The Noh Formation was defined by Riva (1962) for exposures near Noh Corral in T. 43 N., R. 65 E. in the central HD Range.

Graptolites recovered from the Noh Formation suggest a Silurian (Wenlockian to middle Ludlovian) age (Riva, 1962, 1970; Oversby, 1972; Coats, 1985). The Noh overlies the allochthonous Upper Ordovician Agort Chert, here considered a member of the Valmy Formation, along a basal disconformity which represents the lowermost Silurian. The Noh Formation is also allochthonous.

In the H-D Range the Noh Formation is a poorly exposed sequence present in a series of thrust slices, and reaches a maximum thickness of 1,100 feet (Riva, 1962). At the type section the unit has been broken into three informal members. The lower unit is about 140 feet of dark-gray, thin-bedded chert and light-gray siliceous shale; the middle unit is 400 feet of light-brown weathering siliceous shale and siltstone; and the upper unit is about 550 feet of light-brown, thinly bedded siltstone, sandstone and minor shale (Riva, 1962, 1970).

Jordan (1961) described the allochthonous Silurian rocks in the HD Range in some detail. He found that much of the unit is composed of fine-grained, gray to yellowish-orange, calcareous quartz siltite with flow and load casts, and convolute bedding. The calcareous quartz siltite composes 20 to 93 percent of various fault slices of the Noh. Dark brown and black cherts are interbedded with the siltstone unit, and in some sections compose as much as 30 percent of the Noh Formation. Horizontally laminated, graded and cross-bedded, fine-grained, gray, calcareous arenite makes up about 5 percent of the Noh. Dense siliceous laminated subangular to subrounded quartz arenite with interbedded chert lenses composes less than 5 percent of the formation, as do lensoidal, angular to subrounded, graded chert pebble conglomerates which are interfingered with the quartz siltstones (Jordan, 1961). A few percent to 70 percent of various sections of the Noh are composed of bluish-gray, tuffaceous quartz siltite with a matrix of calcite and devitrified tuffaceous material.

In the Wilkins Siding and Summer Camp areas of the Windermere Hills, Oversby (1972) describes the Noh Formation as 325 feet of platty, flaggy and blocky weathering, calcareous quartz siltite which commonly weathers to a distinctive pink or brick-red color. It is occasionally very argillaceous, weathering to a distinctive green color. The top of the unit is commonly a 50 foot thick discontinuous band of gray weathering, black, thin-bedded, silty limestone. The Noh is commonly poorly exposed in the Windermere Hills within a series of thin fault slices which are interleaved with Devonian (Frasnian) carbonates (Oversby, 1972).

The Noh Formation has a thickness of 1,100 feet in the HD Range, and is 325 feet thick to the south in the Windermere Hills (Riva, 1970; Oversby, 1972).

The Noh Formation was designated in the HD Range and has been correlated with similar lithologies present in allochthonous rocks to the south in the Windermere Hills.

The details of depositional setting are poorly understood for the allochthonous Noh Formation which probably represents outer shelf and upper slope sediments. Jordan (1981) felt that the presence of small-scale cross-bedding, grading, flow and load casts, and convolute bedding in the Noh Formation indicated deposition within a submarine fan system by turbidity currents.