In several respects the Nevada Test Site is located in an area that is especially interesting geologically. It lies along the projected trend of the Walker Lane and the Las Vegas Valley Shear Zone (Locke and others, 1940; Longwell, 1960), one of the major crustal features of the Basin-Range province. The shear zone itself, however, may not continue through the Test Site in a simple way (Burchfiel, 1965). The Test Site is in a belt of late Mesozoic thrust faults along the eastern side of the Cordilleran miogeosyncline. The eastern part of the Test Site area is characterized by the parallel Cenozoic topographic and structural elements generally associated with the Basin-Range province; the western part of the area was the locus of intense late Miocene and early Pliocene volcanism whose topographic and structural effects in part overprint the more typical Basin-Range geologic features. The Quaternary basin-filling deposits and some of the Tertiary volcanic rocks of Yucca Flat and nearby areas have been the principal media in which the underground nuclear testing program of the Atomic Energy Commission has been carried out.
