Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite
Tertiary pyroclastic and volcanic mudflow deposits.
Tertiary volcanic flow rocks; minor pyroclastic deposits.
Alluvium, lake, playa, and terrace deposits; unconsolidated and semi-consolidated. Mostly nonmarine, but includes marine deposits near the coast.
Undivided pre-Cenozoic metasedimentary and metavolcanic rocks of great variety. Mostly slate, quartzite, hornfels, chert, phyllite, mylonite, schist, gneiss, and minor marble.
Tertiary intrusive rocks; mostly shallow (hypabyssal) plugs and dikes. Includes some Mesozoic rocks.
Pliocene and/or Pleistocene sandstone, shale, and gravel deposits; in part Miocene.
Quaternary volcanic flow rocks; minor pyroclastic deposits; in part Pliocene and Miocene.
Undivided Cretaceous sandstone, shale, and conglomerate; minor nonmarine rocks in Peninsular Ranges
Glacial till and moraines. Found at high elevations mostly in the Sierra Nevada and Klamath Mountains.
Includes some rocks mapped as the Kate Peak and Alta Formations on the Washoe South map; Wahmonie and Salyer Formations on the Nye South map; Gilbert Andesite on the Esmeralda map; pyroxene, hornblende phenoandesite, and phenodacite on the Elko map; and other unnamed units. It corresponds to the unit Ta3 on the 1978 State map. It is present everywhere except Eureka and White Pine Counties.
Unit is present in all counties. Some counties divided the alluvium into younger and older units, and some did not. For those that did not, or used other generalized terms for Quaternary rocks, the unit Qal has been used for the general undivided alluvium. Additionally, when polygons have been edited and changed to alluvium, Qal was used as the general value; hence it now is present in all counties. Qya-Younger alluvium: Map unit is used in Churchill, Elko, Esmeralda, Eureka, Humboldt, Lander, and Lincoln Counties where geologic information suggests better-defined younger versus older alluvium. It is mostly interchangeable with Qal, except that it implies some specifically younger Quaternary deposits.
Granodiorite, granite, and related rocks make up the largest group of granitic intrusions exposed in Nevada. They are present in every county, and are especially abundant in west-central Nevada in an arcuate belt along the border with California extending north and eastward towards Idaho.
This assemblage is composed of Upper Triassic basinal-marine volcanic and carbonate rocks overlain by Lower Jurassic fine-grained, marine siliciclastic and tuffaceous sedimentary rocks, and by partly nonmarine sandstone, coarse clastic rocks, and volcanic rocks of late Early Jurassic and possibly younger age. This assemblage has stratigraphic similarities to the Luning-Berlin and Pamlico-Lodi assemblages, but shares only part of their late Mesozoic structural history, and is separated from them by the linear trace of the northwesterly trending Pine Nut fault (Oldow, 1984a; Silberling, Jones, and others, 1992). Structurally, the rocks are involved in only a single phase of tight to isoclinal folds with north-northwest striking axial planes, and no major internal thrust faults are known (Oldow, 1984a). The Pine Nut assemblage crops out in southern Washoe, Lyon, Douglas, Carson, and Mineral Counties, and includes rocks originally mapped as the Excelsior Formation, the Peavine sequence, and other metasedimentary and metavolcanic rocks.
Map unit used in all counties for recent lake beds, playas, and flood plains. Polygons from the 1978 State map unit Qp were added where no playa was shown on the county maps.