Corset Spring Shale contains a trilobite fauna indicative of a Late Cambrian age. Fossils from the Corset Spring Shale are like those collected from the upper 65 feet of the Dunderberg Shale near Eureka, as well as portions of the Mendha Formation in eastern Lincoln County (Drewes and Palmer, 1957). The Dunderberg Shale is considered a regional equivalent of the Corset Spring Shale (Hose and Blake, 1976).

General Lithology

The Corset Spring Shale (Dunderberg Shale equivalent) is an olive-gray clay shale with pencil fracture. Near the middle of the formation in the Snake Range, about 20 feet of medium gray, thick-bedded, coarse crystalline, clastic limestone is present. The upper portion of the shale contains limestone nodules up to 3 inches in diameter. Trilobite fragments are present both in the limestone beds and nodules (Drewes and Palmer, 1957; Whitebread, 1969; Hose and Blake, 1976). In the Snake Range, the Corset Spring sharply overlies the Johns Wash Limestone and has an upper gradational contact with unnamed cherty limestones which are equivalent to the Pogonip Group (Drewes and Palmer, 1957).

Rocks correlated with the Corset Spring Shale in the southern Deep Creek Range are composed of greenish-gray fissile shale with abundant 1 to 3 inch thick interbeds of blue-gray, medium-grained limestone (Nelson, 1959). In the Pilot Range, the Corset Spring Shale lies above the Johns Wash Formation as a thin gray fissile shale which is overlain by the Notch Peak Limestone (O'Neill, 1968; Coats, 1985).

Average Thickness

The Corset Spring Shale is 65 feet thick at its type section in the southern Snake Range (Drewes and Palmer, 1957), 50 to 200 feet thick in the southern Deep Creek Range (Nelson, 1959), and may be as much as 100 feet thick in the Pilot Range (O'Neill, 1968).

Areal Distribution

The Corset Spring Shale is equivalent to the Dunderberg Shale and is separately designated in the southern Snake, southern Deep Creek, and Pilot Ranges.

Depositional Setting

The details of depositional setting are not well known for the Corset Spring Shale. In general, the Corset Spring appears to represent shallow marine shelf deposition.


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Last modified: 09/12/06