Deposits of alluvium, mainly poorly sorted sands, gravels and boulders of streams and alluvial fans, and thin discontinuous veneers of colluvium as loose rock, talus sheets and soil, cover the valley floors and lower slopes of the ranges throughout northeastern Nevada. Colluvium sheets commonly accumulate along slopes of more than 10 degrees, and grade down slope into alluvial fan deposits and alluvium. The upper reaches of stream channels contain coarse sands and gravels, with fine sands, silts and clay in the lower portions of streams and along valley floors (Roberts and others, 1967; Gilluly and Gates, 1965; Stewart and McKee, 1977; Coats, 1985). The texture, mineralogy, and extent of alluvial and colluvial deposits are the result of the local source terrain.

Playa deposits of silts and lacustrine clays with local interbedded lenses of fined-grained sand and gravel form alkali flats which appear as "stark white patches on aerial photographs" (Ekren and others, 1972, Roberts and others, 1967). Extensive playas occur within Grass, Crescent, Diamond, Ruby, Railroad, Newark, Clover, Long, Independence, Butte, Steptoe, Spring, Lake, Coal, and Cave Valleys. Small sand dunes and dune fields often occur along ancient shore levels as in Big Smoky, Crescent, and Grass Valleys (Gilluly and Masursky, 1965; McKee, 1976b).

Pluvial deposits are little dissected and poorly exposed, fine grained, lake bottom and margin deposits with locally preserved beaches and bars (Coats, 1985). These lakes were present in most of the modern valleys including Diamond, Ruby, Clover, and Steptoe Valleys, and the Owyhee basin area.

Calcareous and siliceous sinter has been, and is still being locally deposited, as terraces and nodules around hot spring and geyser orifices in several localities. Opaline sinter and brown or yellowish and grayish-brown calcareous mounds of calcium carbonate or travertine are present around active and extinct hot springs. This includes areas within Railroad Valley, Sulphur Hot Springs on the eastern flank of the central Ruby Range, 3 miles northwest of Wells, northwest of Spanish Ranch in Independence Valley, north of Tuscarora, and just east of Deep Creek Reservoir (Coats, 1985).

Small patches of talus, landslide deposits, and fanglomerate aprons occur throughout northcentral Nevada. Landslides form a great deal of the alluvial section both in Nye and Elko Counties (Kleinhampl and Ziony, 1985; Smith and Ketner, 1976; Coats, 1964, 1985). Most of these landslides cover small areas and are the result of slope failure related to non-cohesive sediments. The younger landslides retain an irregular topography while the older landslides are dissected and commonly produce an inversion of topography (Coats, 1985). Landslide and breccia masses associated with caldera collapse or resurgence, and with low-angle normal and transverse faults are present in various portions of the evaluation area. Many landslide masses in Elko County are related to resistant jointed and welded tuffs which overly weak clay-rich volcanic ash along over-steepened slopes (Coats, 1964). Delineation of breccias and landslides of specific origin is difficult and has not been done in most areas.

Moraines such as those in the Shoshone, Ruby and East Humboldt Ranges, Independence and Jarbidge Mountains, and the Bull Run, Rowland, Mountain City and Owyhee Quadrangles are mapped and included with Quaternary Alluvium (Sharp, 1939a; Decker, 1962; Bushnell, 1967; Coats, 1964, 1985; Gilluly and Gates, 1967).