Geologic units containing fine-grained mixed clastic

Earth material > Sedimentary rock > Clastic rock

Fine-grained mixed clastic rock

A mixture of clastic sedimentary rocks varying from mudstone to sandstone, dominated by rocks containing clay-sized or silt-sized particles

This category is also used for fine-grained mixed clastic.

Subtopics:
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Kentucky - Mississippi - Montana - New Jersey - New Mexico - Oregon - Texas - Utah - Wyoming

Kentucky

Salem, Warsaw, and Harrodsburg Limestones, undivided (Mississippian): Salem, Warsaw, and Harrodsburg Limestones, undivided

Mississippi

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.

Montana

Colorado shale (Phanerozoic | Mesozoic | Cretaceous-Early Cretaceous-Middle(?) Cretaceous-Late): Colorado shale: dark-gray shale and siltstone with many concretions and sandy units. Includes equivalents of Fall River, Skull Creek, Newcastle, Mowry, Belle Fourche, Greenhorn, Carlile, and Niobrara formations, and locally Telegraph Creek formation. In the less well-known areas beds of other ages may have been included.
Cretaceous volcanic rocks (Phanerozoic | Mesozoic Cenozoic | Cretaceous-Late Tertiary): Cretaceous volcanic rocks: flows and pyroclastic rocks, mainly of intermediate composition with subordinate amounts of interbedded sedimentary rocks. Some of the rocks have been regarded as belonging to the Livingston formation, but this usage is not adopted here. Where data are inadequate for separation, some Tertiary volcanic rocks may be mapped with the Cretaceous volcanic rocks.
Devonian, undifferentiated (Phanerozoic | Paleozoic | Devonian): Devonian, undifferentiated: comprises Three Forks formation consisting of carbonaceous and calcareous shale with some sandstone and limestone, Jefferson limestone, and unnamed units of Devonian age.
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.
Jurassic, undifferentiated (Phanerozoic | Mesozoic | Jurassic): Jurassic, undifferentiated: calcareous shale and sandstone; includes the Morrison formation, the Ellis group, Sundance formation, and other rocks of Jurassic age.
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.
Montana group, undifferentiated (Phanerozoic | Mesozoic | Cretaceous-Late): Montana group, undifferentiated: mainly sandstone and shale, soft and in part poorly consolidated; some coal; shown undivided only in areas where detailed data are lacking and in these areas some rocks not of Montana age may have been included. In particular, rocks designated Km in southwestern Montana may include some Tertiary strata.
Mowry shale (Phanerozoic | Mesozoic | Cretaceous-Early): Mowry shale: chiefly light-gray silicified shale and claystone with minor amounts of sandy shale and sandstone; contains some thick beds of bentonite.
Permian, undifferentiated (Phanerozoic | Paleozoic | Permian): Permian, undifferentiated: chert, sandstone, limestone, quartzite, and shale with rock phosphate mostly at base; mainly Phosphoria formation
Permian, undifferentiated (Phanerozoic | Paleozoic | Permian): Permian, undifferentiated: chert, sandstone, limestone, quartzite, and shale with rock phosphate mostly at base; mainly Phosphoria formation
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.

New Jersey

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).
Passaic Formation gray bed (Lower Jurassic and Upper Triassic): Passaic Formation gray bed - Rhythmic cycles 2 to 7 m (7-23 ft) of thick gray-bed sequences (Trpg), termed Van Houten cycles by Olsen (1985), contain basal thin-bedded to finely laminated shale to siltstone, which grade upward through laminated to micro-laminated, locally calcareous mudstone to siltstone and finally into massive silty mudstone. Lowest part of cycle has some desiccation features and local fossils; middle part has highest organic content and the most fossils; highest part contains mudcracks, burrows, and root casts. Gray-bed cycles are abundant in lower half of Passaic Formation and less common in upper half.
Passaic Formation gray bed (Lower Jurassic and Upper Triassic): Passaic Formation gray bed - Upper Triassic gray lake deposits (Trpg) consist of gray to black silty mudstone, gray and greenish- to purplish-gray argillaceous siltstone, black shale, and medium- to dark-gray, argillaceous, fine-grained sandstone and are abundant in the lower half of the Passaic Formation. Gray lakebeds occur in groups of two to five cycles although they also occur as single cycles in some parts of the formation. Several lakebed sequences consisting of one or two thick groups of drab-colored beds as much as 30 m (98 ft) thick or more can be traced over tens of kilometers. Many gray-bed sequences are locally correlated within fault blocks; some can be correlated across major faults or intrusive rock units. Thickness of the (entire Passaic) formation between Sourland Mountain and Sand Brook syncline is about 3,500 m (11,483 ft).
Passaic Formation Mudstone facies (Lower Jurassic and Upper Triassic): Passaic Formation Mudstone facies - Sandy mudstone (JTrpms) is reddish-brown to brownish-red, massive, silty to sandy mudstone and siltstone, which are bioturbated, ripple cross-laminated and interbedded with lenticular sandstone. To southwest where similar lithologic units also occur, they have not been mapped separately, but have been included in undivided unit JTrp.
Stockton Formation (Upper Triassic): Stockton Formation - Predominantly medium- to coarse-grained, light-gray, light-grayish-brown, or yellowish- to pinkish-gray arkosic sandstone and medium- to fine-grained, violet-gray to reddish-brown arkosic sandstone; with lesser, reddish to purplish-brown, silty mudstone, argillaceous siltstone, and shale. Some coarse-grained sandstone in lower part contains thick beds of conglomerate (Trsc) which have been mapped in the vicinity of Stockton. Sandstone, deposited in high-gradient stream channels, is mostly planar bedded with scoured bases containing pebble lags and mudstone rip-up clasts. Upper part of channel beds are burrowed. Large-scale trough crossbeds occur in some very coarse grained sandstone beds; smaller scale trough and climbing-ripple cross lamination occur in the upper part of channel sequences and in finer grained sandstone beds. Typical floodplain mudstones are irregularly thin bedded and extensively burrowed. Floodplain beds are thicker and more numerous in the central Newark basin, near the Delaware River. Thickness of the unit (including Trsc) near Stockton is about 1,240 m (4,068 ft).
Stockton Formation (Upper Triassic): Stockton Formation (Kummel, 1897) - Light-gray, light-grayishbrown, yellowish- to pinkish-gray, or violet-gray to reddish-brown, medium- to coarse-grained arkosic sandstone and reddish- to purplish-brown mudstone, silty mudstone, argillaceous siltstone, and shale. Mudstone, siltstone and shale beds thicker and more numerous in central Newark basin west of Round Valley Reservoir. Sandstones mostly planar-bedded, with scoured bases containing pebble lags and mudstone rip-ups. Unit is coarser near Newark basin border fault, where poorly exposed, reddish-brown to pinkish-white, medium- to coarse-grained, feldspathic pebbly sandstone and conglomerate (Trss) and pebble to cobble quartzite conglomerate (Trscq). Maximum thickness of formation about 1,240 m (4,070 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

Abo and Yeso Formations (Phanerozoic | Paleozoic | Permian): Abo and Yeso Formations, undivided
Artesia Group (Phanerozoic | Paleozoic | Permian): Artesia Group; shelf facies forming broad south-southeast trending outcrop from Glorieta to Artesia area; includes Grayburg, Queen, Seven Rivers, Yates, and Tansill Formations; Guadalupian. May locally include Moenkopi Formation (Triassic) at top
Carlile Shale (Phanerozoic | Mesozoic | Cretaceous): Carlile Shale; limited to northeastern area; Turonian-Coniacian
Chinle Group (Phanerozoic | Mesozoic | Triassic): Chinle Group; Upper Triassic; includes Moenkopi Formation (Middle Triassic) at base in many areas; in eastern part of state the following five formations are mapped:
Crevasse Canyon Formation (Phanerozoic | Mesozoic | Cretaceous): Crevasse Canyon Formation; coal-bearing units are Dilco and Gibson Coal Members; other members are Bartlett Barren, Dalton Sandstone, and Borrego Pass Sandstone (or Lentil)
Graneros Shale (Phanerozoic | Mesozoic | Cretaceous): Graneros Shale; limited to northeastern area; Cenomanian
Greenhorn Formation and Carlile Shale (Phanerozoic | Mesozoic | Cretaceous): Greenhorn Formation and Carlile Shale, undivided; locally includes Graneros Shale
intertongued Dakota-Mancos sequence (Phanerozoic | Mesozoic | Cretaceous): Intertongued Dakota-Mancos sequence of west-central New Mexico; includes the Whitewater Arroyo Tongue of Mancos Shale and the Twowells Tongue of the Dakota
Lewis Shale (Phanerozoic | Mesozoic | Cretaceous): Lewis Shale; marine shale and mudstone
Madera Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian): Madera Formation (Limestone, or Group); in Manzano Mountains includes Los Moyos Limestone and Wild Cow Formation; in Lucero Mesa includes Gray Mesa, Atrasdo, and Red Tanks Members; in Sacramento Mountains includes Beeman and Holder Formations; may include strata lumped as Magdalena Group in a few areas
Mancos Shale (Phanerozoic | Mesozoic | Cretaceous): Mancos Shale; divided into Upper and Lower parts by Gallup Sandstone
Mancos Shale, lower part (Phanerozoic | Mesozoic | Cretaceous): Mancos Shale, Lower part
Mancos Shale, upper part (Phanerozoic | Mesozoic | Cretaceous): Mancos Shale, Upper part
Menefee Formation (Phanerozoic | Mesozoic | Cretaceous): Menefee Formation; mudstone, shale, and sandstone; coal-bearing
Mesaverde Group (Phanerozoic | Mesozoic | Cretaceous): Mesaverde Group includes the Gallup Sandstone, Crevasse Canyon Formation, Point Lookout Sandstone, Menefee Formation, and Cliff House Sandstone
Morrison Formation (Phanerozoic | Mesozoic | Jurassic): Morrison Formation; Upper Jurassic nonmarine rocks present only in northern one-third of state
Morrison Formation and upper San Rafael Group (Phanerozoic | Mesozoic | Jurassic): Morrison Formation and upper San Rafael Group
Panther Seep Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian): Panther Seep Formation; Organ, Franklin, and San Andres Mountains
Pierre Shale and Niobrara Formation (Phanerozoic | Mesozoic | Cretaceous): Pierre Shale and Niobrara Formation
Rustler Formation (Phanerozoic | Paleozoic | Permian): Rustler Formation; siltstone, gypsum, sandstone, and dolomite; Upper Permian
San Andres Formation (Phanerozoic | Paleozoic | Permian): San Andres Formation; limestone and dolomite with minor shale; Guadalupian in south, in part Leonardian to north
San Andres Limestone and Glorieta Sandstone (Phanerozoic | Paleozoic | Permian): San Andres Limestone and Glorieta Sandstone; Guadalupian and Leonardian
Sangre de Cristo Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian): Sangre de Cristo Formation, in Sangre de Cristo Mountains
San Rafael Group (Phanerozoic | Mesozoic | Jurassic): San Rafael Group; consists of Entrada Sandstone, Todilto and Summerville Formations, Bluff Sandstone, and locally Zuni Sandstone (or only Acoma Tongue of Zuni)
Seven Rivers Formation (Phanerozoic | Paleozoic | Permian): Seven Rivers Formation; gypsum, anhydrite, salt, dolomite, and siltstone; Guadalupian
Trujillo Formation of Chinle Group (Phanerozoic | Mesozoic | Triassic): Trujillo Formation; Norian
upper Chinle Group (Garita Creek, Trujillo, Bull Canyon, and Redonda Formations) (Phanerozoic | Mesozoic | Triassic): Upper Chinle Group, Garita Creek through Redonda Formations, undivided
Yates and Tansill Formations (Phanerozoic | Paleozoic | Permian): Yates and Tansill Formations; sandstone, siltstone, limestone, dolomite, and anhydrite; Guadalupian
Yeso, Glorieta, and San Andres Formations, undivided (Phanerozoic | Paleozoic | Permian): Yeso, Glorieta and San Andres Formations, undivided
Zuni and Entrada Sandstones (Phanerozoic | Mesozoic | Jurassic): Zuni and Entrada Sandstones, undivided

Oregon

Sedimentary and volcanic rocks, partly metamorphosed (Permian and Permian?) (Permian): Epiclastic and volcaniclastic rocks, chert, limestone, and lava flows of mid- or Early Permian(?) age that are moderately to intensely metamorphosed. Includes part of Hunsaker Creek Formation of Vallier (1977), in the eastern Blue Mountains province, composed mostly of keratophyre flows, keratophyric volcaniclastic rocks and minor spilite, mudstone, and limestone. In Wheeler County, includes phyllite, chert, and fusulinid-bearing crystalline limestone of probable Early Permian (Wolfcampian?) age (Oles and Enlows, 1971), associated with phyllite, chlorite, and muscovite schist, and lawsonite-crossite blueschist (Swanson, 1969b)

Texas

Canyon Group, undivided (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Late [Missouri]): Canyon Group, undivided
Chinle Formation (Phanerozoic | Mesozoic | Triassic-Late): Chinle Formation
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
Dewey Lake Red beds (Phanerozoic | Paleozoic | Permian [Ochoa]): Dewey Lake Red beds
Dockum Group, undivided (Phanerozoic | Mesozoic | Triassic-Late): Dockum Group
Eagle Ford Formation and Buda Limestone, undivided (Phanerozoic | Mesozoic | Cretaceous-Late): Eagle Ford Formation and Buda Limestone, undivided
Gaptank Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Early Pennsylvanian-Middle Pennsylvanian-Late): Gaptank Formation
Haymond Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Early): Haymond Formation
Indio Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene): Indio Formation
Jasper Creek Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Late [Missouri]): Jasper Creek Formation
Midway Group, undivided (Phanerozoic | Cenozoic | Tertiary | Paleocene): Midway Group, undivided
Navarro and Taylor Groups, undivided (Phanerozoic | Mesozoic | Cretaceous-Late [Gulfian]): Navarro and Taylor Groups, undivided
Navarro Group and Marlbrook Marl, undivided (Phanerozoic | Mesozoic | Cretaceous-Late [Gulfian]): Navarro Group and Marlbrook Marl, undivided
Reklaw Formation, Carrizo Sand, and Wilcox and Midway Groups, undivided (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene): Reklaw Formation, Carrizo Sand, and Wilcox and Midway Groups, undivided
Smithwick Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Middle [Atoka]): Smithwick Formation
Tecovas Formation (Phanerozoic | Mesozoic | Triassic-Late): Tecovas Formation
Tesnus Formation (Phanerozoic | Paleozoic | Carboniferous Mississippian-Late Pennsylvanian-Early): Tesnus Formation
Trujillo Formation (Phanerozoic | Mesozoic | Triassic-Late): Trujillo Formation
upper Cretaceous rocks, undivided (Phanerozoic | Mesozoic | Cretaceous-Late): upper Cretaceous rocks, undivided
Ventioner Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian [Missouri]): Ventioner Formation
Victorio Peak Formation (Phanerozoic | Paleozoic | Permian [Leonard]): Victorio Peak Formation
Wilcox Group, undivided (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene): Wilcox Group, undivided

Utah

Cretaceous (3) sedimentary rocks in southwestern Utah (Late Cretaceous)
Cretaceous and Tertiary sedimentary rocks in central Utah (Late Cretaceous to Eocene)
Cretaceous and Tertiary sedimentary rocks in southeastern Utah (Late Cretaceous to Paleocene)
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)
Jurassic (2) sedimentary rocks in central Utah (Late Jurassic)
Mississippian (3) sedimentary rocks in western Utah (Mississippian)
Ordovician sedimentary rocks in western Utah (Ordovician)
Pennsylvanian sedimentary rocks in central Utah (Pennsylvanian)
Permian (1) sedimentary rocks in southeastern Utah (Pennsylvanian to Early 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)
Permian (2) sedimentary rocks in western Utah (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 (1) sedimentary rocks in Uinta Mountains-Unita Basin region (Early to Middle Eocene)
Tertiary (2) sedimentary rocks in central Utah (Eocene)
Tertiary (2) sedimentary rocks in Salt Lake City-Coalville-Randolph region (Eocene)
Tertiary (2) sedimentary rocks in southwestern Utah (Eocene)
Tertiary (2) sedimentary rocks in Uinta Mountains-Uinta Basin region (Eocene)
Younger Precambrian metamorphic rocks in Logan-Huntsville Allochthon (Proterozoic Z)

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.
Absaroka Volcanic Supergroup: Thoroughfare Creek Group--Aycross Formation (Phanerozoic | Cenozoic | Tertiary | Eocene (44-49 Ma)): ABSAROKA VOLCANIC SUPERGROUP: THOROFARE CREEK GROUP (AGE 44 TO 49 Ma) Aycross Formation (age 49 Ma)--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.
Adaville Formation (Phanerozoic | Mesozoic | Cretaceous-Late): ADAVILLE FORMATION--Gray sandstone, siltstone, and carbonaceous claystone; conglomeratic in upper part; coal-bearing in lower part.
Ankareh Formation, Thaynes Limestone, Woodside Shale, and Dinwoody Formation (Phanerozoic | Mesozoic | Triassic-Early Triassic-Middle(?) Triassic-Late): ANKAREH FORMATION, THAYNES LIMESTONE, WOODSIDE SHALE, AND DINWOODY FORMATION. ANKAREH FORMATION--Red and maroon shale and purple limestone. THAYNES LIMESTONE--Gray limestone and limy siltstone. WOODSIDE SHALE--Red siltstone and shale. DINWOODY FORMATION--Gray to olive-drab dolomitic siltstone.
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.
Carlile Shale (Phanerozoic | Mesozoic | Cretaceous-Late): CARLILE SHALE--Dark-gray sandy shale; Sage Breaks Member at top; Turner Sandy Member in middle.
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.
Cloverly, Morrison, Sundance, and Gypsum Spring Formations and Nugget Sandstone (Phanerozoic | Mesozoic | Triassic(?) Jurassic(?) Cretaceous-Early): CLOVERLY, MORRISON, AND SUNDANCE (Js), GYPSUM SPRING FORMATIONS, AND NUGGET SANDSTONE (J@n). 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. NUGGET SANDSTONE--Gray to dull-red, crossbedded quartz sandstone.
Coalmont Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene): COALMONT FORMATION (EOCENE AND PALEOCENE)--Tan to gray arkosic micaceous soft sandstone, claystone, and locally derived conglomerate.
Devils Basin Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene ): DEVILS BASIN FORMATION--Light-gray sandstone interbedded with green and gray claystone; sparse coal and carbonaceous shale.
Fort Union Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene ): FORT UNION FORMATION Tongue River (Tftr) and Lebo (Tfl) Members.
Fort Union Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene ): FORT UNION FORMATION Lebo (Tfl) and Tullock (Fft) Members.
Fowkes Formation (Phanerozoic | Cenozoic | Tertiary | Eocene): FOWKES FORMATION--Light-colored tuffaceous sandstone and siltstone, locally conglomeratic. Locally designated by some as Norwood Tuff.
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: Fontenelle Tongue or Member [NONE ON MAP] (Phanerozoic | Cenozoic | Tertiary | Eocene): WASATCH AND GREEN RIVER FORMATIONS: New Fork Tongue (dull-red and green mudstone, brown sandstone, and thin limestone beds, merging southward in T. 23 N. with other units) of Wasatch and Fontenelle Tongue or Member (oil shale, marlstone, limestone, and siltstone; occurs along Green and New Fork Rivers and on west side of Green River Basin from T. 33 N. south to and lensing out in T. 17 N.) of Green River.
Green River Formation: Luman Tongue (Phanerozoic | Cenozoic | Tertiary | Eocene): GREEN RIVER FORMATION Luman Tongue--Oil shale, carbonaceous shale, and sandstone.
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).
Gypsum Spring Formation and Nugget Sandstone (Phanerozoic | Mesozoic | Triassic-Early Triassic-Middle(?) Triassic-Late(?) Jurassic-Early(?) Jurassic-Middle(?) Jurassic-Late): GYPSUM SPRING FORMATION AND NUGGET SANDSTONE. GYPSUM SPRING FORMATION--Interbedded red shale, dolomite, and gypsum. In north Wyoming wedges out south in T. 39 N. NUGGET SANDSTONE--gray to dull-red, crossbedded quartz sandstone.
Gypsum Spring Formation, Nugget Sandstone, and Chugwater Formation (Phanerozoic | Mesozoic | Triassic-Early Triassic-Middle(?) Triassic-Late(?) Jurassic-Early(?) Jurassic-Middle(?) Jurassic-Late): GYPSUM SPRING FORMATION, NUGGET SANDSTONE, AND CHUGWATER FORMATION. GYPSUM SPRING FORMATION--Interbedded red shale, dolomite, and gypsum. In north Wyoming wedges out south in T. 39 N. NUGGET SANDSTONE--gray to dull-red, crossbedded quartz sandstone. CHUGWATER FORMATION--Red siltstone and shale. Alcova Limestone Member in upper middle part in north Wyoming. Thin gypsum partings near base in north and northeast Wyoming.
Hanna Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene ): HANNA FORMATION--Brown and gray sandstone, shale, conglomerate, and coal; giant quartzite boulders near Medicine Bow Mountains.
Hoback Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene ): HOBACK FORMATION--Interbedded drab and gray sandstone and claystone. Locally contains thick red and gray conglomerate.
Indian Meadows Formation (Phanerozoic | Cenozoic | Tertiary | Eocene): INDIAN MEADOWS FORMATION--Red to variegated claystone, sandstone, and algal-ball(?) limestone; some beds of large Paleozoic boulders and detachment masses of Paleozoic and Mesozoic rocks.
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.
Kootenai and Morrison Formations and Ellis Group (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late(?) Cretaceous-Early): KOOTENAI AND MORRISON FORMATIONS AND ELLIS GROUP. KOOTENAI FORMATION--Rusty thin-bedded sandstone, grayish-red soft claystone, white limestone, and chert-pebble conglomerate. MORRISON FORMATION in northern Yellowstone area--Variegated silty claystone and fine-grained sandstone. ELLIS GROUP includes SWIFT, RIERDON, and SAWTOOTH FORMATIONS. Swift Formation--Calcareous glauconitic sandstone and sandy limestone. Rierdon Formation--Mudstone, siltstone, shale, and basal limestone. Sawtooth Formation--Red beds and limestone.
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.
Lower Miocene and Upper Oligocene rocks, or Rocks equivalent to Upper and Lower Miocene AND White River Formation (Phanerozoic | Cenozoic | Tertiary | Oligocene-Late Miocene-Early(?) Miocene-Middle(?) Miocene-Late): LOWER MIOCENE AND UPPER OLIGOCENE ROCKS--Light-colored soft porous sandstone and underlying white tuffaceous claystone and siltstone. Arikaree Formation in Denver Basin; ROCKS EQUIVALENT TO UPPER AND LOWER MIOCENE ROCKS AND WHITE RIVER FORMATION--Light-colored sandstone, white tuffaceous blocky claystone, and siltstone. Black Hills.
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.
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.
Niobrara Formation (Phanerozoic | Mesozoic | Cretaceous-Late): NIOBRARA FORMATION (AGE ABOUT 83 Ma)--Light-colored limestone and gray to yellow speckled limy shale.
Niobrara Formation and Carlile Shale (Phanerozoic | Mesozoic | Cretaceous-Late): NIOBRARA FORMATION (Kn) AND CARLILE SHALE (Kcl). NIOBRARA FORMATION (AGE ABOUT 83 Ma)--Light-colored limestone and gray to yellow speckled limy shale. CARLILE SHALE--Dark-gray sandy shale; Sage Breaks Member at top; Turner Sandy Member in middle.
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.
Stump Formation, Preuss Sandstone or Redbeds, and Twin Creek Limestone (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late): STUMP FORMATION, PREUSS SANDSTONE or REDBEDS, and TWIN CREEK LIMESTONE. STUMP FORMATION--Glauconitic siltstone, sandstone, and limestone. PREUSS SANDSTONE OR REDBEDS--Purple, maroon, and reddish-gray sandy siltstone and claystone; contains salt and gypsum in thick beds in some subsurface sections. TWIN CREEK LIMESTONE--Greenish-gray shaly limestone and limy siltstone. Includes Gypsum Spring Member.
Tatman Formatin (Phanerozoic | Cenozoic | Tertiary | Eocene): TATMAN FORMATION--Drab nontuffaceous claystone, oil shale, lignite, and sandstone.
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 (SW) (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene): WASATCH FORMATION Main body--Drab sandstone, drab to variegated claystone and siltstone; locally derived conglomerate around basin margins. Lower part is Paleocene.
Wasatch Formation (SW) (Phanerozoic | Cenozoic | Tertiary | Eocene): WASATCH FORMATION Cathedral Bluffs Tongue--Variegated claystone and lenticular sandstone; conglomeratic near south margin of Wind River Range.
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.
Willwood Formation (Phanerozoic | Cenozoic | Tertiary | Eocene): WILLWOOD FORMATION--Variegated claystone, shale, and sandstone; some lenticular gold-bearing quartzite conglomerate.
Wind River Formation and Indian Meadows Formations (Phanerozoic | Cenozoic | Tertiary | Eocene): WIND RIVER AND INDIAN MEADOWS FORMATIONS. WIND RIVER FORMATION Central Wyoming (Twdr2)--Variegated claystone and sandstone; lenticular conglomerate. Age of tuff at top 49 Ma. INDIAN MEADOWS FORMATION (Twim)--Red to variegated claystone, sandstone, and algal-ball(?) limestone; some beds of large Paleozoic boulders and detachment masses of Paleozoic and Mesozoic rocks.

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