The Little Missouri River is a tributary of the Missouri River, 560 miles (901 km) long, in the northern Great Plains of the United States. Rising in northeastern Wyoming, in western Crook County about 15 miles (24 km) west of Devils Tower, it flows northeastward, across a corner of southeastern Montana, and into South Dakota. In South Dakota, it flows northward through the Badlands into North Dakota, crossing the Little Missouri National Grassland and both units of Theodore Roosevelt National Park. In the north unit of the park, it turns eastward and flows into the Missouri in Dunn County at Lake Sakakawea, where it forms an arm of the reservoir 30 miles (48 km) long called Little Missouri Bay and joins the main channel of the Missouri about 25 miles (40 km) northeast of Killdeer.
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.
Peltandra, the arrow arums, is a genus of plants in the family Araceae. It is native to the eastern United States, eastern Canada, and Cuba.
- Peltandra sagittifolia - (Michx.) Morong - Spoon flower or the white arrow arum - southeastern US from eastern Louisiana to Virginia
- Peltandra virginica(L.) Schott - Arum arrow - Cuba, Quebec, Ontario, Oregon, California, Washington; eastern US from Maine to Florida, west to Texas, Kansas, and Minnesota
- †Peltandra primaeva – Eocene, Golden Valley Formation, North Dakota, USA
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 Niobrara Formation, also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is composed of two structural units, the Smoky Hill Chalk Member overlying the Fort Hays Limestone Member. The chalk formed from the accumulation of coccoliths from microorganisms living in what was once the Western Interior Seaway, an inland sea that divided the continent of North America during much of the Cretaceous. It underlies much of the Great Plains of the US and Canada. Evidence of vertebrate life is common throughout the formation and includes specimens of plesiosaurs, mosasaurs, and pterosaurs as well as several primitive aquatic birds. The type locality for the Niobrara Chalk is the Niobrara River in Knox County in northeastern Nebraska. The formation gives its name to the Niobrara cycle of the Western Interior Seaway.
Thunder Butte is a prominent butte landmark located in the northwest corner of Ziebach County, South Dakota, in the United States. Thunder Butte is a large, isolated hill that can be seen for many miles in every direction, and has served throughout history as an important orientation point for area residents or a navigational aide for travelers crossing the surrounding plains. The butte gives its name to a small community at its base, and to a small creek that runs into the Moreau River.
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 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 Brule Formation was deposited between 33 and 30 million years ago, roughly the Rupelian age (Oligocene). It occurs as a subunit of the White River Formation in Nebraska, Colorado, North Dakota, South Dakota, and Wyoming.
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 Arikaree Formation, also Arikaree Group or Arikaree Sandstone is a geological unit in the central High Plains of the western United States. It preserves fossils dating to the late Oligocene to early Miocene.
The Bullion Creek Formation is a geologic formation in western North Dakota. It preserves bones and tracks of an extinct crocodile and other fossils of Late Paleocene age.
The Cannonball Formation is a geologic formation in western North Dakota. It preserves fossils dating back to the Paleogene Period.
The Ludlow Formation is a geologic formation in western North Dakota. It preserves fossils dating back to the Paleogene Period.
The Slope Formation is a geologic formation in western North Dakota. It preserves fossils dating back to the Paleogene Period.
The Tongue River Member is a geologic member of the Fort Union Formation in North Dakota and Wyoming. It preserves fossils dating back to the Paleogene period.
The Pahasapa Formation is a geological unit of primarily limestone and dolostone that is exposed primarily in the Black Hills of South Dakota. Analogous to the Madison Limestone and the Burlington Limestone, other Mississippian-aged limestones in the midwestern United States.
The Benton Shale is a geologic formation in Montana, Wyoming, North Dakota, South Dakota, Colorado, Kansas, and Nebraska. It preserves fossils dating to the Cretaceous Period. The term Benton Limestone has also been used to refer to the chalky portions of the strata, especially the upper beds of the strata presently classified as Greenhorn Limestone. The Benton classification is obsolete in some regions, having been replaced by the ascending sequence Graneros Shale, Greenhorn Limestone, and Carlile Shale.
The Golden Valley Formation is a stratigraphic unit of Late Paleocene to Early Eocene age in the Williston Basin of North Dakota. It is present in western North Dakota and was named for the city of Golden Valley by W.E. Benson and W.M. Laird in 1947. It preserves significant assemblages of fossil plants and vertebrates, as well as mollusk and insect fossils.
United States 