The Pumpernickel Formation was named by Muller and others (1951) for chert, shale and greenstone exposures in Pumpernickel Valley, on the west side of the Sonoma Range (Humboldt County), about 30 miles west of the town of Battle Mountain.

Conodonts from the upper portion of the Pumpernickel Formation in the Battle Mountain area are considered Middle Pennsylvanian (Desmoinian) in age (Roberts, 1964b), although the range of these fossils extends into middle Triassic. The Pumpernickel is conformably and locally disconformably overlain by the Middle Pennsylvanian to Early Permian Havallah Formation.

Little is known about the internal stratigraphy, sequence, or regional facies changes within the Pumpernickel and Havallah Formations (Stewart and McKee, 1977). Both formations are present in the upper plate of the Golconda thrust, and have been designated regionally by general lithologic distinction. The Pumpernickel is composed mainly of chert, argillite, siltstone and shale, and the Havallah additionally contains more abundant quartzite, sandstone, conglomerate and limestone.

Although the base of the formation rests on the Golconda thrust, the best described and thickest section of the Pumpernickel has been documented on Battle Mountain where Roberts (1964b) recognized three units in ascending order: a lower unit up to 500 feet in thickness of gray and black argillite with thin chert lenses; a middle unit of isoclinally folded interbedded chert and argillite at least 1,000 feet in thickness; and an upper folded and faulted unit estimated at 3,500 feet in thickness and composed of dark-red to green argillite, green siliceous argillite, and chert which are intergradational laterally.

Thin conglomerates and brown, coarse-grained, feldspathic sandstones are interbedded throughout the Pumpernickel and contain pebbles of chert, argillite, quartzite and greenstone. The upper portion of the formation contains light to dark gray, fine to medium-grained limestone up to 1 foot thick, interbedded with chert and shale, pillowed and massive greenstone flows, tuff, and tuff breccia 20 to 100 feet in thickness. Mafic volcanic flows are much more abundant west of the study area where they can make up 20 percent of the Pumpernickel (Roberts, 1964b).

Thick-bedded, organic-rich chert, and thin-bedded chert are present within the Pumpernickel. Thin-bedded cherts in layers from 1 to 8 inches thick, grading into siliceous and silty argillite along strike, are common in the upper unit (Roberts, 1964b). The thin-bedded cherts are composed mainly of quartz, chlorite, and clay, with an absence of organic remains (Roberts, 1964b). Thick-bedded cherts occur primarily in the middle portion of the Pumpernickel in beds 2 to 24 inches thick. Finely laminated cherts with alternating light and dark laminae, and nodular and mottled cherts occur. The banded cherts commonly contain abundant sponge spicules and a few radiolaria in the lighter layers, with abundant carbonaceous material in the darker layers. The bedding surfaces of these cherts commonly show well-preserved invertebrate tracks (Roberts, 1964b).

In the Shoshone Range, the Pumpernickel Formation consists of black chert, grayish-red siltstone, and a few thin beds of quartzite. Siltstone makes up a major portion of the Pumpernickel in portions of the Shoshone Range where it is exposed in low rolling hills (Stewart and McKee, 1977).

In the Toiyabe Range, the Pumpernickel is yellow or reddish-grey to brown chert, grey to reddish siltstone, and yellow brown very fine-grained sandstone locally containing chert grains (Stewart and McKee, 1977).

The Pumpernickel is about 5,000 feet thick at Battle Mountain (Roberts, 1964b). No thickness was estimated in the Toiyabe or Shoshone Ranges.

The Pumpernickel is present at Battle Mountain, and in the Shoshone and Toiyabe Ranges, as well as several other ranges to the west of the evaluation area.

The Pumpernickel Formation, like the Havallah is exposed within the Golconda allochthon and is considered part of a deep-marine subduction complex. Water depth, however, is difficult to determine. The thick-bedded cherts in the middle portion of the Pumpernickel represent deposition below wave base where delicate surface tracks of worms, gastropods, and crustaceans can be preserved. Sponge spicules within the cherts are from sponges which thrive in water less than 300 feet deep. This suggests a slope setting for the middle portion of the formation. The thin-bedded cherts in the upper portion of the Pumpernickel probably represent a deeper water deposition with the absence of an abundant infauna (Roberts, 1964b).