| Marlbrook Marl | |
|---|---|
| Stratigraphic range: Cretaceous | |
| Type | Formation |
| Underlies | Saratoga Formation |
| Overlies | Annona Chalk |
| Thickness | 50 to 220 feet [1] |
| Location | |
| Region | Arkansas |
| Country | United States |
| Type section | |
| Named by | Robert Thomas Hill [2] |
The Marlbrook Marl is a geologic formation in Arkansas. [1] It preserves fossils dating back to the Late Cretaceous period.
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The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from Pembina Valley in Canada to New Mexico.
The Demopolis Chalk is a geological formation in North America, within the U.S. states of Alabama, Mississippi, and Tennessee. The chalk was formed by pelagic sediments deposited along the eastern edge of the Mississippi embayment during the middle Campanian age of the Late Cretaceous. It is a unit of the Selma Group and consists of the upper Bluffport Marl Member and a lower unnamed member. Dinosaur and mosasaur remains are among the fossils that have been recovered from the Demopolis Chalk.
During most of the Late Cretaceous the eastern half of North America formed Appalachia, an island land mass separated from Laramidia to the west by the Western Interior Seaway. This seaway had split North America into two massive landmasses due to a multitude of factors such as tectonism and sea-level fluctuations for nearly 40 million years. The seaway eventually expanded, divided across the Dakotas, and by the end of the Cretaceous, it retreated towards the Gulf of Mexico and the Hudson Bay.
The Pudovkino Formation is a Late Cretaceous (Campanian) geologic formation in Saratov Oblast of European Russia. Pterosaur fossils have been recovered from the marine marls of the formation.
The Gravel Point Formation is a geologic formation in western Michigan. It preserves fossils dating back to the middle Devonian period and correlates with the Long Lake Limestone and Alpena Limestone.
The Batesville Sandstone is a geologic formation in northern Arkansas, United States, that dates to the Chesterian Series of the late Mississippian. The base of the Batesville Sandstone, named the Hindsville Limestone Member, unconformably lies on the Moorefield Formation.
The Hale Formation is a geologic formation in northern Arkansas that dates to the Morrowan Series of the early Pennsylvanian. The Hale Formation has two named members: the Cane Hill and the Prairie Grove Members. The lower member is the Cane Hill, a primarily sandstone and shale interval that unconformably overlies the Mississippian-age Pitkin Formation. The upper member, the Prairie Grove Member, is predominately limestone and conformably underlies the Bloyd Formation.
The Imo Formation, or Imo Shale, is a geologic unit in northern Arkansas that dates to the Chesterian Series of the late Mississippian. The Imo is considered to be a member of the upper Pitkin Formation, and is the most recent Mississippian age rock in Arkansas. The Imo Shale unconformably underlies the Pennsylvanian age Hale Formation
The Bloyd Formation, or Bloyd Shale, is a geologic formation in Arkansas. It preserves fossils dating back to the Carboniferous period.
The Annona Chalk is a geologic formation in Arkansas, Texas, Louisiana, and Oklahoma. It preserves fossils dating back to the Cretaceous period. The formation is a hard, thick-bedded to massive, slightly fossiliferous chalk. It weathers white, but is blue-gray when freshly exposed. The unit is commercially mined for cement. Fossils in the Annona Chalk include coelenterates, echinoderms, annelids, bivalves, gastropods, cephalopods, and some vertebrate traces. The beds range in thickness, up to over 100 feet in depth in some areas ., but thins to the east and is only a few feet thick north of Columbus, Arkansas and is completely missing to the east. The break between the Annona Formation and the Ozan Formation appears to be sharp with a few tubular borings up to a foot long extending down from the Annona in to the Ozan.
The Arkadelphia Marl, also called the Arkadelphia Formation, is a geologic formation in Arkansas in Clark, Nevada, and Hempstead counties. It preserves fossils dating back to the late Maastrichtian stage of the Cretaceous period.
The Brownstown Marl is a geologic formation in Arkansas. It preserves fossils dating back to the Cretaceous period.
The Ozan Formation is a geologic formation in Arkansas, Oklahoma and Texas. It preserves fossils dating back to the Cretaceous period.
The White Bluff Formation is a marl, sand, and clay geologic formation in Arkansas that is part of the Jackson Group. It preserves fossils dating back to the Paleogene period, specifically the Eocene.
The Sharps Formation is a geologic formation in South Dakota. It preserves fossils dating back to the Paleogene.
The Taylor Marl is a geologic formation in Texas. It preserves fossils dating back to the Cretaceous period.
The Goodland Limestone or Goodland Formation is a geologic formation in Arkansas and Texas. It preserves fossils dating back to the Cretaceous period.
The Cedar District Formation is a geologic formation exposed on Vancouver Island, the Gulf Islands of British Columbia and San Juan Islands of Washington (state). It preserves fossils dating back to the Campanian Epoch of the Cretaceous period. It dates to the lower mid-Campanian.
Amphissites is an extinct genus of ostracod belonging to the suborder Beyrichicopina and family Amphissitinae. Species belonging to the genus lived from the Devonian to the Permian in Europe, North America, Australia, and east Asia. The genus were likely deposit-feeders, and may have survived briefly into the Triassic.
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