The Antelope Valley Limestone is named for exposures in the Martins Ridge (now Martin Ridge)-Antelope Valley area, about 25 miles southwest of Eureka (Nolan and others, 1956).

On the basis of brachiopod and trilobite collections, the Antelope Valley Limestone is considered Early and Middle Ordovician (Arenigian and Llanvirnian) in age (Merriam, 1960; McKee, 1976b). The Antelope Valley is equivalent to the lower Vinini Formation in the Roberts Mountains, and lower Valmy Formation in the Shoshone Range (Roberts and others, 1967).

The Antelope Valley Limestone is in general a fine grained, thick bedded to massive, blue-grey limestone. The lower 150 feet of the formation is often argillaceous. The lower contact of the Antelope Valley is gradational with the underlying Ninemile Formation. In the type area it is overlain by the Copenhagen Formation (Merriam, 1960), and by the Eureka Quartzite in the Eureka district (Nolan and others, 1956).

In the Copenhagen Canyon area of the Monitor Range, the Antelope Valley is poorly exposed and divided into 3 units. The lower unit is about 428 feet of light to medium-gray, argillaceous calcarenite and calcilutite, with chert nodules and stringers and abundant brachiopods. Interbedded in the lower member are graded, fine-grained, quartz arenite and thin beds of olive-gray, calcareous shale (Bortz, 1959). The middle cliff forming unit is 747 feet of light to medium-gray, argillaceous limestone which is locally silty and argillaceous and commonly contains stringers and nodules of chert. Ostracods, gastropods, and brachiopods are common in the unit. The upper unit is thin-bedded calcilutite and coarsely crystalline, gray to olive-gray, yellowish-weathering limestone with silty beds and partings (Bortz, 1959). In the Clear Creek area, the middle and upper members of the Antelope Valley are present (Wise, 1977). The middle member is composed of thin, argillaceous, blue-gray lime wackestone and minor grainstone commonly in 1 to 3 foot thick beds. Fossils included gastropods, ostracods, and crinoid debris, and ovoid algal nodules. The upper unit is platy and silty, gray lime grainstones with argillaceous partings and blocky medium-gray dolomite. It is commonly burrowed and contains brachiopods, gastropods, corals, bryozoans, and crinoids (Wise, 1977).

In the Toquima, Toiyabe, and Shoshone Ranges, the Antelope Valley is a medium-gray, thin to thick-bedded, fine to medium-grained limestone, with abundant concretionary algal structures and large gastropods in the upper portion, and yellowish silty limestone in the lower 100 to 150 feet of the formation (Stewart and McKee, 1977). The limestones are often mottled with a yellowish-orange color. In most places in Lander County the Antelope Valley rests conformably on the Ninemile Formation, and is overlain by different units in different locales. At Mount Callaghan in the Toiyabe Range it is overlain by the Copenhagen Formation, while in the Toiyabe and Shoshone Ranges it is overlain by the Roberts Mountains Formation.

In the Hot Creek Range, Quinlivan and Rogers (1974) recognized three units within the Antelope Valley Limestone. The upper several hundred feet are cliff-forming, very fine-grained, medium-gray, medium-bedded limestone which is locally silty, dolomitized, and mottled with tan and brownish, argillaceous material. The lower 800 feet of the unit contains three distinctive sequences: an upper, medium-gray, thin to thick-bedded, silty to sandy limestone with a middle zone of laminated to thin-bedded, brown and reddish weathering, fine-grained quartz sandstone; a middle cliff-forming, light to medium-gray, laminated to thick-bedded limestone; and a basal quartz sandstone and siltstone, and sandy to silty, medium-gray, very-fine grained, laminated to thick-bedded limestone. Both the upper and lower units contain intraformational conglomerates (Quinlivan and others, 1974). The Antelope Valley is overlain conformably and gradationally with the Copenhagen Formation.

In the Reveille Range, the Antelope Valley Limestone is divided into 4 informal members (Ekren, Rogers, and Dixon, 1973). The upper member is about 115 feet of light-gray, fine-grained, medium to thick-bedded dolomite with a thin layer of yellowish-brown siltstone near the top. The second member is about 130 feet of light to medium-gray, fine to medium-grained dolomite with interbedded sandy dolomite and dolomitic sandstone. The third member is 200 feet of light to medium-gray, fine to medium grained, thin to thick-bedded dolomite. The basal member is about 155 feet of aphanitic, medium to dark gray, thin-bedded and laminated limestone, quartzose siltstone, and sandstone (Ekren and others, 1973).

In the Pinon Range, about 350 feet of thick to thin-bedded, gray dolomite with thin interbeds of cherty, yellow-brown, fossiliferous shale near the top of the unit, is correlated with the Antelope Valley Limestone (Smith and Ketner, 1975; Coats, 1985). The unit is broadly recrystallized and silicified near an intrusive (Coats, 1985).

In the Buck Mountain-Bald Mountain area to the south of the Ruby Mountains, the Antelope Valley is composed of up to 200 feet of argillaceous, yellow and red-streaked, thin to medium-bedded limestone. Bioclastic beds are abundant near the base of the formation (Rigby, 1960).

In the southern Grant Range, the lower portion of the Antelope Valley is composed of cliff-forming, dark-gray, medium-grained limestone with silty and argillaceous partings which become increasingly thin bedded near the base and grade into the Ninemile Formation (Cebull, 1967). The upper portion is composed of medium-bedded, blue-gray, aphanitic to fine-grained mottled limestone. Brachiopods, algae, ostracodes, and chert nodules are present throughout the formation (Cebull, 1967).

The Antelope Valley Limestone has a variable thickness regionally both as a result of erosion or nondeposition near its upper contact which is locally an unconformity, and the placement of the contact by different geologists. It is about 80 feet thick in the central Pancake Range (Quinlivan and Rogers, 1974), 400 feet in the Eureka area (Nolan and others, 1956), 780 feet near Mount Callaghan in the Shoshone Range (Stewart and Palmer, 1967), 700 to 900 feet in the Toiyabe Range (Washburn, 1970; McKee, 1976), 1,100 to 1,373 feet in the Monitor Range (Bortz, 1959; Merriam, 1963) and 700 to 1425 feet in the Hot Creek Range near Tybo where about 75 feet of rocks equivalent to the Copenhagen Formation are included (Quinlivan and others, 1974), about 600 feet in the northern Reveille Range (Ekren and others, 1973), 350 feet in the Carlin-Pinon Range (Smith and Ketner, 1975), 100 to 200 feet in the Buck Mountain-Bald Mountain area south of the Ruby Mountains (Rigby, 1960), and 770 feet near Rimrock Canyon in the southern Grant Range (Cebull, 1967).

The Antelope Valley Limestone is exposed in the central Shoshone Mountains, Mahogany Hills, Fish Creek, Antelope, Monitor, Lone Mountain (northernmost exposure), northern Toquima, northern Toiyabe, Reveille, Hot Creek, Carlin-Pinon, Egan, Grant, Quinn Canyon, and White Pine Ranges. In other ranges containing the Pogonip Group, the formation is concealed by younger rocks, or as in ranges east of Railroad Valley, has not been recognized as a mappable unit (Kleinhampl and Ziony, 1985).

The Antelope Valley represents basal subtidal shallow shelf limestones (Ross, 1977). Large calcareous mounds up to 76 meters thick are present in the lower member of the Antelope Valley limestone (Ross and Cornwall, 1961; Ross and others, 1975). These mounds often contain stromatolitic algae, and represent growth in intertidal or supratidal waters. Mounds are present at Meiklejohn Peak, near Badger Spring in the Coal Mine Basin and The Narrows Quadrangles in Elko County, and at Lone Mountain (Ross, 1977).

The middle portion of the Antelope Valley represents carbonate mud bank deposition on a subtidal shelf-edge or upper slope, and is characterized by trilobites, brachiopods, and colonies of sponges. This facies is best developed in the Toquima Range and Hot Creek Canyon areas (Ross, 1977).