The term Ely Limestone was first used by Lawson (1906) and was redefined by Spencer (1917) for beds above the Mississippian Chainman Shale and below the Permian Arcturus Limestone in the Ely district. As defined the Ely contained units now put in the Riepetown Formation or Rib Hill Sandstone, the Kaibab Limestone and the Riepe Spring Limestone. The separation of these units from the Ely makes the Ely mainly Pennsylvanian in age with the lower beds locally Mississippian in age.

The Ely Limestone spans the Pennsylvanian (Morrowan, Atokan, and Des Moinesian) age and is locally Mississippian (Chesterian) in the lower portion of several eastern sections (Nolan and others, 1971; Hose and Blake, 1976). The Moleen and Tomera Formations of Dott (1955) in the Elko Area are equivalent to the Ely and are included in the Ely Group. Correlative units in the Tuscarora-Cortez-Battle Mountain area are primarily conglomerate, thin limestone, and calcareous shale (Roberts and others, 1967).

In general, the top of the Ely becomes younger northward from the latitude of Ely (Coats, 1985). In the Eureka area and in western Elko and White Pine Counties, the Ely gradationally overlies the Diamond Peak Formation and is overlain along an erosional unconformity by the Carbon Ridge Formation (Nolan and others, 1956). To the east, the Ely Limestone either overlies the Scotty Wash Quartzite, a sandy eastern facies of the Diamond Peak, or where the Diamond Peak interval is absent lies directly on the Chainman Formation with a covered conformable contact (Hose and Blake, 1976).

In the Grant Range, the Ely is unconformably overlain by Tertiary lacustrine sediments such as the yellowish shale, bluish-black limestone and yellow sandstone which Moores and others (1968) tentatively assigned to the Riepe Spring Formation.

In the southern Schell Creek Range the Ely is overlain by the Tertiary Kinsey Canyon Formation (Young, 1960), and in the southern Butte Mountains and Snake Range by the Permian Riepe Spring Formation (Douglass, 1960). In the Golden Gate and northern Pahroc Ranges the Ely is apparently conformably overlain by Riepe Spring Formation, although definition of map units in the Permian and Pennsylvanian of northern Lincoln County is somewhat hazy (Tschanz and Pampeyan, 1970).

In general, the Ely Limestone is a coarsely crystalline and granular, medium to light olive-gray, organic detrital limestone which forms ledges or cliffs alternating with gentle slope forming, platy, gray or yellowish-gray to brown weathering silty organic detrital limestone (Hose and Blake, 1976). Abundant nodules, lenses, and bands of chert are present throughout the limestone, as in the Golden Gate, Seaman, and Grant Ranges, as well as productid and speriferoid brachiopods and Chaetetes coral. Limestone beds in the upper portion of the formation commonly contain fusulinid-rich zones and are often dolomitized at the contact with the overlying, and lithologically nearly identical Permian Riepe Spring Formation. Chert-pebble conglomerates are present in thin lenses within the upper portion of the Ely Limestone in the Eureka area, Diamond Mountains, Pancake Range and at Buck Mountain (Nolan and others, 1971; Hose and Blake, 1976; Roberts and others, 1967), but have not been reported elsewhere. In northern Nye County, Kleinhampl and Ziony (1985) mapped a lower carbonate unit and an upper unit with significant amounts of clastic detritus which decreases both in size and amount towards the east.

In the Diamond Mountains the Ely Limestone is composed of massive (5-40 foot thick beds) blueish-gray to dark-gray cherty limestone, with thin interbeds of sandstone and chert-pebble conglomerate containing Vinini chert fragments scattered throughout but most conspicuous in a 20 foot thick bed in the lower portion of the formation (Nolan and others, 1956; Roberts and others, 1967). In the Diamond Mountains, the Ely Limestone underlies the Permian Carbon Ridge Formation (Hose and Blake, 1976).

In the Ruby Mountains, the Ely is a gray to light-brown gray, flaggy to massive, fine to medium-grained limestone and dense black carbonaceous limestone which contains abundant chert nodules and lenses. Argillaceous thin-bedded limestone is interbedded throughout but concentrated in the upper portion of the formation (Sharp, 1942).

In the north central Egan Range, the Ely Limestone is cherty, thick-bedded, coarse-grained, light brown to medium gray limestone 10 to 30 feet thick, interbedded with yellowish to reddish weathering, poorly exposed, platy, argillaceous and silty limestone up to 30 feet in thickness (Woodward, 1962). Large lenses and nodules of pinkish to dark-grey chert are scattered through the Ely and occasionally form masses of chert up to 3 feet thick. Thin sandstone laminae and beds are also present and are commonly concentrated in the upper portion of the formation. The upper 60 feet of the unit is made up of light-gray, medium to coarse-grained limestone with sparse chert and no distinctive fossils, in beds up to 2 feet thick. Woodward (1962) suggests that this unit may actually represent the Riepe Spring Limestone but has mapped it with the Ely Limestone because of lack of evidence for a Permian age. A similar sequence was described in the southern Cherry Creek-northern Egan Range area by Fritz (1960, 1968) where about 2,135 feet of Ely have been described. The upper 810 feet of the unit are once again probably correlative with the Riepe Spring Limestone.

In the Grant and White Pine Ranges, as well as in the Butte Mountains, Schell Creek and Snake Ranges, the Ely Limestone is composed of alternating thick and thin-bedded, medium gray limestones which form a characteristic steplike topography. Layers and nodules of cream or black colored chert and silicified brachiopods are common throughout the unit, as are gastropod and crinoid spine fragments (Young, 1960; Moores and others, 1968; Hyde and Huttrer, 1970; Whitebread, 1969). Thin quartz sandstone interbeds and laminae up to a few feet in thickness are present in the Ely and are more abundant in the middle and upper portions of the thin-bedded limestone. Black chert nodules and Chaetetes are more abundant in the lower portion of the unit in the central and southern Butte Mountains (Douglass, 1960; Sides, 1967). A gypsum diapir has been reported in the lower portion of the Ely in the western Red Hills (Bartel, 1968).

The Ely Limestone in the northern Pahroc and Golden Gate Ranges, and on Grassy Mountain, is somewhat poorly described and probably includes beds which belong to the Riepe Spring Limestone. Overall the unit is described as alternating, massive, dark-gray cherty limestone which weathers to a light-gray, and thin-bedded to platy, yellowish-brown, silty or calcareous dolomite layers which weather to a gray-brown or reddish color. The upper 500 feet is nearly chert free and the upper 200 feet are commonly yellowish-brown and brown, fine-grained, calcareous sandstone interbedded with thin dark-gray limestone. The lower 500 feet are commonly gray cherty and fossiliferous limestone with as much as 60 percent brown-weathering chert in the northern Golden Gate Range (Tschanz and Pampeyan, 1970).

In the Pequop Mountains-Wood Hills area, the Ely Limestone is present in several fault slices, and complete in one of these sections (Thorman, 1962). The complete section in the southern Pequop Mountains is divided into two members. The lower member is composed of about 1,500 feet of fine to medium-grained, gray to black, gray weathering limestone in beds 4 to 6 feet thick which are separated by thin-bedded argillaceous limestone commonly in 1 foot thick beds. The lower portion of the member is composed of conglomeratic limestone similar to those in the Diamond Peak Formation that contain red, green, black, and gray chert clasts. Chert comprises about 15 percent of the formation (Thorman, 1962). The upper member is about 490 feet thick and is equivalent to the Hogan Formation as defined by Robinson (1961) in the central Pequop Mountains. The Hogan varies from 0 to 750 feet in thickness in the Pequop Mountains and has not been mapped elsewhere. The Hogan is here considered as part of the Ely Limestone. The upper member is composed of thin-bedded and platy interbedded, brown gray to pink, argillaceous limestone and calcareous siltstone, and olive-gray siltstone with the lower 200 feet composed of thin-bedded argillaceous to silty limestone.

In the Central Pequop Mountains, the Ely has been divided into 5 informal members described in ascending order (Robinson, 1961). The basal member is about 135 feet of medium to thick-bedded, aphanitic to fine-grained limestone, argillaceous limestone, and silty to sandy limestone all of which contain abundant chert nodules. Overlying this is about 250 feet of interbedded micritic limestone, siliceous, dolomitic and gypsiferous limestone, and calcareous dolomite. The third member is 527 feet of light to dark gray micritic limestone, argillaceous and bioclastic limestone, and silty and sandy limestone. Above this is about 50 feet of subangular to subrounded chert and quartzite-pebble conglomerate with lesser amounts of interbedded sandy and pebbly limestone. The upper member of the Ely is about 500 feet of interbedded bioclastic, argillaceous, silty and sandy, and cherty limestone with lesser amounts of calcareous and quartzose siltstone and orthoquartzite which grade upward into the overlying Diamond Peak Formation (Robinson, 1961).

In the Spruce Mountain Quadrangle, the Ely has been divided into an upper and lower unit (Hope, 1972). The lower member is about 900 feet of thick-bedded, gray, fine-grained limestone with abundant layered chert nodules. The upper 1,700 feet is composed of thin to thick-bedded, medium-gray, fine-grained limestone with small black chert nodules (Hope, 1972).

In the Pilot Range, O'Neill (1968) has mapped the Ely Limestone as gray and black, medium to coarse-grained, bioclastic and highly fossiliferous limestone and yellow, brown to pink, thin-bedded argillaceous limestone. In the Pilot Range, the Ely is underlain by the Diamond Peak Formation. In the southern Goshute Range near White Horse Mountain the Ely is a light to medium-gray, thick-bedded limestone with gray and brown chert nodules or continuous beds (Messin, 1973). At Ferguson Mountain, the Ely is alternating gray, thick-bedded limestone, and gray to brown thin-bedded slope-forming limestone with abundant chert and fossils throughout the unit (Berge, 1960). The upper portion of the Ely is apparently missing in both the Pilot and Goshute Ranges.

In the Leppy Range, the Ely is divided into two members (Schaeffer and Anderson, 1960). The lower member is about 1,275 feet of fine to medium crystalline, medium to dark-gray, light gray weathering limestone with bedded and nodular chert. The upper member is 446 feet of reddish-brown, pink weathering, thin-bedded calcareous siltstone, and light to dark gray, fine to coarse-grained, medium-bedded, argillaceous limestone which is overlain by the Strathearn Formation.

Thicknesses of the Ely limestone, particularly in the eastern portion of the study area, are complicated locally because of the structural omission along flat faults which are localized at the contact between the Ely and underlying soft Chainman Formation shales, as well as by local removal by erosion preceding the deposition of overlying Tertiary sediments. Thicknesses are also complicated by early inclusion of rocks now broken out as the Permian Riepe Spring Limestone with the Pennsylvanian age Ely Limestone.

Thicknesses are relatively consistent regionally however with about 1,500 feet of Ely Limestone in the Eureka Area (Nolan and others, 1956), about 1,300 feet in the Diamond Mountains (Dott, 1955; Larson and Riva, 1963), 1,335 feet in the northern Egan-southern Cherry Creek Ranges (Fritz, 1968), 1,860 feet in the northern Schell Creek Range (Dechert, 1967), and 1,000 feet in the northcentral Schell Creek Range (Young, 1960). 2,950 feet are present in the southern Egan Range (Playford, 1961) and 1,550 feet in a faulted section exposed along the west side of the central northern Egan Range (Woodward, 1962). The Ely is 1,600 feet thick in the northern Grant Range and 850 feet thick in the southern White Pine Range (Moores and others, 1968), 2,000 to 2,200 feet about 2 miles west of Moorman Ranch (Hose and Blake, 1976) and in general 2,000 to 2,300 feet in the southern Butte Mountains (Douglass, 1960), about 1,800 feet in the southern Snake Range (Whitebread, 1969), 1,500 feet in the Kern Mountains (Nelson, 1959), and about 1,100 t0 1,500 feet in highly faulted sections in the western part of the Red Hills (Bartel, 1968).

In the Golden Gate Range the Ely Limestone is about 2,000 feet thick and is about 2,500 feet thick in the northern Pahroc Range where it may include a few hundred feet of undifferentiated Riepe Spring Limestone (Tschanz and Pampeyan, 1970). 1,500 feet of Ely are exposed in the central and southern Pequop Mountains (Thorman, 1962; Robinson, 1961), to less than 500 feet at the southern end of the Pequop Mountains (Steele, 1960), 2,600 feet in the Spruce Mountain Quadrangle (Hope, 1972), 505 feet in the Pilot Range (O'Neill, 1968), about 500 feet in the southern Goshute Range (Messin, 1973), 1,411 feet at Ferguson Mountain (Berge, 1960), and 1,741 feet in the Leppy Range (Schaeffer and Anderson, 1960).

The Ely Limestone is exposed in the Pancake, southern Cherry Creek, Egan, Grant, Horse, and White Pine Ranges, Ruby, Diamond, Butte, Pequop and Kern Mountains, Schell Creek, Snake, Golden Gate, Seaman, Pahroc, southern Silver Island and Goshute, Leppy, and Pilot Ranges, Grassy Mountain, Wood and Red Hills, and the Spruce Mountain Quadrangle.

A shallow marine environment is suggested for the Ely on the basis of brachiopod, echinoid spines, crinoids, foraminifera, and lime mud pellets and oolitic beds. Several workers have suggested shallow, warm, moderately turbulent water origins for the Ely (Mollazal, 1961; Sides, 1967), while others have suggested a relatively deep water environment (Rich, 1977, Stevens, 1977).