MID-CONTINENT SEA DEPOSITS

Donald Kenney (donaldkenney@gmail.com)
Last Update: Sat Sep 3 05:53:34 2016



Introduction

During the Mesozoic, before the Rocky Mountains arose, a vast depression developed in the mid-continent of North America. It apparently extended from the Gulf of Mexico to the Arctic and from roughly the line of the current Mississippi River on the East to Arizona, Utah, Idaho, and Alberta on the West. Initially, the depression collected lowland sediments, but as time passed, it deepened and marine waters flooded in forming a shallow sea. The mid-continent sea apparently waxed and waned, but toward the end of the Cretaceous, the sea began to shrink as the land started to rise and the sea filled with sediments. The last remnants of the interior seaway are found in Paleocene age deposits of North Dakota and the prairie provinces.

The rocks associated with the mid continent sea are widely exposed in the prairies of Canada and the US as well as in the Rocky Mountains of the US and in the Eastern Great Basin and Colorado Plateau. In the East, they are deposited unconformally on late Paleozoic marine and lowland beds. Further West they are deposited on more heterogeneous rocks including deposits of Triassic and Jurassic continental and marine rocks. Typically, the inland sea beds consist of cyclic deposits of coal and sediment grading into shallow marine deposits of sandstone, shale and limestone that deepen. Later, the process is reversed with shallow water deposits and cyclic coal and sediment. In the Western part of the region, sometimes thick Tertiary deposits cap the inland sea deposits. In the East there is a hiatus followed by mid-Tertiary deposits composed of material eroded from the Rocky Mountains. Further East, deposits become more scattered and there seems to have been little or no subsequent sedimentation.

The deposits are continuous into the Gulf of Mexico Terrane in the SouthEast. I have chosen to place the arbitrary separation between the two regions in Texas roughly along the line of Interstate 20.

The Rocks

I have (somewhat arbitrarily) included some early Mesozoic beds in these rocks even though there can be substantial hiatus between beds in these sequences and there is a long gap between the Jurassic Morrison formation and the more or less continuously deposited beds of the interior seaway.

Missing Formations: Fossils:

Age Rocky Mountains Western Plains Eastern Plains
Oligocene Kishenehn Cypress Hills
Eocene,Upper Swift Current Creek
Paleocene Paskapoo Paskapoo-Porcupine Hills Ravenscrag
Cretaceous,Upper Brazeau-Coalspur Brazeau-Scollard-Willow Creek Frenchman-Ravenscrag
Cretaceous,Upper Brazeau Battle Creek-St Mary River Battle Creek-Blood Reserve-St Mary River
Cretaceous,Upper Bad Heart-Cardium Whitemud Blood Reserve-St Mary River
Cretaceous,Upper Kotaneelee-Kaskapau-Blackstone Wapiti-Horseshoe Canyon-Blood Reserve-St Mary River Eastend
Cretaceous,Upper Kotaneelee-Dunvegan Dunvegan-Bearpaw Bearpaw
Cretaceous,Upper Fort St John Fort St John-Lea Park-Belly River Belly River
Cretaceous,Upper Fort St John Fort St John-Lea Park-Belly River Oldman-Foremost
Cretaceous,Upper Fort St John Fort St John-Lea Park-Belly River-Judith River Lea Park-Judith River-Pakowki-Milk River-Riding Mountain-Vermillion_River
Cretaceous Fort St John-Colorado Colorado Colorado-Big River
Cretaceous,Lower Fort St John Peace River-Pelican-Bow Island Bow Island-Viking-Flotten Lake-Ashville
Cretaceous,Lower Bullhead-Spirit River-Cadomin-Garbutt-Buckinghorse Blairmore Mannville-Cantuar-Swan River-Joli Fou
Jurassic,Upper Nikanassin- Kootenay-Morrissey-Monteith Vanguard-Shaunavon-Gravelbourg
Jurassic Fernie Fernie-Ellis Gp
Triassic Bocock
Triassic Pardonet
Triassic Baldonnel
Triassic Ludington
Triassic Liard
Triassic Charlie Lake
Triassic Halfway
Triassic,Middle Toad-Montney-Sulfur Mountain Doig
Paleozoic beds ...

Limestone Fossiliferous

"Northern US Sequence"

Age Formation
Upper Tertiary beds ...
Oligocene Wiggins-White River-Brule
Oligocene Cook Ranch-Kishenehn-White River-Chadron
Eocene,Upper Sage Creek-*Kishenehn-Tepee Trail-Wagon Bed**
Eocene,Upper Green River- Aycross-Bridger
Eocene,Upper Green River-Wasatch-Wildwood-Wind River
Eocene,Upper Indian Meadows-Wasatch-EvanstonWildwood- Hanna
Paleocene Cannonball
Paleocene,Lower Willow Creek-Hell Creek
Paleocene,Lower Beaverhead-Pinyon-Hoback-Fort Union
Paleocene,Lower Beaverhead-Pinyon-Fort Union
Cretaceous,Upper Beaverhead-Pinyon-Fort Union-St Mary River-Ferris-Lance
Cretaceous,Upper Medicine Bow-Harebell
Cretaceous,Upper Horsethief-Fox Hills-Lewis-Meeteetse
Cretaceous,Upper Livingston-Bearpaw
Cretaceous,Upper Two Medicine- Judith River
Cretaceous,Upper Elkhorn Mountains-Aspen
Cretaceous,Upper Mesaverde-Pierre-Claggett-Horseshoe
Cretaceous,Upper Mesaverde- Pierre-Adaville-Almond-Blair-Ericson-Bacon Ridge-Rock Springs-Mancos
Cretaceous,Upper Virgelle-Eagle
Cretaceous,Upper Telegraph Creek
Cretaceous,Upper Cody-Steele-Hilliard-Baxter
Cretaceous,Upper Niobrara Limestone-Cody
Cretaceous,Upper Marias River-Colorado- Cody-Frontier-Carlile
Cretaceous,Upper Colorado-Cody-Frontier-Greenhorn Limestone
Cretaceous,Upper Colorado-Cody-Frontier-Belle Fouche-Blackleaf
Cretaceous,Lower Wayan-Bear River-Tygee-Draney-Bechler-Peterson-Ephraim
Cretaceous,Lower Gannett-Thermopolis-Mowry Shale-Newcastle
Cretaceous,Lower Thermopolis-Mowry Shale-Skull Creek
Cretaceous,Lower Fall River - Dakota Sandstone
Cretaceous,Lower Cloverly,Kootenai,Fuson-Lakota
Jurassic,Upper Morrison
Jurassic,Upper Swift,Rierdon-Sundance-Stump-Preuss
Jurassic Gypsum Spring-Twin Creek
Jurassic Sawtooth-Piper
Triassic Nugget-Ankareh
Triassic Thaynes-Chugwater-Spearfish
Triassic Woodside
Triassic Dinwoody
Paleozoic beds ...

Limestone Fossiliferous

"Central Sequence"

Age
Upper Tertiary beds ...
Eocene,Upper Huerfano
Eocene,Upper Chuchara
Eocene,Upper Poison Canyon
Eocene,Upper Raton
Cretaceous,Upper Laramie- Vermejo
Cretaceous,Upper Fox Hills- Trinidad
Cretaceous,Upper Pierre Shale-Pictured Cliffs
Cretaceous,Upper Niobrara Limestone
Cretaceous,Upper Mancos-Carlile
Cretaceous,Upper Greenhorn Limestone
Cretaceous,Upper Graneros Shale
Cretaceous,Lower Mowry Shale
Cretaceous,Lower Dakota Sandstone-Omadi
Cretaceous,Lower Kiowa
Cretaceous,Lower Purgatoire-**Cheyenne
Jurassic,Upper Morrison
Jurassic,Upper Bluff-Sundance
Jurassic,Upper Curtis
Jurassic,Middle Summerville
Jurassic,Middle Entrada
Jurassic,Middle Carmel
Jurassic,Lower Navajo
Jurassic,Lower Kayenta
Triassic Wingate
Triassic Chinle
Triassic Shinarump Dockum-Lykins
Triassic,Lower Thaynes-Moenkopi
Paleozoic beds ...

Limestone Fossiliferous

"Texas High Plains Sequence"

Age Formation
Upper Tertiary beds ...
Paleocene,Lower Hell Creek-Ojo Alamo
Cretaceous,Upper Lance-McDermott
Cretaceous,Upper Lance-Kirtland
Cretaceous,Upper Lance-Fruitland
Cretaceous,Upper Laramie- Vermejo
Cretaceous,Upper Pictured Cliffs
Cretaceous,Upper Fox Hills Sandstone-Trinidad Sandstone
Cretaceous,Upper Lewis- Pierre Shale
Cretaceous,Upper Mesaverde Sandstone - Niobrara Limestone
Cretaceous,Upper Mancos - Carlile
Cretaceous,Upper Greenhorn Limestone
Cretaceous,Upper Frontier-Graneros Shale
Cretaceous,Upper Thermopolis-Mowry Shale
Cretaceous,Lower Fall River-Dakota Sandstone
Cretaceous,Lower Purgatoire,Cloverly,Kootenai,Fuson-Lakota
Cretaceous,Lower Edwards
Cretaceous,Lower Comanche Peak Mural - Morita - Lowell -Cintura
Cretaceous,Lower Walnut
Cretaceous,Lower Antlers
Jurassic,Upper Morrison
Jurassic,Upper Entrada,Rierdon-Sundance
Jurassic Sawtooth-Piper
Triassic Santa Rosa,Chinle(Dockum),Lykins
Triassic Santa Rosa,Trujillo(Dockum)
Triassic Santa Rosa,Tecovas(Dockum)
Triassic Chugwater-Spearfish
Triassic Dinwoody
Paleozoic beds ...

Limestone Fossiliferous

"SouthWest Sequence"

Age Formation
Upper Tertiary beds (mostly volcanics)...
Tertiary Rubio Peak - Timberlake
Eocene Lobo
Cretaceous,Upper Salero
Cretaceous,Upper Fort Crittenden
Cretaceous,Upper Fort Buchanan
Cretaceous,Lower Turney Ranch
Cretaceous,Lower Cintura - Shellenberger Canyon - Hay Flat
Cretaceous,Lower Mural - Apache Canyon - Santa Rosa|
Cretaceous,Lower Morita - Lowell - Willow Canyon - Cowboy Spring - Ringbone Formation - Little Hat Top Formation
Cretaceous,Lower U-Bar Mojado - Broken Jug
Cretaceous,Lower Glance - Hell To Finish
Mesozoic intrusives, Paleozoic beds, PreCambrian beds

Limestone Fossiliferous

Adaville Formation

up to 1660 meters of varicolored Upper Cretaceous clays and coal found in the Green River basin and Uintah uplift of Wyoming,and Utah. Plant fossils.

Almond Formation

up to 200 meters of Upper Cretaceous sandstone,shale,clay and coal found in the Green River basin of Wyoming,and Colorado. Some brackish water invertebrate fossils

Ankareh Formation

Up to 430 meters of Permian(?) and Triassic continental red shale with minor sandstone and limestone with minor limestone found in the Green River and Snake River basins, Uinta and Wasatch uplifts and Yellowstone province of Idaho, Utah, and Wyoming. Petrified wood and bark occasionally present.

Antlers Formation

As much as 250 meters of Lower Cretaceous clay and sandstone found in the Fort Worth syncline,South Oklahoma folded belt,Ouachita folded belt,and Permian basin of New Mexico,Oklahoma,and Texas. Overlies older formations unconformally.

Apache Canyon

Up to 600 meters of Lower Cretaceous limestone,sandstone, and siltstone found in Arizona(se). It overlies the Willow Canyon Formation and is overlain by the Shellenberger Canyon Formation. It is thought to be contemporaneous with the marine Mural Limestone. It is a member of the Bisbee Group

Fossils: A few plants and vertebrates (dinosaur bone fragments)

Ashville Formation

A Cretaceous sandstone found in Saskatchewan and Manitoba. Contains some dinosaur fossils

Aspen Formation

up to 660 meters of dark Upper Cretaceous marine shales with abundant fish scales found in the Green River basin and Uintah uplift of Wyoming,Idaho,and Utah.

Aycross Formation

In excess of 300 meters of Eocene Clay,Tuff,Shale,Sandstone, and Conglomerates exposed in the Wind River Basin of Wyoming. vertebrate fossils.

Bacon Ridge Formation

An Upper Cretaceous sandstone exposed in the Yellowstone region of Northwest Wyoming.

Bad Heart Formation

Up to 8 meters of abundantly fossiliferous red weathering sandstone exposed on Peace River in Northern Alberta with ammonites and bivalves.

Baldonnel

Up to 146 meters of Triassic limestone, dolostone, siltstone and sandstone in Northern British Columbia and Alberta Rocky Mountain foothills. Considered to be part of the Schooler Creek Group.

Battle Creek Formation

Up to 14 meters of dark shale with a few fragmentary fossils found in SouthEast Alberta and Southwest Saskatchewan.

Baxter Formation

Up to 1200 meters of fossiliferous marine Uppermost Cretaceous shale and sandstone found in the Green River basin of Wyoming. Considered to be the lowest formation in the Montana Group.

Bearpaw Formation

Up to 350 meters of marine shales and mudstones with minor sandstones, bentonites, etc. found in Southern Alberta,Southeast Saskatchewan as well as the Powder River basin,Central Montana uplift,Williston basin,Big Horn basin, Montana folded belt province, and Sweetgrass arch of Montana and Wyoming. Fossils include well preserved ammonites, many other invertebrates and numerous marine vertebrates. To the South and East it is equivalent to the Pierre Shale.

Fossils: Marine invertebrates -- ammonites,other invertebrates, marine vertebrates, a few dinosaurs.

Bear River Formation

Coals and sandstones with fresh and brackish water fossils. Generally regarded as Lower Cretaceous. Found in the Green River basin,Snake River basin, and Wasatch uplift of Idaho,Utah and Wyoming

Beaverhead Formation

In excess of 3000 meters of Paleocene sediments in the folded belt province of Montana and the Snake River Basic of Idaho. Consists of two thick conglomerate formations sandwiching limestone and heterogeneous deposits in the middle member. Dated from fresh water gastropods

Bechler Formation

Up to 560 meters of Lower Cretaceous lacustrine shale and conglomerate found Green River basin,Snake River basin,and Wasatch uplift provinces of Idaho and Wyoming. Some fresh water invertebrate fossils.

Belle Fouche Formation

Up to 300 meters of occasionally fossiliferous marine Cretaceous shale and bentonite with a medial limestone bed found in Central Montana uplift,Montana folded belt province,Chadron arch,Williston basin,Powder River basin,Wind River basin,Green River basin,Sweetgrass arch regions of Montana, North Dakota, South Dakota, and Wyoming.

Belly River Formation

Up to 1300 meters of mudstone and fine grained sandstone with minor sandstone, shale bentonite, and coal found across Southern Alberta and Saskatchewan. The name is used interchangeably with the probably preferable term Judith River Formation in the plains area.

Big River

Unknown -- apparently a Cretaceous(?) shale formation overlying the Viking Formation in Southern Alberta and Saskatchewan and the Flotten Lake Sandstone in the Central Plains.

Bisbee Group

More than 1000 meters of heterogeneous Upper Jurassic(?) and Lower Cretaceous found in Arizona(se) and New Mexico(sw). The Bisbee overlies Paleozoic beds/Mesozoic Volcanics and is overlain by the Faraway Ranch Formation/Gila Conglomerate/Little Hat Top

Fossils: Marine invertebrates in some of the limestones

Blackstone

Up to 427 meters of dark grey to black mudstone and siltstone with minor limestone, sandstone, and bentonite found in the Rocky Mountain foothills of Alberta South of the Athabaska River. Yields cephalopods and pelecypods.

Blair Formation

Up to 700 meters of Upper Cretaceous sand and shale found in the Green River basin of Wyoming. Contains marine fossils. Originally assigned to the Montana Group but modern usage puts it in the Mesaverde Group.

Blairmore

Up to 2000 meters of Lower Cretaceous sandstones and pebble conglomerates found in the Rocky Mountains and Foothills in Southwest Alberta and adjacent British Columbia.

Blackleaf Formation

Up to 700 meters of marine Cretaceous sand and shale found in the Montana folded belt province and Sweetgrass arch of Northwest Montana where it is at the base of the Colorado Group. Fossils include bivalves and fish vertebrae.

Blood Reserve Formation

Up to 30 meters of light colored sandstone with abundant Ophiomorpha burrows found in a narrow North-South band in SouthWest Alberta.

Bluff Formation

An Upper Jurassic wind deposited sandstone found in the Paradox and Black Rock Mesa basins of Arizona and Utah where it is overlain by the Morrison Formation

Bocock Formation

Up to 64 meters of unfossiliferous probably Triassic limestone found in the Rock Mountain foothills of NorthEast British Columbia. It is considered by some to be the uppermost formation in the Schooler Creek Group

Bonita Park

100 meters of Tertiary redbeds and volcanic tuff found in Arizona(se). It overlies the Bisbee Group and is overlain by the Faraway Ranch Formation

Fossils: None

Bow Island Formation

Up to 175 meters of Lower Cretaceous sandstone, siltstone and mudstone found mostly subsurface in the plains of Alberta, Saskatchewan and Montana.

Brazeau Formation

Up to 950 meters of non-marine sandstone with minor coal, shale, and bentonite in the Northern and Central Rocky Mountain foothills. Spans the Cretaceous-Paleocene boundary

Bridger Formation

Eocene sandstone found in the Green River basin of Colorado, Utah, and Wyoming. Vertebrate fossils.

Broken Jug Limestone

A probably obsolete term for 1525 meters of Lower Cretaceous limestone,shale,sandstone,and conglomerate found in New Mexico(sw). It overlies the Mojado Formation? and is overlain by the Ringbone Shale. It is a member of the Bisbee Group

Fossils: Marine invertebrates in the upper beds.

Brule Formation

Lower Oligocene clay,volcanic ash, and sand exposed in the Wind River, Denver, and Williston basins as well as the Sioux uplift and Chadron Arch of Colorado, Montana, North Dakota,Nebraska,South Dakota and Wyoming.

Buckinghorse Formation

Up to 1000 meters of dark fossiliferous marine Cretaceous siltstone and fine grained sandstone found on the fringes of the Rocky Mountain foothills in Northern British Columbia.

Bullhead Group

Up to 900 meters fluvial of non-marine conglomerate ad sandstone with minor coal, shale, and bentonite in the Northern and Central Rocky Mountain foothills. Some plants and dinosaur trackways.

Cadomin Formation

Up to 170 meters of Lower Cretaceous silicon cemented conglomerate with minor siltstone and sandstone and a little coal. Found in the Rocky Mountain foothills of Alberta and British Columbia.

Cannonball Formation

Up to 100 meters of fossiliferous Paleocene marine shale and sandstone found in the Williston Basin of North Dakota. This is the youngest marine unit in the inland sea deposits in the US.

Cantuar Formation

Up to 120 meters of Lower Cretaceous mudstone and sandstone found in the Williston Basin area of Saskatchewan. Middle part of the Mannville Group

Cardium Formation

Up to 108 meters of fossiliferous marine sandstones separated by non-marine shales. Found along essentially the full length of the Canadian Rocky foothills from near the US border to Dawson Creek, BC

Carlile Formation

Up to 200 meters of fossiliferous Upper Cretaceous marine shale and limestone. Widely distributed along the Rocky Mountain front and the plains East to Iowa and Minnesota. It is part of the Colorado Group.

Carmel Formation

Up to 200 meters of fossiliferous marine middle Jurassic sandstone with shale gypsum and limestone. Found in the Black Mesa basin,Great Basin province,Green River basin,Paradox basin,Plateau sedimentary province,San Juan basin,Uinta basin, and Uinta uplift of Arizona, Colorado,New Mexico,Utah,and Wyoming. It occupies the interval between the Navajo and Entrada sandstones. Marine fossils are found in the limestones.

Chadron Formation

10 to 20 meters or more of latest Eocene and Earliest Oligocene clay and gravel exposed in narrow bands in the Wind River, Denver, and Williston basins as well as the Sioux uplift and Chadron Arch of Colorado, Montana, North Dakota,Nebraska,South Dakota and Wyoming. Vertebrate fossils. It is exposed in the Bighorn and Wind River Basins as well as the Yellowstone region of Wyoming.

Charlie Lake Formation

Up to 405 meters of Triassic calcareous Sandstone, siltstone, limestone, anhydrite in the Rocky Mountain foothills of Northern British Columbia and Alberta. It is part of the Schooler Creek Group.

Cheyenne Formation

Up to 43 meters of Lower Cretaceous friable sandstone found in the Anadarko basin,Sedgwick basin, and Central Kansas uplift of Kansas where it is the lowest part of the Purgatoire Group and lies between the upper parts of the Purgatoire and Triassic redbeds. Contains wood fragments and Cycad fossils

Chugwater Formation

Up to 400 meters of Permian and Triassic shales, limestones, and gypsum found in the Big Horn,Denver,Powder River,Green River,and Wind River Basins and the Yellowstone province of Colorado, Montana, and Wyoming. Fossils reported.

Chinle Formation

Up to 400 meters of Upper Triassic shales with minor limestones,sandstones,conglomerates,and gypsum found in the Black Mesa basin,Great Basin province,Green River basin,Las Vegas-Raton basin,Orogrande basin,Palo Duro basin,Paradox basin,Permian basin,Piceance basin,Plateau sedimentary province,San Juan basin,Sierra Grande uplift,Uinta basin,Uinta uplift, and Wasatch uplift of Arizona,Colorado,Nevada,New Mexico,Texas and Utah. Is treated as a subdivision of the Dockum Group in Texas. Fossils include petrified wood, plant fossils, and vertebrates

Cintura Formation

600 meters of Lower Cretaceous Shale, limestone, and Sandstone found in Arizona(se) and New Mexico(sw). It overlies the Mural Limestone and is overlain by recent deposits. It is a member of the Bisbee Group

Fossils: A few marine invertebrates.

Claggett Formation

130 meters of Upper Cretaceous marine shale and sandstone found in the Powder River basin and Central Montana uplift of Montana and adjacent Wyoming. Fossils are found in some beds.

Cloverly

up to 130 meters of Lower Cretaceous continental sandstones and clays found in the Powder River and Big Horn basins of Colorado,Montana,Utah,and Wyoming where it rests unconformally on Jurassic beds

Coalspur Formation

Up to 550 meters of Uppermost Cretaceous (and Paleocene?) sandstone, shale, mudstone, siltstone, coal, bentonite, and conglomerate found in the Rocky Mountain foothills along the North Saskatchewan and Athabaska Rivers.

Cody Formation

Up to 800 meters of Upper Cretaceous marine and continental (?) shale and sandstone found in the Montana folded belt province,Central Montana uplift,Big Horn basin,Powder River basin, and Wind River basin of Montana,Wyoming, and possibly Idaho. It is apparently the lateral equivalent of several better known and better differentiated formations such as the Niobrara Limestone that are found to the South and East.

Colorado Group

Up to 1500 meters of Cretaceous shales and limestones with minor inclusions of other rock types found across Southern Alberta and Saskatchewan and Southward through the US midcontinent exposures except possibly in Arizona. In Canada is mostly known from subsurface coring Members include the Medicine Hat Sandstone,Martin,Cardium Sandstone,Bowdoin Sandstone,and Phillips Sandstone. In the US it includes the Coberly,Dunkleberg,Frontier,Graneros,Greenhorn,Marias River,Mowry,Niobrara,Thermopolis,and Warm Creek Formations.

Comanche Peak Formation

In excess of 30 meters of fossiliferous Lower Cretaceous marine limestone found in the Permian basin,Strawn basin,Bend arch,Ouachita folded belt,Llano uplift* of Texas where it occupies the interval between the sands of the Antlers/Walnut formations and the Edwards Limestone. Abundant fossils reported in the lower part of the formation.

Cook Ranch Formation

Oligocene volcanic rocks clay found in Beaverhead County, MT. May have been reassigned to the Sage Creek Group.

Corbett Sandstone

An obsolete term for 1220 meters of Lower Cretaceous Mojado Formation found in New Mexico(sw). The beds are part of the Bisbee Group

Fossils: Marine invertebrates?

Cowboy Spring

At least 300 meters of Lower Cretaceous limestone cobbles,sandstone,shale, and tuff found in New Mexico(sw). It overlies the Mojado Formation/U Bar Formation and is overlain by the Timberlake Fanglomerate

Fossils: None?

Cuchara Formation

Up to 1670 meters of Eocene floodplain deposits conglomerate, shale, clay and sandstone found in the Las Vegas-Raton basin of New Mexico.

Curtis Formation

Up to 85 meters of marine mid Jurassic sandstone shale and conglomerate found in the Green River basin,Paradox basin,Plateau sedimentary province,Snake River basin,Uinta uplift,Wasatch uplift,Yellowstone province of Colorado, Idaho, Utah, and Wyoming. Overlies the Entrada formation and is overlain by the Summerville formation. Fossils resemble those of the Sundance formation.

Cypress Hills Formation

Up to 80 meters of Oligocene sand and gravel with a few conglomerates or marls exposed in scattered plateaus in Southern Saskatchewan and Alberta.

Dakota Formation

60 to 100 meters of Lower Cretaceous continental sandstone with minor beds of other sorts in places found in all US portions of the midcontinent sea region except Idaho. Fossils include leaves and wood. In many places, the Dakota is the lowest Cretaceous formation

Dinwoody Formation

Up to 230 meters of Lower Triassic calcareous shales and sandstones grading laterally into gypferous redbed sandstones and shales found in the Montana folded belt province,Yellowstone province,Big Horn,Green River,Wind River basins, and the uplift of Idaho,Montana,Utah,and Wyoming. Contains obscure mollusk fossils

Dockum Formation

Up to 130 meters of Middle and Upper Triassic conglomerate,sandstone,shale and clay found in the Permian basin,Las Vegas-Raton basin,Palo Duro basin,Sierra Grande uplift and Anadarko basin of Colorado,Kansas,New Mexico,Oklahoma and Texas. Petrified wood is commonly found and vertebrate fossils are reported. Generally lies on Permian formations.

Doig Formation

Up to 364 meters of grey Triassic siltstone and shale with phosphate nodules near the base found in NorthEast British Columbia, NorthWest Alberta and the Southern Yukon Territory.

Draney Formation

Up to 100 meters of Cretaceous lacustrine algal limestone found Green River basin,Snake River basin,Wasatch uplift,and Yellowstone provinces of Idaho and Wyoming. Some fresh water invertebrate fossils.

Dunvegan Formation

Up to 300 meters of late Cretaceous sandstone and shale exposed in the Northern Rocky mountain foothills and plains. It is marine in the East grading to continental in the West.

Eagle Formation

Up to 90 meters of late Cretaceous continental sandstone, greenish shale, conglomerate and occasionally lignite found in the Powder River basin,Central Montana uplift,Montana folded belt province,and Sweetgrass arch regions of Montana and Wyoming. Contains plant fossils and fresh water mollusks.

Eastend Formation

Up to 30 meters of late Cretaceous sandstone, greenish shale, conglomerate and occasionally lignite found in Southwest Saskatchewan and SouthEast Alberta. There are a few poorly preserved marine invertebrates in the lower portions.

Edwards Formation

As much as 150 meters of fossiliferous Lower Cretaceous marine limestone found in the Permian basin,Strawn basin,Kerr basin,Ouachita folded belt,Gulf Coast basin, and Llano uplift of Texas.

Elkhorn Mountains Formation

As much as 2000 meters of Upper Cretaceous volcanics tuffs,breccias,and conglomerates found in the folded belt province of West Central Montana. Fossils rare or absent.

Ellis Group

Up to 150 meters of Jurassic shale and sandstones in the plains of Southern Alberta and Northern Montana. It is divided into the Swift, Rierdon, and Sawtooth Formations

Entrada Formation

Up to 500 meters (but usually much thinner) of mid to late Jurassic sandstone found in the Anadarko basin,Black Mesa basin,Denver basin,Great Basin province,Green River basin,Las Vegas-Raton basin,Paradox basin,Piceance basin,Plateau sedimentary province,San Juan basin and Sierra Grande uplift of Arizona,Colorado,New Mexico,Utah and Wyoming.

Ephraim Formation

Up to 330 meters of Cretaceous(?) conglomerate found Green River basin,Snake River basin,and Wasatch uplift provinces of Idaho and Wyoming. It is the basal member of the Gannett group

Ericson Formation

200 to 300 meters of unfossiliferous Upper Cretaceous sandstone found in the Green River basin of Wyoming, Utah, and Colorado. It is a member of the Mesaverde Group.

Evanston Formation

Up to 500 meters of Eocene(?) sandstone and coal in the Green River Basin,Wasatch uplift,and Uinta uplift of Idaho,Utah, and Wyoming.

Fall River

Lower Cretaceous sandstones found in the Chadron arch,Powder River basin, and Williston basin of Montana,North Dakota,Nebraska,South Dakota and Wyoming.

Faraway Ranch Formation

250 meters of Tertiary volcanics found in Arizona(se) where it overlies the Bonita Park Formation/Bisbee Group and is overlain by the Rhyolite Canyon Formation

Fossils: None

Fernie Formation

Up to 400 meters of dark Jurassic marine shales with minor limestones, siltstones and sandstones exposed in the Canadian Rockies and Westernmost plains of British Columbia and Alberta. Numerous members and formations have been identified within the beds. Some Geologists believe that it should be treated as a group rather than a formation. Marine invertebrate fossils are reported from some beds.

Ferris

Up to 2000 meters of non-marine Late Cretaceous and possibly Early Paleocene sandstone,siltstone,shale and coal found in the Green River Basin of Wyoming

Flotten Lake

Up to 21 meters of Lower Cretaceous sandstone overlying the Viking Formation in East Central Alberta and West Central Saskatchewan. Exposed in the valley of the Saskatchewan River.

Foremost

Up to 140 meters of fresh and brackish water Upper Cretaceous sandstone,shale,shell beds, and coal found in Southern Alberta and adjacent Saskatchewan. Dinosaur remains are fairly common and mollusks are abundant in some layers. It is the lowest formation in the Judith River Group

Fort Buchanan

600 meters of sandstone and shale above a basal conglomerate. It overlies an unnamed lava/Bisbee Group and is overlain by the Fort Crittenden Formation

Fossils: None?

Fort Crittenden

700 meters or more of Upper Cretaceous conglomerate, sandstone and shale found in Arizona(se). It overlies the Fort Buchanan Formation/Bisbee Group and is overlain by the Salero Formation It is a member of the Sonoita Group.

Fossils: Dinosaurs, fish, other vertebrates

Fort Union Formation

Up to 2200 meters of fossiliferous Latest Cretaceous and Early Paleocene sandstone shale, limestone and coal (but usually much thinner) found in Powder River basin,Williston basin,Uinta basin,Piceance basin,Central Montana uplift,Green River basin,Big Horn basin,and Wind River basin of Colorado,Montana,North Dakota,South Dakota and Wyoming

Fox Hills Formation

Up to 160 meters of fossiliferous Late Cretaceous marine sandstone and clay found in Denver basin,Green River basin,Powder River basin,Williston basin of Colorado,Montana,North Dakota,South Dakota and Wyoming

Fort St John Group

Up to 2000 meters (mostly subsurface?) of dark Cretaceous shale with sandstone, conglomerate and bentonite. It is found in NorthEast British Columbia, Northern Alberta, the Yukon and the Northwest Territories. There are numerous subgroupings into the following formations: Cruiser Formation, Goodrich Formation, Hasler Formation, Gates Formation, Moosebar Formation, Shaftesbury Formation, Peace River Formation, Spirit River Formation, Sully Formation, Sikanni Formation, Lepine Formation, Scatter Formation, Garbutt Formation, Buckinghorse Formation

Frenchman Formation

Up to 113 meters of latest Cretaceous non-marine sandstone and claystone found in Saskatchewan and SouthEast Alberta

Frontier Formation

Up to 2600 meters of fossiliferous Cretaceous marine shale and sandstone with some coal beds near the top in some areas found in Big Horn basin,Central Montana uplift,Green River basin,Montana folded belt province,Piceance basin, Powder River basin,Snake River basin,Uinta basin,Uinta uplift,Wasatch uplift.Wind River basin,Yellowstone province of Montana,Wyoming,Colorado,Idaho,and Utah. It is part of the Colorado Group.

Fruitland Formation

Up to 170 meters of Upper Cretaceous coastal swamp shale,sandstone,and coal found in the Paradox basin,San Juan basin,and San Juan Mountains province of Colorado and New Mexico. Occupies interval between the Pictured Cliffs and Kirtland formations. Diverse vertebrate fossils.

Fuson Formation

Up to 30 meters of Early Cretaceous continental shale and sandstone found in the Chadron arch,Powder River basin,and Williston basin of Montana,North Dakota,Nebraska,South Dakota and Wyoming.

Gannett Group

Up to 1000 meters of Cretaceous continental/lacustrine sediments found Green River basin,Snake River basin,and Wasatch uplift provinces of Idaho and Wyoming. It consists of the Ephraim conglomerate, the Draney Limestone, the Bechler Formation, the Peterson limestone and the Tygee(Smoot) Sandstone.

Garbutt

Up to 290 meters of occasionally fossiliferous Lowest Cretaceous sandstone and siltstone in NorthEast British Columbia.

Gila Conglomerate

200 meters of Upper Tertiary terrestrial sediments interbedded with volcanics found in Arizona(se) and New Mexico(sw). It overlies the Bisbee Group and is overlain by unnamed Quaternary beds. The Gila is divided by some authors into San Manuel, Quiburis and Sacaton Formations

Fossils: pockets of vertebrate remains in the Quiburis beds.

Glance Conglomerate

Up to 1200 meters of Upper Jurassic and Lower Cretaceous conglomerate found in Arizona(se) and New Mexico(sw) It overlies Mesozoic intrusives, Precambrian intrusives or Paleozoic limestones/Concha Limestone. It is overlain by the Willow Canyon Formation/Morita Limestone It is the lowest member of the Bisbee Group

Gravelbourg Formation

Up to 60 meters of Jurassic limestones, shales and sandstones found in Southern Alberta, Saskatchewan and Manitoba as well as adjacent Montana. Marine fossils are found. Abundant fish scales are found in the basal beds

Graneros Formation

As much as 300 meters of fossiliferous Upper Cretaceous marine dark shale and sandstone widely distributed from the Rocky Mountains East to Iowa and Minnesota. Found in all parts of the region except Arizona,Idaho,and Utah above the Dakota Sandstone and below the Greenhorn Limestone.

Greenhorn Formation

Up to 100 meters of fossiliferous Upper Cretaceous Limestone widely distributed from the Rocky Mountains East to Iowa and Minnesota.

Green River Formation

Up to several hundred meters of lacustrine Eocene shales and oil shales found in the Green River, Piceance, and Uinta basins in Colorado, Wyoming and Utah as well as in exposures along the Wasatch front in Utah. Noted for its well preserved fish and plant fossils, but other vertebrates, insects, bird tracks, etc are found in some beds.

Gypsum Spring Formation

Up to 90 meters of Middle Jurassic gypsum, sandstone, shale and limestone found in the Green River,Uinta,Wind River,Powder River and Snake River basins, Wasatch uplift and Yellowstone province of Idaho, Montana, South Dakota, Utah, and Wyoming.

Halfway Formation

Up to 416 meters of Triassic sandstones with minor other rock types found in Northern British Columbia and Alberta. Marine fossils are found. It is the oldest formation in the Schooler Creek Group.

Hanna Formation

Up to 2000 meters of non-marine Paleocene and Early Eocene river delta mudstone,sandstone,conglomerate and coal found in the Hanna Basin of Wyoming. Fossils reported

Harebell Formation

Up to 1600 meters of non-marine Uppermost Cretaceous sandstone,siltstone,shale and conglomerate found in the Green River basin and the adjacent Yellowstone region. Abundant plant and fresh water mollusk fossils.

Hay Flat Limestone

600 meters(?) of Lower Cretaceous limestone found in Arizona(se). It is a member of the Bisbee Group. It overlies the Mural Limestone and is overlain by Tertiary sediments. It is probably an (unnecessary) alternate name for the Cintura Limestone

Fossils: Unknown-Probably at least a few marine invertebrates

Hell Creek Formation

Up to 70 meters of mostly non-marine Uppermost Cretaceous and Early Paleocene. sandstone,and clay found in the Williston basin, Central Montana uplift, and Powder River basin of Montana and North and South Dakota. Abundant vertebrate and invertebrate fossils.

Hell To Finish

Up to 2000 meters of Lower Cretaceous shales and mudstones with minor limestones found in New Mexico(sw). It overlies the Concha Limestone [WCPALEO.HTM#Concha]/Earp Formation and is overlain by the U-Bar Limestone. It is a member of the Bisbee Group

Fossils: Abundant bivalves in the upper beds

Hilliard Formation

Up to 2200 meters of marine Uppermost Cretaceous shale with minor limestone found in the Green River basin of Wyoming and Utah. Contains ammonites and bivalves.

Hoback Formation

Up to 1600 meters of non-marine Paleocene(?) sandstone, and shale with some limestone found in the Green River Basin and adjacent Yellowstone region of Wyoming. Fossils include some fresh water mollusks and possibly some vertebrates.

Horseshoe Formation

400 meters of Upper Cretaceous sandstone,clay,and coal found in Idaho(e). It overlies the Bacon Ridge Formation

Fossils: Marine mollusks in one bed

Horseshoe Canyon Formation

Up to 230 meters of latest Cretaceous floodplain and estuarine mudstone shale and sandstone with minor coal and other rocks. It is Found in west central Alberta. It yields fairly abundant dinosaur remains as well as other fossils.

Horsethief Formation

Up to 100 meters Upper Cretaceous brackish water and marine sandstone found in the Sweetgrass arch and folded belt province of Montana. Fossils include brackish water and near shore marine mollusks.

Huerfano

Up to 1500 meters of Eocene floodplain conglomerate,sandstone,shale,clay, and marl found in the Las Vegas-Raton basin of Colorado and possibly adjacent New Mexico.

Indian Meadows

Roughly 300 meters of early Eocene clay and conglomerate found in Wyoming's Wind River Valley. Abundant vertebrate fossils.

Joli Fou Formation

Up to 60 meters of early Cretaceous shale, mudstone, and sandstone found in the Southern Plains and central plains of Alberta and Saskatchewan.

Judith River Formation

Up to 360 meters of late Cretaceous siltstone, mudstone, sandstone, bentonite and coal found in the Southern Plains of Alberta and Saskatchewan as well as the Sweetgrass arch,Central Montana uplift,and Williston basin of Montana,North Dakota,and Wyoming It yields fairly abundant dinosaur remains as well as other vertebrates and invertebrates.

Kaskapau Formation

Up to 900 meters of fossiliferous late Cretaceous marine dark grey shale with some sandstone interbeds in NorthEastern British Colombia and adjacent Alberta. Contains bivalves, cephalopods and foraminifers

Kayenta Formation

Up to 215 meters of non-marine Late Triassic and/or Early Jurassic sandstone with a few thin fossiliferous limestone beds found in the Paradox basin,Plateau sedimentary province,Black Mesa basin,San Juan basin and Great Basin province of Arizona,Colorado,Nevada,and Utah. Fossils consist mostly of fresh water gastropods and reptile trackways. Occupies the interval between the Wingate and Navajo Sandstones.

Kiowa Formation

Up to 30 meters of Lower Cretaceous shale found in the Anadarko basin of Colorado, Kansas, Oklahoma, and possibly New Mexico. Is the uppermost member of the Purgatoire Group

Kirtland Formation

Up to 594 meters of Upper Cretaceous and/or Paleocene non-marine shale found in the San Juan basin of Colorado and New Mexico. Occupies interval between the Fruitland and McDermott formations. Diverse and vertebrate fossils.

Kishenehn Formation

Up to 230 meters of fossiliferous Oligocene(?) lakebed deposits found in the vicinity of Kishenehn Creek, BC and adjacent Montana.

Kootenay Group

Up to 1335 meters of continental Late Jurassic and Early Cretaceous sandstone, shale and coals found in the Southern Rocky Mountains of Alberta,British Columbia and Montana. Sometimes referred to as a formation, modern usage is to regard it as a group including Morrissey, Mist Mountain, and Elk formations. Is spelled Kootenai in the US where it is present in the Big Horn basin,Yellowstone province,Snake River basin,Montana folded belt province,Sweetgrass arch,Central Montana uplift and Powder River basin of Idaho and Montana

Kotaneelee Formation

Up to 152 meters of Upper Cretaceous marine sandstone, shale, and conglomerate found in the Northern Canadian Rockies and the adjacent plains. Contains some pelecypods and cephalopods

Lakota Formation

Up to 100 meters of Early Cretaceous continental shale,sandstone,clay,and coal found in the Chadron arch,Powder River basin,and Williston basin of Nebraska,South Dakota and Wyoming. Where present, the Lakota is the oldest Cretaceous unit.

Lance

Up to 800 meters of non-marine Upper Cretaceous and Earliest Paleocene sandstone,siltstone,shale and coal found in the Powder River basin,Green River basin,Wind River basin, and Big Horn basin with plant,shells and dinosaur fossils.

Langton Bay

320 meters of Lower Cretaceous shale and coal found in the Canadian Northwest Territories.

Fossils: Foraminifera, bivalve fragments, palynomorphs, fish scales, plant fragments.

La Plata Formation

An obsolete name for 30 meters of Jurassic continental sandstones and limestone found in Colorado(sw), New Mexico(nw), and Utah(se). It overlies the Dolores Formation and is overlain by the McElmo Formation. In modern usage, the La Plata beds are assigned to the Morrison and Entrada Formations.

Fossils: Sparse

Laramie

Up to 250 meters of non-marine late Upper Cretaceous clay and sandstone found in the Denver basin or Colorado. Contains some plant fossils

Lewis Formation

Up to 600 meters of Late Cretaceous sandy marine shales found in the Big Horn basin,Green River basin,Powder River basin,San Juan basin Wind River basin of Colorado,New Mexico,Utah and Wyoming

Liard Formation

Up to 417 meters of Middle to Late Triassic dolomitic sandstone and siltstone with minor limestones found in the plains of NorthEast British Columbia

Lea Park Formation

Up to 270 meters of late Cretaceous shale with siltstone, calcite, and ironstone concretions. Found in NorthEast Alberta and adjacent Saskatchewan

Little Hat Top

100 meters of Middle Tertiary conglomerate found in New Mexico(sw). It overlies the Mojado formation and is overlain by Tertiary lavas.

Fossils:

Livingston Group

Up to 2300 meters of Upper Cretaceous continental shales, sandstones and conglomerates found in the Central Montana uplift and folded belt provinces of Southwest Montana. Fossils include abundant leaves in the basal beds and some fresh water mollusks.

Lobo

up to 600 meters of Eocene shale,limestone,conglomerate and sandstone found in New Mexico(sw). It overlies igneous rocks/El Paso/Bliss/Montoya/Fusselman/Mojado/Gym beds and is overlain by the Rubio Peak Formation/Sarten Sandstone

Fossils: None

Lowell

350 meters of heterogeneous marine sediments -- Limestone,Dolomite,Sandstone, Shale,Conglomerate -- found in Arizona(se). It corresponds to parts of the Mural Limestone and Morita Formation. It overlies the remainder of the Morita Formation and is overlain by the remainder of the Mural Limestone. It is a member of the Bisbee Group

Fossils: Unknow. Probably some marine invertebrates

Ludington

At least 600 meters of fossiliferous Triassic sandstone and silty/sandy limestone in Northern British Columbia Rocky Mountain foothills. Considered to be part of the Schooler Creek Group.

Lykins Formation

Up to 260 meters of Late Permian and/or Early Triassic redbed sandstone, shale, and minor limestone found in the Las Animas arch,Las Vegas-Raton basin,Denver basin of eastern Colorado where it occupies the interval between Permian formations below and the Jurassic Morrison formation. Fossils are reported to be present.

Mancos Formation

Up to 1000 meters of Late Cretaceous marine shale with minor sandstone. It is widely distributed in Arizona,Colorado,New Mexico,Utah and Wyoming.

Mannville Group

Up to 145 meters of Cretaceous continental and marine sandstone and shale near shore marine and terrestrial sandstone and shale found in the central plains of Alberta.

Marias River Formation

Up to 400 meters of Upper Cretaceous marine shale and sandstone found in the folded belt and Sweetgrass Arch provinces of Northwest Montana. Ammonites found. Part of the Colorado Group.

McDermott Formation

Up to 400 meters of Upper Cretaceous and/or Paleocene non-marine sandstone,shale,and conglomerate found in the San Juan basin of Colorado and New Mexico. Occupies interval between the Kirtland and Ojo Alamo formations. Plants and vertebrate fossils.

McElmo Formation

An obsolete name for up to 300 meters of sandstone and shale of the Jurassic Morrison Formation found in Colorado(sw), New Mexico(nw) and Utah(se). It overlies the La Plata Sandstone/Entrada Formation/Carmel Formation and is overlain by the Dakota Formation

Fossils: plants? Vertebrates?

Medicine Bow

Up to 2000 meters of non-marine Upper Cretaceous sandstone,siltstone,shale and coal found in the Green River Basin of Wyoming with plant and dinosaur fossils.

Meeteetse Formation

Up to 350 meters of Late Cretaceous sandstone,shale,coal and tuff found in the Wind River basin and the Big Horn basin of Wyoming. Plant fossils.

Mesaverde Formation

Up to 1400 meters of non-marine Upper Cretaceous sediments widely exposed in Arizona,Colorado,Idaho,Montana,New Mexico,Utah,and Wyoming. Consists of heterogeneous sediments -- mostly shale, marl, coal and sandstone sandwiched between two massive sandstone layers that separate the Mesaverde from marine shales/limestones that overlay and underlay it. Fossil vertebrates have been found, but are rare.

Milk River Formation

Up to 113 meters of fossiliferous Upper Cretaceous near shore marine and terrestrial sandstone and shale found in the Southern plains of Alberta.

Moenkopi Formation

Up to 500 meters of Triassic shale and sandstone with thin gypsum layers found in the Paradox basin,Piceance basin,Uinta basin,Plateau sedimentary province,Black Mesa basin,San Juan basin,Green River basin,Great Basin province,Palo Duro basin,Las Vegas-Raton basin, and Orogrande basin of Arizona,California,Colorado,Nevada,New Mexico and Utah. Sparse marine and lacustrine fossils reported

Mojado Formation

1500 meters or more of Cretaceous sandstone and shale found in New Mexico(sw). It overlies the U-bar formation and is overlain by the Cowboy Spring formation/Ringbone Formation/Little Formation/Lobo Formation. It is a member of the Bisbee Group

Fossils: Marine invertebrates-gastropods, ammonites, mollusks, pelecypods in upper part.

Montney Formation

Up to 280 meters of dark Triassic siltstone and shale found in NorthEast British Columbia and NorthWest Alberta. In its area of exposure it is the oldest Mesozoic sediment and rests unconformally on Paleozoic sediments.

Morita Formation

As much as 1400 meters of Lower Cretaceous marine sandstone and shale found in Arizona(SE) and New Mexico(sw). It overlies the Glance Conglomerate and is overlain by the Mural Limestone/Lowell Formation. It is a member of the Bisbee Group

Fossils: Sparse at best.

Morrissey Formation

Up to 80 meters of brown to orange Uppermost Jurassic sandstone found in the Rocky Mountain and foothills of SouthWest Alberta and SouthEast British Columbia.

Monteith Formation

Up to 600 meters of fine grained Uppermost Jurassic and Early Cretaceous sandstone and shale found in the Rocky Mountain and foothills of Central Alberta and adjacent British Columbia.

Morrison Formation

Up to 200 meters of occasionally fossiliferous continental Upper Jurassic sandstone,clay and limestone and shale found in Anadarko basin,Big Horn basin,Black Mesa basin,Central Montana uplift,Chadron arch,Denver basin,Green River basin,Las Vegas-Raton basin,Montana folded belt province,North Park basin,Palo Duro basin,Paradox basin,Piceance basin,Plateau sedimentary province,Powder River basin,San Juan basin,San Luis basin,Sierra Grande uplift, Sweetgrass arch,Uinta basin,Wasatch uplift,Williston basin of Arizona,Colorado,Montana,North Dakota,New Mexico,Oklahoma,South Dakota,Utah,and Wyoming. Dinosaur remains and plants are abundant in some locations.

Mowry Formation

Up to 100 meters of fossiliferous Upper Cretaceous black shale with minor Sandstone found in the Big Horn basin,Central Montana uplift,Chadron arch,Denver basin,Green River basin,Montana folded belt province,North Park basin,Powder River basin,Sweetgrass arch,Uinta uplift,Williston basin,Wind River basin,Yellowstone province of Colorado,Montana,North Dakota,South Dakota,Utah,and Wyoming Fossils include fish scales and teeth.

Mural Limestone

Up to 1000 meters of Lower Cretaceous limestone and sandstone found in Arizona(se) and New Mexico(sw). It ovelies the Morita Formation/Lowell Formation and is overlain by the Cintura Formation/Hay Flat Limestone It is a member of the Bisbee Group

Fossils: Abundant marine mollusks. forams

Navajo Formation

More than 460 meters of unfossiliferous Late Triassic and/or Early Jurassic sandstone with a few thin limestone beds found in the Black Mesa basin,Great Basin province,Paradox basin,Piceance basin,Plateau sedimentary province,San Juan basin,Uinta basin and Uinta uplift of Arizona,Colorado,New Mexico,and Utah.

Newcastle Formation

Up to 30 meters of very near shore Lower(?) Cretaceous black shale,sandstone,bentonite,and coal found in Williston basin,Powder River basin, and Chadron arch of Montana,North Dakota,Nebraska,South Dakota, and Wyoming.

Nikanassin Formation

Up to 400 meters of near shore marine and continental Late Jurassic and Early Cretaceous sandstone, grey shale and thin coals found in the North Central Rocky Mountains of Alberta.

Niobrara Formation

Up to 230 meters of marine Uppermost Cretaceous limestone and/or shale found in the San Juan basin,Salina basin,Central Montana uplift,Powder River basin,Denver basin,Sioux uplift,Las Vegas-Raton basin,Williston basin,Iowa shelf,North Park basin of Colorado, Kansas,Minnesota,Montana,North Dakota,Nebraska,New Mexico,South Dakota and Wyoming. Contains marine vertebrates.

Nugget

Up to 800 meters of Triassic and/or Jurassic sandstones with minor limestones and shales in some areas. Found in the Denver,Green River,Wind River and Snake River basins and Yellowstone province of Colorado,Idaho,Utah,and Wyoming. Possibly some ichnofossils

Ojo Alamo Formation

Up to 70 meters of Uppermost Cretaceous and Early Paleocene(?) shale and sandstone found in the San Juan Basin of New Mexico where it overlies the Kirtland formation and is overlain by the Puerco formation. Abundant vertebrate fossils-dinosaurs,turtles,fish teeth.

Oldman

Up to 328m meters of Upper Cretaceous calcareous sandstone,shale,coal and bentonite found in Southern Alberta. Dinosaur remains and plant fossils are abundant It is the middle formation in the Judith River Group

Omadi Formation

Up to 50 meters of marine Lower Cretaceous Sandstone found in the Salina basin and Denver Basin of Colorado,Kansas,Nebraska,and Wyoming. The uppermost formation of the Dakota Group.

Pakowki Formation

Up to 200 meters of Upper Cretaceous grey mudstone with some sandstone and siltstone found in the plains of Southern Alberta and Saskatchewan

Pardonet Formation

Up to 137 meters of Triassic limestone and calcareous shale and siltstone with abundant bivalve fragments in some beds. Found in the Rocky Mountain foothills of NorthEast British Columbia. It is considered by some to be a part of the Schooler Creek Group

Paskapoo Formation

600 meters of Paleocene mudstone,siltstone,and sandstone with minor conglomerate,coal,limestone and bentonite with terrestrial vertebrate fossils and invertebrates in the limestones. Found in the Rocky Mountain foothills as well as exposures in the Northern, Western, and Central plains. May include some Cretaceous beds.

Peace River Formation

Up to 60 meters of Lower Cretaceous graywacke, sandstone, coal and shale found in the plains of Northern Alberta. Fossils include mollusks and starfish.

Pelican Formation

Up to 12 meters of Lower Cretaceous sandstone, siltstone and shale with often abundant carbonized plant fragments found in the plains of Northern Alberta.

Peterson Formation

Up to 83 meters of Cretaceous lacustrine algal limestone found Green River basin,Snake River basin,Wasatch uplift,and Yellowstone provinces of Idaho and Wyoming. Some fresh water invertebrate fossils. Part of the Gannett Group.

Pictured Cliffs Formation

Up to 90 meters of fossiliferous Upper Cretaceous near shore marine sandstone exposed in the San Juan basin of Colorado and New Mexico.

Pierre Formation

Up to 1400 meters of fossiliferous Upper Cretaceous dark marine shales with minor clay,limestone,and sandstone and large concretions widely exposed in Colorado,Kansas.Minnesota,Montana,North Dakota,Nebraska,New Mexico,South Dakota and Wyoming.

Pinyon Formation

Up to 200 meters of Latest Cretaceous/Early Paleocene conglomerate found in the Southwest part of the Yellowstone area of Wyoming.

Piper

Up to 100 meters of Jurassic marine shale,limestone,and dolomite interbedded with gypsum and redbeds. Found in the Central Montana uplift,Powder River,Williston,and Big Horn basins, and the Sweetgrass arch of Montana,North Dakota,and Wyoming. A few ammonites and gastropods found

Playas Peak

1070 meters of Lower(?) Cretaceous shale and sandstone found in New Mexico(sw). It overlies the Corbett Sandstone and is overlain by the Skunk Ranch Conglomerate It is a member of the Bisbee Group

Fossils: non-marine mollusks, petrified wood in lower beds. Sometimes abundant marine invertebrates in the Upper beds.

Porcupine Hills Formation

Up to 1220 meters of Paleocene brown shale,calcareous sandstone and siltstone. With abundant fresh water mollusks in some beds. Exposed in the Porcupine Hills of Southwestern Alberta.

Poison Canyon

Up to 2600 meters of Early Tertiary sandstone,conglomerate,clay,marl, and shale found in the Las Vegas-Raton basin of Colorado. A few vertebrates (turtles) reported

Preuss Formation

Up to 430 meters of late Jurassic redbed sandstone found in the Green River,Uinta and Snake River basins, Uinta and Wasatch uplifts and Yellowstone province. Of Idaho, Utah, and Wyoming. Includes a 60 meter fossiliferous marine limestone.

Purgatoire Formation

Up to 100 meters of Lower Cretaceous largely marine sandstone,shale, and coal found in the Anadarko basin,Sierra Grande uplift,Palo Duro basin,Las Vegas-Raton basin, and Denver basin of Colorado,New Mexico,and Oklahoma. A few marine invertebrate fossils reported. Generally includes all the beds below the Dakota sandstone and above the Jurassic Morrison formation. Subdivisions include the Kiowa, Glencarin, and Tucamcari shales and the Cheyenne and Lytle Sandstone.

Raton Formation

Up to 550 meters of very early Tertiary conglomerate,sandstone,coal, and shale found in the Las Vegas-Raton basin of Colorado or New Mexico. Some petrified wood and plant fossils reported.

Ravenscrag Formation

Up to 244 meters of Paleocene and Uppermost Cretaceous claystone,sandstone,shale and coal found in the Eastend-Cypress Hills area of Southwest Saskatchewan.

Rhyolite Canyon

Up to 700 meters of Middle Tertiary (Oligocene?, Micoene?) volcanic tuff and lava found in Arizona(se). It overlies the Faraway Ranch Formation

Fossils: None?

Rierdon Formation

Up to 70 meters of abundantly fossiliferous marine Middle or Upper Jurassic shale and limestone found in the Central Montana uplift,Sweetgrass arch,Williston basin,and Montana folded belt province of Montana, North Dakota, and Wyoming.

Riding Mountain

Up to 280 meters of Cretaceous clay and shale found in SouthEast Saskatchewan and adjacent Manitoba and North Dakota.

Ringbone Shale

Up to 2300 meters of Cretaceous sandstone,shale and conglomerate found in New Mexico(sw). It overlies the Mojado Formation, is contemperaneous with the Broken Jug Limestone and is overlain by Tertiary volcanics. It is a member of the Bisbee Group

Fossils: Cretaceous non-marine mollusks and plants

Rock Springs Formation

Up to 550 meters of Late Cretaceous sandstone,shale,and coal found in the Green River basin of Southwest Wyoming. Some of the sandstone and shale contain marine fossils

Rubio Peak Formation

Up to 1500 meters of poorly dated Middle Tertiary volcanics and gravels found in New Mexico(sw). It overlies volcanics/Lobo Formation sediments and is overlain by volcanics.

Fossils: None? Plants in lakebeds that may be contemporaneous

Sage Creek Formation

A Latest Eocene or Earliest Oligocene sandstone formation found in Beaverhead County, MT. Vertebrate fossils

Salero

1500 meters of Upper Cretaceous volcanics and sediments found in Arizona(se). It overlies the Fort Crittenden Formation and is overlain by Tertiary beds

Fossils: None?

Santa Rosa Formation

Up to 140 meters of Middle to Upper Triassic conglomeritic redbed sandstone interbedded with shale found below the Chinle formation in the Las Vegas-Raton basin,Palo Duro basin,Permian basin,Estancia basin,and Orogrande basin of New Mexico and Texas. In some places is mapped as undivided Dockum Group. Fossils include plant remains and vertebrate bones

Sarten Sandstone

Up to 100 meters of Lower and Middle Cretaceous sandstone and shale found in New Mexico(sw). It overlies the Santa Rosa Formation and is overlain by the Colorado Group/Dakota Formation

Fossils: marine molluscs in some beds.

Sawtooth Formation

Up to 45 meters of abundantly fossiliferous marine Jurassic sandstone,shale,and limestone found in the Central Montana uplift,Montana Folded Belt Province and Sweetgrass Arch of Idaho, Utah, and North Dakota.

Scollard Formation

Up to 85 meters of Uppermost Cretaceous and Lowest Paleocene sandstone, shale, mudstone, siltstone, and coal found in the westernmost part of the southern Alberta plains along the Red Deer River and adjacent areas

Shaunavon Formation

Up to 60 meters of marine Jurassic lithographic limestone capped with calcareous sandstone with abundant corals, pelecypods, gastropods, echinoids, algae. Found in the Southern Saskatchewan and adjacent Montana and North Dakota.

Shellenberger Canyon Formation

1200 meters of Lower Cretaceous shale,siltstone and sandstone with minor limestone found in Arizona(se). It overlies the Apache Canyon Formation and is overlain by the Turney Ranch Formation

Fossils: plants, bivalves

Shinarump Formation

Up to 18 meters of Upper Triassic conglomerate capping up to 60 meters of sandstone found in the Black Mesa basin,Great Basin province,Orogrande basin,Paradox Basic,Plateau sedimentary province,and San Juan basin of Arizona,Colorado,Nevada, and Utah where it underlies the Chinle sandstone. Petrified wood is commonly found in the conglomerate.

Skull Creek Formation

Up to 100 meters of marine Lower Cretaceous shale found in the Denver,Powder River,and Williston basins of Colorado,Montana,North Dakota,Nebraska,South Dakota, and Wyoming. Dated from forams and other microfossils

Skunk Ranch Formation

About 1000 meters of Lower Cretaceous cobbles in a shale and sandstone matirx found in New Mexico(sw). It overlies the Playas Peak Formation and is overlain by middle-Tertiary volcanics. May be the same as the Ringbone Formation. It is the uppermost member of the Bisbee Group

Fossils: Unknown? Enough for dating?

Sonoita Group

Upper Cretaceous sediments found in Arizona(se). It overlies the Lower Cretaceous Bisbee Group and is overlain by the SaleroFormation/Tertiary volcanics. It includes the Fort Buchanan and Fort Crittenden formations.

Fossils: Some vertebrates -- dinosaurs,fish -- in the Fort Crittenden Beds

Spearfish Formation

Up to 150 meters of Permian and Triassic redbed sandstone with thin gypsum interbeds found in the Williston basin, Powder River basin,Chadron arch,and Denver basin of Montana,North Dakota,Nebraska,South Dakota,and Wyoming.

Spirit River

Up to 348 meters of heterogeneous Lower Cretaceous clastic beds -- shale, sandstone, mudstone, ironstone, graywacke, coal -- found in the subsurface of the Northwestern plains of British Columbia and Alberta. Ammonites are present.

St Mary River

Up to 760 meters of Upper Cretaceous sandstone and friable shale with vertebrate bones. There are coal and fossiliferous marine limestones near base.

Steele Formation

Up to 760 meters of marine Upper Cretaceous shale and Sandstone found in the Green River and Powder River basins of Montana and Wyoming with a few ammonites. Considered to be the basal member of the Cody Shale.

Stump Formation

Up to 200 meters of mid to late Jurassic fossiliferous sandstone and siltstone with minor limestone found in the Green River and Snake River basins, Uinta and Wasatch uplifts and Yellowstone province. Of Colorado, Idaho, Utah, and Wyoming.

Sulphur Mountain Formation

Up to 557 meters of Lower Triassic shale and sandstone found in the Rocky Mountain foothills of Alberta and British Columbia.

Summerville Formation

Up to 110 meters of Middle Jurassic shale and sandstone found in the Paradox basin and Plateau sedimentary province of Arizona,Colorado,New Mexico,and Utah. The basal beds are from a hypersaline marine environment, the upper beds are continental red beds.

Sundance Formation

Up to 70 meters of abundantly fossiliferous marine Middle or Upper Jurassic shale and sandstone with thin limestone beds found in the Big Horn basin,Central Montana uplift,Chadron arch,Denver basin, Green River basin,Montana folded belt province,North Park basin,Powder River basin,Uinta basin,Williston basin, and Wind River basin of Colorado,Idaho,Montana,Nebraska,South Dakota,Utah, and Wyoming.

Swan River

At least 150 meters of Lower Cretaceous sandstone and clay with some plant fragments found in SouthWest Manitoba and adjacent Saskatchewan

Swift Formation

Up to 50 meters of fossiliferous marine Upper Jurassic sandstone and shale found in the Sweetgrass arch,Montana folded belt province, Central Montana uplift,Williston basin,Powder River basin,Big Horn basin,Chadron arch, and Wind River basin of North Central Montana. assorted marine invertebrates.

Swift Current Creek Formation

16 meters of Upper Eocene soft sandstone and conglomeritic gravel with vertebrate faunas. Scattered Exposures SE of Swift Current, SK.

Teepee Trail Formation

Late Eocene tuff,shale,conglomerate exposed at a few localities in the Wind River basin of Wyoming. vertebrate fossils.

Telegraph Creek Formation

Up to 300 meters of fossiliferous marine Upper Cretaceous shale and Sandstone found in the Sweetgrass arch,Williston basin,Montana folded belt province and Central Montana uplift of Montana and Wyoming.

Tecovas Formation

Up to 70 meters of Middle to Upper Triassic red and yellow shales found below Trujillo formation sandstones in the,Palo Duro basin,Permian basin,Estancia basin,and Orogrande basin of New Mexico and Texas. In some places is mapped as undivided Dockum Group where it is the lowest member. Fossils include petrified logs

Timberlake Fanglomerate

Up to 200 meters of Tertiary limestone conglomerate found in New Mexico(sw). It overlies the Cowboy Spring Formation/Mojado Formation and is overlain by Tertiary igneous rocks

Fossils: None

Trujillo Formation

Up to 70 meters of Middle to Upper Triassic sandstone found in the Las Vegas-Raton basin,Palo Duro basin,Permian basin,and Anadarko basin of New Mexico and Texas. Overlies the Tecovas formation. In some places is mapped as undivided Dockum Group. Triassic fossils reported

Thaynes Formation

Up to 1200 meters of fossiliferous Permian and Triassic marine shales, sandstones and limestones found in the Green River,Snake River,and Uintah basins, Uinta and Wasatch uplifts and Yellowstone province of Idaho, Montana, Nevada, Utah, and Wyoming. Fossils are reported to be present

Thermopolis Formation

Up to 100 meters of fossiliferous Upper Cretaceous black shale, Sandstone found in the Montana folded belt province,Big Horn basin,Chadron arch,Denver basin,Green River basin,Williston basin,Snake River basin,Wind River basin,Powder River basin, and Central Montana uplift provinces of Idaho,Wyoming, and Montana. It is the basal formation of the Colorado group. Fossils include plants and shark teeth.

Toad Formation

Triassic calcareous siltstones with minor sandstone, shale and limestone found in British Colombia. Includes the Grayling formation.

Trinidad Formation

As much as 70 meters of Upper Cretaceous sandstone found in the Las Vegas-Raton basin of Colorado and New Mexico. Fossils include fish and invertebrates.

Turney Ranch Formation

1200 meters of Lower Cretaceous shale,siltstone,sandstone and bentonite found in Arizona(se). It overlies the Shellenberger Canyon Formation and is overlain by the Fort Crittenden Formation/Salero Formation. It is a member of the Bisbee Group

Fossils: Unknown

Two Medicine Formation

Up to 700 meters of Upper Cretaceous continental shale with minor sandstone and limestone found in the folded belt and Sweetgrass Arch provinces of Northwest Montana. Fossils include dinosaurs and some fresh water mollusks.

Twin Creek Formation

Almost 1200 meters of fossiliferous marine Jurassic shale,limestone and sandstone found in the Green River,Uinta and Snake River basins, Uinta and Wasatch uplifts and Great Basin and Yellowstone provinces. Of Idaho, Utah, and Wyoming.

Tygee Formation

Up to 86 meters of Upper Cretaceous sandstone and shale found Green River basin,Snake River basin,and Wasatch uplift of Idaho and Wyoming. The beds have been reassigned to the Bear River or Smiths formations.

U-bar Limestone

1200 meters of Lower Cretaceous limestone with minor shale found in Arizona(se) and New Mexico(sw) It overlies the Hell-to-Finish Formation and is overlain by the Mojado Formation. It is a member of the Bisbee Group

Fossils: Sometimes abundant marine invertebrates

Vanguard Formation

Up to 180 meters of calcareous Jurassic marine shale with sandstone in the middle layers. It is found in Southernmost Saskatchewan and adjacent Montana and North Dakota. It is sometimes considered a group with three formations -- the Masefield Shale, Roseray Formation, and Rush Lake Shale. Bivalves and ammonites are reported.

Vermejo Formation

Up to 130 meters of Early Tertiary sandstone, shale, and coal found in the Las Vegas-Raton basin of Colorado and New Mexico. With abundant plant fossils in areas.

Vermillion River Formation

Up to 130 meters of terrestrial? Upper Cretaceous shales and marlstones found in Manitoba and adjacent Saskatchewan.

Viking

Up to 50 meters of terrestrial Cretaceous sandstone with minor conglomerates, chert and other rocks found in the subsurface of Southern Alberta and Saskatchewan. Plant fragments are abundant.

Virgelle Formation

Up to 80 meters of Upper Cretaceous marine sandstone with some shale and concretions exposed in the Folded belt,Central Montana Uplift and Sweetgrass Arch regions of Montana and Wyoming. Fossils restricted to a few poorly preserved bivalves.

Wagon Bed Formation

In excess of 200 meters of Late Eocene sandstone,siltstone,mudstone,tuffs and volcanic flows exposed in the Wind River basin of Wyoming. vertebrate fossils. Fossils include plants and vertebrates.

Walnut Formation

As much as 10 meters of fossiliferous Lower Cretaceous marine clay,sandstone,and limestone found in the Ouachita folded belt,Arkla basin,East Texas basin,Strawn basin,Llano uplift,Kerr basin, Permian basin,South Oklahoma folded belt,and Fort Worth synclines of Arkansas,Louisiana,New Mexico,Oklahoma,and Texas. Overlies the Antlers formation in many areas

Wapiti

Unfossiliferous sandstone with minor coal and conglomerate found in river bank exposures in Northern plains.

Wasatch Formation

Almost two kilometers of Late Paleocene and Eocene shale and sandstone found in the Wasatch uplift, Uinta uplift, Green River basin, Piceance basin, Powder River basin, Uinta basin, Paradox basin, Colorado Plateau, Yellowstone province, San Juan basin of Colorado, Idaho, New Mexico, Utah,Wyoming.

Wayan Formation

Roughly 4km of fossiliferous Lower Cretaceous sandstone and shale found in Green River basin,Snake River basin, and Wasatch uplift of Idaho and Wyoming

Whitemud

6 meters of non-marine bentonitic shale and sandstone found along the North Saskatchewan and Red Deer Rivers near Edmonton, AB.

White River Formation

At least 300 meters of Eocene and Oligocene siltstone,sandstone,conglomerate,and volcanic tuff exposed in the Wind River, Denver, and Williston basins as well as the Sioux uplift and Chadron Arch of Colorado, Montana, North Dakota,Nebraska,South Dakota and Wyoming. Abundant plant and vertebrate fossils.

Wiggins Formation

Middle to Late Eocene to Oligocene conglomerate,sandstone,lava breccias and clay exposed in the Bighorn and Wind River Basins as well as the Yellowstone region of Wyoming.

Wildwood Formation

At least 600m of Eocene floodplain sediments exposed in the Bighorn basin of Wyoming. Not to be confused with the marine(?) Wildwood Formation, also Eocene, of New Jersey.

Willow Canyon

As much as two kilometers of Upper Jurassic/Lower Cretaceous conglomerate, sandstone and siltstone found in Arizona(se). It overlies the Glance Conglomerate and is overlain by the Apache Canyon Formation. The name conflicts with the a formation of the same name in Nevada and it is unclear what name will be used by future authors. It is a member of the Bisbee Group

Fossils: Fresh water gastropods, petrified wood

Wind River Formation

Early(?) Eocene abundantly fossiliferous sandstones and claystones found in the Wind River Basin of Wyoming.

Willow Creek Formation

Up to 1006m of varicolored shale with concretions and grey sandstone found in the plains of SouthWest Alberta and adjacent Montana.

Wingate Formation

Up to 150 meters of unfossiliferous red Late Triassic and/or Early Jurassic sandstone with a few thin limestone beds found in the Black Mesa basin,Paradox basin,Plateau sedimentary province,and San Juan basin of Arizona,Colorado,New Mexico,and Utah. Underlies the Navajo formation where the latter is present. Contains a very few dinosaur tracks?

Woodside Formation

Up to 400 meters of Permian and Lower Triassic redbed sandstones and shales found in the Uinta and Wasatch uplifts and Snake River and Green River basins of Colorado,Idaho,Montana,Utah,and Wyoming. Abundant bivalves in some beds near the top.

Maps and Figures

Geologic Maps


Alberta Higher resolution map -


Arizona High Resolution map -


British Columbia

There are several maps at varying resolutions at http://www.empr.gov.bc.ca/MINING/GEOSCIENCE/PUBLICATIONSCATALOGUE/DIGITALGEOLOGYMAPS/Pages/default.aspx. They are all huge. This is the smallest


Colorado High Resolution map -


Iowa High Resolution map -


Idaho High Resolution map


Kansas High Resolution map


Manitoba I could not fine a modern bedrock map for Manitoba on-line. Here is an early 20th Century map of the prairie provinces including Southern Manitoba but omitting Paleozoic outcrops in the Arctic portions of Manitoba.


Minnesota High Resolution map


Montana High Resolution map


North Dakota High Resolution map


Nebraska High Resolution map


New Mexico High Resolution map


Oklahoma High Resolution map


South Dakota High Resolution map


Saskatchewan Higher resolution map. There may be one available but not free. This is the best free map I could find although the map linked for Manitoba may also be useful -


Texas High Resolution map


Utah High Resolution map


Wyoming High Resolution map


Yukon No bedrock map of the Yukon found on-line. It's this or nothing


Formations

See Rocks


References

[http://web.archive.org/web/20091231184415/http://fossilsoftexas.webs.com/]


Copyright 2006-2012 Donald Kenney (Donald.Kenney@GMail.com). Unless otherwise stated, permission is hereby granted to use any materials on these pages under the Creative Commons License V2.5.

This page will have been validated as Valid HTML 4.01 Transitional prior to posting on the web site. W3C Logo Image omitted.