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Geologic units containing claystone

Alabama

Claiborne Group; Tallahatta Formation (Eocene)

Tallahatta Formation - (Claiborne group), White to very light-greenish-gray thin-bedded to massive siliceous claystone; interbedded with thin layers of fossiliferous clay, sandy clay, and glauconitic sand and sandstone. White to light-greenish-gray fine to coarse sand and fine gravel occur at the base of the formation in southwest Alabama (Meridian Sand Member).

Fort Payne Chert (Mississippian)

Fort Payne Chert - Very light to light-olive-gray, thin to thick-bedded fine to coarse-grained bioclastic (abundant pelmatozoans) limestone containing abundant nodules, lenses and beds of light to dark-grey chert. Upper part of formation locally consists of light-bluish-gray laminated siltstone containing vugs lined or filled with quartz and scattered throughout the formation are interbeds of medium to greenish-gray shale, shaly limestone and siltstone. Commonly present below the Fort Payne is a light-olive-gray claystone or shale (Maury Formation) which is mapped with the Fort Payne. The apparent thickness of the Fort Payne in this province varies due to differnetial dissolution of carbonate in the formation.

Fort Payne Chert (Mississippian)

Fort Payne Chert - Very light to light-olive-gray, thin to thick-bedded fine to coarse-grained bioclastic (abundant pelmatozoans) limestone containing abundant nodules, lenses and beds of light to dark-grey chert. Upper part of formation locally consists of light-bluish-gray laminated siltstone containing vugs lined or filled with quartz and scattered throughout the formation are interbeds of medium to greenish-gray shale, shaly limestone and siltstone. Commonly present below the Fort Payne is a light-olive-gray claystone or shale (Maury Formation) which is mapped with the Fort Payne.

Tuscumbia Limestone and Fort Payne Chert undivided (Mississippian)

Tuscumbia Limestone and Fort Payne Chert undivided - Tuscumbia Limestone -- light-gray partly oolitic limestone; very coarse bioclastic crinoidal limestone common; light-gray chert nodules and concretions locally abundant. Fort Payne Chert -- very light to light-olive-gray, thin to thick-bedded fine to coarse-grained bioclastic (abundant pelmatozoans) limestone containing abundant nodules, lenses and beds of light to dark-grey chert. Upper part of formation locally consists of light-bluish-gray laminated siltstone containing vugs lined or filled with quartz and scattered throughout the formation are interbeds of medium to greenish-gray shale, shaly limestone and siltstone. Lenses of dark-gray siliceous shale occur locally at the base of the Fort Payne in Wills Valley. Commonly present below the Fort Payne is a ligh-olive-gray claystone or shale (Maury Formation) which is mapped with the Fort Payne. The Tuscumbia and Fort Payne are undifferentiated in Murphrees and Wills Valleys.

Wilcox Group; Nanafalia Formation (Paleocene)

Nanafalia Formation - (Wilcox Group), Members of the Nanafalia Formation follow in descending order. Grampian Hills Member - medium-gray massive clay, claystone, sandy fossiliferous clay, and fossiliferous fine sand. "Ostrea thirsae beds" - glauconitic, abundantly fossiliferous, quartzose fine to medium sand. Gravel Creek Sand Member - pale-yellowish-orange to moderate-reddish-brown micaceous cross-bedded fine to very coarse sand containing gravel and clay pebbles in some exposures. Gravel Creek Member is absent locally and near the base may contain thin beds of lignite. Updip deposits in northern Henry County and southern Barbour County include beds of alternating medium-gray and white clay, carbonaceous clay, white and grayish-yellow fine to coarse sand and lenses of bauxite and bauxitic clay. Sand beds commonly are cross-bedded, gravelly, and contain numerous clay pebbles. The sequence of beds is often obscured by weathering and the collapse of beds into sinkholes in the underlying Clayton Formation.

Arizona

Cretaceous sedimentary rocks (Cretaceous)

Tan sandstone (Dakota Sandstone) overlain by gray shale (Mancos Shale); deposited in beach, river delta, and shallow sea settings. The Mancos Shale is overlain by the Mesaverde Group (map unit Kmv). This unit includes related sandstone and shale exposed near Show Low, Morenci (Pinkard Formation), and around Deer Creek south of Globe. (about 88-97 Ma)

Middle Proterozoic sedimentary rocks (Middle Proterozoic)

Red-brown shale and sandstone, buff to orange quartzite, limestone, basalt, black shale, and sparse conglomerate. This unit includes the Grand Canyon Supergroup, Apache Group, and Troy Quartzite. These rocks were deposited in shallow marine, coastal nonmarine, and fluvial settings. (700-1300)

Moenkopi Formation (Early and Middle(?) Triassic)

Dark red sandstone and mudstone; includes gypsum beds in northwestern Arizona; deposited on a low-relief coastal plain. (230-245 Ma)

Pliocene to late Miocene basaltic rocks (Late Miocene to Pliocene)

Mostly dark, inconspicuously flat, low-lying or mesa-forming basalt deposited as lava flows. Rocks included in this unit are located almost entirely in the large volcanic fields south and west of Flagstaff, in smaller fields in northwesternmost Arizona, and in the Hopi Buttes volcanic field on the Navajo and Hopi Indian Reservations north of Holbrook. Original volcanic landforms have been obscured by erosion. (4-8 Ma)

Shinarump Conglomerate Member, Chinle Formation (Late Triassic)

Basal conglomerate and pebbly sandstone of the Chinle Formation is relatively resistant to erosion and forms extensive benches in some parts of the Colorado Plateau. (210-230 Ma)

California

Pliocene marine rocks (Miocene to Pleistocene)

Sandstone, siltstone, shale, and conglomerate; in part Pleistocene and Miocene.

Plio-Pleistocene and Pliocene loosely consolidated deposits (Miocene to Pleistocene)

Pliocene and/or Pleistocene sandstone, shale, and gravel deposits; in part Miocene.

Colorado

Bridger Fm (Phanerozoic | Cenozoic | Tertiary)

Claystone and mudstone; in Sand Wash basin

Green River Fm--Laney Member (Phanerozoic | Cenozoic | Tertiary)

Claystone, oil shale, and sandstone; in Sand Wash basin

Green River Fm--Tipton Tongue (Phanerozoic | Cenozoic | Tertiary)

Claystone and oil shale; in Sand Wash basin. In extreme northwest includes rocks of Wilkins Peak Member

Laramie Fm (Phanerozoic | Mesozoic | Cretaceous)

Shale, claystone, sandstone, and major coal beds

Wasatch Fm (Phanerozoic | Cenozoic | Tertiary)

Claystone, shale, and sandstone

Wasatch Fm--Cathedral Bluffs Tongue (Phanerozoic | Cenozoic | Tertiary)

Claystone, mudstone, and sandstone; in Sand Wash basin

White River Fm or Group (Phanerozoic | Cenozoic | Tertiary)

East: Ashy claystone and sandstone. Includes Castle Rock Conglomerate in region southeast of Denver. Northwest: Ashy claystone in North Park

Florida

Alum Bluff Group (Miocene)

Alum Bluff Group - West of the Apalachicola River, the Hawthorn Group is replaced by the Alum Bluff Group. The Alum Bluff Group includes the Chipola Formation, Oak Grove Sand, Shoal River Formation, Choctawhatchee Formation and the Jackson Bluff Formation (Huddlestun, 1984; Braunstein et al., 1988). The formations included in this group are generally defined on the basis of their molluscan faunas and stratigraphic position (Schmidt and Clark, 1980). Puri (1953) described sediment facies as they relate to the formations of the Alum Bluff Group These sediments are lithologically distinct as a group, not as individual units. Brooks (1982) mapped much of the Alum Bluff Group as the Shoal River Formation. The Alum Bluff Group crops out or is beneath a thin overburden in the western panhandle from river valleys in Okaloosa County eastward to western Jackson County. The Alum Bluff Group consists of clays, sands and shell beds which may vary from fossiliferous, sandy clays to unfossiliferous sands and clays and occasional carbonate beds (Huddlestun, 1984). Mica is a common constituent and glauconite and phosphate occur sporadically. Induration varies from essentially nonindurated in sands to well indurated in carbonate lenses. Colors range from cream to olive gray with mottled reddish brown in weathered sections. Sand grain size varies from very fine to very coarse with sporadic occurrences of gravel. These sediments generally have low permeabilities and are part of the intermediate confining unit/aquifer system.

Residuum on Miocene sediments (Miocene)

Residuum on Miocene sediments - The undifferentiated Miocene residuum, mapped on parts of the Chattahoochee "Anticline", characteristically consists of reddish brown, variably sandy clay with inclusions of variably fossiliferous, silicified limestone. The residuum includes Lower to Upper Miocene and younger weathered sediments.

Georgia

Neogene undifferentiated (Neogene)

Neogene undifferentiated, includes Altamaha Grit (Dall, 1892); Citronelle Formation (Matson & Berry, 1916); and "Hawthorn Formation" (Cooke, 1939). (*) - outcrops of indurated sandstone and claystone

Iowa

Cherokee Group (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Middle [Des Moines])

Cyclic deposits with carbonaceous shale, clay, siltstone, with lesser sandstone, and thick coal beds; minor but persistent limestone beds; may include parts of Atoka or Morrow Series.

Idaho

Sandstone, conglomerate, siltstone, tuff, claystone, limestone, and diatomite; Pliocene tuffaceous alluvial and lacustrine deposits; Snake River Plain and vicinity, southeastern Idaho (Pliocene )

Pliocene stream and lake deposits; may be due to volcanic and block-faulting events.

Tuffaceous shale, sandstone, conglomerate, and lignite; Eocene to Pliocene alluvial and lacustrine deposits; central and southern Idaho (Tertiary)

Tertiary continental sediments; predominantly Upper Tertiary in age; subdivisions are:(Tpd, Tmd, and Ted).

Tuff, arkose, claystone, siltstone, conglomerate, lignite; Miocene alluvial and lacustrine deposits (Miocene)

Miocene stream and lake deposits; generally associated with volcanic episodes.

Illinois

Caseyville Formation (Pennsylvanian)

Caseyville

Kansas

Dakota Formation (Phanerozoic | Mesozoic | Cretaceous-Early)

White, gray, red, brown and tan kaolinitic claystone, mudstone, shale and siltstone interbedded with grayish to yellowish brown thick lenticular sandstone beds. It also contains lignite and sandstone is commonly well cemented with iron oxide and calcite.

Ogallala Formation (Phanerozoic | Cenozoic | Tertiary | Miocene)

massive to cross-bedded, generally arkosic sand, silt and gravel, locally cemented with calcium carbonate; also contains limestone, volcanic ash, diatomaceous marl, opaline sandstone and bentonitic clay

Maryland

Allegheny Formation and Pottsville Formation (Pennsylvanian)

Allegheny Formation - Interbedded sandstone, siltstone, claystone, shale, and coal beds; Upper Freeport coal at top; where present, Brookville coal defines base; thickness 275 feet in northeast, increases to 325 feet in south and west. And Pottsville Formation - Interbedded sandstone, siltstone, claystone, shale, and coal beds; conglomeratic orthoquartzite and protoquartzite at base; thickness 60 feet in northeast, increases to 440 feet in southwest

Conemaugh Formation (Pennsylvanian)

Conemaugh Formation - Includes the rocks between the base of the Pittsburgh coal and the top of the Upper Freeport coal; consists of two unnamed members which are separated by the Barton coal; both members are gray and brown claystone, shale, siltstone and sandstone, with several coal beds; lower member also contains redbeds and fossiliferous marine shales; thickness 825 to 925 feet.

Monongahela Formation (Pennsylvanian)

Monongahela Formation - Interbedded claystone, argillaceous limestone, shale, sandstone, and coal beds; Waynesburg coal at top; Pittsburg coal at base; thickness 240 feet in west, increases to 375 feet in east.

Minnesota

North Range Group; Mahnomen Formation (Early Proterozoic)

North Range Group; Mahnomen Formation - Claystone, shale, siltstone, and graywacke metamorphosed to the greenschist facies

Sioux Quartzite (Early Proterozoic)

Sioux Quartzite - Red quartzite of fluvial to possibly marginally marine origin. Includes quartz-pebble conglomerate, claystone (catlinite, also called pipestone), a basal (rhyolite) pebble conglomerate in Pipestone County, and a basal (granite, quartz, chert, iron-formation) conglomerate in Nicollet County on the Minnesota River

Mississippi

Tallahatta formation and Neshoba sand (Eocene)

Tallahatta formation and Neshoba sand - (Claiborne group), Southeast of Pearl River predominantly more or less glauconitic claystone and clay with lenses of sand and some sandstone; highly cross-bedded sand at base; northwest of Pearl river predominantly sand, locally glauconitic, containing claystone and clay lenses and abundant clay stringers; Neshoba sand, sparingly glauconitic fairly coarse sand not recognized southeast of Newton County or north of Yalobusha River.

Montana

Wasatch formation (Phanerozoic | Cenozoic | Tertiary)

Wasatch formation: Light-colored massive sandstone; drab-colored shale and coal in southeastern Montana; and variegated, dominantly red beds of clay and sandstone in north-central Montana.

White River formation (Phanerozoic | Cenozoic | Tertiary)

White River formation: Light-colored clay with minor beds of sandstone and local beds of nodular limestone.

Nebraska

White River Group (Phanerozoic | Cenozoic | Tertiary | Oligocene)

Clay, some claystone, silt and siltstone. Predominantly greenish gray and volcaniclastic. Other occurrences are greenish gray to white and bentonitic. Local channel sandstone at base. Aprox thickness 195 ft.

Nevada

Chinle Formation and associated rocks (Late Triassic)

CHINLE FORMATION AND ASSOCIATED ROCKS (Upper Triassic)-Continental deposits of variegated bentonitic claystone, siltstone, and clayey sandstone; ledge-forming sandstone; and red siltstone

Sedimentary rocks (Late Cretaceous to Oligocene)

SEDIMENTARY ROCKS-Includes Sheep Pass Formation (Eocene) and related units and unnamed tuffaceous sedimentary rocks

Shale, mudstone, siltstone, sandstone, and carbonate rock; sparse volcanic rock (Late Triassic to Early Jurassic)

SHALE, MUDSTONE, SILTSTONE, SANDSTONE, AND CARBONATE ROCK; SPARSE VOLCANIC ROCK (Upper Triassic and Lower Jurassic)-Includes Auld Lang Syne Group, Nightingale sequence of Bonham (1969), and Gabbs and Sunrise Formations

Ohio

Allegheny and Pottsville Groups, Undivided (Pennsylvanian)

Allegheny and Pottsville Groups, Undivided - Shale, siltstone, and underclay: Shale, black, gray, and olive; clayey to silty; locally contains marine fossils; calcareous in part. Siltstone, gray, greenish and olive; clayey to sandy; thin bedded to medium bedded; locally contain marine fossils. Underclay, gray and olive; generally 3 feet or less in thickness; clayey to silty; commonly rooted and underlying coal beds; nonbedded; locally varies from flint to plastic clay. Sandstone, light to medium gray weathers to shades of yellow-brown; mostly very fine to medium grained, locally quartzose and conglomeratic in lower one-third of unit; thin to massive to cross bedded; locally calcareous; Limestone, flint and coal. Limestone, black to light gray; micritic to medium grained; locally grades into flint; thin to medium bedded to discoidal concretions containing marine fossils; locally nonmarine, micritic limestones occur beneath coal beds in upper one third of unit. Coal, mostly banded bituminous, locally cannel; thin to locally as much as 12 feet thick; generally in discrete beds but locally contain shale partings and split into multiple beds. Lateral and vertical lithic variability and gradation common. Unit as much as 700 feet thick.

Oklahoma

Bokchito Formation (Phanerozoic | Mesozoic | Cretaceous-Early )

ARDMORE-SHERMAN- Clay, illitic, kaolinitic, with some tan limestones and sandstones. Subdivided into "Pawpaw Clay" at top, 40 to 60 feet thick; "Quarry Limestone," 13 feet thick; "Weno Clay," 100 to 135 feet thick; and basal "Denton Clay," 50 to 70 feet thick.

Oregon

Cowlitz Formation (upper and middle Eocene) (Middle Eocene to Late Eocene)

Micaceous, arkosic to basaltic marine sandstone, siltstone, and mudstone. Foraminiferal assemblages are referred to the upper Narizian Stage of Mallory (1959) in Newton and Van Atta (1976)

Marine sedimentary rocks (lower Miocene and Oligocene) (Oligocene to Early Miocene)

Fossiliferous marine tuffaceous arkosic sandstone, and lesser conglomerate, sandstone, claystone, nonmarine volcanic sedimentary rocks, and minor coal. Molluscan and vertebrate (Cetacea) fossils indicate late Oligocene and Miocene age (Orr and Miller, 1983; Miller and Orr, 1984b). Includes Butte Creek beds of Harper (1946), and several Miocene and late Oligocene units of Miller and Orr (1984a, b)

Pennsylvania

Pottsville Formation (Pennsylvanian)

Pottsville Formation - Predominantly gray sandstone and conglomerate; also contains thin beds of shale, claystone, limestone, and coal; includes Olean and Sharon conglomerates of northwestern Pennsylvania; thin marine limestones present in Beaver, Lawrence, and Mercer Counties; minable coals and commercially valuable high-alumina clays present locally.

South Dakota

Arikaree Group (Phanerozoic | Cenozoic | Tertiary | Eocene Oligocene)

Includes: Rosebud Formation (Miocene)- Pink siltstone with channel sandstone and concretions. Thickness up to 250 ft (76 m). Harrison Formation (Miocene)- Gray, silty sandstone and reworked volcanic ash with calcareous siltstone and marl. Thickness 180 ft (55 m). Turtle Butte Formation (Miocene)- Light-green to gray siltstone with sandstone channels containing claystone pebbles. Thickness 65 ft (20 m). Monroe Creek Formation (Oligocene)- Tan to grayish-tan, massive sandy siltstone and reworked volcanic ash. Thickness 100 ft (30 m). Sharps Formation (Oligocene)- Pink siltstone and claystone with concretionary layers, paleochannels, and beds of reworked volcanic ash. Thickness 360 ft (110 m).

Batesland Formation (Phanerozoic | Cenozoic | Tertiary | Miocene)

Tan to green, calcareous siltstone, claystone, channel sandstone, conglomerate, and arkose. Thickness up to 50 ft (15 m).

Belle Fourche Shale, Mowry Shale, Newcastle Sandstone,and Skull Creek Shale (Phanerozoic | Mesozoic | Cretaceous-Early Cretaceous-Middle(?) Cretaceous-Late)

Note: see individual unit descriptions

Cannonball Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene )

Gray and tan siltstone, sandy to silty claystone, and fine-grained, calcareous clayely to silty sandstone, and abundant, round to lenticular carbonate concretions. Thickness up to 180 ft (55 m).

Greenhorn Formation, Belle Fourche Shale, Mowry Shale, Newcastle Sandstone, Skull Creek Shale, Inyan Kara Group, Morrison Formation, Unkpapa Sandstone, Sundance Formation, Spearfish Formation, Minnekahta Limestone, Opeche Shale, Minnelusa Formation, and Pahasapa Limestone (Phanerozoic | Paleozoic Mesozoic | Carboniferous Mississippian Permian(?) Triassic(?) Jurassic(?) Cretaceous-Early(?) Cretaceous-Middle(?) Cretaceous-Late)

Note: see individual unit descriptions

Ludlow Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene )

White, tan, yellow, and gray, cross-bedded, fine- to medium-grained,silty sandstone interbedded with locally bentonitic, gray siltstone, claystone, and sandy to silty claystone. Characterized by uranium-bearing lignite beds and "clinker" beds fromed by burning coalseams. Thickness up to 420 ft (128 m).

Morrison Formation, Unkpapa Sandstone, Sundance Formation, and Gypsum Spring Formation (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late)

Morrison Formation (Late Jurassic)- Light-gray to green and variegatedred, brown, yellow, or lavender, silceous claystone, shale, and siltstone containing interbedded sandstone and fresh-water limestone lenses. Thickness up to 150 ft (46 m). Unkpapa Sandstone (Late Jurassic)- White, massive to thin-bedded, fine-grained, argillaceous sandstone. May be variegated to banded red, yellow, brown, or lavender. Thickness up to 267 ft (81 m). Sundance Formation (Late to Middle Jurassic)- Greenish-gray, yellow, tan, red to orange, and white, variegated, interbedded, fine- to coarse-grained sandstone, siltstone, clay, and limestone. Thickness 250-350 ft (76-107 m). Gypsum Springs Formation (Middle Jusassic)- Massive white gypsum and minor maroon siltstone and shale. Thickness up to 40 ft (12 m).

Mowry Shale, Newcastle Sandstone, and Skull Creek Shale (Phanerozoic | Mesozoic | Cretaceous-Early )

Mowry Shale- Black to gray, siliceous, fissile shale and siltstone containing bentonite layers, and sparse sandstone dikes and sills. Thickness 125-250 ft (38-76 m). Newcastle Sandstone- Gray, light-brown to yellow, discontinuously distributed siltstone, claystone, sandy shale, and fine-grained sandstone. Thickness up to 290 ft (88 m). Skull Creek Shale- Dark-gray to blueish-gray shale containing ferruginous, and carbonate concretions. Thickness 150-275 ft (46-84 m).

Ogallala Group (Phanerozoic | Cenozoic | Tertiary Quaternary | Miocene Pliocene(?) Pleistocene-Early)

Includes: Ash Hollow Formation- White, tan, and gray, well-cemented, calcareous sandstone and silty limestone often referred to as "mortar beds". Thickness 90-250 ft 27-76 m) Valentine Formation- Gray, unconsolidated, fine- to coarse grained, fluvial siltstone, channel sandstone, and gravel derived from western sources. Thickness 175-225 ft (53-69 m). Fort Randall Formation- Pink and gray claystone with interbedded sandstone. Also includes green to gray orthoquartzite, bentonitic clay, and conglomerate. Thickness up to 130 ft (40 m).

Tongue River Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene )

White, gray, and tan, massive, cross-bedded sandstone with interbedded gray, brown, and green claystone, bentonitic claystone, clayely siltstone, carbonate concretions, and lignite. Thickness up to 285 ft (87 m).

White River Group (Phanerozoic | Cenozoic | Tertiary | Eocene Oligocene)

Includes: Brule Formation (Oligocene)- White, pink, light-green, and light-brown, massive to thin-bedded, bentonitic claystone, tuffaceous siltstone, and well-bedded, calcareous, tuffaceous quartz sandstone. Thickness up to 150 ft (46 m). Chadron Formation (Eocene)- Upper beds are gray, light-brown to maroon bentonite, claystone, siltstone tuffaceous fine-grained sandstone, and local, silicified carbonate lenses. Basal portion consists of poorly cemented, white, coarse-grained arkose and conglomerate. Thickness up to 160 ft (49 m). Chamberlain Pass Formation (Eocene)- Pale olive to pale red, mottled mudstone containing white, cross-bedded channel sandstone with basal conglomerate. Thickness up to 32 ft (10 m). Slim Buttes Formation (Eocene)- White, grayish- to yellowish-orange,pale-red to pink siltstone, clayey siltstone, bentonitic claystone,medium- to fine-grained sandstone, and conglomerate. Thickness up to 48 ft (15 m).

Tennessee

Bays Formation (Ordovician)

Bays Formation - Maroon, well-jointed claystone and siltstone, commonly mottled greenish, evenly bedded; light- gray sandstone beds and metabentonite in upper part. Maximum thickness 1,000 feet.

Bays Formation (Ordovician)

Bays Formation - Maroon claystone and siltstone, commonly mottled greenish, evenly bedded; to northeast, light- gray to white, thick-bedded sandstone; metabentonite in upper part. Maximum thickness 1,000 feet.

Juniata Formation (Ordovician)

Juniata Formation - Maroon, claystone, siltstone, and shale; uniformly bedded; some faint greenish mottling; less calcareous than Sequatchie Formation. Thickness about 300 feet.

Middle and Lower Parts of Chickamauga Group, including Mocassin Formation, Bays Formation, Sevier Shale, Ottosee Shale, Holston Formation, Lenoir Limestone and Athens Shale (Ordovician)

Middle and Lower Parts of Chickamauga Group - A sequence of about 1,400 feet of limestone in the northeast, which thickens and becomes more clastic to the southeast and is divided into the formations shown at right. Maximum thickness about 8,000 feet. Includes Mocassin Formation - Maroon calcareous shale, siltstone, and limestone; thin metabentonite layers in upper part; mud cracks, ripple marks common. Thickness 800 to 1,000 feet; (Ob) Bays Formation - Maroon claystone and siltstone, commonly mottled greenish, evenly bedded; to northeast, light- gray to white, thick-bedded sandstone; metabentonite in upper part. Maximum thickness 1,000 feet. (Osv) Sevier Shale - Calcareous, bluish-gray shale, weathers yellowish-brown; with thin gray limestone layers; sandstone, siltstone, and locally conglomerate to the east. Thickness 2,000 to 7,000 feet; (Oo) - Ottosee Shale - Bluish-gray calcareous shale, weathers yellow; with reef lenses of coarsely crystalline reddish fossiliferous limestone ("marble"). Thickness about 1,000 feet; (Oh) - Holston Formation - Pink, gray, and red coarsely crystalline limestone (Holston Marble); in many areas upper part is sandy, crossbedded ferruginous limestone and brown to greenish calcareous shale. Thickness 200 to 600 feet; (Ol) Lenoir Limestone - Nodular, argillaceous, gray limestone; in places basal sedimentary breccia, conglomerate, quartz sand; Mosheim Limestone Member (dense, light- to medium-gray limestone) near base. Thickness 25 to 500 feet; (Oa) Athens Shale - Medium- to dark-gray, calcareous, graptolitic shale; calcareous gray sandstone, siltstone, and locally fine-pebble quartz conglomerate; nodules of shaly limestone near base. Maximum thickness 1,500 feet.

Middle and Lower parts of Chickamauga Group, including Moccassin Formation, Bays Formation, Sevier Shale, Ottosee Shale, Holston Formation, Lenoir Limestone, and Athens Shale (Ordovician)

Middle and Lower Parts of Chickamauga Group - A sequence of about 1,400 feet of limestone in the northwest part of Valley and Ridge, which thickens and becomes more clastic to the southeast and is divided into the formations shown at right. Maximum thickness about 7,000 feet. Includes Moccasin Formation - Maroon calcareous shale, siltstone, and limestone; thin metabentonite layers in upper part; mud cracks, ripple marks common. Thickness 800 to 1,000 feet;. (Ob) Bays Formation - Maroon, well-jointed claystone and siltstone, commonly mottled greenish, evenly bedded; light- gray sandstone beds and metabentonite in upper part. Maximum thickness 1,000 feet; (Osv) Sevier Shale - Calcareous, bluish-gray shale, weathers yellowish-brown; with thin, gray limestone layers; sandstone, siltstone, and locally conglomerate to the east. Thickness 2,000 to 7,000 feet; (Oo) Ottosee Shale - Bluish-gray calcareous shale, weathers yellow; with reef lenses of coarsely crystalline reddish fossiliferous limestone ("marble"). Thickness about 1,000 feet; (Oh) Holston Formation - Pink, gray, and red coarsely crystalline limestone (Holston Marble); in many areas upper part is sandy, crossbedded ferruginous limestone and brown to greenish calcareous shale. Thickness 200 to 600 feet; (Ol) Lenoir Limestone - Nodular, argillaceous, gray limestone; in places basal sedimentary breccia, conglomerate, quartz sand; Mosheim Limestone Member (dense, light- to medium-gray limestone) near base. Thickness 25 to 500 feet; (Oa) Athens Shale - Medium- to dark-gray, calcareous, graptolitic shale; calcareous gray sandstone, siltstone, and locally fine-pebble quartz conglomerate; nodules of shaly limestone near base. Maximum thickness 1,500 feet.

Texas

Antlers Sand (Phanerozoic | Mesozoic | Cretaceous-Early)

Antlers Sand

Edwards Limestone and Antlers Sand, undivided (Phanerozoic | Mesozoic | Cretaceous-Early)

Edwards Limestone and Antlers Sand, undivided

El Picacho Formation (Phanerozoic | Mesozoic | Cretaceous-Late)

El Picacho Formation

Paluxy Sand and Glen Rose Limestone, undivided (Phanerozoic | Mesozoic | Cretaceous-Early)

Paluxy Sand and Glen Rose Limestone, undivided

Twin Mountains Formation (Phanerozoic | Mesozoic | Cretaceous-Early)

Twin Mountains Formation

Washington

Lower upper Eocene marine and nonmarine rocks (Eocene)

Predominantly massive to well-bedded tuffaceous marine siltstone with interbedded arkosic and basaltic sandstone. Includes conglomerate in King County and along north side of Olympic Peninsula. Minor lava flows and breccia in western Lewis County and eastern Grays Harbor County. Coal seams in central Lewis County and north-central Pierce County.

Miocene nonmarine rocks (Late Miocene)

Poorly to moderately consolidated tuffaceous sandstone, conglomerate, siltstone, and claystone in western Washington. Chiefly clay and shale with minor sand, gravel, and diatomaceous earth near Spokane. Includes diatomite beds near Yakima and Quincy, and some marine beds in Western Washington.

Tertiary nonmarine rocks, undivided (Tertiary; mostly Eocene)

Sandstone, shale, conglomerate, agglomerate, and tuff; includes some lava flows. Massive conglomerate, sandstone, siltstone, and ferruginous shale in northwestern Whatcom County.

Wyoming

Camp Davis Formation (Phanerozoic | Cenozoic | Tertiary | Miocene)

CAMP DAVIS FORMATION--Upper 5,000 ft chiefly red conglomerate and red claystone; underlain by white tuff, limestone, claystone, and basal gray conglomerate.

Cloverly and Morrison Formations (N,S) or Cloverly Formation, Inyan Kara Group, and Morrison Formation (Phanerozoic | Mesozoic | Jurassic-Late Cretaceous-Early)

CLOVERLY FORMATION and MORRISON FORMATION. 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; CLOVERLY FORMATION (Hartville uplift) or INYAN KARA GROUP (Black Hills) and MORRISON FORMATION. CLOVERLY FORMATION--Rusty to light-gray sandstone containing lenticular chert-pebble conglomerate interbedded with variegated bentonitic claystone. INYAN KARA GROUP--Rusty to light-gray sandstone containing lenticular chert-pebble conglomerate interbedded with variegated bentonitic claystone. Includes Fall River and Lakota Formations. MORRISON FORMATION, in northeast Wyoming, dully variegated siliceous claystone, nodular white limestone, and gray silty sandstone.

Harebell Formation (Phanerozoic | Mesozoic | Cretaceous-Late)

HAREBELL FORMATION--Gold-bearing quartzite conglomerate, olive-drab sandstone, and green claystone.

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.

Miocene Rocks (Phanerozoic | Cenozoic | Tertiary | Miocene)

MIOCENE ROCKS--Southwest Wyoming: Southern Rock Springs uplift--Pale-green to tan tuffaceous sandstone and claystone of Miocene(?) age. Conglomerate of uncertain correlation locally at base. Saratoga Valley and west and southwest to Colorado--White massive soft tuffaceous sandstone and lesser amounts of white marl; lower part conglomeratic. Underlies North Park Formation in Saratoga Valley. To the west and southwest is called Browns Park Formation. Rawlins area--White massive soft tuffaceous sandstone; Central Wyoming: White soft tuffaceous sandstone. Locally derived conglomerate in upper and lower parts of sequence; in places lower conglomeratic sequence may be of Oligocene age. In Granite Mountains K/Ar age of tuff in lower part of sandstone sequence about 17 Ma and fission-track age of lower conglomerate about 24 Ma.

Upper Miocene Rocks (Phanerozoic | Cenozoic | Tertiary | Miocene-Late)

UPPER MIOCENE ROCKS--Southwest Wyoming: South end of Wind River Range--Siliceous, arkosic, and locally radioactive sandstone, claystone, and conglomerate. Fission-track age about 27 Ma. Recent work suggests that part of these deposits may be of Eocene age. Pliocene and Miocene (as originally defined 2) South Pass Formation. Saratoga Valley--White to greenish-gray tuffaceous sandstone, siltstone, and claystone; locally conglomeratic. North Park Formation; Central Wyoming: Arkosic sandstone, conglomerate, and siltstone; some light-colored tuffaceous radioactive claystone and white cherty limestone. North of Sweetwater River in Granite Mountains--Light-colored tuffaceous radioactive claystone, siltstone, sandstone, and arkose. Moonstone Formation; East Wyoming: Light-colored tuffaceous claystone, sandstone, and conglomerate. Ogallala Formation in Denver Basin.

Wagon Bed Formation (Phanerozoic | Cenozoic | Tertiary | Eocene (45-49 Ma))

WAGON BED FORMATION (AGE ABOUT 45 TO 49 Ma)--Southwest and central Wyoming--Green and gray tuffaceous claystone, sandstone, and conglomerate; some uranium-phosphate marlstone and variegated bentonitic claystone. Locally contains oil shale between Wind River and Bighorn Basins; Central Wyoming (west side of Laramie Mountains)--Dull-green siliceous bentonitic claystone and tuff; giant granite boulder conglomerate in tuffaceous matrix.

Wind River Formation (Phanerozoic | Cenozoic | Tertiary | Eocene)

WIND RIVER FORMATION Northwest Wyoming (Jackson Hole)--Variegated red and white claystone and siltstone; largely nontuffaceous except near the top; lenticular coal unit in middle. At base locally includes equivalent of Indian Meadows Formation; Central Wyoming--Variegated claystone and sandstone; lenticular conglomerate. Age of tuff at top 49 Ma.