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The Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type that is formed under warm, shallow marine conditions.
These two formations are not recognised within the northern province i.e. the outcrop north from East Anglia to Yorkshire, where the entire sequence is now referred to as the 'Ferriby Chalk Formation'. The thickness of the Grey Chalk Subgroup strata varies, averaging around 200 ft (61 m), depending upon the location.
The stratigraphy of the formation was most recently revised in a 1971 study. [14] A stratigraphic column at the Mount Bonnell location starts with the Lower Cretaceous Trinity Group overlain by the Edwards Group. Upper Cretaceous formations follow, starting with the Del Rio Clay, Buda Limestone, and then the Eagle Ford Group.
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 putative galloanseran bird Austinornis lentus has been found in the Austin Chalk. [2] [3] The general absence of dinosaurs is a reflection of the Austin limestone being marine in origin, primarily composed of microscopic shell fragments from floating sea organisms known as "coccolithophores" (the same organisms that contributed to the White Cliffs of Dover, on the south coast of England). [4]
The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group (a sequence of rock strata) ... Purbeck Limestone Formation and Purbeck Stone. [1] ...
A stratigraphic column at the Mount Bonnell Fault location starts with the Lower Cretaceous Trinity Group overlain by the Edwards Group. Upper Cretaceous formations follow, starting with the Del Rio Clay, Buda Limestone, and then the Eagle Ford Group. Formations within the Edwards Group include the Kainer Formation and the Person Formation.
The Sannine Formation, also called the Sannine Limestone, is a Cretaceous geologic formation in Lebanon.It is a Konservat-Lagerstätte that contains a high diversity of well-preserved fish, reptiles, and invertebrates from the Tethys Ocean within its three main localities: Haqel (alternatively Hakel or Haqil), Hjoula (alternatively Hadjoula, Hajoula, or Hgula), and Nammoura (alternatively ...