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The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin cover 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah and Arizona. Specifically, the basin occupies space in the San Juan, Rio Arriba, Sandoval, and McKinley counties in New Mexico, and La Plata and Archuleta counties in Colorado. The basin extends roughly 100 miles (160 km) N-S and 90 miles (140 km) E-W.
The Laramie Formation is a geologic formation of Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States. It was deposited on a coastal plain and in coastal swamps that flanked the Western Interior Seaway. It contains coal, clay and uranium deposits, as well as plant and animal fossils, including dinosaur remains.
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 Formation is a sedimentary geologic formation composed of sandstones, mudstones, and shales deposited in the late-Early to early-Late Cretaceous Western Interior Seaway. The unit is noted for being exceptionally widespread, producing massive colorful rock formations, and preserving dinosaur footprints and early deciduous tree leaves.
The Fort Union Formation is a geologic unit containing sandstones, shales, and coal beds in Wyoming, Montana, and parts of adjacent states. In the Powder River Basin, it contains important economic deposits of coal, uranium, and coalbed methane.
The Chuckanut Formation in northwestern Washington, its extension in southwestern British Columbia, and various related formations in central Washington are fluvial sedimentary formations of Eocene age, deposited from about 54 Ma to around 42 to 34 Ma. The nature of the deposits and included plant fossils indicate a low-lying coastal plain with a subtropical climate; the nature of the sediments indicates metamorphic sources in northeastern Washington.
The Wapiti Formation is a geological formation of the Western Canada Sedimentary Basin in northwestern Alberta, and Northeastern British Columbia, Canada. Its deposition spanned the time interval from Late Cretaceous to early Paleocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event. It was named by G.M. Dawson in 1881, presumably for exposures along the lower part of the Wapiti River and downstream along the Smoky River in Alberta.
The Willow Creek Formation is a stratigraphic unit of Late Cretaceous to Early Paleocene age in the Western Canada Sedimentary Basin of southwestern Alberta. It was first described by George Mercer Dawson in 1883 along the Willow Creek, a tributary of the Oldman River. Williams and Dyer defined the type section in 1930 at the mouth of Willow Creek, east of Fort Macleod.
The North Horn Formation is a widespread non-marine sedimentary unit with extensive outcrops exposed in central and eastern Utah. The formation locally exceeds 3,600 feet (1,100 m) in thickness and is characterized by fluvial, lacustrine, and floodplain dominated systems, representing a terrestrial, high energy, depositional environment. The sediments date from Late Cretaceous (Maastrichtian) to early Paleocene in age and include the K-Pg extinction event boundary; however, this boundary is extremely difficult to locate and there is no strong stratigraphic evidence available that indicates a specific marker bed such as an iridium rich clay layer. Thus far, the only visible evidence is represented in the form of faunal turnover from dinosaur to mammal-dominated fossil assemblages. Taxa from the Cretaceous part of the formation include squamates, testudines, choristoderes, crocodyliforms, sharks, bony fishes, amphibians, mammals, dinosaurs, eggshell fragments, trace fossils, mollusks, plant macrofossils, such as wood fragments, and palynomorphs.
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The Arapahoe Formation is a geological formation of latest Cretaceous (Maastrichtian) age that is present within the Denver Basin that underlies the Denver, Colorado, area. The formation includes fossil leaves and dinosaur remains, although none of the latter have yet been referred to a specific genus. It also includes aquifers that are important sources of water for the area.
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 Santa Lucía Formation is a Maastrichtian to Paleocene (Danian) geologic formation in Bolivia. Fossil ornithopod tracks have been reported from the Cretaceous lower part of the formation. It is the type formation of the Tiupampan South American land mammal age.
The Edmonton Group is a Late Cretaceous to early Paleocene stratigraphic unit of the Western Canada Sedimentary Basin in the central Alberta plains. It was first described as the Edmonton Formation by Joseph Burr Tyrrell in 1887 based on outcrops along the North Saskatchewan River in and near the city of Edmonton. E.J.W. Irish later elevated the formation to group status and it was subdivided into four separate formations. In ascending order, they are the Horseshoe Canyon, Whitemud, Battle and Scollard Formations. The Cretaceous-Paleogene boundary occurs within the Scollard Formation, based on dinosaurian and microfloral evidence, as well as the presence of the terminal Cretaceous iridium anomaly.
The Ojo Alamo Formation is a geologic formation in New Mexico spanning the Mesozoic/Cenozoic boundary.
The Mancos Shale or Mancos Group is a Late Cretaceous geologic formation of the Western United States.
The Burro Canyon Formation is an Early Cretaceous Period sedimentary geologic formation, found in western Colorado, the Chama Basin and eastern San Juan Basin of northern New Mexico, and in eastern Utah, US.
The Mesaverde Group is a Late Cretaceous stratigraphic group found in areas of Colorado, New Mexico, Utah, and Wyoming, in the Western United States.
The Mount Whyte Formation is a stratigraphic unit that is present on the western edge of the Western Canada Sedimentary Basin in the southern Canadian Rockies and the adjacent southwestern Alberta plains. It was deposited during Middle Cambrian time and consists of shale interbedded with other siliciclastic rock types and limestones. It was named for Mount Whyte in Banff National Park by Charles Doolittle Walcott, the discoverer of the Burgess shale fossils, and it includes several genera of fossil trilobites.
References
- 1 2 3 Raynolds, R.G. 2002. Upper Cretaceous and Tertiary stratigraphy of the Denver Basin, Colorado. Rocky Mountain Geology, vol. 37, no. 2, p. 111-134.
- ↑ Richardson, G.B. 1915. Castle Rock, Colorado. U.S. Geological Survey Atlas Folio 198.
- ↑ U.S. Geological Survey. "Geologic Unit: Dawson" . Retrieved 2014-12-27.
- ↑ Johnson, K.R., Reynolds, M.L., Werth, K.W., and Thomasson, J.R. 2003. Overview of the Late Cretaceous, early Paleocene, and early Eocene megafloras of the Denver Basin, Colorado. Rocky Mountain Geology, vol. 38, no. 1, p. 101-120.
- ↑ Raynolds, R.G. and Johnson, K.R. 2003. Synopsis of the stratigraphy and paleontology of the uppermost Cretaceous and lower Tertiary strata in the Denver Basin, Colorado. Rocky Mountain Geology, vol. 38, no. 1, p. 171-181.
- ↑ Barclay, R.S., Johnson, K.R., Betterton, W.J., and Dilcher, D.L., 2003. Stratigraphy and megaflora of a K-T boundary section in the eastern Denver Basin, Colorado. Rocky Mountain Geology vol. 38, no. 1, p. 45-71.
