Kimmeridge Clay

The Kimmeridge Clay is a sedimentary deposit of fossiliferous marine clay which is of Late Jurassic to lowermost Cretaceous age and occurs in southern and eastern England and in the North Sea. This rock formation is the major source rock for North Sea oil. The fossil fauna of the Kimmeridge Clay includes turtles, crocodiles, sauropods, plesiosaurs, pliosaurs and ichthyosaurs, as well as a number of invertebrate species.

Description
Kimmeridge Clay is named after the village of Kimmeridge on the Dorset coast of England, where it is well exposed and forms part of the Jurassic Coast World Heritage Site. Onshore, it is of Late Jurassic (Kimmeridgian) age and outcrops across England, in a band stretching from Dorset in the south-west, north-east to North Yorkshire. Offshore, it extends into the Lower Cretaceous (Berriasian 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 estuary.

Economic importance
Kimmeridge Clay is of great economic importance, being the major source rock 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:

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.

Invertebrates
The invertebrate fauna of the Kimmeridge Clay includes:
 * Mollusca:
 * Cardium striatulum
 * Ostrea deltoidea
 * Gryphaea (Exogyra) virgula
 * Trigonellites
 * Belemnotheutis
 * Etchesia
 * Arthropoda:
 * Phlyctosoma sp.
 * Eryma sp.
 * Magita latimana
 * Mechochirus sp.
 * Archaeolepas redtenbacheri