The Moleen Formation was named for the Moleen siding with a type section in Secs. 33 and 34, T. 33 N., R. 54 E., on the north end and along the western side of Grindstone Mountain, at the northern end of the Carlin-Pinon Range (Dott, 1955).

The Moleen is considered Early to early-Middle Pennsylvanian (Morrowan to Atokan) in age. The Moleen is equivalent to the lower part of the Ely Limestone (Dott, 1955). The Moleen gradationally overlies the Diamond Peak Formation and is in turn gradationally overlain by the Tomera Formation.

The Moleen Formation is a sequence of light to dark gray, fine to coarse-grained, ledge-forming fossiliferous limestone commonly in beds 1 to 4 feet thick, with intervening thin-bedded quartz sandy and silty limestones commonly in brown platy weathering beds a few inches in thickness (Smith and Ketner, 1975). Steele (1960) described three members in the Moleen. The lower member gradationally overlies the Diamond Peak Formation and is composed of chert-pebble conglomerate, red to greenish-tan siltstone, and brachiopod-bearing silty limestones. Smith and Ketner (1975) report thin 5 to 15 foot thick lenses of chert- pebble conglomerate with green, brown, and gray chert pebbles up to an inch long, in a calcareous or calcareous sandstone matrix.

The middle member of the Moleen is composed of gray locally silty and oolitic limestone with gray to dark gray, brown weathering chert pods and irregular layers as much as 8 inches thick and 10 feet long (Steele, 1960; Smith and Ketner, 1975). The upper member contains alternating silty limestones and chert-pebble conglomerates and occasional fusulinid coquinas. Biostromal beds with brachiopods, bryozoans, and Chaetetes coral are particularly abundant in the upper 200 feet of the formation. The Moleen is gradationally overlain by the Tomera Formation (Steele, 1960; Smith and Ketner, 1975).

In the central Pancake Range, Mount (1972) broke the Ely interval into the Moleen and Tomera Formations. Kleinhampl and Ziony (1985) felt that the unit should be designated the Ely Formation with an upper and lower member and mapped about 3,500 feet of the Ely in the Pancake Range near Duckwater. The lower 2,000 feet of the Ely is a gray, coarsely crinoidal, silty to argillaceous limestone, and thin-bedded to laminated, massive to slabby, yellowish, fine-grained limestone near the base (Kleinhampl and Ziony, 1985). Mount (1972) correlated this lower unit with the Moleen which is followed here.

In the central Pancake Range, the Moleen is characterized by alternating thick-bedded limestone and medium-bedded slope-forming silty limestone which can be divided into three members. The lower member is about 390 feet of thin-bedded, platy, calcareous siltstone and silty limestone which weather to light gray and brown, with several interbeds of massive bioclastic crystalline limestone with mollusks and crinoids (Mount, 1972). The middle unit is composed of about 1,270 feet of cherty, bioclastic crystalline limestone with interbedded thin-bedded silty limestone and cherty thick-bedded limestone with bryozoans, brachiopods and trilobite fragments. The upper member is about 530 feet of coarsely bioclastic limestone with abundant Chaetetes, fusulinid coquinas, and silty and sandy limestone (Mount, 1972). Rigby (1960) described the Moleen in the Buck Mountain-Bald Mountain area as alternating thick-bedded, finely crystalline, medium-brown to light gray limestone, and thin-bedded argillaceous or silty bioclastic limestone. The upper limestones appear reefoidal.

Separation of the Moleen and Tomera is based on the presence of chert in the Moleen, and more clastic fragments and conglomerate, and well developed coquinites in the Tomera (Smith and Ketner, 1975). In some cases the Moleen and Tomera cannot be easily divided and are mapped together (Coats, 1985).

At the type section in the northern Carlin-Pinon Range, the Moleen varies from 1,200 to 1,600 feet (Dott, 1955). It is 2,200 feet thick in the central Pancake Range (Mount, 1972), and about 1,200 feet are exposed in the Buck Mountain - Bald Mountain area.

The Moleen is exposed in the Elko-Carlin-Pinon Range area, Pancake Range, and in the Buck Mountain - Bald Mountain area.

The Moleen is equivalent to the lower portion of the Ely Limestone and represents a similar depositional environment. The Moleen was deposited in a local depositional basin along the eastern margin of the Antler belt from which it received coarse clastic detritus. The lower portion of the unit probably represents fan-delta sedimentation and the upper biostromal portion of the formation indicates shallowing and a general shutting off of clastic influx.