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Geologic units containing clastic

Earth material > Sedimentary rock
Clastic rock
A composed principally of broken fragments that are derived from preexisting rocks or minerals and that have been transported some distance from their place of origin.
This category is also used for Clastic sedimentary rock and clastic.
Subtopics:
Mudstone
Fine-grained mixed clastic rock
Sandstone
Medium-grained mixed clastic rock
Conglomerate
Sedimentary breccia
Coarse-grained mixed clastic rock
Olistostrome

Alabama - Arkansas - California - Colorado - Idaho - Maine - Michigan - Minnesota - Mississippi - Montana - North Carolina - New Jersey - New Mexico - Nevada - Oregon - Pennsylvania - Texas - Utah - Washington - Wisconsin - West Virginia - Wyoming
Alabama
Parkwood and Pennington Formations (Pennsylvanian-Mississippian)
Parkwood and Pennington Formations undifferentiated - Interbedded medium to dark-gray shale and light to medium-gray sandstone, locally contains lithic conglomerate, dusky-red and grayish-green mudstone, argillaceous limestone, and clayey coal.
Parkwood and Pennington Formations undifferentiated (Pennsylvanian-Mississippian)
Parkwood and Pennington Formations undifferentiated - Interbedded medium to dark-gray shale and light to medium-gray sandstone, locally contains lithic conglomerate, dusky-red and grayish-green mudstone, argillaceous limestone, and clayey coal.
Parkwood Formation (Pennsylvanian-Mississippian)
Parkwood Formation - Interbedded medium to dark-gray shale and light to medium-gray sandstone; locally contains dusky-red and grayish-green mudstone, argillaceous limestone, and clayey coal.
Parkwood Formation (Pennsylvanian-Mississippian)
Parkwood Formation - Interbedded medium to dark-gray shale and light to medium-gray sandstone; locally contains dusky-red and grayish-green mudstone, argillaceous limestone, and clayey coal.
Parkwood Formation and Floyd Shale undifferentiated (Pennsylvanian-Mississippian)
Parkwood Formation and Floyd Shale undifferentiated - Parkwood Formation -- Interbedded medium to dark-gray shale and light to medium-gray sandstone; locally contains dusky-red and grayish-green mudstone, argillaceous limestone, and clayey coal. Floyd Shale -- Dark-gray shale, sideritic in part; thin beds of sandstone, limestone and chert are locally present; beds of partly bioclastic, partly argillaceous limestone are abundant in parts of Calhoun and Cherokee Counties.
Pennington Formation (Mississippian)
Pennington Formation - Medium-gray shale, containing interbedded limestone, dolomite, argillaceous sandstone, dusky-red and grayish-olive mudstone, and minor shaly coal. Mainly restricted to northeastern AL and part of the Sequatchie anticline. Where less than 100 feet thick the formation is included in the Bangor Limestone.
Pennington Formation (Mississippian)
Pennington Formation - Medium-gray shale, containing interbedded limestone, dolomite, argillaceous sandstone, dusky-red and grayish-olive mudstone, and minor shaly coal. Mainly restricted to eastern part of Interior Low Plateaus province and where less than 100 feet thick the formation is included in the Bangor Limestone.
Arkansas
Cretaceous rocks (Phanerozoic | Mesozoic | Cretaceous)
Cretaceous rocks
Nacatoch Sand (Phanerozoic | Mesozoic | Cretaceous-Late)
Nacatoch Sand
California
Jurassic marine rocks, unit 1 (Western Sierra Nevada and Western Klamath Mountains) (Triassic to Late Jurassic)
Shale, sandstone, minor conglomerate, chert, slate, limestone; minor pyroclastic rocks
Jurassic marine rocks, unit 2 (Coast Ranges) (Late Jurassic to Early Cretaceous)
Shale, sandstone, minor conglomerate, chert, slate, limestone; minor pyroclastic rocks
Jurassic marine rocks, unit 5 (Northern Sierra Nevada and Eastern Klamath Mountains) (Devonian to Late Jurassic)
Shale, sandstone, minor conglomerate, chert, slate, limestone; minor pyroclastic rocks
Mesozoic volcanic rocks, unit 3 (Mojave Desert, Death Valley area, and Eastern Sierra Nevada) (Triassic to Cretaceous)
Undivided Mesozoic volcanic and metavolcanic rocks. Andesite and rhyolite flow rocks, greenstone, volcanic breccia and other pyroclastic rocks; in part strongly metamorphosed. Includes volcanic rocks of Franciscan Complex: basaltic pillow lava, diabase, greenstone, and minor pyroclastic rocks
Mesozoic volcanic rocks, unit 4 (Peninsular Ranges) (Late Jurassic to Early Cretaceous)
Undivided Mesozoic volcanic and metavolcanic rocks. Andesite and rhyolite flow rocks, greenstone, volcanic breccia and other pyroclastic rocks; in part strongly metamorphosed. Includes volcanic rocks of Franciscan Complex: basaltic pillow lava, diabase, greenstone, and minor pyroclastic rocks
Mesozoic volcanic rocks, unit 5 (Northern Sierra Nevada and Eastern Klamath Mountains) (Late Permian(?) to Jurassic)
Undivided Mesozoic volcanic and metavolcanic rocks. Andesite and rhyolite flow rocks, greenstone, volcanic breccia and other pyroclastic rocks; in part strongly metamorphosed. Includes volcanic rocks of Franciscan Complex: basaltic pillow lava, diabase, greenstone, and minor pyroclastic rocks
Oligocene nonmarine rocks, unit 1 (Northern California) (Oligocene to Miocene)
Sandstone, shale, and conglomerate; in part Miocene and Eocene.
Tertiary volcanic flow rocks, unit 10 (Alverson) (Tertiary (14-18 Ma))
Tertiary volcanic flow rocks; minor pyroclastic deposits.
Tertiary volcanic flow rocks, unit 11 (Jacumba) (Tertiary (12-19 Ma))
Tertiary volcanic flow rocks; minor pyroclastic deposits.
Colorado
Animas Fm (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary)
Arkosic sandstone, shale, and conglomerate; contains abundant volcanic materials; Upper Cretaceous volcaniclastic McDermott Member at base
Mesozoic and Paleozoic rocks (Phanerozoic | Paleozoic Mesozoic | Carboniferous Pennsylvanian)
Mainly as in Mesozoic unit (MZ) plus Permian and Pennsylvanian Fms
Mesozoic rocks (Lower Phanerozoic | Mesozoic | Cretaceous-Triassic)
Mainly Lower Cretaceous, Jurassic, and Triassic Fms
Middle Park Fm exclusive of Windy Gap Member (Phanerozoic | Cenozoic | Tertiary)
Arkosic sandstone and conglomerate containing abundant volcanic materials. Arbitrary line between Middle Park and Coalmont Formations is at Continental Divide
Idaho
Basalt flows, basaltic pyroclastic and clastic debris; Middle Pleistocene canyon-filling and plateau lava flows, pyroclastic debris, alluvium, and colluvium; Snake River Plain (Middle Pleistocene)
Middle Pleistocene plateau and canyon-filling basalt in and near Snake Plain.
Basalt flows, pyroclastic debris, clastic sediments, and diatomite; Pliocene basaltic volcanics and clastic sediments; Snake River Plain and vicinity (Pliocene)
Pliocene olivine basalt flows and associated tuff and detritus of southern Idaho.
Dacite to rhyolite (or rhodacite) ignimbrites; Eocene rhyodacitic cauldron complex; east-central Idaho, central Challis volcanic field (Eocene)
Eocene mixed silicic and basaltic volcanic ejecta, flows and reworked debris.
Rhyolite ignimbrites, latite and basalt lava flows, late Eocene rhyolitic ignimbrite cauldron complex; east-central Idaho, northern Challis volcanic field (Eocene)
Eocene mixed silicic and basaltic volcanic ejecta, flows and reworked debris.
Shale, arenite, conglomerate, intermediate and felsic volcanic rocks; Late Proterozoic rifted continental margin; southeastern Idaho (Late Proterozoic)
Younger Precambrian volcanic and diamictic units of central and southeastern Idaho.
Tuff, arkose, claystone, siltstone, conglomerate, lignite; Miocene alluvial and lacustrine deposits (Miocene)
Miocene stream and lake deposits; generally associated with volcanic episodes.
Maine
Devonian Trout Valley Formation (Devonian)
Devonian Trout Valley Formation
Michigan
Menominee Group; Hemlock Formation (Early Proterozoic)
Menominee Group; Hemlock Formation - Predominantly mafic to intermediate volcanic flows and pyroclastic rocks with interlayered slate and tuff beds
Porcupine Volcanics (Middle Proterozoic)
Porcupine Volcanics - Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks
Minnesota
Animikie Group; Shale, siltstone, feldspathic graywacke, and associated volcaniclastic rocks (Early Proterozoic)
Animikie Group; Shale, siltstone, feldspathic graywacke, and associated volcaniclastic rocks - Includes the Rove Formation in Cook County, the Virginia Formation in St. Louis, Itasca, and Lake Counties, and the Thomson Formation in Carlton County
Chengwatana Volcanic Group (Middle Proterozoic)
Chengwatana Volcanic Group - Basalt and related volcanogenic and interflow sedimentary rocks in east-central Minnesota
North Shore Volcanic Group; Normally polarized volcanic rocks, undivided (Middle Proterozoic)
North Shore Volcanic Group; Normally polarized volcanic rocks, undivided - Basalt, andesitic basalt, rhyolite and related volcanogenic interflow sedimentary rocks along and inland from the North Shore of Lake Superior.
Mississippi
Cockfield (Eocene)
Cockfield - (Claiborne group), Irregularly bedded, more or less laminated liginitic clay, sand, and lignite; sparingly glauconitic.
Forest Hill formation and Red Bluff clay (Oligocene)
Forest Hill formation and Red Bluff clay - Forest Hill sand, cross-bedded fine gray sand, laminated fine sand and clay, and a little lignite; in Wayne and Clarke Counties lower part merges eastward into Red Bluff clay, blue-green glauconitic, gypsiferous, fossiliferous clay and thin limestone beds.
Prairie Bluff chalk and Owl Creek formation (Upper Cretaceous)
Prairie Bluff chalk and Owl Creek formation - (Selma group), Prairie Bluff chalk, compact brittle chalk, sandy chalk, and calcareous clay; at base contains many phosphatic molds of fossils; in Ponotoc and Union Counties merges northward into Owl Creek formation, tough blue glauconitic sandy clay.
Ripley formation (Upper Cretaceous)
Ripley formation - (Selma group), gray to greenish-gray fine glauconitic sand, clay, and sandy limestone; south of Oktibbeha County is very sandy micaceous chalk.
Montana
Jurassic and Triassic rocks, undifferentiated (Phanerozoic | Mesozoic | Triassic Jurassic)
Jurassic and Triassic rocks, undifferentiated: in east-central Madison County where scale did not permit differentiation on map.
Livingston formation (Phanerozoic | Cenozoic | Tertiary Cretaceous)
Livingston formation: water-laid volcanic material, mainly andesitic in composition; includes agglomerate, conglomerate, sandstone, and shale. The name here is used only for the rocks orginally named, mainly near and north of Livingston. These rocks include age equivalents of various Cretaceous and Paleocene units.
Mississippian, undifferentiated (Phanerozoic | Paleozoic | Carboniferous Mississippian)
Mississippian, undifferentiated: sandstone, shale, and limestone, in part dolomitic, with chert nodules, some quartzite; includes Big Snowy group in central part of State, Madison group in central and southwestern parts; and Hannan and Brazer limestones in the northwestern part; may include small amounts of Pennsylvanian rocks in areas where stratigraphic studies are incomplete.
Ordovician, undifferentiated (Phanerozoic | Paleozoic | Ordovician)
Ordovician, undifferentiated: Mainly Bighorn dolomite; near Idaho, Kinnikinic quartzite.
Triassic, undifferentiated (Phanerozoic | Mesozoic | Triassic)
Triassic, undifferentiated: conglomerate, sandstone, shale, and impure limestone belonging to the Dinwoody and Thaynes formations and other units of Triassic age, and the Chugwater of Triassic and Permian age.
Two Medicine formation (Phanerozoic | Mesozoic | Cretaceous-Late)
Two Medicine formation: greenish-gray clay with local nodular limestone and crossbedded sandstone; locally some coal in lower part. Rocks equivalent to Judith River formation, Claggett formation, and upper part of Eagle sandstone are included in this unit.
North Carolina
Newark Supergroup, Chatham Group; Cumnock Formation (Triassic)
Cumnock Formation - sandstone and mudstone, gray to black; coal beds and carbonaceous shale. Grades into Pekin and Sanford formations.
New Jersey
Cohansey Formation (Middle Miocene, Serravallian)
Cohansey Formation - Sand, white to yellow with local gravel and clay. Locally stained red or orange brown by iron oxides and (or) cemented into large blocks of ironstone. Unweathered clay is typically dark gray, but commonly weathers white where interbedded with thin beds of ironstone. Unit is a complex of interfingering marine and nonmarine facies. Sand is typically medium grained and moderately sorted although it ranges from fine to very coarse grained and from poorly to well sorted. Sand consists of quartz and siliceous rock fragments. Some beds are locally micaceous, and in the Lakehurst area, Ocean County, some beds have high concentrations of "black" sand (pseudorutile) that was once extensively mined. In general, the sand is crossbedded, although the style of crossbedding varies significantly with the paleoenvironment. Trough crossbedding predominates, especially in the nonmarine channel fill deposits, and the scale of the crossbeds varies from small to large. In some areas, planar bedding is well developed in sections that have abundant marine burrows (mostly the clay-lined trace fossil Ophiomorpha nodosa). Such marine-influenced beds (largely foreshore deposits) occur on the central sheet west of Asbury Park, near Adelphia, Monmouth County, north of the Lakehurst Naval Air Station, Ocean County, and at Juliustown, Burlington County (Owens and Sohl, 1969), and on the southern sheet as far north as Salem, Salem County. Gravel beds occur locally, especially in updip areas such as near New Egypt, Ocean County, in the Atlantic Highlands and in the highlands west of Barnegat, Ocean County, in the southern part of the central sheet and in mixed marine and nonmarine facies in the northeastern part of the southern sheet where gravel occurs in well-defined channels. Most of the gravel is 1.3 to 2.5 cm (0.5-1.0 in) in diameter, but pieces as long as 10 cm (4 in) are present. The gravel is composed of quartz with small amounts of black chert and quartzite. Clay commonly occurs as discrete, thin, discontinuous beds, is dark gray where unweathered, white or red where weathered. Lesser, thin laminated clay strata also are present. Locally, as near Lakehurst, thick, dark-gray, very lignitic clay was uncovered during the mining of ilmenite and is informally called the Legler lignite (Rachele, 1976). An extensive, well-preserved leaf flora was collected from a thick clay lens in a pit near Millville, Cumberland County. The leaf flora was dominated by Alangium sp., a tree no longer growing in eastern North America (J.A. Wolfe, written commun., 1992). Maximum thickness in the map area is about 60 m (197 ft); however, thickness is difficult to determine because of the irregular basal contact and extensive post-depositional erosion. There is as much as 18 m (59 ft) of relief along the basal contact. The basal contact is sharp, undulatory, and directly overlain by a thin gravel bed. The Cohansey Formation unconformably overlies the Kirkwood Formation and is found in channels cut down into the Kirkwood. Where the Kirkwood consists of sandy, light-colored sediments, the basal contact of the Cohansey is drawn below crossbedded sediments. Where the Kirkwood consists of dark-colored silty beds, the basal contact is drawn between light-colored Cohansey sediments and the underlying dark-colored sediments. The Cohansey was markedly thinned because of erosion prior to deposition of overlying units in the western and southern parts of the southern sheet (Owens and Minard, 1975). The unit has been extensively eroded and stripped from large areas of the New Jersey Coastal Plain, particularly in the central sheet where outliers are common. In spite of its widespread nature, the Cohansey is poorly exposed because of its loose sandy composition, which causes it to erode easily (Newell and others, in press). Because of this same sandy nature, the Cohansey has been widely mined for sand, and manmade exposures are common in many areas. The age of the Cohansey is controversial because no calcareous microfauna or macrofauna have been found in this formation. The best indication of age comes from pollen and spores obtained from dark carbonaceous clay. Rachele (1976) analyzed the microflora from the Legler site and noted that the Cohansey had a rich and varied assemblage including several genera labeled "exotics" which no longer occur in the northeastern United States: Engelhardia, Pterocarya, Podocarpus, and Cyathea. Greller and Rachele (1984) estimated a middle Miocene age. Ager's (in Owens and others, 1988) analysis of the Cohansey from a corehole at Mays Landing also suggests a middle Miocene (Serravallian) age.
Feltville Formation (Lower Jurassic)
Feltville Formation (Olsen, 1980) - Interbedded brownish-red to light-grayish-red, fine- to coarse-grained sandstone, gray and black, coarse siltstone in upward-fining cycles, and silty mudstone. Fine-grained sandstone and siltstone are moderately well sorted, commonly cross-laminated, and have 15 percent or more feldspar; interbedded with brownish-red, indistinctly laminated, bioturbated calcareous mudstone. Thermally metamorphosed into hornfels where in contact with Preakness Basalt. Near the base are two thin, laterally continuous beds of black, carbonaceous limestone and gray, calcareous siltstone, each up to 3 m (10 ft) thick. These contain abundant fish, reptile, anthropod, and diagnostic plant fossils. Three or four, thin, gray to black siltstone and mudstone sequences occur in upper part of unit. Near Oakland, subrounded pebbles to cobbles of quartzite and quartz in a red siltstone and sandstone matrix (Jfc) interfinger with sandstone and siltstone of the Feltville Formation. Maximum thickness about 155 m (510 ft).
Feltville Formation (Lower Jurassic)
Feltville Formation - Mostly fine-grained, feldspathic sandstone, coarse siltstone, and silty mudstone, brownish-red to light-grayish-red. Fine-grained sandstone is moderately well sorted, cross laminated, and contains 15 percent or more feldspar; interbedded with mudstone, indistinctly laminated, bioturbated, and calcareous in places. A thin bed (0-2 m (0-7 ft) thick) of black, microlaminated carbonaceous limestone and gray calcareous mudstone occurs near the base and contains fish and plant fossils, and thermally mature hydrocarbons. Thickness of unit in the Sand Brook syncline is about 155 m (509 ft).
Towaco Formation (Lower Jurassic)
Towaco Formation (Olsen, 1980) - Reddish-brown to brownish-purple, fine- to medium-grained micaceous sandstone, siltstone, and silty mudstone in upward-fining sequences 1 to 3 m (3-10 ft) thick. Distributed throughout formation are eight or more sequences of gray to greenish- or brownish-gray, fine-grained sandstone, siltstone and calcareous siltstone and black, microlaminated calcareous siltstone and mudstone containing diagnostic pollen, fish and dinosaur tracks. Sandstone is commonly trough cross laminated; siltstone is commonly planar laminated or bioturbated, but can be indistinctly laminated to massive. Thermally metamorphosed into hornfels where in contact with Hook Mountain Basalt. Conglomerate and conglomeratic sandstone with subrounded quartzite and quartz clasts in matrix of light-red sand to brownish-red silt (Jtc) interfingers with rocks of the Towaco Formation north and west of New Vernon. Maximum thickness is about 380 m (1,250 ft).
New Mexico
andesite and basaltic andesite flows and associated volcaniclastic units (Phanerozoic | Cenozoic | Tertiary)
Lower Tertiary, (Lower Oligocene and Eocene) andesite and basaltic andesite flows, and associated volcaniclastic units. Includes Rubio Peak Formation, and andesite of Dry Leggett Canyon
Animas Formation (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary)
Animas Formation; in northeast San Juan Basin
Carlile Shale (Phanerozoic | Mesozoic | Cretaceous)
Carlile Shale; limited to northeastern area; Turonian-Coniacian
Cretaceous rocks, undivided (Phanerozoic | Mesozoic | Cretaceous)
Cretaceous rocks, undivided
Dakota Sandstone and Rio Salado Tongue of the Mancos Shale (Phanerozoic | Mesozoic | Cretaceous)
Dakota Sandstone and Rio Salado Tongue of the Mancos Shale. In northwest Socorro County locally includes overlying Tres Hermanos Formation
Fence Lake Formation (Phanerozoic | Cenozoic | Tertiary)
Fence Lake Formation; conglomerate and conglomeratic sandstone, coarse fluvial volcanoclastic sediments, minor eolian facies, and pedogenic carbonates of the southern Colorado Plateau region; Miocene
Lead Camp Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian)
Lead Camp Formation; San Andres and Organ Mountains
Lower Cretaceous, unidivided (Phanerozoic | Mesozoic | Cretaceous)
Lower Cretaceous, undivided; in northern Lea and Roosevelt Counties includes equivalents of Tucumcari Shale. In Cornudas Mountains includes Campogrande, Cox and other Washita Group formations, and the Boquillas Formation; Cenomanian. In the southwest includes Hell-To-Finish, U-Bar, and Mojado Formations which are equivalent to Bisbee Group of Arizona
Mancos Formation and Beartooth Quartzite (Phanerozoic | Mesozoic | Cretaceous)
Mancos Formation and Beartooth Quartzite (and Sarten Sandstone); Mancos includes what was formerly referred to as Colorado Shale which in turn may include equivalents of Tres Hermanos Formation
middle and upper Jurassic rocks, unidivided (Phanerozoic | Mesozoic | Jurassic)
Jurassic rocks, Middle and Upper, undivided
Missippian through Cambrian rocks, undivided (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous Mississippian)
Mississippian through Cambrian rocks, undivided; includes Lake Valley Limestone; Mississippian; Devonian rocks, undivided; El Paso Formation and Montoya Group (or Formation); Ordovician; and Bliss Sandstone; Cambrian and Ordovician
rhyolitic pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary)
Upper Oligocene rhyolitic pyroclastic rocks (ash-flow tuffs); includes Davis Canyon Tuff, South Crosby Peak Formation, La Jencia, Vick's Peak, Lemitar, South Canyon, Bloodgood Canyon, Shelley Peak Tuffs, tuff of Horseshoe Canyon, Park Tuff, Rhyolite Canyon Tuff, Apache Springs Tuff, Diamond Creek, Jordan Canyon, Garcia Camp Tuffs, the Turkey Springs Tuff, the tuff of Little Mineral Creek, the Amalia Tuff, and others. Some contain volcaniclastic and reworked volcaniclastic rocks, and eolian sandstone; (24-29 Ma)
Santa Fe Group (Phanerozoic | Cenozoic | Tertiary Quaternary)
Santa Fe Group, undivided. Basin fill of Rio Grande rift region; middle Pleistocene to uppermost Oligocene
sedimentary and vocaniclastic sedimentary rocks (Phanerozoic | Cenozoic | Tertiary)
Mostly Oligocene and upper Eocene sedimentary and volcaniclastic sedimentary rocks with local andesitic to intermediate volcanics; includes Espinaso, Spears, Bell Top, and Palm Park Formations
silicic flows, domes, and associated pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary)
Lower Oligocene silicic (or felsic) flows, domes, and associated pyroclastic rocks and intrusions; includes Mimbres Peak Formation
silicic pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary)
Lower Oligocene silicic pyroclastic rocks (ash-flow tuffs); includes Hell's Mesa, Kneeling Nun, lower part of Bell Top Formation, Caballo Blanco, Datil Well, Leyba Well, Rock House Canyon, Blue Canyon, Sugarlump and Tadpole Ridge Tuffs, the tuffs of the Organ cauldron, Treasure Mountain Tuff (now known as Chiquito Peak Tuff), Bluff Creek Tuff, Oak Creek Tuff, tuff of Steins Mountain, tuff of Black Bill Canyon, tuff of Farr Ranch, Woodhaul Canyon, Gillespie and Box Canyon Tuffs, Cooney Tuff, and other volcanic and interbedded fluvial and pumiceous units; (31-36.5 Ma)
Upper Santa Fe Group (Phanerozoic | Cenozoic | Tertiary Quaternary)
Upper Santa Fe Group. Includes Camp Rice, Fort Hancock, Palomas, Sierra Ladrones, Ancha, Puye, and Alamosa Formations; middle Pleistocene to uppermost Miocene
upper Tertiary sedimentary units (Phanerozoic | Cenozoic | Tertiary)
Upper Tertiary sedimentary units; includes Bidahochi Formation, the Picuris Formation, and Las Feveras Formation, and locally fanglomerates; Pliocene to upper Miocene
volcanic rocks, lower Oligocene and Eocene (Phanerozoic | Cenozoic | Tertiary)
Lower Oligocene and Eocene volcanic rocks, undifferentiated; dominantly intermediate composition, with interbedded volcaniclastic rocks; (31-44 Ma)
Yeso, Glorieta, and San Andres Formations, undivided (Phanerozoic | Paleozoic | Permian)
Yeso, Glorieta and San Andres Formations, undivided
Nevada
Koipato Group and related rocks (Permian to Early Triassic)
KOIPATO GROUP AND RELATED ROCKS (Lower Triassic)-Altered andesitic flows, rhyolitic tuffs and flows, and clastic rocks. Includes rocks mapped by Silberling (1959) as Pablo Formation and originally considered to be Permian in the Shoshone Mountains, Nye County. Includes Tallman Fanglomerate (Permian?) in Humboldt County
Oregon
Andesite and dacite and sedimentary rocks (Miocene? and Oligocene) (Oligocene to Miocene)
Lava flows, breccia, volcaniclastic and epiclastic rocks mostly of andesitic and dacitic composition; includes minor amounts of altered basaltic rocks. Joint surfaces and cavities commonly lined with hematite or montmorillonite clay, secondary silica minerals, zeolites, celadonite, or calcite. Andesite and dacite typically have plagioclase, hornblende, and clinopyroxene phenocrysts; some flows aphyric. Platy flow-jointing common. Age, mostly Oligocene; may include some rocks of early Miocene age. As shown, may include some rocks older than Oligocene, correlative with upper parts of unit Tea. One potassium-argon age of about 28 Ma on porphyritic hornblende andesite from Sheep Creek, southwest corner of Union County, indicates in part coeval with unit Tsf
Basalt and andesite (Miocene) (Miocene)
Lava flows and breccia of aphyric and plagioclase porphyritic basalt and aphyric andesite; locally includes flow breccia, peperite, some palagonite tuff and breccia, and minor silicic ash-flow tuff and interbeds of tuffaceous sedimentary rocks. In Basin and Range and Owyhee Upland provinces unit grades upward into more silicic, andesitic, and quartz latitic flows and flow breccia, as well as some interbedded tuffs and ash-flow tuffs; also in this region includes aphyric and highly porphyritic, plagioclase-rich basalt. Interfingers with and grades laterally into units Tit and Tts. Commonly contains montmorillonite clays, zeolites, calcite, and secondary silica minerals as alteration products on fractures and in pore spaces. Age, mostly middle Miocene, but includes some rocks of early Miocene age based on vertebrate fossils from related sedimentary units and on potassium-argon ages that range from about 13 Ma to about 19 Ma; most isotopic ages are about 13 to 16 Ma. Includes Steens Basalt (Steens Mountain Basalt of Fuller, 1931) Owyhee Basalt of Corcoran and others (1962) and Kittleman and others (1967), Hunter Creek Basalt and "unnamed igneous complex" of Kittleman and others (1965, 1967), and flows of Prineville chemical type (Uppuluri, 1974; Swanson and others, 1979), which previously were considered part of the Columbia River Basalt Group (Swanson, 1969a)
Basalt (upper and middle Miocene) (Middle to Late Miocene)
Basalt flows, flow breccia, and basaltic peperite; minor andesite flows; some interbeds of tuff and tuffaceous sedimentary rocks. Basalt is aphyric to moderately porphyritic with phenocrysts of plagioclase and olivine and exhibits both subophitic and diktytaxitic textures. Includes Picture Rock Basalt of Hampton (1964), radiometrically dated by potassium-argon methods as middle(?) and late Miocene in age (see Fiebelkorn and others, 1983), flows of Deer Butte Formation of Kittleman and others (1967), and extensive unnamed flow sequences in the Basin-Range and Owyhee Upland Provinces of southern Lake, Harney, and Malheur Counties that are younger than Steens Basalt, dated at about 15 Ma (Baksi and others, 1967) and the Owyhee Basalt, dated at about 14 Ma (Bottomley and York, 1976; see also Fiebelkorn and others, 1983), and older than 7 or 8 Ma. Partly coeval with the Saddle Mountains Basalt of the Columbia River Basalt Group (Swanson and others, 1979)
Flows and clastic rocks, undifferentiated (Miocene) (Miocene)
Chiefly basaltic andesite and andesite lava flows and flow breccia containing plagioclase and pyroxene (hypersthene and augite) phenocrysts, mudflows (lahars), and volcanic conglomerates; locally includes some dacite flows. Includes lesser, coarse- to fine-grained epiclastic volcanic sedimentary rocks and ash-flow and air-fall tuffs. Partly equivalent in age to unit Tba and may be partly coeval with younger parts of unit Tstb. Locally altered adjacent to larger intrusions. The oldest radiometrically dated rocks assigned to this unit are about 17 Ma (Sutter, 1978); in part lapped by flows questionably assigned to unit Tba, radiometrically dated at about 10 Ma, and unconformably overlain by flows of unit Trb. Includes some of rocks formerly mapped as Sardine Formation and some mapped as Rhododendron Formation
Undifferentiated tuffaceous sedimentary rocks, tuffs, and basalt (Miocene and Oligocene) (Oligocene to Miocene)
Heterogeneous assemblage of continental, largely volcanogenic deposits of basalt and basaltic andesite, including flows and breccia, complexly interstratified with epiclastic and volcaniclastic deposits of basaltic to rhyodacitic composition. Includes extensive rhyodacitic to andesitic ash-flow and air-fall tuffs, abundant lapilli tuff and tuff breccia, andesitic to dacitic mudflow (lahar) deposits, poorly bedded to well-bedded, fine- to coarse-grained tuffaceous sedimentary rocks, and volcanic conglomerate. Originally included in Little Butte Volcanic Series (Peck and others, 1964); includes Mehama Volcanics and Breitenbush Tuffs or Series of Thayer (1933, 1936, 1939), Breitenbush Formation of Hammond and others (1982), Mehama Formation of Eubanks (1960), and Molalla Formation of Miller and Orr (1984a). In Columbia River Gorge, includes Miocene and older rocks previously assigned to the Skamania Volcanic Series (Trimble, 1963), or to the Eagle Creek Formation (Waters, 1973). Lower parts of unit exhibit low-grade metamorphism with primary constituents altered to clay minerals, calcite, zeolites (stilbite, laumontite, heulandite), and secondary silica minerals. In contact aureoles adjacent to stocks and larger dikes of granitic and dioritic composition or in areas of andesitic dike swarms, both wallrocks and intrusions are pervasively propylitized; locally rocks also have been subjected to potassic alteration. Epiclastic part of assemblage locally contains fossil plants assigned to the Angoonian Stage (Wolfe, 1981) or of Oligocene age. A regionally extensive biotite-quartz rhyodacite ash-flow tuff, the ash-flow tuff of Bond Creek of Smith and others (1982), is exposed in southern part of Western Cascade Range near and at base of unit. A K-Ar age of 34.9 Ma was determined on biotite from the tuff (Smith, 1980). Ash-flow tuffs, higher in the section and in the same area, have been radiometrically dated at 22 to 32 Ma by potassium-argon methods (J.G. Smith, unpublished data; Evernden and James, 1964; Fiebelkorn and others, 1983). In the central part of the Western Cascade Range, the unit has yielded a number of K-Ar ages in the range of about 32 to 19 Ma (Verplanck, 1985, p. 53-54). A fission-track age of 23.8 +/- 1.4 Ma was obtained on a red, crystal-rich ash-flow tuff (J.A. Vance, oral communication, 1983) collected at an elevation of about 3,000 ft on U.S. Highway 20 west-southwest of Echo Mountain. Most ages from basalt and basaltic andesite lava flows are in the range of about 35 to 18 Ma. Locally intruded by small stocks of granitoid rocks and by dikes, sills, plugs, and invasive flows of basaltic andesite and basalt; in many places, the intrusions are indistinguishable from poorly exposed interbedded lava flows; K-Ar ages on several of the mafic intrusions or invasive flows are about 27 to 31 Ma. In places subdivided into Tus, Tut, and Tub
Volcanic and metavolcanic rocks (Upper Triassic) (Late Triassic)
Green to gray spilite and keratophyre flows and flow breccia; and subordinate amounts of coarse volcaniclastic sandstone, tuff, sandstone, siltstone, chert, conglomerate, and limestone. Marine fauna from interlayered sedimentary rocks indicates unit is mostly of Karnian (Late Triassic) age. Includes Late Triassic "andesitic and basaltic rocks" of Nolf and Taubeneck (1963), and the basaltic to rhyolitic metavolcanic rocks and interbedded sedimentary rocks of the Huntington Formation of Brooks (1979). Equivalent, in part, to unit TrPv
Pennsylvania
Casselman Formation (Pennsylvanian)
Casselman Formation - Cyclic sequences of shale, siltstone, sandstone, red beds, thin, impure limestone, and thin, nonpersistent coal; red beds are associated with landslides; base is at top of Ames limestone.
Conemaugh Group (Pennsylvanian)
Conemaugh Group - Includes, in descending order, the Casselman Formation (PAcc) and the Glenshaw Formation (PAcg), which are described separately below. Casselman: Cyclic sequences of shale, siltstone, sandstone, red beds, thin, impure limestone, and thin, nonpersistent coal; red beds are associated with landslides; base is at top of Ames limestone. Glenshaw: Cyclic sequences of shale, sandstone, red beds, and thin limestone and coal; includes four marine limestone or shale horizons; red beds are involved in landslides; base is at top of Upper Freeport coal.
Glenshaw Formation (Pennsylvanian)
Glenshaw Formation - Cyclic sequences of shale, sandstone, red beds, and thin limestone and coal; includes four marine limestone or shale horizons; red beds are involved in landslides; base is at top of Upper Freeport coal.
Onondaga Formation through Poxono Island Formation, undivided (Devonian and Silurian)
Onondaga Formation through Poxono Island Formation, undivided - In descending order: Onondaga Formation--gray calcareous, sandy shale; Ridgeley Formation--brown sandstone; Rondout Formation--gray interbedded limestone, dolomite, and shale; Decker Formation--gray calcareous sandstone, and Andreas Red Beds at top; Bossardville Limestone--gray, mud-cracked shaly limestone; Poxono Island Formation--olive-gray, calcareous and dolomitic shale, siltstone, and sandstone.
Pottsville Formation (Pennsylvanian)
Pottsville Formation - Gray conglomerate, fine- to coarse-grained sandstone, and siltstone and shale containing minable anthracite coals. Includes three members, in descending order: Sharp Mountain--conglomerate and conglomeratic sandstone; Schuylkill--sandstone and conglomeratic sandstone; Tumbling Run--conglomeratic sandstone and sandstone.
Texas
Chisos Formation of Schiebout et al (1987) and the Big Yellow Sandstone Member of their Tornillo Formation, undivided (Phanerozoic | Cenozoic | Tertiary | Eocene Oligocene)
Chisos Formation of Schiebout et al (1987) and the Big Yellow Sandstone Member of their Tornillo Formation, undivided
Comanche Peak Limestone, Walnut Clay, and Antlers Sand, undivided (Phanerozoic | Mesozoic | Cretaceous-Early)
Comanche Peak Limestone, Walnut Clay, and Antlers Sand, undivided
Cow Creek Limestone, Hammett Shale, and Sycamore Sand, undivided (Phanerozoic | Mesozoic | Cretaceous-Early)
Cow Creek Limestone, Hammett Shale, and Sycamore Sand, undivided
Paleozoic rocks, undivided (Phanerozoic | Paleozoic)
Paleozoic rocks, undivided
upper Cretaceous rocks, undivided (Phanerozoic | Mesozoic | Cretaceous-Late)
upper Cretaceous rocks, undivided
Victorio Peak Formation (Phanerozoic | Paleozoic | Permian [Leonard])
Victorio Peak Formation
Utah
Cretaceous and Tertiary sedimentary rocks in Uinta Mountains-Uinta Basin region (Late Cretaceous to Paleocene)
Jurassic (1) sedimentary rocks in Salt Lake City-Coalville-Randolph region (Middle to Late Jurassic)
Pennsylvanian and Permian sedimentary rocks in central Utah (Pennsylvanian to Permian)
Permian (1) sedimentary rocks in southwestern Utah (Early Permian)
Permian (1) sedimentary rocks in western Utah (Early Permian)
Permian (2) sedimentary rocks in Uinta Mountains-Uinta Basin region (Permian)
Tertiary (1) sedimentary rocks in central Utah (Late Paleocene to Early Eocene)
Tertiary (1) sedimentary rocks in southwestern Utah (Late Paleocene to Early Oligocene)
Tertiary (2) sedimentary rocks in central Utah (Eocene)
Tertiary (2) sedimentary rocks in southwestern Utah (Eocene)
Tertiary (2) sedimentary rocks in Uinta Mountains-Uinta Basin region (Eocene)
Tertiary (3) sedimentary rocks in Uinta Mountains-Uinta Basin region (Middle Eocene to Early Oligocene)
Tertiary (4) sedimentary rocks in central Utah (Middle Miocene to Late Pliocene)
Tertiary (4) sedimentary rocks in Salt Lake City-Coalville-Randolph region (Middle Miocene to Late Pliocene)
Tertiary (4) sedimentary rocks in western Utah (Middle Miocene to Late Pliocene)
Washington
Carboniferous rocks (Late Devonian to Mississippian)
Thin-bedded graywacke, shale, argillite, slate, schist, volcanic breccia, gritstone, conglomerate, and limestone on northeast shore of Orcas Island. Limestone or dolomitic limestone, apparently interbedded with limy argillite and graywacke, forms belt of small separate outcrops between Springdale and Valley in southeastern Stevens County. Late Devonian to Early Pennsylvanian in age.
Wisconsin
Porcupine Volcanics (Middle Proterozoic)
Porcupine Volcanics - Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks
Volcanic rocks, undivided (Early Proterozoic)
Volcanic rocks, undivided - Mafic to felsic flows, pyroclastic rocks, impure quartzite, and conglomerate in Eau Claire River, Eau Claire and northern Clark Counties. Rhyolite has zircon ages of 1,858 +/- 5 Ma. Possibly correlative with Milladore Volcanic Complex.
West Virginia
Tonoloway, Wills Creek, and Williamsport Formations (Silurian)
Tonoloway, Wills Creek, and Williamsport Formations - includes the thin-bedded platy argillaceous limestones of the Tonoloway, the thin-bedded shale with fossiliferous limestones of the Wills Creek, the Bloomsburg red clastic facies, and the greenish-brown to white Williamsport Sandstone. The Wills Creek contains anhydrite and rock salt, the latter supplying brine from deep wells along the Ohio River.
Wyoming
Absaroka Volcanic Supergroup: Hominy Peak Formation (Phanerozoic | Cenozoic | Tertiary | Eocene)
ABSAROKA VOLCANIC SUPERGROUP--HOMINY PEAK FORMATION (AGE ABOUT 49 Ma)--Mafic volcaniclastic conglomerate and tuff; sparse claystone in upper part; gold-bearing quartzite conglomerate at base.
Blind Bull Formation (Phanerozoic | Mesozoic | Cretaceous-Late)
BLIND BULL FORMATION--Gray to tan conglomeratic sandstone, siltstone, claystone, coal, and bentonite.
Bridger Formation (Phanerozoic | Cenozoic | Tertiary | Eocene)
BRIDGER FORMATION--Greenish-gray, olive-drab, and white tuffaceous sandstone and claystone; lenticular marlstone and conglomerate.
Bug Formation (Phanerozoic | Cenozoic | Tertiary Quaternary | Pliocene Pleistocene)
BUG FORMATION (PLEISTOCENE OR PLIOCENE)--Lacustrine white marl, claystone, sandstone, conglomerate, and tuff; generally radioactive.
Cloverly, Morrison, and Sundance Formations (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late(?) Cretaceous-Early)
CLOVERLY, MORRISON, AND SUNDANCE (Js) FORMATIONS. CLOVERLY FORMATION--Rusty sandstone at top, underlain by brightly variegated bentonitic claystone; chert-pebble conglomerate locally at base. MORRISON FORMATION--Dully variegated claystone, nodular limestone, and gray silty sandstone. In southern Yellowstone and Jackson Hole areas the presence of Morrison is questionable. SUNDANCE FORMATION--Greenish-gray glauconitic sandstone and shale, underlain by red and gray nonglauconitic sandstone and shale.
Cloverly, Morrison, Sundance, and Gypsum Spring Formations (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late(?) Cretaceous-Early)
CLOVERLY, MORRISON, AND SUNDANCE (Js), AND GYPSUM SPRING FORMATIONS. CLOVERLY FORMATION--Rusty sandstone at top, underlain by brightly variegated bentonitic claystone; chert-pebble conglomerate locally at base. MORRISON FORMATION--Dully variegated claystone, nodular limestone, and gray silty sandstone. In southern Yellowstone and Jackson Hole areas the presence of Morrison is questionable. SUNDANCE FORMATION--Greenish-gray glauconitic sandstone and shale, underlain by red and gray nonglauconitic sandstone and shale. GYPSUM SPRING FORMATION--Interbedded red shale, dolomite, and gypsum. In north Wyoming wedges out south in T. 39 N.
Fowkes Formation (Phanerozoic | Cenozoic | Tertiary | Eocene)
FOWKES FORMATION--Light-colored tuffaceous sandstone and siltstone, locally conglomeratic. Locally designated by some as Norwood Tuff.
Frontier Formation and Mowry and Thermopolis Shales (Phanerozoic | Mesozoic | Cretaceous-Early Cretaceous-Middle(?) Cretaceous-Late)
FRONTIER FORMATION (Kf) AND MOWRY (Kmr) AND THERMOPOLIS SHALES. FRONTIER FORMATION--Gray sandstone and sandy shale. In Northern Yellowstone area, Yellowish- to medium-gray sandstone; tuffaceous and carbonaceous in lower part. MOWRY SHALE (AGE 94 TO 98 Ma)--Silvery-gray hard siliceous shale containing abundant fish scales and bentonite beds. THERMOPOLIS SHALE--Black soft fissile shale; Muddy Sandstone Member at top.
Greenhorn Formation and Belle Fourche and Mowry Shale (Phanerozoic | Mesozoic | Cretaceous-Early)
GREENHORN FORMATION AND BELLE FOURCHE AND MOWRY (Kmr) SHALE. GREENHORN FORMATION--Light-colored limestone, marl, and limy sandstone interbedded with gray concretionary shale. BELLE FOURCHE SHALE--Black soft bentonitic concretionary shale. MOWRY SHALE (AGE 94 TO 98 Ma)--Silvery-gray hard siliceous shale containing abundant fish scales and bentonite beds.
Greenhorn Formation and Belle Fourche Shale (Phanerozoic | Mesozoic | Cretaceous-Late)
GREENHORN FORMATION AND BELLE FOURCHE SHALE. GREENHORN FORMATION--Light-colored limestone, marl, and limy sandstone interbedded with gray concretionary shale. BELLE FOURCHE SHALE--Black soft bentonitic concretionary shale. CARLILE SHALE--Dark-gray sandy shale; Sage Breaks Member at top; Turner Sandy Member in middle.
Green River Formation: Wilkins Peak Member (Phanerozoic | Cenozoic | Tertiary | Eocene)
GREEN RIVER FORMATION Wilkins Peak Member (age about 49 Ma)--Green, brown, and gray tuffaceous sandstone, shale, and marlstone; contains evaporites in subsurface sections.
Green River Formation: Wilkins Peak Member and Tipton Shale member or Tongue (Phanerozoic | Cenozoic | Tertiary | Eocene)
GREEN RIVER FORMATION Wilkins Peak Member (age about 49 Ma) (green, brown, and gray tuffaceous sandstone, shale, and marlstone; contains evaporites in subsurface sections) and Tipton Shale Member or Tongue (oil shale and marlstone).
Jelm and Chugwater Formations, Forelle Limestone, and Satanka Shale (Phanerozoic | Paleozoic Mesozoic | Permian Triassic-Early)
JELM AND CHUGWATER FORMATIONS, FORELLE LIMESTONE, AND SATANKA SHALE. CHUGWATER FORMATION OR GROUP--Red shale and siltstone containing thin gypsum partings near base. Group includes Popo Agie Formation (red shale and red, yellow, and purple siltstone; lenses of lime-pellet conglomerate), Crow Mountain Sandstone (red and gray, thick bedded), Alcova Limestone, and Red Peak Formation (red siltstone and shale). Chugwater Formation includes as members all the units listed above. Includes overlying Jelm Formation in Shirley and Seminoe Mountains and at northern end of Laramie Basin. JELM FORMATION--Red sandstone. FORELLE LIMESTONE--Thin-bedded limestone. Locally is a member of the Goose Egg Formation. SATANKA SHALE--Red shale.
Lance Formation, Fox Hills Sandstone, Meeteetse Formation, Bearpaw and Lewis Shales (Phanerozoic | Mesozoic | Cretaceous-Late)
LANCE FORMATION (Kl north), FOX HILLS SANDSTONE (Kfh), MEETEETSE FORMATION (Km), AND BEARPAW AND LEWIS (Kle) SHALES--In the Bighorn Basin consists of Lance, Meeteetse and, in the southeastern part, tongue of Lewis Shale; in the northern part of the Wind River Basin, of Lance, Meeteetse, and Lewis, and, in the southeastern part of the basin, of Lance and Lewis; on the west side of the Powder River Basin north of T. 45 N., of Lance, Fox Hills, and Bearpaw, and, to the south, of Lance, Fox Hills, and Lewis. LANCE FORMATION--Thick-bedded buff sandstone and drab to green shale; thin conglomerate lenses. FOX HILLS SANDSTONE--Light-colored sandstone and gray sandy shale containing marine fossils. MEETEETSE FORMATION (AGE ABOUT 73 Ma)--Chalky-white to gray sandstone, yellow, green, and dark-gray bentonitic claystone, white tuff, and thin coal beds. BEARPAW SHALE--Dark-greenish-gray shale containing thin gray sandstone partings. LEWIS SHALE (AGE ABOUT 68 Ma)--Gray marine shale containing many gray and brown lenticular concretion-rich sandstone beds.
Landslide Creek Formation (Phanerozoic | Mesozoic | Cretaceous-Late)
LANDSLIDE CREEK FORMATION--Greenish-gray bentonitic tuffaceous sandstone and conglomerate.
Meeteetse Formation (Phanerozoic | Mesozoic | Cretaceous-Late)
MEETEETSE FORMATION (AGE ABOUT 73 Ma)--Chalky-white to gray sandstone, yellow, green, and dark-gray bentonitic claystone, white tuff, and thin coal beds.
Meeteetse Formation and Lewis Shale (Phanerozoic | Mesozoic | Cretaceous-Late)
MEETEETSE FORMATION AND LEWIS SHALE. MEETEETSE FORMATION (AGE ABOUT 73 Ma) (Km)--Chalky-white to gray sandstone, yellow, green, and dark-gray bentonitic claystone, white tuff, and thin coal beds. LEWIS SHALE (AGE ABOUT 68 Ma) (Kle)--Gray marine shale containing many gray and brown lenticular concretion-rich sandstone beds.
Mesozoic and Paleozoic rocks (Phanerozoic | Paleozoic Mesozoic | Carboniferous Mississippian-Late Pennsylvanian(?) Permian(?) Triassic(?) Jurassic(?) Cretaceous-Late)
MESOZOIC AND PALEOZOIC ROCKS (north Wyoming). Shown in small areas of complex structure. East Flank of Absaroka Range--Dinwoody Formation, Phosphoria Formation and related rocks., Tensleep Sandstone, and Amsden Formation (Lower Triassic through Upper Mississippian). East flank of Bighorn Mountains--Cloverly, Morrison, Sundance, Gypsum Spring, Chugwater and Gypsum Spring Formations (Lower Cretaceous through Permian). MESOZOIC AND PALEOZOIC ROCKS (south Wyoming). Shown in small areas of complex structure. South side of Granite Mountains north of Green Mountain--Nugget Sandstone, Chugwater and Goose Egg Formations, Tensleep Sandstone, and Amsden Formation (Jurassic? through Upper Mississippian). South flank of Ferris Mountains--Nugget Sandstone and Chugwater and Goose Egg Formation (Jurassic? through Permian). Northeast flank of Seminoe Mountians--Cloverly, Morrison, Sundance, Chugwater, and Goose Egg Formations (Lower Cretaceous through Permain). West flank of Sierra Madre--Chugwater, Goose Egg, Casper, and Fountain Formations (Upper Triassic through Middle Pennsylvanian). East Flank of Laramie Mountains--Cloverly, Morrison, Sundance, Chugwater, and Goose Egg Formations, and, east of fault in T. 19 N., Casper Formation (Lower Creatceous through Middle Pennsylvanian). NUGGET SANDSTONE in south--Gray to dull-red, massive to coarsely crossbedded quartz sandstone.
Middle and Lower Eocene Rocks (Phanerozoic | Cenozoic | Tertiary | Eocene-Early Eocene-Middle)
MIDDLE AND LOWER EOCENE ROCKS--Equivalent to Aycross (Ta) and Wind River (Twdr) Formations. AYCROSS FORMATION (ABSAROKA VOLCANIC SUPERGROUP: THOROFARE CREEK GROUP)--Brightly variegated bentonitic claystone and tuffaceous sandstone, grading laterally into greenish-gray sandstone and claystone. In and east of Jackson Hole contains gold-bearing lenticular quartzite conglomerate. WIND RIVER FORMATION--Variegated claystone and sandstone; lenticular conglomerate.
Mowry and Thermopolis Shales (Phanerozoic | Mesozoic | Cretaceous-Early)
MOWRY (Kmr) AND THERMOPOLIS SHALES. MOWRY SHALE (AGE 94 TO 98 Ma)--Silvery-gray hard siliceous shale containing abundant fish scales and bentonite beds. THERMOPOLIS SHALE--Black soft fissile shale; Muddy Sandstone Member at top.
Niobrara and Frontier Formations, and Mowry and Thermopolis Shales (Phanerozoic | Mesozoic | Cretaceous-Early Cretaceous-Middle(?) Cretaceous-Late)
NIOBRARA (Kn) AND FRONTIER (Kf) FORMATIONS, AND MOWRY (Kmr) AND THERMOPOLIS SHALES. NIOBRARA FORMATION (AGE ABOUT 83 Ma)--Light-colored limestone and gray to yellow speckled limy shale. FRONTIER FORMATION--Gray sandstone and sandy shale. MOWRY SHALE (AGE 94 TO 98 Ma)--Silvery-gray hard siliceous shale containing abundant fish scales and bentonite beds. THERMOPOLIS SHALE--Black soft fissile shale; Muddy Sandstone Member at top.
Pass Peak Formation and Equivalents (Phanerozoic | Cenozoic | Tertiary | Eocene)
PASS PEAK FORMATION AND EQUIVALENTS--Includes Lookout Mountain Conglomerate Member of Wasatch Formation. On the south side of Gros Ventre Range consists of gold-bearing quartzite conglomerate; intertongues southward with sandstone and claystone of main body of Wasatch Formation.
Salt Lake Formation (Phanerozoic | Cenozoic | Tertiary | Miocene Pliocene)
SALT LAKE FORMATION--White, gray, and green limy tuff, siltstone, sandstone, and conglomerate.
Shooting Iron Formation (Phanerozoic | Cenozoic | Tertiary | Pliocene)
SHOOTING IRON FORMATION--Greenish-gray to pink tuffaceous lacustrine and fluviatile claystone and siltstone, fine-grained sandstone, and conglomerate.
Steele Shale and Niobrara Formations (Phanerozoic | Mesozoic | Cretaceous-Late)
STEELE SHALE (Ks) AND NIOBRARA FORMATIONS (Kn). STEELE SHALE (AGE ABOUT 78 TO 82 Ma)--Gray soft marine shale containing numerous bentonite beds and thin lenticular sandstone. NIOBRARA FORMATION (AGE ABOUT 83 Ma)--Light-colored limestone and gray to yellow speckled limy shale.
Teewinot Formation (Phanerozoic | Cenozoic | Tertiary | Miocene)
TEEWINOT FORMATION (AGE ABOUT 9 Ma)--White lacustrine clay, tuff, and limestone. In thrust belt includes conglomerate.
Transitional unit between Battle Spring and Wasatch Formations (Phanerozoic | Cenozoic | Tertiary | Eocene)
TRANSITIONAL UNIT BETWEEN BATTLE SPRING AND WASATCH FORMATIONS--Contains interbedded lithologies of Battle Spring (Tbs) and Wasatch (Tw2) Formations.
Wasatch Formation (E) (Phanerozoic | Cenozoic | Tertiary | Eocene)
WASATCH FORMATION Kingsbury Conglomerate Member--Conglomerate of Paleozoic clasts, interbedded with drab sandstone and variegated claystone.
Wasatch Formation (TB) (Phanerozoic | Cenozoic | Tertiary | Eocene)
WASATCH FORMATION Diamictite and sandstone--Diamictite grades laterally into other members of the formation.
White River Formation (Phanerozoic | Cenozoic | Tertiary | Oligocene (31-35 Ma))
WHITE RIVER FORMATION (AGE 31 TO 35 Ma)--White to pale-pink blocky tuffaceous claystone and lenticular arkosic conglomerate.
White River Formation--Brule Member (Phanerozoic | Cenozoic | Tertiary | Oligocene )
WHITE RIVER FORMATION Brule Member--Pale-pink to white blocky tuffaceous claystone and lenticular sandstone. Locally includes the Upper Conglomerate Member (Twru).
White River Formation--Chadron Member (Phanerozoic | Cenozoic | Tertiary | Oligocene )
WHITE RIVER FORMATION Chadron Member--Light-gray to dark-red tuffaceous claystone, sandstone, and lenticular conglomerate.
White River Formation--Upper conglomerate member (Phanerozoic | Cenozoic | Tertiary | Oligocene )
WHITE RIVER FORMATION Upper conglomerate member--Light-gray soft conglomeratic tuffaceous sandstone and conglomerate of Precambrian clasts.

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