| Belle Fourche Formation | |
|---|---|
| Stratigraphic range: Cretaceous | |
| Type | Formation |
| Location | |
| Region | Montana, North Dakota, South Dakota, Wyoming |
| Country | United States |
The Belle Fourche Formation or Belle Fourche Shale is a fossiliferous early Late-Cretaceous geologic formation classification in Wyoming. Named for outcrops in Belle Fourche River, Wyoming, this unit name is also used in Montana, North Dakota, and South Dakota. [1]
The unit records the gradual opening and expansion of the Greenhorn Cycle of the Western Interior Seaway, and as such is lithologically identical to the Graneros Shale Formation (that is, it is the same formation under a different name). [2]
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
The Cloverly Formation is a geological formation of Early Cretaceous age that is present in parts of Montana, Wyoming, Colorado and Utah in the western United States. It was named for a post office on the eastern side of the Bighorn Basin in Wyoming by N.H. Darton in 1904. The sedimentary rocks of formation were deposited in floodplain environments and contain vertebrate fossils, including a diverse assemblage of dinosaur remains. In 1973, the Cloverly Formation Site was designated as a National Natural Landmark by the National Park Service.
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Interior Seaway. The usage of the name Dakota for this particular Albian-Cenomanian strata is exceptionally widespread; from British Columbia and Alberta to Montana and Wisconsin to Colorado and Kansas to Utah and Arizona. It is famous for producing massive colorful rock formations in the Rocky Mountains and the Great Plains of the United States, and for preserving both dinosaur footprints and early deciduous tree leaves.
The Naturita Formation is a classification used in western Colorado and eastern Utah for a Cretaceous Period sedimentary geologic formation. This name was "applied to the upper or carbonaceous part of Dakota Group" by R.G. Young in 1960, naming it for Naturita, Colorado. The name is not used by U.S. Geological Survey authors, but has found growing acceptance by the Utah Geological Survey
Colorado is a geologic name applied to certain rocks of Cretaceous age in the North America, particularly in the western Great Plains. This name was originally applied to classify a group of specific marine formations of shale and chalk known for their importance in Eastern Colorado. The surface outcrop of this group produces distinctive landforms bordering the Great Plains and it is a significant feature of the subsurface of the Denver Basin and the Western Canadian Sedimentary Basin. These formations record important sequences of the Western Interior Seaway, and as the geology of this seaway was studied, this name came to be used in states beyond Colorado, but was later replaced in several of these states with more localized names.
The Fox Hills Formation is a Cretaceous geologic formation in the northwestern Great Plains of North America. It is present from Alberta on the north to Colorado in the south.
The Mowry Shale is an Early Cretaceous geologic formation. The formation was named for Mowrie Creek, northwest of Buffalo in Johnson County, Wyoming.
The Kiowa Formation or Kiowa Shale is a Cretaceous geologic formation in Kansas, diminishing to member status in Colorado and Oklahoma. In Colorado, the Kiowa Shale was classified as a member of the now abandoned Purgatoire Formation. In the vicinity of Longford, Kansas, the local Longford member comprises thinly bedded siltstone, clay, polished gravel, lignite, and sandstone suggests a river and estuary environment.
The Carlile Shale is a Turonian age Upper/Late Cretaceous series shale geologic formation in the central-western United States, including in the Great Plains region of Colorado, Kansas, Nebraska, New Mexico, North Dakota, South Dakota, and Wyoming.
The Mancos Shale or Mancos Group is a Late Cretaceous geologic formation of the Western United States.
The Graneros Shale is a geologic formation in the United States identified in the Great Plains as well as New Mexico that dates to the Cenomanian Age of the Cretaceous Period. It is defined as the finely sandy argillaceous or clayey near-shore/marginal-marine shale that lies above the older, non-marine Dakota sand and mud, but below the younger, chalky open-marine shale of the Greenhorn. This definition was made in Colorado by G. K. Gilbert and has been adopted in other states that use Gilbert's division of the Benton's shales into Carlile, Greenhorn, and Graneros. These states include Kansas, Texas, Oklahoma, Nebraska, and New Mexico as well as corners of Minnesota and Iowa. North Dakota, South Dakota, Wyoming, and Montana have somewhat different usages — in particular, north and west of the Black Hills, the same rock and fossil layer is named Belle Fourche Shale.
The Greenhorn Limestone or Greenhorn Formation is a geologic formation in the Great Plains Region of the United States, dating to the Cenomanian and Turonian ages of the Late Cretaceous period. The formation gives its name to the Greenhorn cycle of the Western Interior Seaway.
The Deadwood Formation is a geologic formation of the Williston Basin and Western Canada Sedimentary Basin. It is present in parts of North and South Dakota and Montana in the United States, and in parts of Alberta, Saskatchewan, and southwestern corner of Manitoba in Canada. It is of Late Cambrian to Early Ordovician age and was named for exposures in Whitewood Creek near Deadwood, South Dakota. It is a significant aquifer in some areas, and its conglomerates yielded significant quantities of gold in the Black Hills of South Dakota.
The Inyan Kara Group is a geologic group classification applied in South Dakota and adopted in portions of Wyoming and Montana. It preserves fossils of the mid-Cretaceous period. Of late Albian age, this classification correlates with the lower Dakota Formation known in the southwest corner of the State.
The Valentine Formation is a geologic unit formation or member within the Ogallala unit in northcentral Nebraska near the South Dakota border. It preserves fossils dating to the Neogene period and is particularly noted for Canid fossils. A particular feature of the Valentine is lenticular beds of green-gray opaline sandstone that can be identified in other states, including South Dakota, Nebraska, Kansas, and Colorado. Even though three mammalian fauna stages can be mapped throughout the range of the Ogallala, no beddings of the Ogallala are mappable and all attempts of formally applying the Valentine to any mappable lithology beyond the type location have been abandoned. Even so, opaline sandstone has been used to refer to the green-gray opalized conglomerate sandstone that is a particular feature of the lower Ogallala.
The Pahasapa Formation is a geological unit of primarily limestone and dolomite that is exposed in the Black Hills of South Dakota and northwestern Wyoming, and underlies parts of Nebraska. Also referred to as the Pahasapa Limestone, this unit is analogous to the Madison Limestone and the Burlington Limestone, other Mississippian-aged limestones and dolomites in the midwestern United States. Two of the ten longest caves in the world are found in the Pahasapa.
The Benton Shale is a geologic formation name historically used in Montana, Wyoming, North Dakota, South Dakota, Colorado, Kansas, and Nebraska. In the "mile high" plains in the center of the continent, the named layers preserve marine fossils from the Late Cretaceous Period. The term Benton Limestone has also been used to refer to the chalky portions of the strata, especially the beds of the strata presently classified as Greenhorn Limestone, particularly the Fencepost limestone.
The Thermopolis Shale is a geologic formation which formed in west-central North America in the Albian age of the Late Cretaceous period. Surface outcroppings occur in central Canada, and the U.S. states of Montana and Wyoming. The rock formation was laid down over about 7 million years by sediment flowing into the Western Interior Seaway. The formation's boundaries and members are not well-defined by geologists, which has led to different definitions of the formation. Some geologists conclude the formation should not have a designation independent of the formations above and below it. A range of invertebrate and small and large vertebrate fossils and coprolites are found in the formation.
The Newcastle Sandstone is a geologic formation in Wyoming, United States. It preserves fossils dating back to the Late Cretaceous period.
The Kootenay Group, originally called the Kootenay Formation, is a geologic unit of latest Jurassic to earliest Cretaceous age in the Western Canada Sedimentary Basin that is present in the southern and central Canadian Rockies and foothills. It includes economically important deposits of high-rank bituminous and semi-anthracite coal, as well as plant fossils and dinosaur trackways.
The lithologic equivalent of the Graneros in the Black Hills and surrounding areas is the Belle Fourche Shale. Considerable similarity exists between these two formations, and, if the name Graneros is to be perpetuated in the Black Hills region, it would be best used to replace the name Belle Fourche over which the former has priority.
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