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Geologic units containing Medium-grained mixed clastic rock

Medium-grained mixed clastic rock
A mixture of clastic sedimentary rocks varying from siltstone to conglomerate, dominated by rocks containing sand-sized particles
This category is also used for medium-grained mixed clastic.
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Michigan - Montana - New Mexico - Texas - Utah - Wyoming

Michigan

Montana

Frontier formation (Phanerozoic | Mesozoic | Cretaceous-Late)
Frontier formation: mainly gray sandy shale; locally Torchlight sandstone member constitutes upper third and thinner Peay sandstone member is at base; contains some thick beds of bentonite.
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.
Kootenai formation and associated rocks (Phanerozoic | Mesozoic | Jurassic Cretaceous-Early)
Kootenai formation and associated rocks: conglomerate, sandstone, shale, and mudstone; purplish and green beds are common; mainly the Kootenai; in southern Montana includes strata that have been mapped as Cloverly formation. Includes Second Cat Creek and Third Cat Creek sands of drillers in central part of State; Sunburst sand of drillers in north-central part; and Cut Bank sand of drillers in western part. As here mapped, may locally include thin units 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.
Ordovician, undifferentiated (Phanerozoic | Paleozoic | Ordovician)
Ordovician, undifferentiated: Mainly Bighorn dolomite; near Idaho, Kinnikinic quartzite.
Tertiary sedimentary rocks, undifferentiated (Phanerozoic | Cenozoic | Tertiary)
Tertiary sedimentary rocks, undifferentiated: clastic deposits in western Montana, mostly in valleys, and in most places not divided into formations; mostly poorly consolidated gravel, sand, silt, and clay; includes some tuffaceous material and locally lenses of lignite and bentonite; a little hot spring tufa; and in areas not yet mapped in detail, lava may be included. These rocks were in part laid down in lakes but a large part was formed in streams and alluvial fans. These rocks are Tertiary in age and as now mapped may even include some beds of Cretaceous age. Some late Tertiary terrace deposits may be included.
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 Mexico

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:
continental red beds (Phanerozoic | Mesozoic | Triassic)
Triassic rocks, undivided; continental red beds
Cutler Formation (Phanerozoic | Paleozoic | Permian)
Cutler Formation; used in northern areas and Chama embayment only
Dakota Group (Phanerozoic | Mesozoic | Cretaceous)
Dakota Group of east-central and northeast New Mexico; in ascending order, Mesa Rica Sandstone, Pajarito Shale, and Romeroville Sandstone; includes the underlying Tucumcari Shale in Tucumcari area and Glencairn Formation in Union County. Encompasses both Upper and Lower Cretaceous rocks
Dakota Sandstone (Phanerozoic | Mesozoic | Cretaceous)
Dakota Sandstone; includes Oak Canyon, Cubero, and Paguate Tongues plus Clay Mesa Tongue of Mancos Shale; Cenomanian
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
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
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
Mississippian and Devonain rocks, undivided (Phanerozoic | Paleozoic | Devonian Carboniferous Mississippian)
Mississippian and Devonian rocks, undivided; includes the Lake Valley Limestone, Caballero, Las Cruces, Rancheria, and Helms Formations and Escabrosa Group; Mississippian; the Onate, Sly Gap, Contadero Formations, and Percha Shale of south-central New Mexico, and Canutillo Formation of Northern Franklin Mountains and Bishops Cap area; Devonian
Mississippian rocks, undivided (Phanerozoic | Paleozoic | Carboniferous Mississippian)
Mississippian rocks, undivided; Arroyo Penasco Group in Sangre de Cristo Mountains, Sierra Nacimiento, San Pedro Mountain, and Sandia Mountains; Lake Valley Limestone in south-central New Mexico
Pennsylvanian rocks, undivided (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian)
Pennsylvanian rocks, undivided; in Sangre de Cristo Mountains may include Sandia Formation, Madera Limestone, La Pasada, Alamitos, and Flechado Formations; elsewhere may include Bar-B, Nakaye, Red House, Oswaldo, and Syrena Formations
Permain and Pennsylvanian rocks, undivided (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian)
Permian and Pennsylvanian rocks, undivided; includes Horquilla Limestone, Earp Formation, Epitaph and Scherrer Formations, and Concha Limestone
San Jose Formation (Phanerozoic | Cenozoic | Tertiary)
San Jose Formation; Eocene, San Juan Basin
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)
sedimentary units, Palogene (Phanerozoic | Cenozoic | Tertiary)
Paleogene sedimentary units; includes Baca, Galisteo, El Rito, Blanco Basin, Love Ranch, Lobo, Sanders Canyon, Skunk Ranch, Timberlake, and Cub Mountain Formations
undivided, Upper Cretaceous (Phanerozoic | Mesozoic | Cretaceous)
Upper Cretaceous, undivided. Includes Virden Formation in northern Hidalgo County, Ringbone Formation in Hidalgo and Luna and Grant Counties, and locally Beartooth and Sarten, Mancos in Silver City area; Cenomanian - Maastrichtian for most part, although Beartooth is pre-Cenomanian
upper Chinle Group (Garita Creek, Trujillo, Bull Canyon, and Redonda Formations) (Phanerozoic | Mesozoic | Triassic)
Upper Chinle Group, Garita Creek through Redonda Formations, undivided

Texas

Utah

Wyoming

Absaroka Volcanic Supergroup: Thoroughfare Creek Group--Tepee Trail Formation (Phanerozoic | Cenozoic | Tertiary | Eocene (44-49 Ma))
ABSAROKA VOLCANIC SUPERGROUP: THOROFARE CREEK GROUP (AGE 44 TO 49 Ma) Tepee Trail Formation (age probably about 48 Ma)--Green and olive-drab hard generally well bedded andesitic conglomerate, sandstone, and claystone.
Blind Bull Formation (Phanerozoic | Mesozoic | Cretaceous-Late)
BLIND BULL FORMATION--Gray to tan conglomeratic sandstone, siltstone, claystone, coal, and bentonite.
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.
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 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.
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.
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.
Oligocene and (or) Upper and Middle Eocene rocks (Phanerozoic | Cenozoic | Tertiary | Eocene Oligocene)
OLIGOCENE AND (OR) UPPER AND MIDDLE EOCENE ROCKS--Light-gray tuff, arkosic sandstone, and lenticular conglomerate.
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.
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 | 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.
Washakie Formation (Phanerozoic | Cenozoic | Tertiary | Eocene (43-44 Ma))
WASHAKIE FORMATION (AGE ABOUT 43 TO 44 Ma)--Gray, green, tan, and dull-red tuffaceous arkosic sandstone and claystone.
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.
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.