Formal Lithostratigraphic Units Occurring in Nevada


Formal lithostratigraphic units are defined in accordance with the North American Stratigraphic
Code
(Ashley and others, 1933; American Commission on Stratigraphic Nomenclature, 1961,
1970; North American Commission on Stratigraphic Nomenclature, 1983, 2005), or they are
recognized through long usage prior to adoption of this code.  Authors may find these units
listed in “GEOLEX,” the online USGS database containing records of all formal lithostratigraphic
unit names of the United States as they are used in publications. The link to the GEOLEX
database is:

http://ngmdb.usgs.gov/

As a convenience to authors of Nevada publications, all the formal lithostratigraphic units recog-
nized in Nevada found in the USGS GEOLEX database were excerpted (on March 1, 2010). They
are listed alphabetically below.

NBMG does not use the revised term “Dolostone” that is found in GEOLEX. NBMG adheres to
the original term “Dolomite.” Please use the term “Dolomite” (with upper case “D”) instead of
“Dolostone” for formal unit names in NBMG publications.

Adam Peak Formation (NV*)
Agort Chert (NV)
Alamo Range Formation (NV)
Aldrich Station Formation of Wassuk Group (NV)
Alta Formation (NV*)
Alta Andesite (NV)
American Ravine Andesite Porphyry (NV*)
Ammonia Tanks Tuff of Timber Mountain Group (CA*,NV*)
Anchor Member of Monte Cristo Limestone (AZ*,CA*,NV*)
Anchor Member of Monte Cristo Dolomite (NV)
Andorno Formation of Auld Lang Syne Group (NV*)
Andrews Mountain Member of Campito Formation (CA*,NV*)
Antelope Range Formation (NV*)
Antelope Springs Formation of Pershing Ridge Group (NV)
Antelope Valley Limestone of Pogonip Group (CA*,NV*)
Antler Peak Limestone (NV*)
Arcturus Formation (NV*,UT*)
Arcturus Limestone (NV*,UT*)
Arcturus Group (NV,UT)
Arrow Canyon Formation (NV)
Arrow Canyon Limestone (NV)
Arrowhead Member of Monte Cristo Limestone (AZ*,CA*,NV*)
Arrowhead Limestone of Monte Cristo Group (NV)
Ashdown Tuff (NV*)
Augusta Mountain Formation of Star Peak Group (NV*)
Auld Lang Syne Group (NV*)
Aura Formation (NV)
Aysees Member of Antelope Valley Limestone of Pogonip Group (NV*)
Aztec Sandstone (AZ?,CA,NV*)
Aztec Quartzite (CA*) [Discrepancy concerning areal extent. See remarks under "Publication History".]
Aztec Granodiorite
Badger Valley Basalt (NV)
Bailey Creek Member of Schoonover Formation (NV)
Bailey Spring Limestone*
Bald Mountain Formation (NV*)
Bald Mountain Lake Beds Member of Esmeralda Formation (NV*)
Baldhills Tuff Member of Isom Formation (NV*?,UT*) [Discrepancy concerning areal extent. See remarks under "Publication History".]
Banbury Basalt of Idaho Group (ID*)
Banbury Formation of Idaho Group (ID*)
Banded Mountain Member of Bonanza King Formation (CA*, NV*)
Banner Formation (NV*,ID?)
Banner Limestone (NV,ID?) [Discrepancy concerning areal extent. See remarks under "Publication History".]
Barn Hills Member of Ely Springs Dolostone (NV,UT)
Bartine Member of McColley Canyon Formation (NV*)
Barton Canyon Member of Windfall Formation (NV)
Basco Formation (NV)
Baseline Sandstone (AZ*,NV*)
Bastille Limestone Member of Masket Shale (NV)
Bastille Limestone (NV)
Bates Mountain Tuff (NV*)
Battle Formation (NV*)
Battle Conglomerate (NV*)
Battleship Wash Formation (NV)
Battleship Wash Formation of Bird Spring Group (NV)
Bauers Tuff Member of Condor Canyon Formation of Quichapa Group (NV*,UT*)
Bauers Tuff Member Quichapa Formation (UT)
Bauers Tuff of Quichapa Group (UT)
Bay State Dolomite (NV*)
Beacon Flat Formation (NV)
Beacon Peak Dolomite (NV*)
Beatty Wash Formation (NV*)
Beaverdam Formation of Idavada Volcanics (ID,NV?)
Belleville Tuff (NV*)
Belmont Fanglomerate (NV)
Belted Range Group (NV*)
Benton Spring Group (NV*)
Bernice Formation (NV)
Bieroth Andesite (NV)
Bieroth volcanics [informal?] (ID) [Unclear if formal or informal. For informal usage, the rank or lithologic term should not be capitalized.]
Big Horse Limestone Member of Orr Formation (UT*)
Big Horse Limestone (UT*)-recognized locally in Crater Island, Box Elder Co. ? Big Horse Limestone of [?]Orr Group (NV*?,UT*)[Discrepancy concerning areal extent and usage. See remarks under "Publication History".]
Big Island Formation (ID*,NV*)
Big Pole Formation of Pony Trail Group (NV*)
Bird Spring Formation (AZ*,CA*,NV*,UT*)
Bird Spring Group (NV)
Bishop Tuff (CA*)
Bishop ash (informal) (CA*,CO*,ID*,NE*,NV*,NM*,UT*,WY*)
Bishop ash bed (informal) (CA*,CO*,ID*,NE*,NV*,NM*,UT*,WY*) For informal usage, the rank or lithologic term should not be capitalized.
Bitter Ridge Limestone Member of Horse Spring Formation (NV*)
Black Canyon Group
Black Dyke Formation (NV)
Blackrock Quartzite
Blind Spring Formation (NV)
Blue Sphinx Tuff (NV*)
Bluepoint Limestone (NV*)
Bluestone Mine Tuff (NV)
Bonanza King Dolomite (CA*,NV*)
Bonanza King Formation (AZ, CA*,NV*,UT)
Bonita Canyon Formation (NV)
Boulder Wash Group
Bouse Formation (AZ*,CA*,NV*)
Box Canyon Formation (NV)  [Name preempted by Box Canyon Member of Mutual Quartzite of Williams (1953) in UT.]
Boyer Ranch Formation (NV*)
Brady Canyon Member of Toroweap Formation (AZ*,NV*,UT*)
Bright Angel Shale (CA*,NV*,UT*)
Bright Angel Schist (CA*)
Bright Angel Shale of Tonto Group (AZ*)
Bristol Pass Limestone
Broad Canyon Formation (NV)
Brock Canyon Formation (NV*)
Brougher Rhyolite*
Brougher Dacite*
Buckskin Mountain Formation (NV)
Buffalo Canyon Formation (NV)
Buffington Formation (NV)
Bullfrog Tuff of Crater Flat Group (NV*)
Bullion Member of Monte Cristo Limestone (AZ*,NV)
Bullion Dolomite Member of Monte Cristo Limestone (CA*,NV*)
Bullion Limestone Member of Monte Cristo Limestone (CA)
Bullion Limestone of Monte Cristo Group (NV)
Bullwhacker Member of Windfall Formation (NV*)
Bunejug Formation (NV*)
Burnt Canyon Member of Highland Peak Formation (NV*)
Burnt Canyon Limestone (NV,UT?)
Burnt Canyon Formation (UT?)  [Discrepancy concerning areal extent. See remarks under "Publication History".]
Burrows Member of Highland Peak Formation (NV*)
Burrows Dolomite (NV)
Burrows Limestone (NV)
By-Day Member of Eureka Valley Tuff of Stanislaus Group (CA*,NV*)
Byers Canyon Formation (NV)
Cadiz Formation (CA*,NV*)
Caesar Canyon Limestone
Caetano Tuff (NV*)
Calico Hills Formation (NV*)
Calloway Well Formation (NV)
Callville Limestone (AZ*,NV*,UT*)
Camp Canyon Member of Chainman Formation (NV,UT)
Campito Formation (CA*,NV)*
Campito Sandstone (NV)
Candelaria Formation (CA,NV*)
Candelaria Junction Tuff (NV)
Candland Shale Member of Orr Formation (UT*)
Candland Formation (UT*-recognized locally in Crater Island, Box Elder Co.)
[?] Candland Formation of [?]Orr Group (NV*?,UT*) [Discrepancy concerning areal extent and usage. See remarks under "Publication History".]
Cane Spring Formation of Star Peak Group (NV*)
Cap Winn Member of Schoonover Formation (NV)
Carbon Ridge Formation (NV*,UT*)
Carbon Ridge Group (NV,UT)
Carlin Formation
Carlin Canyon Formation (NV)
Carrara Formation*
Carrico Lake Formation (NV)
Carson Desert Formation
Carson Sink Bed of  Mono Basin Formation (NV)  [Mono Basin Formation preempted by    Mono Basin Glaciation of Sharp and Birman (1963) in CA.]
†Carter Spring Member of Chainman Shale (NV) No current usage. Considered abandoned? Uncertain if still in use by the NV Geol. Survey. Not used by the USGS.)
[Discrepancy concerning status. See remarks under "Publication History".]
Catlin Member of Windfall Formation (NV*)
Cave Valley Formation
Cedar Canyon tuff [informal?] of Bieroth Volcanics (ID,NV)  [Not clear if unit was intended to be formal or informal.]
Celta Formation
Chainman Shale (CA*,NV*,UT*)
Chainman Formation (NV*)
Charcoal Canyon Formation of Clipper Canyon Group (NV)
Charcoal Ovens Tuff (NV*)
Chellis Formation
Chemehuevi Formation (AZ*,CA*,NV*)
Chicken Creek Formation (NV)  [Name preempted by Chicken Creek Tuff of Evernden and James (1964) in western UT.]
China Mountain Formation*
Chinle Formation of Dockum Group (CO*,NM*,TX)
Chinle Formation (AZ*,NM,NV*,UT*)
Chinle Group (NM,TX)
Chisholm Formation (NV,UT)
Chisholm Shale (NV*,UT*)
Chispa Andesite*
Chloropagus Formation
Circle Creek Rhyolite*
Civet Cat Canyon Member of Stonewall Flat Tuff (NV*)
Clan Alpine Volcanics (NV)
Clarks Spring Member* of Secret Spring Shale
Claron Formation (NV,UT*)
Claron Limestone (UT)
Clifside Limestone (NV*)
Clipper Canyon Group (NV)
Coal Valley Formation*
†Cockalorum Wash Formation -  No current usage (Rocks of †Cockalorum Wash Formation (NV) reallocated to Devils Gate Limestone, Pilot Shale, Woodruff Formation, Antelope Range Formation, and Webb Formation. See Devils Gate, Pilot, Woodruff, Antelope Range, and Webb.)
Coconino Sandstone (AZ*,CA*,NV*,UT*)
Coconino Quartzite (CA*)
Coils Creek Member* of McColley Canyon Formation
Combined Metals Member of Pioche Shale (NV*)
Combs Canyon*Dolomite Member* of Hanson Creek Formation
Comet Shale (NV)
Comus Formation (NV*)
Condor Member of Highland Peak Formation (NV*)
Condor Member* of Swasey Limestone (NV,UT)
Condor Formation (NV,UT)
Condor Canyon Formation of Quichapa Group (NV*,UT*)
Congress Canyon Formation of Star Peak Group (NV*)
Copenhagen Formation*
†Cornfield Springs Formation No current usage (CA,NV) is synonym of Nopah Formation. See Nopah.
Corset Spring Shale Member of Orr Formation (UT*)
Corset Spring Shale (NV*,UT*)
[?] Corset Spring Shale of [?]Orr Group (NV*,UT*) [Discrepancy concerning usage. See remarks under "Publication History".]
Cottonwood Wash Tuff of Needles Range Group (NV*, UT*)
Cottonwood Wash Tuff Member of Needles Range Formation (NV*,UT)
Cougar Point Welded Tuff (ID*,NV*)
Cougar Point Formation of Idavada Volcanics (ID,NV)
Cove Mountain Formation (NV,UT)
Coyote Holes Formation
Crater Flat Group (NV*)
Crone Gulch Andesite*
Crosby Formation
Crystal Pass Member* of Sultan Limestone
Currant Tuff*
Dale Canyon Formation (NV*)
Danger Point Tuff (NV*)
Darrough Felsite (NV*)
Davidson Granodiorite*
Davidson Diorite
Davis Spring Formation*
Dawn Member of Monte Cristo Limestone (AZ*,CA,NV*)
Dawn Limestone of Monte Cristo Group (NV-recognized locally in Arrow Canyon Range and Muddy Mountains)
[?] Dawn Dolomite Member of Redwall Limestone (UT)
Dead Horse Tuff*
Dead Horse Flat Formation of Belted Range Group (NV*)
Decathon Member of Laketown Dolostone (NV,UT)
Decoy Limestone (NV*)
Deep Spring Formation (CA*,NV*)
Deer Park Andesite
Delamar Lake Tuff*
Delle Phosphatic Member of Woodman Formation (NV*,UT*-notably in Deep Creek and South Lakeside Mountains)
Delle Phosphatic Member of Chainman Shale (NV*,UT*-notably in Needle Range)
Delle Phosphatic Member of Deseret Limestone (NV*,UT*-notably in Oquirrh Mountains)
Delle Phosphatic Member of Deep Creek Formation (ID*-notably in Deep Creek Mountains)
Delle Phosphatic Member of Little Flat Formation (UT*,ID*-notably in Chesterfield Range)
Delle Phosphatic Member of Aspen Range Formation (UT*,WY*,ID*-notably in Aspen Range)
Delle Phosphatic Member of Brazer Dolomite (WY*,UT*-notably in Crawford Mountains)
Denay Limestone (NV*)
Desert Peak Formation (NV)
Desert Range Limestone Member of Carrara Formation (CA*,NV*)
Desert Valley Formation
Devils Gate Limestone*
Diablo Formation (CA?,NV*) [Name preempted by Diablo Formation of Axelrod (1944) in CA.] [Discrepancy concerning areal extent. See remarks under "Publication History".]
Diamond A Formation (NV)
Diamond King Formation (NV*)
Diamond Peak Formation (CA,NV*,UT*)
Diana Limestone (NV)
Dibekulewe Bed (NV)
Dinosaur Canyon Member of Moenave Formation (AZ*,NV*,UT*)
Dinosaur Canyon Sandstone Member of Moenave Formation (AZ*,UT*)
Divide Andesite (NV*)
Dixie Valley Formation of Star Peak Group (NV*)
Dixie Valley Formation (NV*)
Dodge Spring member (informal) of Claron Formation (NV,UT)
Informal. The rank or lithologic term should not be capitalized.
Dome Limestone (NV,UT*)
Dome Formation (NV,UT)
Donner Member of Chainman Formation (NV,UT)
Dorsey Creek Member of Schoonover Formation (NV)
Double Spring Formation
Dry Lake Member of Thirsty Canyon Tuff (NV*)
Duffer Peak Granodiorite*
Dun Glen Formation of Auld Lang Syne Group (NV*)
Dunderberg Shale Member of Nopah Formation (CA*,NV*)
Dunderberg Shale* (NV,UT)
Dunderberg Formation* (NV)
Dunlap Formation*
Dyer Canyon Formation
Eagle Mountain Shale Member of Carrara Formation (CA*,NV*)
Eagles House Rhyolite (NV*)
Eastgate Volcanics (NV)
Echo Shale Member* of Carrara Formation [Name preempted by Echo Granite of Miller (1930, 1933, 1934) in CA.]
Edgemont Formation
Edna Mountain Formation (NV*)
Edwards Creek Tuff (NV*)
Eetza Alloformation (NV)
Eetza Formation of Lahontan Valley Group (NV*)
Elder Sandstone (NV*)
Eleana Formation (NV*)
Elko Formation (NV*)
Elko Prince Rhyolite (NV)
Ely Limestone (NV*,UT*)
Ely Group (NV)
Ely Springs Dolostone (CA*,ID*,NV*,UT*)
Ely Springs Dolomite (CA*,NV*,UT*)
Ely Springs Limestone (CA*)
Emigrant Formation (CA*,NV*)
Emigrant Pass Member of Zabriskie Quartzite (CA*,NV*?) [Discrepancy in areal extent. See remarks under "Publication History".]
Emigrant Springs Limestone (NV)
Escalante Desert Formation of Needles Range Group (UT*)
Esmeralda Formation*
Espina Breccia (NV*)
Etchart Limestone (NV*)
Eureka Quartzite (CA*,ID*,NV*,UT*)
Eureka Quartzite of Pogonip Group (CA)
Eureka Group (CA)
Eureka Canyon Tuff (NV*)
Eureka Valley Tuff* of Stanislaus Group
Eureka Valley Member of Stanislaus Formation
Evening Star Formation
Excelsior Formation (NV)
Extension Breccia (NV*)
Fallon Formation (NV*)
Fallon Alloformation (NV)
Farrel Canyon Formation (NV*)
Favret Formation (NV*)
Favret Formation of Star Peak Group (NV*)
Fenstermaker Wash Formation (NV*)
Ferguson Hill Member of Sunrise Formation of Volcano Peak Group (NV)
Ferguson Mountain Formation (NV,UT)
[?] Ferguson Mountain Formation of Arcturus Group (NV,UT) [Uncertain if Ferguson Mountain Formation of Arcturus Group is used by the NV and UT Geol. Surveys. Not used by the USGS.]
†Ferguson Springs Formation (NV,UT) No current usage.Replaced with Ferguson Mountain Formation. See Ferguson Mountain.)
Fillmore Limestone of Pogonip Group (NV,UT)
Fillmore Formation of Pogonip Group (UT*)
Fish Creek Mountains Tuff (NV*)
Fish Haven Dolostone (ID*,NV*,UT*)
Five Card Draw Member of Sunrise Formation of Volcano Peak Group (NV)
Floride Member of Ely Springs Dolomite (NV, UT*)
Forest Home Ignimbrite (NV)
Fortification Basalt Member of Muddy Creek Formation (AZ*,NV*)
Fossil Hill Member of Favret Formation of Star Peak Group (NV*-recognized locally in southern Tobin Range and Augusta Mountain)
Fossil Hill Member of Prida Formation of Star Peak Group (NV*-recognized locally in Humboldt Range and northern East Range)
Fossil Hill Formation of Star Peak Group (NV*-recognized locally in China Mountain and southern Augusta Mountain)
Fossil Mountain Member of Kaibab Formation (AZ*,NV*,UT)
Fourmile Canyon Formation (NV*)
Fraction Tuff (NV*)
Fraction Breccia (NV*)
Frenchie Creek Rhyolite of Pony Trail Group (NV*)
Frenchie Creek Quadrangle Volcanics (NV)
Frost Creek Member of Schoonover Formation (NV)
Fry Creek Member of Schoonover Formation (NV)
Gabbs Formation (NV*)
Gabbs Formation of Volcano Peak Group (NV)
Gale Hills Formation (NV)
Garden Valley Formation (NV*)
Gardnerville Formation (NV)
Garrett Ranch Group (NV)
Gatecliff Formation (NV)
Geddes Limestone (NV*)
Gerster Formation (UT*)
Gerster Formation of Park City Group (NV*,UT*)
Gerster Limestone of Park City Group (NV*,UT*)
Gettel Member of Laketown Dolostone (NV,UT)
Ghost Dance Lava Member of Hu-pwi Rhyodacite (NV*)
Gilbert Andesite (NV*)
Gillis Formation
Gilmore Gulch Formation (NV*)
Glen Canyon Group (AZ*,CO*,NV*,NM*,UT*)
Glen Canyon Sandstone (CO*,UT*)
Gods Pocket Dacite*
Gold Ace Limestone Member of Carrara Formation (CA*?,NV*)
Gold Bug Formation (NV)
Gold Butte Granite (AZ,NV)
Gold Flat Tuff of Thirsty Canyon Group (NV*)
Gold Hill Formation*
Gold Range Formation (NV)
†Golden Door Volcanics (AZ,NV) No current usage.  Replaced with informal "tuff of Bridge Spring."
Goodsprings Dolomite (CA*,NV*)
Goodwin Limestone of Pogonip Group (NV*)
Goodwin Formation of Mount Hamilton Group (NV)
Goshute Limestone (NV*,UT*)
Goughs Canyon Formation (NV*)
Grantsville Formation (NV*)
Grapevine Spring Member* of Kane Wash Tuff
Grass Valley Formation of Auld Lange Syne Group (NV*)
†Grays Canyon Limestone Member of Nevada Formation (NV) No current usage. Synonym of McColley Canyon Formation. See McColley Canyon.
Greens Canyon Tuff Member of Ryan Spring Formation of Needles Range Group (NV*,UT*)
Gregerson Basin Member* of Kane Wash Tuff
Grossman Formation (NV*)
Grouse Canyon Tuff of Belted Range Group (NV*)
Guild Mine Member of Mickey Pass Tuff of Benton Spring Group (NV*)
Guilmette Formation (NV*,UT*)
Guilmette Limestone (NV*)
Hales Limestone (NV*)
Halfpint Member* of Nopah Formation
Hamilton Canyon Formation (NV)
Hammond Canyon Formation (NV)
Hanauer Formation (NV,UT*)
Hanson Creek Formation (ID*,NV*)
Happy Camp Formation (NV)
Happy Creek Volcanic Complex (NV*)
Happy Creek Igneous Complex (NV)
Harkless Formation (CA*,NV*)
Harmony Formation (NV*)
Harmony Hills Tuff of Quichapa Group (NV*,UT*)
Harmony Hills Tuff Member of Quichapa Formation (UT)
Harrington Creek Member of Schoonover Formation (NV)
Harrisburg Member of Kaibab Formation (AZ*,NV*,UT*)
†Hartford Hill Rhyolite Tuff (NV) No current usage. Replaced with (in ascending order) Mickey Pass Tuff, Lenihan Canyon Tuff, Nine Hill Tuff, Eureka Canyon Tuff, and Santiago Canyon Tuff. See Eureka Canyon, Lenihan Canyon, Mickey Pass, Nine Hill, and Santiago Canyon.)
Havallah Formation (NV*)
Hay Ranch Formation*
Hayden Canyon Formation (NV)
Hayes Canyon Member of Devils Gate Limestone (NV*)
†Hedwig Breccia Member of Esmeralda Formation or †Hedwig Breccia (NV) No current usage. Renamed "megabreccia unit of Sloppy Gulch" and assigned to lower member of Round Rock Formation. See Round Rock.).
†Heller Dacite or Rocks of †Heller Tuff (NV) No current usage. Reallocated to part of Fraction Tuff. See Fraction.
Hells Bells Canyon Formation
Hermit Formation (AZ*,NV*,UT*)
Hermit Schist (CA*)
High Lake Member of Laketown Dolostone (NV,UT)
Highland Peak Limestone (NV*)
Highland Peak Formation (NV*,UT)
Highway Limestone (NV*)
Hiko Tuff (NV*,UT)
Hiko Tuff Member of Page Ranch Formation (NV,UT)
Hogan Formation (UT)
Hogan Formation of Ely Group (NV)
Hole-in-the-Wall Tuff Member of Isom Formation (NV*,UT*)
Hole-in-the-Wall Tuff Member of Leach Canyon Formation (UT)
Hollywood Formation of Pershing Ridge Group (NV)
Home Station Member of Augusta Mountain Formation of Star Peak Group (NV*)

Horse Camp Formation (NV)
Horse Spring Formation*
Hoyt Canyon Formation (NV)
Hu-pwi Rhyodacite (NV*)
Hualapai Limestone (AZ*,CA*?,NV*)
Hualapai Limestone Member of Muddy Creek Formation (AZ) [Formerly called Hualpai Limestone.] [Discrepancy concerning areal extent. See remarks under "Publication History".]
Huckleberry Ridge Tuff of Yellowstone Group (ID*,MT*,WY*)
Huckleberry Ridge Tuff (AZ*,CA*,ID*,KS*,IA*,MT*,NE*,NV*,TX*,UT*,WY*)
Humboldt Formation (NV*)
Ibex Member of Ely Springs Dolostone (NV,UT)
Idaho Canyon Tuff (NV*,OR*)
Idavada Volcanics (ID*,NV*)
Idavada Group (ID)
Illipah Formation (NV)
Indian Canyon Formation of Park City Group (NV,UT)
Indian Lakes Alloformation (CA)
Indian Lakes Formation of Lahontan Valley Group (CA*)
Indian Ranch Tongue of Guilmette Formation (NV*)
Indian Springs Formation (NV*)
†Indian Trail Formation - No current usage. Replaced with Belted Range Tuff. See Belted Range.
Indian Well Formation (NV*)
Inskip Formation (NV*)
Irontown Member of Page Ranch Formation (NV,UT)
Isom Formation (NV*,UT*)
Isom Formation of Needles Group (UT*)
Italian Springs Formation (NV)
Jack Valley Member of Laketown Dolostone (NV,UT)
Jacks Peak Formation of Valmy Group (NV)
Jangle Limestone Member* of Carrara Formation
Jarbidge Rhyolite*
Jenkins Peak Formation (NV)
Jenny Creek Tuff (ID,NV*)
Jenny Creek Formation of Idavada Volcanics (ID,NV)
Jensen Member of Chainman Shale (NV,UT)
Joana Limestone (NV*,UT*)
Joana Limestone of White Pine Group (NV)
Joes Canyon Formation of Clipper Canyon Group (NV)
Johnnie Formation (CA*,NV*)
Johns Wash Limestone Member of Orr Formation (NV*,UT*)
Johns Wash Limestone (NV*,UT*)
[?] Johns Wash Limestone of [?]Orr Group (NV*,UT*)  [Discrepancy concerning usage. See remarks under "Publication History".]
Joker Peak Member of Sunrise Formation of Volcano Peak Group (NV)
Jory Member of Havallah Formation (NV*)
Juab Limestone of Pogonip Group (NV,UT*)
June Bell Rhyolite (NV)
Kaibab Limestone (AZ*,NV*,UT*)
Kaibab Limestone of Park City Group (NV*,UT*)
Kaibab Formation (AZ*,NV*,UT)
Kaibab Marble (CA*)
Kaibab Group (UT)
Kalamazoo Volcanics (NV)
Kane Wash Tuff (NV*,UT*)
Kane Wash Formation (NV,UT)
Kanosh Shale of Pogonip Group (NV*,UT*)
Kanosh Formation (NV,UT)
Kate Peak Formation (NV*)
Kayenta Formation of Glen Canyon Group (AZ*,CO*,UT*)
Kayenta Formation (NV*)
Killian Springs Formation (NV*,UT*)
King Lear Formation*
King Tonopah Member of Fraction Tuff (NV)
Kinkead Spring Limestone (NV*)
Kinsey Canyon Formation (NV)
Knickerbocker Andesite (NV*)
Kobeh Member* of McColley Canyon Formation
Koipato Formation (NV*)
Koipato Group (NV*)
†Labyrinth Canyon Member of Thirsty Canyon Tuff (NV) No current usage. Replaced with Spearhead Member of Stonewall Flat Tuff. See Spearhead.
Lahontan Valley Group (NV*)
Lake Newark Formation (NV)
Lamb Dolomite (NV*,UT*)
Lampson Formation (NV)
Las Vegas Formation (NV*)
Lava Creek Tuff of Yellowstone Group (ID*,MT*,WY*)
Lava Creek Tuff (CO)
Lava Creek ash (informal) (CA*,CO*,ID*,IA*,KS*,MT*,NE*,NV*,NM*,OK*,SD*,TX*,UT*,WY*)
For informal usage, the rank or lithologic term should not be capitalized.
Leach Formation (NV)
Leach Canyon Formation of Quichapa Group (NV*,UT*)
Leach Canyon Tuff of Quichapa Group (UT)
Lehman Formation of Pogonip Group (NV,UT)
Lehman Limestone of Pogonip Group (NV*,UT*)
Lenihan Canyon Tuff (NV*)
? Leter Ranch Bed of Pyramid Lake Member of Mount Mazama Formation (NV) [Discrepancy concerning the validity of this unit. See remarks under "Publication history".]
Limerick Greenstone of Koipato Group (NV*)
Lincoln Peak Formation (NV*)
Lion Spring Limestone (NV*)
Lithic Ridge Tuff*
Little Meadow Formation (NV)
Lone Mountain Dolomite (NV*)
Lone Mountain Formation (NV,UT)
Loray Formation of Arcturus Group (NV,UT)
Lori Formation of Pershing Ridge Group
Lost Canyon Member of Ely Springs Dolostone (NV,UT)
Lousetown Formation (CA,NV*)
Lovell Wash Member of Horse Spring Formation (NV*)
Lovelock Alloformation
Lovelock Formation
Lund Formation of Needles Range Group (NV*,UT*)
Lund Tuff of Needles Range Group (UT)
Lund Tuff Member of Needles Range Formation (NV,UT)
Luning Formation (NV*)
Lyndon Limestone (AZ,CA,NV*,UT)
Mackleprang Tuff Member of Ryan Spring Formation of Needles Range Group (NV*,UT*)
Magpie Hill Basalt (NV*)
Malpais Basalt (NV*)
Marble Bluff Bed
†Maris Rhyolite (NV) No current usage. Synonym of Oddie Rhyolite. See Oddie.
Masket Shale
Mayflower Schist*
Mazama Member of Mount Mazama Formation (CA,NV)
[An identical geographic name may not be applied to a unit and its parts (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983).]
McAfee Adamellite (Also see McAfee Creek Granite of Hanson and others, 1987)
McAfee Creek Granite (Also see McAfee Adamellite of Emerson, 1966)
McClellan Peak Olivine Basalt (NV*)
McColley Canyon Formation*
McCoy Creek Group (NV,UT)
McCullough Formation (NV*)
McGee Till (CA*,NV*)
McGinty Monzogranite (NV*,UT*)
McMonnigal Limestone (NV*)
Meade Peak Member of Phosphoria Formation (ID*,MT*,NV*,UT*,WY*)
Meade Peak Tongue of Phosphoria Formation (ID*,NV*,UT*)
Meadow Fork Formation*
Meadow Valley Member of Highland Peak Formation (NV*)
Meda Rhyolite (NV*)
Mehrten Formation (CA*,NV)
Meister Member of Devils Gate Limestone (NV*)
Mendha Formation (NV*)
Mercury Limestone (NV*)
Mesa Basalt (NV,OR)
Metallic City Tuff
Mexican Dam Bed (NV-recognized locally in Mexican Dam area, Lyon Co.)
Mickey Pass Tuff of Benton Spring Group (NV*)
Middlegate Formation (NV)
Midnight Quartzite (NV)
Mikes Creek Member of Schoonover Formation (NV)
Mill Canyon Member of Havallah Formation (NV*)
Milltown Andesite (NV*)
Mina Formation (NV)
Mina Peak Member of Sunrise Formation of Volcano Peak Group (NV)
Miners Spring Granite (NV*,UT*)
Mira Basalt (NV*)
Mission Spring Formation (NV)
Mitchell Creek Formation*
Mizpah Trachyte (NV*)
Moapa Formation (NV)
Moenave Formation of Glen Canyon Group (AZ*,NV*,UT*)
Moenkopi Formation (AZ*,CA*,CO*,NM*,NV*,UT*)
Moenkopi Group (AZ)
Moleen Formation (NV*)
Moleen Formation of Ely Group (NV)
Moleen Member of Ely Limestone (NV)
Monarch Mill Formation (NV)
Mono Basin Formation (CA,NV) [Name preempted by Mono Basin Glaciation of Sharp and Birman (1963) in CA.]
Monocline Valley Formation
Monotony Tuff (NV*)
Monte Cristo Limestone (AZ*,CA*,NV*,UT*)
Monte Cristo Dolomite (NV*)
Monte Cristo Group (NV)
Monte Neva Formation (NV)
Montenegro Member of Campito Formation (CA*,NV*)
Moonshine Creek Latite (NV*)
Moorman Ranch Member of Pequop Formation of Arcturus Group (NV,UT)
Moorman Ranch Formation (NV,UT)
Morgan Pass Formation (NV*)
Morgan Ranch Formation of Wassuk Group (NV)
Mount Davis Volcanics*
Mount Hamilton Group (NV)
Mount Hyatt Member of Gabbs Formation of Volcano Peak Group (NV)
Mount Kate Volcanics (NV)
Mount Mazama Formation (CA,NV,OR)
Mount Mazama Pumice (OR,WA)
Mount St. Helens Lava (WA)
Mount St. Helens Formation (NV,WA)
Mountain City Formation (NV*)
Mountain Springs Formation (CA?,NV)
Muav Limestone of Tonto Group (AZ*)
Muav Limestone (NV*,UT*)
Muav Marble (CA*)
Muav Dolostone (AZ*)
Mud Springs Canyon Formation
Muddy Creek Formation (AZ*,CA*,NV*,UT*)
Muddy Peak Limestone*
Mule Spring Limestone (CA*,NV*)
Mule Spring Formation (CA,NV)
Mullen Formation (NV)
Muller Canyon Member of Gabbs Formation of Volcano Peak Group (NV)
Mulligan Canyon Rhyolite*
Mullinix Formation of Auld Lang Syne Group (NV*)
Murdock Mountain Formation of Park City Group (NV*,UT*)
Murdock Mountain Formation (UT*)
Mustang Andesite (NV*)
Muttlebury Formation (NV)
Narrow Canyon Limestone (NV*)
Narrows Tuff Member of Leach Canyon Formation of Quichapa Group (NV*,UT*)
Narrows Member of Leach Canyon Tuff (UT)
Natchez Pass Formation of Star Peak Group (NV*)
Needle Siltstone Member of Chainman Shale (NV*,UT*)
Needle Siltstone Member of Woodman Formation (NV*,UT*)
Needles Range Group (NV*,UT*)
Needles Range Formation (NV,UT)
Nelson Formation (NV*)
Nenzel Rhyolite Breccia (NV*)
†Nevada Formation (NV*) or †Nevada Group (NV) No current usage. Abandoned.
New Pass Tuff (NV*)
New York Canyon Member of Sunrise Formation of Volcano Peak Group (NV)
New York Peak Quartz Monzonite*
Newark Canyon Formation (NV*)
Nine Hill Tuff (NV*)
Ninemile Formation of Pogonip Group (NV*)
Noh Formation
Noonday Dolomite (CA*,NV*)
Nopah Formation*
Nopah Dolomite*
Northumberland Tuff (NV*)
Notch Peak Formation (NV*,UT*)
[?] C Tuff Member of Hu-pwi Rhyodacite (NV*)
Nun Mine Member of Gabbs Formation of Volcano Peak Group (NV)
O'Neill Formation of Auld Lang Syne Group (NV*)
†Oak Spring Group - No current usage. Reallocated to numerous geologic units. See Orkild (1965).
Oasis Formation (NV*)
Oddie Rhyolite (NV*)
†Ogden Quartzite (NV*,UT*) No current usage. Abandoned.
Ola Sandstone (NV*,UT*)
Old Gregory Formation (NV)
Ophir Formation (AZ*,CO*,NV*,NM*,UT*)
Ophir Shale (UT*)
Oreana Peak Formation (NV)
Oreanna Bed (NV)
Orr Formation (UT*)
[?] Orr Group (NV*,UT*)  [Discrepancy concerning usage. See remarks under "Publication History".]
Osceola Argillite of McCoy Creek Group (NV,UT)
Osgood Mountain Quartzite (NV*)
Osobb Formation of Auld Lang Syne Group(NV*)
Ott Creek Member of Schoonover Formation
Ottawanah Rhyolite (NV*)*
Overton Conglomerate Member of Baseline Sandstone (NV*)
Ox Valley Tuff (NV*,UT*)
Oxyoke Canyon Sandstone (NV*)
Oxyoke Canyon Formation (NV)
Pablo Formation (NV*)
Packard Wash Formation of Pershing Ridge Group
Page Ranch Formation (NV,UT*)
Pah Canyon Tuff of Paintbrush Group (NV*)
Pah Rah Formation
Pahranagat Formation*
Pahrump Hills Shale Member* of Carrara Formation
Pahute Mesa Tuff of Thirsty Canyon Group (NV*)
Paintbrush Group (CA*,NV*)
Paiute Alloformation (NV)
Paiute Formation (NV*)
Paiute Ridge Member* of Antelope Valley Limestone
Pakoon Dolomite (UT*)
Pakoon Limestone (AZ*,NV*,UT)
Pakoon Limestone of Supai Group (AZ)
Palisade Canyon Rhyolite (NV*)
Pamlico Formation (NV)
Panaca Formation*
Pancake Summit Tuff (NV*)
Pansy Lee Conglomerate (NV*)
Panther Canyon Member of Augusta Mountains Formation of Star Peak Group (NV*)
Papoose Lake Member of Bonanza King Formation*
Paradise Valley Chert (NV*)
Paris Peak Member of Fish Haven Dolostone (ID,NV,UT)
Park City Formation (CO*,ID*,MT*UT*,WY*)
Park City Group (NV*,UT*)
Parker Spring Formation of Pogonip Group (NV)
Patsy Mine Volcanics*
Patterson Pass Shale (NV)
Peach Spring Tuff (AZ*,CA*,NV*)
†Peach Springs Tuff (AZ,CA,NV) No current usage. Renamed Peach Spring Tuff. See Peach Spring -note singular form.
Peasley Member of Highland Peak Formation (NV*)
Peasley Limestone (AZ,NV,UT*)
Peers Spring Formation (NV*)
? Pelican Island Bed of Pyramid Lake Member of Mount Mazama Formation (NV)
Pequop Formation of Arcturus Group (NV,UT)
Pequop Formation of Carbon Ridge Group (NV,UT)
Perish Spring Dacite (NV)
Perkins Canyon Formation (NV)
Pershing Ridge Group (NV)
Petes Summit Formation of Clipper Canyon Group
Petrified Forest Member of Chinle Formation (AZ*,CO*,NM*,NV*,UT*)
Petrified Spring Tuff of Benton Spring Group (NV*)
Petroglyph Cliff Ignimbrite (NV)
Phosphoria Formation (ID*,MT*,NV*,UT*,WY*)
Piapi Canyon Formation (NV*)
†? Piapi Canyon Group (NV*)
Piermont Formation (NV)
Pilot Shale (NV*,UT*)
Pine Nut Limestone Member of Gold Hill Formation (NV*)
Pinecone Formation (NV)
Pinto Basin Tuff Member of Pinto Peak Rhyolite (NV*)
Pinto Peak Rhyolite (NV*)
Pioche Formation (NV*,UT*)
Pioche Shale (CA*,NV*,UT*)
Piute Formation (NV)
Plympton Formation of Park City Group (NV*,UT*)
Pogonip Group (CA*,ID*,NV*,UT*)
Pogonip Formation of Mount Hamilton Group (NV)
Pogonip Limestone (NV)
Poinsettia Tuff Member of Hu-pwi Rhyodacite (NV*)
Pole Canyon Limestone*
Pole Creek Dacite*
Poleta Formation (CA*,NV*)
Pony Trail Group*
Poorman Peak Formation (NV)
Popovich Formation (NV*)
Portage Canyon Member of Laketown Dolostone (NV,UT)
Porter Peak Limestone
Preachers Formation (NV)
Preble Formation (NV*)
Prida Formation of Star Peak Group (NV*)
Proskey Formation (NV)
Prospect Mountain Quartzite (CA*,NV*,UT*)
Prow Pass Member* of Crater Flat Tuff
Prow Pass Tuff* of Crater Flat Group
Pumpernickel Formation (NV*)
Pyramid Formation (NV)
Pyramid Shale Member* of Carrara Formation
Pyramid Lake Member of Mount Mazama Formation (CA,NV)
Queantoweap Sandstone*
Quichapa Group NV*,UT*)
Quichapa Formation (UT)
Quilici Formation (NV)
Quinn River Formation (NV*)
Rabbit Hill Limestone (NV*)
Rabbit Spring Formation (NV*)
Raiff Limestone (NV)
Railroad Bridge Basalt (NV)
Railroad Valley Rhyolite (NV)
Rainbow Gardens Member of Horse Spring Formation (AZ*,NV*)
Raine Ranch Formation (NV)
Rainier Mesa Tuff of Timber Mountain Group (CA*,NV*)
Rainstorm Member of Johnnie Formation (CA*,NV*)
Ranger Mountains Member* of Antelope Valley Limestone
Raspberry Formation of Auld Lang Syne Group (NV*)
Rattlesnake Spring Granodiorite (NV*)
Ratto Spring Rhyodacite (NV*)
Rawhide Formation (NV)
Red Pass Limestone Member* of Carrara Formation
Redrock Valley Tuff*
Reed Dolomite (CA,NV)
Rescue Canyon Rhyolite
Reservation Hill Formation (NV*)
Resting Spring Formation (CA,NV)
Retort Tongue of Phosphoria Formation (ID*,MT*,UT*WY*)
Retort Phosphatic Shale Member of Phosphoria Formation (ID*,MT*,NV*,UT*,WY*)
[Use of simple lithic terms is preferred (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983).]
Rib Hill Formation (NV*)
Rib Hill Sandstone (NV*)
Richmond Mountain Andesite (NV*)
Riepe Spring Limestone of Arcturus Group (NV,UT)
Riepe Spring Limestone of Carbon Ridge Group (UT)
Riepetown Sandstone of Arcuturus Group (NV,UT)
Riepetown Sandstone of Carbon Ridge Group (NV,UT)
Rio Tinto Formation (NV)
Ripgut Formation of Needles Range Group (NV*,UT*)
Roberts Mountains Formation*
Robinson Creek Tuff*
Rock Canyon Conglomerate Member of Moenkopi Formation (AZ*,NV*,UT*)
Rocket Wash Tuff* of Thirsty Canyon Group
Rocky Canyon Granite (NV)
Rogers Spring Limestone*
Round Rock Formation*
†Ruth Limestone (NV) No current usage. Considered abandoned? Uncertain if still in use by the NBMG. Abandoned by the USGS.)
Ryan Spring Formation of Needles Range Group (NV,UT*)
Rye Patch Alloformation
S Bar S Formation of Lahontan Valley Group (NV)
Saddle Mountain Andesite (NV)  [Not proposed in accordance with ACSN (1961). Name preempted by Saddle Mountain porphyry of Bain (1900) in OK, Saddle Mountain Lava of Williams (1932) in CA, Saddle Mountain Diorite of Dott (1965) in OR, and is too similar to Saddle Mountains Basalt of Mackin (1961) in WA.]
Sadler Ranch Formation
Safford Canyon Formation (NV)
Salt Wells Member of /Mono Basin Formation (NV)  [Name preempted by Mono Basin Glaciation of Sharp and Birman (1963) in CA.]
Salyer Formation*
Sams Spring Formation of Clipper Canyon Group
Sandgrass Andesite (NV*)
Sandstorm Formation (NV*)
Santiago Canyon Tuff (NV*)
Schoonover Formation
Scossa Slate (NV)
Scott Canyon Formation (NV*)
Scotty Wash Quartzite (NV*-recognized locally in Lincoln Co.)
Scotty Wash Sandstone (NV*-recognized locally in southern Egan Range)
Scotty Wash Formation (NV-recognized locally in Pahranagat Range)
Scotty Wash Quartzite Member of Chainman Formation (NV-recognized locally in southeastern NV)
Secret Canyon Shale (NV*)
Sehoo Alloformation (NV)
Sehoo Formation (NV)
Sehoo Formation of Lahontan Valley Group (NV*)
Sentinel Mountain Dolomite*
Seventy Six Basalt*
Sevy Dolomite (NV*,UT*)
Sevy Dolostone (NV*,UT*)
Shafter Formation (NV*)
Sheep Pass Formation (NV*)
Sheep Spring Rhyolite (NV*)
Sherwin Till (CA*,NV)
Sherwin Drift (CA*)
Shinarump Member of Chinle Formation (AZ*,NM*,NV*,UT*)
Shinarump Conglomerate (AZ,NV)
Shingle Limestone of Pogonip Group (NV)
Shingle Creek Quartzite of McCoy Creek Group (NV,UT)
Shingle Creek Quartzite (NV*,UT*)
Shingle Pass Tuff*
Shnabkaib Member of Moenkopi Formation (AZ*,NV*,UT*)
Shwin Formation (NV*)
Sidehill Spring Formation (NV)
Siebert Tuff (NV*)
Sierra Springs Tuff Member of Pinto Peak Rhyolite (NV*)
Silver King Dolomite Member of Bonanza King Formation (CA,NV)
Silverhorn Dolomite (NV*)
Simon Quartz Keratophyre (NV*)
Simonson Dolostone (NV*,UT*)
Singas Formation of Auld Lang Syne Group (NV*)
Singatse Tuff of Benton Spring Group (NV*)
Skinner Canyon Granite
Skunk Spring Limestone Bed of Chainman Shale (UT*)
Slaven Chert (NV*)
Slide Creek Gravel (NV*) [Name preempted by Slide Creek Member of Strawberry Volcanics of Thayer (1957) in OR.]
Smelser Pass Member of Augusta Mountain Formation of Star Peak Group (NV*)
Smoky Member of Nopah Formation (CA,NV*)
Snow Canyon Formation (NV)
Snow Canyon Formation of Valmy Group (NV)
Sod House Tuff* of Pony Trail Group
Soda Lake Bed of Carson Desert Formation (NV) [Name preempted by Soda Lake Formation of Dibblee (1952) in CA.]
Soldier Meadow Tuff*
South Hill Sandstone*
South Ridge Sandstone
South Willow Formation
Spearhead Member of Stonewall Flat Tuff (NV*)
Spillway Breccia (AZ,NV)
Spring Mountain Formation (NV)
Springdale Sandstone Member of Moenave Formation of Glen Canyon Group (AZ*,NV*,UT*)
Springdale Sandstone (NV)
Stanislaus Group*
Star Peak Group (NV*)
Steamboat Hills Rhyolite (NV*)
Steens Basalt (NV*,OR*)
Stella Lake Quartzite of McCoy Creek Group (NV,UT?) [Discrepancy concerning areal extent. See remarks under "Publication History".]
Step Ridge Member of Highland Peak Formation (NV*)
Stinking Spring Conglomerate (NV)
Stirling Quartzite (CA*,NV*)
Stockade Wash Tuff (NV*)
Stone Cabin Formation*
Stoneberger Shale of Pogonip Group (NV)
Stonewall Flat Tuff*
Storff Formation
Strathearn Formation (NV*,UT*)
Strawberry Creek Formation of McCoy Creek Group
Sultan Limestone (CA*,NV*,UT*)
Summit Lake Tuff*
Summit Springs Member of Pequop Formation of Arcturus Group (NV,UT)
Sunflower Formation (NV)
Sunflower Mountain Tuff*
Sunrise Formation (NV*)
Sunrise Formation of Volcano Peak Group (NV)
Supai Group (AZ*)
Supai Formation (AZ*,CA*,NM*,NV*,UT*)
†Survey Butte Member of Piapi Canyon Formation of Oak Spring Group (NV) No current usage. Replaced with bedded tuff in Paintbrush Tuff. See Paintbrush.
Susan Duster Limestone Member of Pioche Shale (NV*)
Sutro Member* of Alta Formation
Swarbrick Formation (NV*)
Swasey Limestone (NV,UT*)
Swett Tuff Member of Condor Canyon Formation of Quichapa Group (NV*,UT*)
Swett Tuff Member of Quichapa Formation (UT)
Swett Ingimbrite Member of Condor Canyon Formation (NV)
Table Butte Tuff Member of Leach Canyon Formation of Quichapa Group (NV*,UT*)
Table Mountain Latite of Stanislaus Group (CA*,NV*?)
Table Mountain Latite Member of Stanislaus Formation (CA)
[?] Table Mountain Latite (CA) [Discrepancy concerning areal extent and usage. See remarks under "Publication History".]
Tahoe Drift (CA*)
Tahoe Till (CA*,NV*)
Tallman Fanglomerate (NV*)
Tank Hill Limestone (NV*)
Tank Hill Limestone of Pogonip Group (NV)
Tapeats Sandstone of Tonto Group (AZ*)
Tapeats Sandstone (NV*,UT*)
Tapeats Quartzite (CA*)
Taylor Canyon Formation (NV)
Tecopa Shale (CA,NV)
†Telegraph Canyon Formation (NV) No current usage. Replaced with Sentinel Mountain Dolomite. See Sentinel Mountain.)
Tennessee Mountain Formation (NV)
Teutonia Quartz Monzonite (CA*,NV*?) [Discrepancy concerning areal extent. See remarks under "Publication History".]
Thaynes Formation (ID*,MT*,NV*,UT*,WY*)
Thaynes Limestone (UT*,WY*)
? Thaynes Group (ID*)
Theodore Quartz Diorite (NV*)
Thimble Limestone Member* of Carrara Formation
Third Canyon Formation
Thirsty Canyon Group*
Thisbe Formation (NV)
Thousand Creek Formation (NV,OR)
Thumb Member of Horse Spring Formation (AZ*,NV*)
Timber Lake Bed of Pyramid Lake Member of Mount Mazama Formation (NV)
Timber Mountain Group (CA*,NV*)
Timpoweap Member of Moenkopi Formation (AZ*,NV,UT*)
Tippipah Limestone (NV*)
Tiser Limestone
Titus Canyon Formation (CA*,NV*)
Tiva Canyon Tuff of Paintbrush Group (CA*,NV*)
Tiva Canyon Member of Piapi Canyon Formation (NV)
Toano Limestone (NV*,UT*)
Tobin Formation of Star Peak Group (NV*)
†Toiyabe Quartz Latite (NV) No current usage. Abandoned.)
Tollhouse Flat Member* of Eureka Valley Tuff of Stanislaus Group
Tomera Formation (NV*)
Tomera Formation of Ely Group (NV)
Tomera Member of Ely Limestone (NV)
Tonka Formation (NV)
Tonopah Formation*
Tonopah Summit Member of Fraction Tuff
Tony Grove Lake Member of Laketown Dolostone (NV,UT)
Topopah Spring Tuff of Paintbrush Group (CA*,NV*)
Topopah Spring Member of Piapi Canyon Formation (NV)
Toquima Formation*
Tor Limestone (NV*)
Toroweap Formation (AZ*,NV*,UT*)
Toroweap Marble (CA*)
Trail Ridge Tuff of Thirsty Canyon Group (NV*)
Tram Tuff of Crater Flat Group (NV*)
Trego Hot Springs Bed of Pyramid Lake Member of Mount Mazama Formation (CA,NV)
Trego Hot Springs Tephra (OR?)
Trenton Canyon Member of Havallah Formation (NV*)
Tripon Pass Limestone (NV*,UT*)
Truckee Formation (CA,NV*)
? Tsoyawata Bed of /Mazama Member of Mount Mazama Formation (NV)
? Tsoyawata Bed (CA) [Discrepancy concerning validity. See remarks under "Publication History".]
Tub Spring Tuff (NV*)
Tungstonia Granite
Tunnel Formation*
Turupah Alloformation (NV)
Turupah Formation of Lahontan Valley Group (NV*)
Twin Canyon Member of Osgood Mountain Quartzite (NV*)
Tybo Shale*
Underdown Tuff
†Union Mountain Formation (NV) No current usage. Replaced with Beacon Peak Dolomite, Bartine Member (upper part) of McColley Canyon Formation, Sadler Ranch Formation, and Oxyoke Canyon Sandstone. See Beacon Peak, Bartine, Sadler Ranch, and Oxyoke.
Upsal Hogback Bed of Carson Desert Formation
Uvada Granite
Valder Formation (NV)
Valmy Formation (NV*)
Valmy Group (NV)
Van Duzer Limestone (NV*)
Veta Grande Formation (NV)
Victor Andesite (NV)
Vindicator Rhyolite (NV*)
Vinini Formation (NV*)
Virgin Limestone Member of Moenkopi Formation (AZ*,NV*,UT*)
Virgin Formation (AZ,NV,UT)
Virgin Valley Formation (NV,OR)
Volcano Peak Group (NV)
Wadsworth Bed of Eetza Formation
Wah Wah Limestone of Pogonip Group (NV,UT*)
Wah Wah Springs Formation of Needles Range Group (NV*,UT*)
Wah Wah Springs Member of Needles Range Formation (UT)
Wah Wah Springs Tuff Member of Needles Range Formation (NV,UT)
Wah Wah Springs Tuff (UT*)
Wahmonie Formation*
Walker Lake Bed of Salt Wells Member of /Mono Basin Formation (NV) [Mono Basin Formation preempted by Mono Basin Glaciation of Sharp and Birman (1963) in CA.]
Warner Basalt (CA,OR?,NV?) [Discrepancy concerning areal extent. See remarks under "Publication History".]
Washington Hill Rhyolite (NV*)
Wassuk Group (NV)
Waterpipe Canyon Formation (NV)
Weaver Rhyolite of Koipato Group (NV*)
Webb Formation*
Weed Heights Member of Mickey Pass Tuff of Benton Spring Group (NV*)
Wenban Limestone (NV*)
West End Rhyolite (NV*)
West Range Limestone (NV*)
Westgate Formation (NV*)
Whipple Cave Formation (NV*)
Whirlwind Formation (NV*,UT*)
Whistler Mountain Alaskite (NV)
White Caps Limestone Member of Gold Hill Formation (NV*)
Whitmore Point Member of Moenave Formation of Glen Canyon Group (AZ*,NV*,UT*)
Wichman Formation (NV)
Wildcat Peak Formation (NV*)
Willard Creek Quartzite of McCoy Creek Group (NV)
Willow Canyon Formation (NV*)
Willow Gap Limestone Member of Chainman Formation (UT*)
Willow Gap Member of Chainman Shale (UT)
Willow Tank Formation*
Windfall Formation*
Windmill Limestone (NV*)
Windous Butte Formation (NV*)
Winnemucca Formation of Auld Lang Syne Group (NV*)
? Wono Bed of Pyramid Lake Member of Mount Mazama Formation (NV)
Wono Tephra (OR?) [Discrepancy concerning validity and areal extent. See remarks under "Publication History".]
Wood Canyon Formation (CA*,NV*)
Woodpecker Limestone*
Woodruff Formation*
Woods Ranch Member of Toroweap Formation (AZ*,NV*,UT*)
Wyemaha Alloformation (NV)
Wyemaha Formation of Lahontan Valley Group (NV*)
Yellow Hill Limestone (NV*)
Yellow Hill Limestone of Pogonip Group (NV)
Yellowpine Member of Monte Cristo Limestone (AZ*,CA*,NV*)
Yellowpine Limestone of Monte Cristo Group (NV) [Misspelled Yellow Pine in some reports.]
Young America Gravel (NV)
Yucca Mountain Tuff of Paintbrush Group (NV*)
Yucca Mountain Member of Paintbrush Tuff of Piapi Canyon Group (NV)
Yucca Mountain Member of Piapi Canyon Formation (NV)
Zabriskie Quartzite (CA*,NV*)
Zabriskie Formation (NV)
Zabriskie Quartzite Member of Wood Canyon Formation (CA,NV)
Zanzibar Limestone (NV*)