The Western Interior Seaway was a large inland sea that split the continent of North America into two landmasses. The ancient sea, which existed from the early Late Cretaceous to the earliest Paleocene, connected the Gulf of Mexico to the Arctic Ocean. The two land masses it created were Laramidia to the west and Appalachia to the east. At its largest extent, it was 2,500 feet (760 m) deep, 600 miles (970 km) wide and over 2,000 miles (3,200 km) long.
The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid-Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where William Lee Stokes first studied the exposures in 1944.
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
Ptychodus is a genus of extinct durophagous (shell-crushing) sharks from the Late Cretaceous. Fossils of Ptychodus teeth are found in many Late Cretaceous marine sediments worldwide. Numerous species have been described. The youngest remains date to around 85 million years ago. A large number of remains have been found in the former Western Interior Seaway. A 2016 publication found that Ptychodus are likely true sharks belonging to Selachimorpha, rather than hybodonts or batoids as previously thought. Their life history coincides with the typical life of many other large sharks: they lived relatively long lives and were slow growing and produced large offspring and small litters.
The Moreno Hill Formation is a geological formation in western New Mexico whose strata were deposited in the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. The age of the formation is dated between approximately 90.9 to 88.6 million years ago based on detrital zircons.
The Woodbine Group is a geological formation in east Texas whose strata date back to the Early to Middle Cenomanian age of the Late Cretaceous. It is the producing formation of the giant East Texas Oil Field from which over 5.42 billion barrels of oil have been produced. The Woodbine overlies the Maness Shale, Buda Limestone, or older rocks, and underlies the Eagle Ford Group or Austin Chalk. In outcrop the Woodbine Group has been subdivided into the Lewisville Sandstone, Dexter Sandstone, and/or Pepper Shale formations. Thin-bedded sands of the Woodbine and Eagle Ford are collectively referred to as the "Eaglebine" oil and gas play in the southwestern portion of the East Texas region.
The Blackhawk Formation is a geological formation in east-central Utah, USA. It was named for the former town of Blackhawk on the east side of the Wastach Plateau, Carbon County. The formation is composed of mostly light-brown, light-gray and brownish-gray, thin- to medium-bedded, fine- to medium-grained quartzose sandstone that is interbedded with shaly siltstone, shale, carbonaceous shale, and coal. There are many thin to thick bituminous coal seams, including several economically important beds, such as the Sunnyside Coal. The formation thickness ranges from about 120 m to about 270 m. It conformably overlies the Star Point Sandstone and unconformably underlies the Castlegate Sandstone.
Pycnodonte is a genus of extinct oysters, fossil marine bivalve mollusks in the family Gryphaeidae, the foam oysters or honeycomb oysters. Shells of species in this genus are found around the world in fossil shell beds from the Valanginian to the Early Pleistocene. They are a commonly found fossil in Cretaceous shellbeds of the Navesink Formation in New Jersey.
The Birdrong Sandstone is an Early Cretaceous geologic formation of the Barrow Group in Western Australia. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.
The Tres Hermanos Formation is a geologic formation in central and west-central New Mexico. It contains fossils characteristic of the Turonian Age of the late Cretaceous.
The Tropic Shale is a Mesozoic geologic formation. Dinosaur remains are among the fossils that have been recovered from the formation, including Nothronychus graffami. The Tropic Shale is a stratigraphic unit of the Kaiparowits Plateau of south central Utah. The Tropic Shale was first named in 1931 after the town of Tropic where the Type section is located. The Tropic Shale outcrops in Kane and Garfield counties, with large sections of exposure found in the Grand Staircase–Escalante National Monument.
The Straight Cliffs Formation is a stratigraphic unit in the Kaiparowits Plateau of south central Utah. It is Late Cretaceous in age and contains fluvial, paralic, and marginal marine (shoreline) siliciclastic strata. It is well exposed around the margin of the Kaiparowits Plateau in the Grand Staircase – Escalante National Monument in south central Utah. The formation is named after the Straight Cliffs, a long band of cliffs creating the topographic feature Fiftymile Mountain.
The Pajarito Formation is a geologic formation in eastern New Mexico and west Texas. It preserves fossils dating back to the Albian Age of the Cretaceous Period.
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 Aoufous Formation is a geological formation that contains some of the vertebrate assemblage of the Kem Kem Group, of Late Cretaceous date. Two other formations comprise the Kem Kem beds: the underlying Ifezouane Formation and the overlying Akrabou Formation.
The Mesa Rica Sandstone is a geologic formation in Oklahoma and New Mexico. It preserves fossils dating back to the Cretaceous period.
Juana Lopez refers to both the uppermost member of the Carlile Shale formation and to the environment that caused it to form. The Juana Lopez Member is calcareous sandstone dated to the Turonian age of the Upper Cretaceous and is exposed in the southern and western Colorado, northern and central New Mexico, and northeastern Utah. The unit has been described as "the most enigmatic" member of the Carlile Shale.
