Hague (1883) designated the Secret Canyon Shale for exposures along Secret Canyon on the south slopes of Prospect Peak, and the formation was later refined by Wheeler and Lemmon (1939) as all strata between the Geddes Limestone and Hamburg Dolomite.

The Secret Canyon is considered late Middle Cambrian in age. The lower contact of the Secret Canyon is sharp and conformable with the underlying Geddes Limestone, while the upper contact with the Hamburg Dolomite is gradational (Roberts and others, 1967).

The Secret Canyon is often broken into two members as originally described by Nolan and others (1956). These units are the Lower Shale Member, and an upper platy limestone unit which was named the Clark Spring Member for outcrops near Clark Spring near the head of the southwesterly branch of New York Canyon in the Eureka area. The Lower Shale Member is a poorly exposed, argillaceous, green to gray shale which is brown, red, or yellow when fragmented in weathered talus. There is a gradational contact between the lower member and the Clarks Spring Member. This upper member is a thin-bedded, blue grey, silty limestone with yellow or red argillaceous partings (Nolan and others, 1956).

In the Ruby Mountains, a structurally complicated section of the Secret Canyon Shale is described by Millikan (1978). The lower member is composed of about 1,400 feet of dark to medium gray, yellowish-orange weathering, fissile, slightly silty clay shale with a few thin interbeds of medium-gray micritic limestone. The upper Clark Springs Member is about 630 feet of argillaceous and recrystallized dark blue-gray micritic limestone with dark yellowish-orange and red weathering shale partings. (Millikan, 1978)

The Secret Canyon is about 650 feet thick in the Eureka District (Nolan and others, 1956). Millikan (1978) assigned 2,030 feet to a structurally complicated section in the southern Ruby Mountains.

The Secret Canyon Shale is exposed in the Eureka area, and within the Ruby Mountains.

The details of depositional setting are poorly understood for the Secret Canyon Shale which in general represents outer shelf sedimentation.