The Kimmeridge Clay is a

sedimentary Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

deposit of fossiliferous marine

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay part ...

which is of

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the ...

to lowermost

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

age and occurs in southern and eastern England and in the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

. This rock

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

is the major

source rock In petroleum geology, source rock is rock which has generated hydrocarbons or which could generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been deposi ...

for

North Sea oil North Sea oil is a mixture of hydrocarbons, comprising liquid petroleum and natural gas, produced from petroleum reservoirs beneath the North Sea. In the petroleum industry, the term "North Sea" often includes areas such as the Norwegian Sea an ...

. The fossil fauna of the Kimmeridge Clay includes turtles,

crocodile Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant ...

sauropods Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

plesiosaurs The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

pliosaurs Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive too ...

and

ichthyosaur Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...

s, as well as a number of

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

species.

Description

Kimmeridge Clay is named after the village of

Kimmeridge Kimmeridge () is a small village and civil parish on the Isle of Purbeck, a peninsula on the English Channel coast in Dorset, England. It is situated about south of Wareham and west of Swanage. In 2013 the estimated population of the civil p ...

on the

Dorset Dorset ( ; archaically: Dorsetshire , ) is a county in South West England on the English Channel coast. The ceremonial county comprises the unitary authority areas of Bournemouth, Christchurch and Poole and Dorset. Covering an area of ...

coast of England, where it is well exposed and forms part of the

Jurassic Coast The Jurassic Coast is a World Heritage Site on the English Channel coast of southern England. It stretches from Exmouth in East Devon to Studland Bay in Dorset, a distance of about , and was inscribed on the World Heritage List in mid-Decembe ...

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for ...

. Onshore, it is of Late Jurassic (

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxford ...

) age and outcrops across England, in a band stretching from Dorset in the south-west, north-east to

North Yorkshire North Yorkshire is the largest ceremonial county (lieutenancy area) in England, covering an area of . Around 40% of the county is covered by national parks, including most of the Yorkshire Dales and the North York Moors. It is one of four cou ...

. Offshore, it extends into the Lower Cretaceous (

Berriasian In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years a ...

Stage) and it is found throughout the Southern, Central and Northern North Sea. The foundations of the Humber Bridge on the southern (Barton) side of the bridge are on Kimmeridge Clay beneath superficial deposits, under the

Humber The Humber is a large tidal estuary on the east coast of Northern England. It is formed at Trent Falls, Faxfleet, by the confluence of the tidal rivers Ouse and Trent. From there to the North Sea, it forms part of the boundary betw ...

estuary.

Economic importance

Kimmeridge Clay is of great economic importance, being the major

for oil fields in the North Sea hydrocarbon province. It has distinctive physical properties and log responses.

Vertebrate fauna

Fauna uncovered from the Kimmeridge Clay include:Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 545–549. .

Ray-finned fish

Lobe-finned fish

Cartilaginous fish

Turtles

Archosaurs

Thalattosuchians

Ornithischians

Indeterminate ankylosaur osteoderms have been found in Wiltshire, England. Indeterminate stegosaurid remains have been found in Dorset and Wiltshire, England.

Saurischians

Indeterminate ornithomimmid remains have been found in Dorset, England. An undescribed theropod genus was found in Dorset.

Pterosaurs

Plesiosaurs

Ichthyosaurs

Invertebrates

The invertebrate fauna of the Kimmeridge Clay includes:http://www.fullbooks.com/The-Student-s-Elements-of-Geology7.html The Student's Elements of Geology by Sir Charles Lyell Part 7 out of 14 accessed 13 February 2009. * Mollusca: **''Cardium striatulum'' ** ''Ostrea deltoidea'' **''Gryphaea'' (''Exogyra'') ''virgula'' ** '' Trigonellites'' ** ''

Belemnotheutis ''Belemnotheutis'' is an extinct coleoid cephalopod genus from the middle and upper Jurassic, related to but morphologically distinct from belemnites. ''Belemnotheutis'' fossils are some of the best preserved among coleoids. Remains of soft ti ...

'' **''

Etchesia ''Etchesia'' is a genus of muensterellid stem-octopod from the Kimmeridge Clay Formation of southern England. It is monotypic, consisting solely of type species In zoological nomenclature, a type species (''species typica'') is the species n ...

'' *

Arthropoda Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

: **''Phlyctosoma sp.'' ** ''

Eryma ''Eryma'' is a genus of fossil lobster-like crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, ...

sp.'' ** ''Magitalatimana sp.'' ** ''Mechochirus sp.'' ** ''Archaeolepas redtenbacheri''

References

Bibliography

* Galton, P.M. 1999. Cranial anatomy of the hypsilophodontid dinosaur Bugenasaura infernalis (Ornithischia: Ornithopoda) from the Upper Cretaceous of North America. Revue Pale´obiologie, 18, 517–534.