The McMonnigal Limestone was named for McMonnigal Creek which flows through Ikes Canyon in the northern Toquima Range. The type section location is "in the hill west of March Spring" (Kay and Crawford, 1964). McKee and others (1972) designated the ridge forming the south side of Ikes Canyon about one mile west of the range front as the type section for the McMonnigal.

A varied fauna of coral and brachiopods suggest that the McMonnigal is Early Devonian (Helderbergian and Oriskanian) age (Kay and Crawford, 1964). The McMonnigal and Tor Limestones are correlative formations in separate thrust plates within the Toquima Range. The McMonnigal is interpreted as being deposited about 15 miles southeast of the Tor limestone based upon structural reconstructions (McKee and others, 1972). The upper portion of the McMonnigal correlates with the Rabbit Hill Limestone in the Antelope Valley region, and the name Windmill Limestone (Johnson, 1962) has been applied to strata equivalent to the lower McMonnigal to the northeast of the Toquima Range.

The McMonnigal gradationally overlies the Masket Shale (Roberts Mountains Formation) over an interval of about 50 feet at its type section in the Toquima Range (McKee and others, 1972; McKee, 1976). The contact is drawn where medium-bedded gray fossiliferous limestone dominate thin-bedded platy limestone below. The upper contact is removed both along a fault, and an erosional unconformity (Kleinhampl and Ziony, 1985).

The McMonnigal Limestone is composed of massive gray limestones interbedded with thinner bedded tan-weathering limestones which are locally chert-bearing (McKee and others, 1972; Kay and Crawford, 1964). The upper portion of the McMonnigal is commonly thin to thick-bedded gray limestone while the lower portion is tan weathering, very thin-bedded, platy limestones (Kleinhampl and Ziony, 1985).

Skeletal packstone and grainstone beds in the McMonnigal contain brachiopod and coralline coquinas which are 30 to 60 centimeters in thickness. These units are often normally graded near their bottom and are commonly massive near the top, suggesting deposition as debris flow sheets (McKee and others, 1972).

Along the south side of Ikes Canyon in the Toquima Range, 215 feet of the McMonnigal are exposed. Based upon a structural section pieced together from exposures in various thrust plates, 300 to 400 feet is a reasonable estimate of thickness for the McMonnigal Limestone (McKee and others, 1972).

The McMonnigal Limestone is exposed locally within the northern Toquima Range.

The McMonnigal Limestone represents proximal turbidite or debris flow deposition in a quiet and stagnant silled basin along the outer Devonian shelf (Matti and McKee, 1977). The calcareous debris in the formation was shed from the shoal water carbonate buildup of the Tor Limestone to the west (Matti and McKee, 1977).