The type section of the Devils Gate Limestone is Devils Gate Pass about 8 miles northwest of Eureka where it overlies the Pilot Formation (Merriam, 1940). The type section is "faulted, intruded by igneous rocks, and lacks an exposed stratigraphic base" (Merriam, 1963).

The Devils Gate is Middle and Late Devonian (Frasnian to Famennian) in age. The Devils Gate is an equivalent of the Guilmette Limestone to the east, and the upper portion of the Denay Limestone in the Antelope Range. It overlies the Denay in the Roberts Mountains, and Sulphur Spring Range (along with the informally designated Red Hill beds). The Devils Gate conformably overlies the Telegraph Canyon Member of the Nevada Formation in the Diamond Mountains (Roberts and others, 1967). The formation has a gradational lower contact with the Nevada Formation and a sharp upper contact with the overlying Pilot Formation in the Diamond Mountains (Roberts and others, 1967).

The Devils Gate forms very prominent and characteristic gray cliffs marked with caves and solution cavities. It is primarily a medium to dark-gray, flaggy to thick-bedded, medium to very fine-grained limestone with interbedded pinkish weathering argillaceous limestone (Nolan and others, 1956; Merriam, 1963). The lower portion of the formation commonly contains more thinly bedded and darker gray carbonates. The base of the formation is often a yellowish-gray-weathering, argillaceous, platy to laminated or thin-bedded limestone and/or dolomite. The Devils Gate Limestone is highly fossiliferous and biohermal with brachiopods, gastropods, crinoids, algal stromatolites material, abundant stromatoporoid (Amphipora) heads up to 2 feet in diameter, colonial Clodopora and rugose coral patches in "spaghetti beds" (Kleinhampl and Ziony, 1985; Merriam, 1963).

Soft sediment folds and intraformational breccias and conglomerates with angular and rounded limestone clasts up to 8 inches across are present in the Devils Gate in the Mahogany Hills and Diamond Mountains, and several sections in northern Nye County (Kleinhampl and Ziony, 1985; Merriam, 1963). These structures are slump and solution-type features, as opposed to tectonic breccias which are also locally present in the Devils Gate along thrust faults.

In the southern Diamond Mountains two members, the Meister and Hayes Canyon were locally broken out by mapping a thin bed of oolitic limestone (Nolan and others, 1956; Merriam, 1963). Dark grey chert nodules are common in the upper few hundred feet of the formation, as are patches and irregular bodies of white-weathering dense dolomite (Nolan and others, 1956; Merriam, 1963). Dolomite is common in the Devils Gate in the Pancake Range near Portuguese Mountain where it is interbedded with limestone, and local patches of dolomitized limestone (Quinlivan and others, 1974).

In the Sulphur Spring Range, the entire Devils Gate section is smooth weathering, medium-to thick-bedded, gray-blue to dark gray limestone, with abundant stromatoporoid and "spaghetti" beds and nodular chert beds. Striped, light and dark gray dolomite up to 10 feet thick occurs locally, and is particularly common at Mineral Hill (Carlisle and others, 1957).

In the Carlin-Pinon Range, the Devils Gate is present in several sections with fault or unconformity bounded tops (Smith and Ketner, 1975). It is composed of medium to thick-bedded, light and dark-gray, fine-grained limestone which weathers gray and blue-gray. Coral spaghetti beds are present throughout the unit, as are a few thin 1 foot lenses of chert-pebble conglomerate. In the Railroad mining district, the Devils Gate contains alternating dolomite and limestone in light and dark bands. Locally the unit has also been recrystallized to a marble along intrusives, or silicified along fault zones (Smith and Ketner, 1975). The Devils Gate is unconformably overlain by Mississippian rocks such as the Webb Formation.

In the Pancake Range, the Devils Gate is medium to dark-gray, fine-grained, laminated to very thick-bedded, mottled to wavy, yellowish-orange weathering limestone, and yellowish-brown to medium-gray, aphanitic to medium-grained, laminated to wavy bedded, limy dolomite and dolomite, and interbedded silty limestone and mudstone (Quinlivan and others, 1974). The carbonates become sandier upsection with an upper argillaceous sandy and quartzitic zone in the upper few hundred feet of the unit. Dolomitization is greatest in the central portion of the formation; limestone occurs erratically throughout the section, and darker limey dolomite and dolomite form most of the upper portion of the Devils Gate (Quinlivan and others, 1974).

In the northern Hot Creek Range, the Devils Gate is thin to thick-bedded, highly fractured, micritic limestone with extensive solution caves. A few beds of oolitic pelletal grainstones are present in the lower portion of the formation and algal biscuits have also been reported in the formation (Potter, 1976).

In the Ruby Mountains, the Devils Gate was divided into two informal units by Sharp (1942). The lower 900 feet is dark gray to black, dense, massive limestone with a few thin beds of light gray, dense, calcareous dolomite near the base. The upper member is platy, arenaceous and argillaceous, gray, red-brown weathering limestone with chert-pebble conglomerate near the base. Willden and Kistler (1969) describe a similar medium to thick bedded gray limestone section with amphipora and other stromatoporoids in the Jiggs Quadrangle.

The Devils Gate thins to the east from the Lone Mountain-Roberts Mountains area to the Diamond Mountains as result of non-deposition or a slower depositional rate to the east (Nolan and others, 1956). It is 1,100 feet thick at Devils Gate (Merriam, 1963), over 1,250 feet in the Sulphur Spring Range (Carlisle and others, 1957), 850 to 940 feet in the Pinon Range (Smith and Ketner, 1975), 1,200 feet at Newark Mountain, 750 feet northeast of Black Point and 675 feet at Phillipsburg Mine in the Diamond Mountains (Nolan and others, 1956), 1,200 feet in the southern Ruby Mountains (Sharp, 1942), 1,000 to 2,000 feet in the Hot Creek Range (Potter, 1976), and more than 3,000 feet thick in the Portuguese Mountain area of the Pancake Range (Quinlivan and others, 1974).

The Devils Gate is exposed at Devils Gate, Mahogany Hills, Ruby, Diamond, and Roberts Mountains, southern Sulphur Spring, Pinon, Pancake and Hot Creek Ranges, and is partially eroded from the Antelope Range.

Depositional Setting

The biohermal Devils Gate Limestone was unquestionably deposited along a very shallow inner-shelf under subtidal and intertidal conditions.

Caves, solution cavities, and vugs are abundant within the Devils Gate. Some of this solution is the result of recent weathering, while a large portion may have formed as a karst during Devonian uplift and local emergence. This vugular porosity may locally provide excellent porosity in potential Devils Gate reservoirs.