Nevada lies within the Basin-and-Range Province of the western United States and embraces an area of 110,690 square miles. The state is divided into two sedimentary provinces: a western basin of Permo-Triassic rocks and an eastern basin of Paleozoic rocks. These basins are separated by the Manhattan geanticline, an arcuate Paleozoic high area near the middle of the state. The geanticline consists of metamorphosed Cambrian and Ordovician rocks intruded in many places by igneous material. Both Devonian and Permian sediments lie unconformably on the metamorphic rocks.
Permo-Triassic basin.—The Permo-Triassic basin covers an area of about 34,560 square miles. Sediments within the basin have been subjected to considerable deformation and some metamorphism. Not enough is known about the area to estimate the volume of sediments. As shown in Figure 44, however, there are at least 30,000 feet of sediments present in part of the area. Minor evidence of oil has been found in Triassic fossils, and some Triassic oil shales have been reported. No active oil or gas seeps have been found. Intensity of deformation and accompanying metamorphism make the Permo-Triassic basin unattractive for exploration at the present time.
Paleozoic basin.—The Paleozoic basin covers an area of about 71,727 square miles. The line of Permian facies change (Fig. 44) is believed to mark the western edge of the basin. The basin extends eastward into western Utah.1 The largest continuous exposure of metamorphic rocks is in the Ruby Mountains east of Elko. The rocks consist of metamorphosed schists, limestones, and dolomites of