The Ely Springs Dolomite was first described by Westgate and Knopf (1932) for exposures in the Ely Springs Range west of Pioche, in central Lincoln County.

Coral and brachiopod fauna show the Ely Springs Dolomite is Upper and Middle Ordovician in age. As discussed in some detail under the Hanson Creek Formation, the Ely Springs Dolomite is the equivalent of the Hanson Creek and Fish Haven Dolomites. It conformably and gradationally overlies the Eureka Quartzite with intertonguing quartzite and sandstone and dolomite over a 5 to 10 foot interval. The Ely Springs Dolomite also shows a gradational contact with the overlying Laketown Dolomite (Hose and Blake, 1976; Tschanz and Pampeyan, 1970).

At its type section, and in the Limestone Hills area, the Ely Springs Dolomite is a dark-gray to black, smoky brown weathering, medium to coarse-grained, fossiliferous and cherty dolomite. Some light gray dolomites are present near the top of the formation, with the lower 50 feet of the formation composed of limestone that contains as much as 30 percent nodular chert (Tschanz and Pampeyan, 1970). Chert nodules are commonly concentrated in the lower and middle portions of the formation (Westgate and Knopf, 1932). Beds range in thickness from a few inches to 15 feet and are commonly about 5 feet in thickness (Hose and Blake, 1976). Individual beds of the Ely Springs Dolomite have been traced for more than 15 miles in the Egan Range (Kellogg, 1960).

In the Pancake Range (Portuguese Mountain Quadrangle), the upper portion of the Ely Springs Dolomite is a medium to dark-gray, gray to yellowish weathering, fine-grained, laminated to medium-bedded dolomite with a 10 to 15 foot thick unit of cherty dark-gray dolomite about 45 feet below the top of the unit (Quinlivan and others, 1974). The lower dolomites are dark-gray, fine to medium grained, laminated to thick-bedded containing brachiopods, pelmatazoan debris and Girvanella, with a basal 20 foot thick zone of dark-gray-brown-weathering dolomitic sandstone. Sedimentary breccias and clastic dolomites are present throughout the unit (Quinlivan and others, 1974).

Northwest of Lockes Station in the Pancake Range, Kleinhampl and Ziony (1985) found an excellent exposure of the Ely Springs Dolomite which they divided into 4 main units, the upper three of which correlate with the upper member described by Quinlivan and Rogers (1974). In the southern Pancake Range, Scott (1969) described the Ely Springs interval as black to dark-brown, coarse to medium-grained dolomite with interbeds of finer-grained, medium gray dolomite. Nodular chert and intraformational conglomerate and breccia are common throughout the unit, while crinoids and corals are locally present in the upper portion of the formation.

In the Reveille Range, the Ely Springs Dolomite is composed of an upper 50 foot sequence of light-gray, fine-grained, poorly bedded dolomite, overlying a lower sequence composed of about 40 feet of dark-gray, fine-grained dolomite with abundant brown-gray chert nodules (Ekren, Rogers, and Dixon, 1973).

In the Hot Creek Range, the Ely Springs is composed of an upper member of light to dark-gray, yellowish weathering, silty, fine to medium-grained dolomite (Quinlivan and Rogers 1974). This dolomite is laminated to thickly bedded with a thin quartz sand zone about 10 to 15 feet below the top of the formation, and is phosphatic throughout. The lower portion is a dark-gray, fine to medium-grained, laminated to thickly bedded dolomite with small irregular dark-gray chert nodules and lenses. Abundant Pelmatazoan debris is found throughout the dolomites (Quinlivan and Rogers, 1974).

In the Grant and Cherry Creek Ranges, the Ely Springs has been lumped with the overlying Laketown Dolomite (Cebull, 1967; Hyde and Huttrer, 1970; Fritz, 1968) and is composed of medium to thick-bedded, light gray to chocolate brown weathering, fine to medium-grained dolomite, which is often in alternating light and dark bands containing brown to black chert nodules and thin lenses. Locally in the Grant Range, the formation contains limestone and no dolomite, and in the Egan Range the upper portion of the formation is thin and largely light to dark-brown argillaceous dolomite (Kellogg, 1960; Kleinhampl and Ziony, 1985).

In the western White Pine Range, the Ely Springs is composed of dark gray to black, massive to thin-bedded, fine-grained dolomite with occasional brown and gray chert nodules in the lower portion of the formation (Gaal, 1958). Lumsden (1964) described the basal portion of the Ely Springs in the White Pine Range as about 120 feet of brecciated, fine-grained, brownish-black, mottled dolomite with corals and crinoids and thin blue and orange nodular cherts. This is overlain by about 300 feet of light brown-gray dolomite with brachiopods and corals, which becomes porcelenaeous and contains thin beds of black chert near the upper contact of the formation.

In the Egan Range near Lund, the Ely Springs interval consists of fine to medium crystalline, medium to dark gray, gray-brown weathering, thick-bedded to massive dolomite. Thin-bedded, light-gray dolomite is interbedded, and several horizons contain chert nodules and lenticular beds of chert (Playford, 1961). In the Quinn Canyon Range (Big Creek Area), the lower portion of the unit is a dark brown-black to gray dolomite while the upper portion is a slabby, laminated, lighter grey or brown-gray dolomite which locally weathers to a pink color. Local zones of intraformational conglomerate are present in the Ely Springs in the Quinn Canyon Range (Kleinhampl and Ziony, 1985). In the northern Bristol and Wilson Creek Ranges, the Ely Springs is a dark-gray to black, medium to coarse-grained, cherty dolomite with some light-gray dolomite beds near the top of the unit (Tschanz and Pampeyan, 1970).

The Ely Springs Dolomite varies from 525 feet in the Ely Springs Range (Westgate and Knopf, 1932), 495 to 527 feet in the southern Egan Range (Kellogg, 1963), 200 to 250 feet in the Pancake Range (adjusted from Quinlivan and others, 1974), 310 to 413 feet near Lockes Station in the Pancake Range (Kleinhampl and Ziony, 1985), 640 feet in the southern Pancake Range (Scott, 1969), 790 feet in the northern Reveille Range (Ekren, Rogers, and Dixon, 1973), 105 to 145 feet in the Hot Creek Range (Quinlivan and Rogers, 1974), 700 to 770 feet in the Horse Range (Kleinhampl and Ziony, 1985), and 418 to 510 feet in the White Pine Range (Lumsden, 1964).

The Ely Springs plus Laketown Dolomite interval is about 2,200 feet thick in the central Grant Range, and 1,680 feet in the southern Cherry Creek- northern Egan Range area (Hyde and Huttrer, 1970; Fritz, 1968), the Ely Springs interval alone is about 500 feet thick in the Grant Range (Kleinhampl and Ziony, 1985), 640 feet in the Egan Range near Lund (Playford, 1961), and about 235 to 400 feet thick in the Cherry Creek Range.

The Ely Springs designation is the most commonly used throughout central Nevada for equivalent Ordovician dolomites including the Fish Haven and Hanson Creek. The Ely Springs has been designated in the Ruby Mountains, Pancake, Reveille, Hot Creek, Cherry Creek, southern Egan and Schell Creek Ranges, the Pioche district, Red Hills, Limestone Hills, and northern Wilson Creek, and Bristol Ranges. Kleinhampl and Ziony (1985) extended the usage into the Grant, Horse, Quinn Canyon and White Pine Ranges as well. These sections are referred to as the Fish Haven by other workers (Moores and others, 1968; Kellogg, 1963). The Monitor Range is the western limit of Ely Springs exposures according to Kleinhampl and Ziony (1985).

The Ely Springs Dolomite is a subtidal to intertidal, shallow restricted shelf carbonate. It was deposited in water depths of about 100 feet in both lagoonal and shoal water environments (Chamberlin, 1975).