Alluvium and colluvium
Lake Bonneville deposits
Mud and salt flats
Glen Canyon Group (Navajo Ss, Kayenta Fm, and Wingate Ss). Includes Rainbow Bridge.
Duchesne River Fm, Uinta Formation (south of Uinta Mtns.) and Bridger Formation (north of Uinta Mtns.).
Older alluvial deposits
Eastern Uinta Basin Members of the Green River Formation (Evacuation Creek Mbr, Parachute Creek Mbr (oil shale), Garden Gulch Mbr, and Douglas Creek Mbr.).
In Western Utah: Quichapa Group and other volcanic rocks (Tmb,Tmr,Tma). In Central Utah: Silver Shield Latite (17 my) and Pinyon Creek Conglomerate.
Mancos Shale (Masuk Shale Mbr, Emery Sandstone Mbr, Blue Gate Shale Mbr, Ferron Sandstone Mbr, and Tununk Shale Mbr).
Bluff Ss, Summerville Fm, Curtis Fm, Entrada Ss, and Carmel Formation. Includes Arches National Park.
Cutler Group (White Rim Ss, De Chelly Ss, Organ Rock Shale, Cedar Mesa Ss, Halgaito Fm, and Elephant Canyon Fm). Includes Natural Bridges National Monument.
Morrison Formation (Brushy Basin and Salt Wash Members).
Iron Springs Formation of Cedar City Area (Wahweap Ss and Straight Cliffs Fm).
Dakota Ss and Cedar Mtn or Burro Canyon Formations.
Uinta Mountain Group (24,000 feet thick along the Green River). Red Pine Shale (950 my).
Wasatch/Colton Formations and Flagstaff Limestone.
Wasatch and Evanston? Formations undivided.
Navajo Sandstone, Kayenta and Moenave Formations. Includes Zion National Park (Navajo Ss).
Chinle Shale and Shinarump Conglomerate Member.
Tertiary volcanic rocks, undivided.
Isom Fm (tuff), Needles Range Fm (ash-flow tuff), Escalante Desert Fm (ash-flow tuff), Sawtooth Peak Fm (ash-flow tuff), and Tunnel Springs Tuff.
North Horn and Canaan Peak Formations.
Claron Formation. Includes Bryce Canyon/Cedar Breaks Nat. Park.
Oquirrh Group (maximum thickness 25,000 feet), including Bridal Veil Limestone.
Mesaverde Group (Price River Fm, Castlegate Ss, Blackhawk Fm (coal), and Star Point Ss).
Oquirrh Group (10,000+ feet thick) of Cedar Mountains and vicinity, is equivalent, in part to Arcturus Formation and Ely Limestone elsewhere
Entrada and Carmel Formations (Arapien Shale at Marysvale).
In Cedar City area: Isom Fm and Needles Range Fm (29 my). In Marysvale area: Bullion Canyon Volcanics.
Alluvial materials, Axtell and Harkers Formations
Pilot Shale, Guilmette Formation, and Simonson and Sevy Dolomites.
Salt Lake Formation and other Basin & Range valley-filling alluvial, lacustrine, and volcanic materials. Valley fill is more than 8,000 feet thick in places and includes salt masses under the Sevier Desert.
Notch Peak, Orr, Lamb, Weeks, and Wah Wah Summit Formations.
Laguna Springs Latite, Tintic Mountain Group (latite, porphyry & tuff), Packard Quartz Latite, and Apex Conglomerate.
North Horn Formation.
Trippe Ls, Marjum/Pierson Cove Fms, Wheeler Shale, Swasey Ls, Whirlwind Fm, Dome Ls, Chisholm Fm, Howell Fm, and Pioche Fm.
In Northwestern Utah: Dacitic tuff (8.5 my). In Logan-Huntsville Allochthon: rhyolite.
Salt Lake Formation (?) and other Basin & Range valley-filling alluvial, lacustrine, and volcanic materials. Valley fill is more than 13,000 feet thick in the central part of Utah Valley.
Ely Springs Dm, Eureka Qtz, Crystal Peak Dm, Watson Ranch Qzt, and the Pogonip Group (Lehman Formation, Kanosh Shale, Juab, Wah Wah, Fillmore, and House Limestones).
Iron Springs Formation of Cedar City Area (Kaiparowits Fm).
Mancos Shale (Hilliard Shale and Blair Formation north of Uinta Mountains), Frontier Ss, and Mowry Shale.
Prospect Mountain Quartzite (3,500 feet thick).
Quartz Monzonite (in Cedar City area) and monzonite and granite (in Marysvale area).
North Horn and Currant Creek Formations.
McCoy Creek and Sheeprock Groups (10,000+ feet thick).
Iron Springs Formation of Cedar City Area (Tropic Shale and Dakota Sandstone).
Green River Formation.
Sevier River Formation.
Great Blue Ls, Humbug Formation, and Deseret Limestone.
Gerster Limestone, Plympton Formation and Kaibab Limestone.
Chinle Formation and Shinarump Conglomerate Member.
Evanston Formation (lower part).
Schist of Stevens Spring, Quartzite of Yost, Schist of Upper Narrows, and Elba Quartzite
Kaibab Limestone and Toroweap Formation.
Tuffaceous sediments, mudstone, sandstone, valley fill.
Bloomington, Blacksmith, Ute, and Langston Formations.
Farmington Canyon Complex and Little Willow Schist and Gneiss (2.6 billion years old).
Ochre Mountain Limestone (Great Blue equivalent) and Woodman Formation (Deseret Humbug equivalent).
Intrusions, chiefly granitic, of various dates.
Fish Haven Dolomite, Swan Peak Quartzite, and Garden City Limestone.
Park City Formation.
St. Charles Formation, Worm Creek Quartzite, and Nounan Dolomite.
Frontier Formation - includes the following members: Upton Ss, Judd Sh, Grass Creek, Dry Hollow, Oyster Ridge Ss, Allen Hollow, Shale Member, Coalville Member, Chalk Creek, Springs Canyon, and Longwall Ss.
Geertsen Canyon Quartzite (upper part of the Bingham Group).
Duchesne River, Uinta and Bridger Formations
Laccolithic intrusions mostly diorite porphyry (24-28 my).
Nugget (Navajo) Sandstone.
Arapien Shale (Summerville Formation, Entrada Sandstone and Carmel Formation).
Muddy Creek Formation (in Cedar City area).
Moenkopi and Dinwoody Formations.
Hermosa Group (Honaker Trail Fm, Paradox Fm (oil, salt, potash), Pinkerton Trail Fm) and Molas Formation.
Morgan Formation and Round Valley Limestone.
In Southwestern Utah: In Cedar City area: Page Ranch Fm, Rencher Fm and Quichapa Group (24my). In Marysvale area: Joe Lott Tuff, Mt. Belknap Volcanics, Osiris Tuff and Mt. Dutton Formation.
Curtis Fm, Entrada Ss, and Carmel Fm.
Great Blue, Humbug and Deseret Formations.
Leatham Formation, Beirdneau Sandstone, Hyrum Dolomite, and Water Canyon Formation.
Precambrian rocks of the Canyon Range (Mutual Fm, Inkom Fm, Caddy Canyon Qtz, Papoose Creek Fm, Blackrock Canyon Ls, and upper part of Pocatello Fm).
Stump and Preuss Sandstones and Twin Creek Limestone.
Diamond Creek Sandstone and Kirkman Limestone.
Aspen Shale and Kelvin Formation.
Mutual Formation, Mineral Fork Tillite, and Big Cottonwood Formation (16,000 feet thick).
Price River Formation.
Maxfield Limestone (Opex Fm, Cole Canyon Dm, Bluebird Dm, Herkimer Ls, Dagmar Dm, and Teutonic Ls) and Ophir Formation.
Tuffaceous sediments, mudstone, sandstone, conglomerate.
Humbug Formation and Deseret Limestone.
Morrison Formation (Dinosaur National Monument).
Echo Canyon Conglomerate and Henefer Formation.
Adamellite intrusion 2.5 b.y. by Rb-Sr
Chinle Shale and Garta Sandstone Member.
Clayton Peak and Pine Creek stocks.
Thanes Formation, Woodside Shale, and Dinwoody Formation.
Granitic rocks (140 my) in House Range and near Wendover.
Dakota and Cedar Mountain Formations.
Fish Haven Dolomite, Eureka Quartzite, and Pogonip Group
Ajax Dolomite and Opex Formation (upper member of Maxfield Limestone).
Bald Knoll and Gray Gulch Formations.
Coconino Sandstone, Supai Group, and Pakoon Formation.
Bloomington Formation, Maxfield Limestone, and Ophir Formations.
Browns Park Formation.
Silver City Monzonite (31 my), Sunrise Peak Monzonite Porphyry, Swanson Quartz Monzonite
Green Creek Complex
Hambug Formation and Deseret Limestone.
Gardison and Lodgepole Limestones.
Park City and Phosphoria Formations.
Little metamorphosed allochthonous remnants.
Canaan Peak Formation.
Manning Canyon Shale.
Schist, gneiss, and granite (1.5 billion years old).
Schist of Mahogany Peaks, Quartzite of Clarks Basin
Browns Hole (570 my), Mutual, Inkom Formations; Caddy Canyon Quartzite, Papoose Creek, Kelley Canyon, Maple Canyon, and Perry Canyon Formations; Diamictite member
Redwall Limestone (chert).
Fish Haven Dolomite and Opohonga Limestone.
Moenkopi (in Blue Mountain) and Thaynes (north of Confusion Range) Formations.
Gardison Limestone and Fitchville Formation.
Park City and Phosphoria Formations.
Manning Canyon Shale.
Pinyon Peak Limestone and Victoria Formation.
Red Creek Quartzite (20,000 feet thick) 2.3 billion years old.
Beirdneau Sandstone, Hyrum Dolomite, and Water Canyon Formation.
Nopah and Bonanza King Formations, Muav Limestone, and Pioche Shale
Vishnu Schist and granitic intrusions (1650 my).
Morgan Formation and Round Valley Limestone.
St. Charles Formation and Nounan Dolomite.
Navajo Sandstone (Star Range and Blue Mountain).
Salt Lake Formation and valley-filling alluvial, lacustrine and volcanic materials.
Granitic intrusions at Granite Peak.
Temple Butte and Muddy Peak Limestones.
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.
Castle Valley Conglomerate.
Metaquartzite and schist.
Crazy Hollow Formation.
Granitic rock (26 my).
Thaynes Formation and Woodside Shale.
Gravel and subordinate sand and silt deposited at mouths of canyons; largest fans are in Basin and Range Province in east-central and southeastern Idaho. (Quaternary Sediments).
Fish Haven Dolomite and Garden City Limestone.
Marine dolostone and limestone and sandstone in east-central and southeastern Idaho (Summerhouse, Kinnikinic, and Swan Peak sandstones, Fish Haven, Laketown, Jefferson, Three Forks, and Darby formations) and deep-water carbonaceous mudrocks of Phi Kappa, Trail Creek, and Milligen formations east of Ketchum. (Paleocene to Neoproterozoic Sedimentary and Igneous Rocks of the Cordilleran System).
Greenish-gray, olive-drab, and white tuffaceous sandstone and claystone; lenticular marlstone and conglomerate.
Prospect Mountain Quartzite.
Little metamorphosed allochthonous remnants.
Park City and Phosphoria Formations.
Marine limestone, dolomite, and subordinate shale and sandstone of Cambrian carbonate bank of southeast Idaho stratigraphically up to St. Charles Formation and Ordovician Garden City Limestone. Includes Bayhorse succession (Cash Creek Quartzite, Garden Creek Phyllite, Bayhorse Dolomite, Ramshorn Slate, and Clayton Mine Quartzite) of Clayton area and Pioneer Mountains; quartzite of Kamiak Butte north of Moscow; and Cambrian Gold Creek quartzite, Rennie Shale, and Lakeview Limestone east of Bayview. (Paleocene to Neoproterozoic Sedimentary and Igneous Rocks of the Cordilleran System).
Silt, clay, sand, and gravel deposited in and at margins of former Lake Bonneville (33-11 calibrated ka) and sand and gravel deposited in giant flood bars by outburst floods from the lake (17.4 calibrated ka). The 1,575-m (5,170 ft) Lake Bonneville shoreline was used to determine the maximum extent of the lake deposits. Flood deposits follow Bonneville flood path from near Downey and the Portneuf River westward along the Snake River to Lewiston. They include sand and silt deposited in slack-water areas to 740 m (2,430 ft) elevation in the Boise, Weiser, Payette, and Snake river drainages. (Quaternary Sediments).
Tuffaceous and other young Tertiary sedimentary rocks. Most of these rocks are sedimentary with a strong volcanic component - a few are tuffaceous with a strong sedimentary component. This unit includes rocks originally mapped as the High Rock sequence in Washoe County; the Horse Camp Formation in northern Nye County; the Esmeralda Formation in Mineral and Esmeralda Counties; older lake beds in Lincoln County; the Belted Range Tuff; the Indian Trail Formation (now abandoned); Timber Mountain, Paintbrush, and Crater Flat Tuffs; Wahmonie and Salyer Formations in southern Nye County; the Siebert Tuff in Esmeralda County; the Muddy Creek Formation in Clark County; and the Thousand Creek and Virgin Valley “beds” in Humboldt County; and other unnamed units. It corresponds to units Ts3 and Tts from the 1978 State map. It is present in all counties.
Sandstone, shale, and conglomerate. In northwest and west-central: Lower Cretaceous. In southwest: Lower and Upper Cretaceous.
Locally includes intermixed landslide and glacial deposits, talus, and rock-glacier deposits.
Ely Limestone (chert).
Mostly alluvium, colluvium, and glacial and landslide deposits. Primarily in Yellowstone area and Bighorn Mountains.
Upper part consists of shallow marine and fluvial quartzose sandstone, and minor siltite, shale, and limestone of the Brigham Group of southeast Idaho, Wilbert Formation of east-central Idaho, and quartzites of unknown affinity west of Borah Peak. More highly metamorphosed equivalents are quartzite, metaconglomerate, metasiltite, calc-silicate marble, and schist of Gospel Peaks successions C and D in central Idaho; mature quartzite, biotite schist, and minor calc-silicate rocks of Syringa metamorphic sequence east of Moscow; and schist and quartzite in the Albion Range (Elba Quartzite, schist of Upper Narrows, quartzite of Yost, schist of Stevens Spring, quartzite of Clarks Basin, schist of Mahogany Peaks, and Harrison Summit Quartzite). Lower part consists of diamictite, immature sandstone, and bimodal volcanic rocks related to continental rifting. Includes Pocatello Formation (700-665 Ma), formation of Leaton Gulch near Challis, Shedroof Conglomerate in extreme northwest Idaho, and metamorphic equivalents (schist, marble, calc-silicate rocks, metaconglomerate, and ~686 Ma metavolcanic rocks) of Gospel Peaks successions A and B in central Idaho. (Paleocene to Neoproterozoic Sedimentary and Igneous Rocks of the Cordilleran System).
(Thrust Belt) Main body--Variegated red to gray, brown, and gray mudstone and sandstone; conglomeratic lenses. (in southwest Wyoming) - Drab to variegated claystone and siltstone, carbonaceous shale and coal, buff sandstone, arkose, and conglomerate. In northwestern part of Green River Basin is thick arkosic light-yellowish-tan sandstone intertonguing with pale-green to gray claystone and shale. (in east Wyoming) - Drab sandstone and drab to variegated claystone; numerous coal beds in lower part.
Drab sandstone, drab to variegated claystone and siltstone; locally derived conglomerate around basin margins. Lower part is Paleocene.
Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.
Rhyolitic flows, domes, plugs, breccias, quartz latite, rhyodacite, quartz porphyry dikes, and other shallow intrusive rocks. This unit includes rocks mapped as the Cañon Rhyolite on the Washoe North map, the Jarbidge Rhyolite and phenorhyolitic and phenodacitic flows and domes on the Elko County map, and other unnamed units. It has a distribution similar to Tt3, with exposures in the northern and southern parts of the State, but only crops out in a few places in the central region. It corresponds to unit Tr3 on the 1978 State map, and also includes a few rocks mapped as Trt on the 1978 State map. This unit is exposed in every county except White Pine.
Present in Elko, White Pine, Lincoln, and Clark Counties. This unit represents mostly Upper Pennsylvanian and Lower Permian rocks that have not otherwise been separated into units Psc or IPMbc. Unit includes unnamed Pennsylvanian and Lower Permian limestone and sandstone beds in Lincoln County, the Bird Spring Formation in Clark County, the Riepe Spring and Ely Limestones (undivided) in White Pine County, and limestone and dolomite rocks not otherwise assigned in Elko County. This unit lies depositionally below unit Psc and above the Ely Limestone (IPMbc) where it is mapped separately. Where unit IPMbc is not mapped separately in southern Nevada, the unit lies directly on Mississippian carbonate (Mc) and in White Pine County it rests on undivided Chainman and Pilot Shales and Joana Limestone (shown as either unit IPMcl or MDcl).
Till and outwash consisting of gravel, sand, silt, and clay. Formed by valley glaciers at higher elevations and by the Cordilleran ice sheet in northern Idaho. Includes deposits of several glacial episodes. Includes rock glacier deposits and some modern alluvium derived from reworked till and outwash. (Quaternary Sediments).
Marine phosphorite, shale, and chert of Phosphoria Formation, fine-grained sandstone and mudrock of Wells, Quadrant, Amsden, and Shedhorn formations, and fine-grained sandstone, carbonaceous mudstone, and limestone of the Snaky Canyon Formation and Sun Valley and Oquirrh groups. Located in south-central and eastern Idaho. (Paleocene to Neoproterozoic Sedimentary and Igneous Rocks of the Cordilleran System).
(Northwest, Southwest, and Central Wyoming) - Brown to gray sandstone, gray to black shale, and thin coal beds. (East Wyoming) - Light-colored massive sandstone, drab shale, and thick coal beds.
Summerville Fm: Shale and siltstone
Older gravel, sand, and silt deposited in fans, streams, and lakes. Includes older terrace gravels and Tuana Gravel northwest of Twin Falls. (Quaternary to Eocene Continental Sediments and Sedimentary 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.
Welded and nonwelded silicic ash flow tuffs. Aside from alluvium, this unit covers more of Nevada than any other rock, with over 4,000 polygons representing it on this map. It is principally exposed in the central regions of the State. It locally includes thin units of air fall tuff and sedimentary rocks. It includes rocks mapped on the Washoe South, Lyon, Douglas, and Carson Counties maps as the Hartford Hill Rhyolite Tuff (now abandoned); on the Nye South map as the tuff of White Blotch Spring, the tuffs of Antelope Springs, and the tuff of Monotony Valley; in Lander County it is mapped as the Bates Mountain Tuff, Caetano Tuff, Edwards Creek Tuff, New Pass Tuff, tuff of Hall Creek, and the tuff of McCoy Mine; in Lander and Pershing Counties it is the Fish Creek Mountains Tuff; on both of the Nye County maps it is the Fraction Tuff; it also includes the Pancake Summit Tuff, Northumberland Tuff, Shingle Pass Tuff, some outcrops of Darrough Felsite shown to be Tertiary (other outcrops have been shown to be Mesozoic or Paleozoic), tuffs of Moores station, tuffs of Peavine Canyon, tuffs of the Pancake caldera complex, the Stone Cabin Formation, tuff of Saulsbury Wash, tuff of Kiln Canyon, the Tonopah Formation, tuffs of Hannapah, tuff of Bald Mountain, the Needles Range Formation, and the Calloway Well Formation on the Nye North map; in Esmeralda County it is the Kendall Tuff and latite; and in northern Nye and Lander Counties it is the Toiyabe Quartz Latite (now abandoned), and other unnamed units. It corresponds to unit Tt2 on the 1978 State map. It crops out in every county except Clark.
Fluvial and lacustrine deposits associated with Columbia River Basalt Group and equivalent basalts (17-8 Ma); consolidated to weakly consolidated sandstone, siltstone, arkose, conglomerate, claystone, and tuffaceous sediment; subordinate intercalated basalt and rhyolitic tuff. Includes Payette and Sucker Creek formations in southwestern Idaho, sediments associated with basalt of Weiser in western Idaho, and Latah Formation in northern Idaho. Includes sedimentary rocks of uncertain origin in southwest corner of Idaho. (Quaternary to Eocene Continental Sediments and Sedimentary Rocks).
Unconsolidated to strongly consolidated alluvial and eolian deposits. This unit includes: coarse, poorly sorted alluvial fan and terrace deposits on middle and upper piedmonts and along large drainages; sand, silt and clay on alluvial plains and playas; and wind-blown sand deposits. (0-2 Ma)
Rock Springs uplift. White massive sandstone; lenticular chert-grit conglomerate in upper part.
Rock Springs uplift. White to brown sandstone, shale, and claystone; numerous coal beds.
Andesite flows and breccias and other related rocks of intermediate composition such as dacite, rhyodacite, quartz latite, and biotite-hornblende porphyries. This unit includes units mapped as the South Willow Formation on the Washoe North map, the Milltown Andesite on the Nye South and Esmeralda County maps, the Mizpah Trachyte on the Nye North map, and other units. It corresponds to unit Ta2 on the 1978 State map. It crops out in all counties except Clark, Eureka, Lyon, Douglas, and Carson.
Till and outwash of sand, gravel, and boulders.
Fluvial, fan, and lacustrine deposits and intercalated volcanic rocks of the Basin and Range Province (~16-2 Ma); consolidated to weakly consolidated sandstone, siltstone, arkose, conglomerate, mudstone, tuffaceous sediment, basalt, basaltic tephra, and rhyolite tuff. Includes deposits of Lake Idaho (Idaho Group) in western Snake River Plain and Salt Lake Formation deposited in Basin and Range Province of east-central Idaho. (Quaternary to Eocene Continental Sediments and Sedimentary Rocks).
Pend Oreille granodiorite gneiss near Priest River (~2650 Ma); schist, gneiss, and subordinate quartzite along North Fork Clearwater River; Kelly Creek granite gneiss northeast of Pierce (~2670 Ma); orthogneiss in Pioneer Mountains (~2600 Ma and 695 Ma); granite gneiss, granite, schist, and amphibolite of Green Creek complex in Albion Mountains (~2600 Ma); granite gneiss in Beaverhead Mountains east of Leadore (~2450 Ma); and marble, quartzite, schist, and amphibolite of uncertain age near Henrys Lake. (Mesoproterozoic to Archean Basement Rocks).
Clasts of red quartzite, gray chert, and limestone in a gray to white tuffaceous sandstone matrix.
Commonly cliff-forming, cross-bedded sandstone lenses alternating with slope-forming siltstone, mudstone and shale. Colors are highly variable, and include greenish gray, reddish brown, pink, white, and purple. Sands were deposited by braided streams with finer sediment representing overbank or lacustrine deposits. (145-160 Ma)
Commonly cross-bedded, ledge-forming sandstone and slope-forming siltstone. Rock typically has a striped red and white aspect. The Carmel Formation and Entrada Sandstone are prominent members of this group. (Late to Middle Jurassic, about 160-180 Ma)
Green River Formation.
This largely siliciclastic unit of siltstone, sandstone, limestone, and dolomite crops out in Elko, White Pine, Lincoln, and Clark Counties. It includes rocks originally mapped as the Arcturus Formation, Rib Hill Sandstone, undivided Kaibab Limestone, Toroweap Formation, and Coconino Sandstone in Clark County; and the Pequop Formation and red beds in Lincoln County. Unit Psc represents a strong influx of clastic material over the carbonate shelf during the Early Permian, presumably derived primarily from the craton to the east. It is depositionally overlain by unit Pc and lies conformably above unit PIPc. At its western and northern edges it can be difficult to distinguish from Permian clastic rocks of the Siliciclastic overlap assemblage (units Pacl and PIPacl). It follows closely with unit Psc of Stewart and Carlson (1978).
Quartzite, conglomerate, and shale
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.
Biotite, muscovite-biotite, and muscovite granite of the Almo pluton (29 Ma) at City of Rocks National Reserve and Castle Rocks State Park southeast of Oakley. (Quaternary to Eocene Continental Volcanic and Intrusive Rocks).
Deposits in valleys consisting of gravel, sand, and silt. Includes younger terrace deposits. May contain some glacial deposits and colluvium in uplands. (Quaternary Sediments).
Light-colored tuffaceous sandstone and siltstone, locally conglomeratic. Locally designated by some as Norwood Tuff.
Sage Junction Formation - Gray and tan siltstone and sandstone. Quealy Formation - Variegated mudstone and tan sandstone. Cokeville Formation - Tan sandstone, claystone, limestone, bentonite, and coal. Thomas Form Formation - Variegated mudstone and gray sandstone. Smiths Formation - Ferruginous black shale and tan to brown sandstone.
Claystone, shale, and sandstone
Unit includes andesite or dacite flows, flow breccias, and hypabyssal rocks in Lander County, andesitic to latitic flows, pyroclastic rocks, and phenoandesitic and phenolatitic flows in Elko County, and other undifferentiated volcanic rocks in other counties. Present in Humboldt, northern Nye, Churchill, Elko, Eureka, Lander, and White Pine Counties. It corresponds to the 1978 State map unit Ta1.
Unconsolidated deposits associated with modern fluvial systems. This unit consists primarily of fine-grained, well-sorted sediment on alluvial plains, but also includes gravelly channel, terrace, and alluvial fan deposits on middle and upper piedmonts. (0-10 ka)
Includes dune sand and silt and Peoria Loess
Variegated claystone, mudstone, sandstone, and local beds of limestone
In southwest, Glen Canyon Group consists of Navajo Sandstone, Kayenta Fm (red siltstone, shale, and sandstone) and Wingate Sandstone; Chinle is red siltstone
Gray to black soft sandy shale and shaly sandstone.
Includes units mapped as the High Rock sequence on the Washoe North map; the Timber Mountain, Paintbrush, Crater Flat, and Belted Range Tuffs, and Indian Trail Formation (now abandoned) on the Nye South map; the Thirsty Canyon Tuff on the Nye South and Esmeralda maps; and other unnamed units. Locally it includes tuffaceous sedimentary rocks interstratified with tuffs. It is present in the northernmost part and southernmost parts of the State, and is not exposed in the central region. It corresponds to unit Tt3 on the 1978 State map, although a few rocks also mapped as Trt on the 1978 State map also are included. It is present in Clark, Churchill, Washoe, Nye, Lincoln, Lyon, Douglas, Carson, Esmeralda, Elko, Humboldt, Pershing, and Mineral Counties.
Moderately to strongly consolidated conglomerate and sandstone deposited in basins during and after late Tertiary faulting. Includes lesser amounts of mudstone, siltstone, limestone, and gypsum. These deposits are generally light gray or tan. They commonly form high rounded hills and ridges in modern basins, and locally form prominent bluffs. Deposits of this unit are widely exposed in the dissected basins of southeastern and central Arizona. (2-16 Ma)
Metamorphic complex of Mt. Nebo.
Includes Piney Creek Alluvium and younger deposits
Metaquartzite, amphibolite, and mica schist. Present only in small area at Utah border in Uinta Mountains
In northwest and west-central: Intertongues complexly with units of overlying Mesaverde Group or Fm; lower part consists of a calcareous Niobrara equivalent and Frontier Sandstone and Mowry Shale Members; in areas where the Frontier and Mowry Members (Kmfm), or these and the Dakota Sandstone (Kfd) are distinguished, map unit (Km) consists of shale above Frontier Member. In Southwest: Lower part contains Juana Lopez Member (Kmj)
Red siltstone and sandstone
Gray siltstone, sparse red sandstone, and lignite beds.
Partly consolidated gravel above and flanking some major streams.
Calcareous siltstone and sandstone
Locally includes talus, rock-glacier, and thick colluvial deposits
Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest
Basalt flows, plugs and dikes, some olivine basalt, and andesite and latitic rocks. This unit corresponds with unit Tb on the 1978 State map. It is present on the Washoe North, Washoe South, Lincoln, Clark, Elko, Eureka, Humboldt, Nye South, and Lander County maps.
This unit is present in southern Nye, Lincoln, and Clark Counties. Unit includes the Monte Cristo Limestone, and Lower Mississippian rocks referred to as the Joana, Mercury, Bristol Pass, and Rogers Spring Limestones. It generally lies depositionally above Devonian carbonate rocks and beneath Pennsylvanian carbonate and clastic rocks. In the Meadow Valley Mountains in southern Lincoln County it is also shown sitting on a thin horizon of Pilot Shale and overlain by a thin Mississippian clastic unit assigned to unit IPMcl.
In extreme southwestern Moffat County, includes thin wedge of Carmel Fm (red siltstone and sandstone) beneath Entrada
Marine limestone of Mississippian carbonate banks and turbiditic sandstone, mudstone, and conglomerate of Antler flysch trough; includes Madison and Lodgepole formations and Chesterfield Range Group of southeastern Idaho; McGowan Creek Formation, White Knob Limestone, and overlying carbonate bank of Lost River Range; and Copper Basin Group of Pioneer Mountains. Includes poorly dated Salmon River assemblage east of Stanley, consisting of argillite, siltstone, calcareous sandstone, and limestone. (Paleocene to Neoproterozoic Sedimentary and Igneous Rocks of the Cordilleran System).
Coarse relict alluvial fan deposits that form rounded ridges or flat, isolated surfaces that are moderately to deeply incised by streams. These deposits are generally topographically high and have undergone substantial erosion. Deposits are moderately to strongly consolidated, and commonly contain coarser grained sediment than younger deposits in the same area. (0.75-3 Ma)
These Permian rocks include cherty limestone, dolomite, shale, sandstone, bioclastic limestone, and phosphatic limestone exposed in Elko, White Pine, Lincoln, and Clark counties. This unit includes rocks mapped as the Phosphoria Formation; the Gerster Limestone, Plympton Formation, Kaibab Limestone, and Grandeur Formation of the Park City Group; the Park City Group undivided; the Toroweap Formation; and the Coconino Sandstone. Unit Pc is disconformably overlain by Triassic unit TRmt in scattered places in eastern and southern Nevada. It depositionally overlies unit Psc. It matches closely with unit Pc of Stewart and Carlson (1978).
Sandstone and siltstone; west of Park Range
Oil shale and marlstone.
White, gray, and green limy tuff, siltstone, sandstone, and conglomerate.
Includes the Sheep Pass Formation and equivalents in northern Nye, Lincoln, Elko, Eureka, Lander, and White Pine Counties. In most places the Sheep Pass Formation is Paleocene or Eocene (Fouch, Hanley, and Forester, 1979), although rocks from the Carlin-Piñon Range area that contain Late Cretaceous fossils have been included in the Sheep Pass Formation (Smith and Ketner, 1976, 1978). It corresponds to unit Ts1 on the 1978 State map.
(Thrust Belt) - Buff to pink crossbedded well-sized and well-sorted quartz sandstone and quartzite; locally has oil and copper-silver-zinc mineralization. (North Wyoming) - Gray to dull-red, crossbedded quartz sandstone.
Includes generally cliff-forming, thin- to thick-bedded limestone. These rocks are mainly shallow water subtidal, intertidal, and supratidal deposits formed on a broad inner carbonate shelf (Stewart, 1980). The Devils Gate Limestone and Guilmette Formation in northern Nevada are the principal units, and the Sultan Limestone is included from the southern part of the State. Unit is overlain (usually disconformably) by the Pilot Shale of unit MDcl except in southernmost Nevada where it is overlain by Mississippian carbonate (Mc). It depositionally overlies Middle and Lower Devonian unit Dcd. In a few places, such as southern Nevada and parts of Eureka County, regional mapping did not distinguish the Upper and Middle Devonian section from the Lower Devonian section, and all of the Devonian is included in unit Dc. Rocks mapped as the Simonson Dolomite would fit into this depositional sequence (sequences 9 and 10 of Cook and Corboy, 2004), but they are not differentiated from the underlying dolomites in White Pine or Elko Counties, so they are all included in unit Dcd here, not unit Dc. This unit crops out in Clark, Elko, Eureka, Lander, Lincoln, Nye, and White Pine Counties.
Dark red sandstone and mudstone; includes gypsum beds in northwestern Arizona; deposited on a low-relief coastal plain. (230-245 Ma)
Upper Jurassic nonmarine rocks.