The Gault Formation is a geological formation of stiff blue clay deposited in a calm, fairly deep-water marine environment during the Lower Cretaceous Period (Upper and Middle Albian). It is well exposed in the coastal cliffs at Copt Point in

Folkestone Folkestone ( ) is a port town on the English Channel, in Kent, south-east England. The town lies on the southern edge of the North Downs at a valley between two cliffs. It was an important harbour and shipping port for most of the 19th and 20t ...

, Kent, England, where it overlays the Lower Greensand formation, and underlies the Upper Greensand Formation. These represent different

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ...

, with the sandier parts probably being deposited close to the shore and the clay in quieter water further from the source of sediment; both are believed to be shallow-water deposits. The etymology of the name is uncertain and probably of local origin.

Distribution

It is found in exposure on the south side of the North Downs and the north side of the South Downs. It is also to be found beneath the

scarp Scarp may refer to: Landforms and geology * Cliff, a significant vertical, or near vertical, rock exposure * Escarpment, a steep slope or long rock that occurs from erosion or faulting and separates two relatively level areas of differing elevatio ...

of the Berkshire Downs, in the Vale of White Horse, in

Oxfordshire Oxfordshire is a ceremonial and non-metropolitan county in the north west of South East England. It is a mainly rural county, with its largest settlement being the city of Oxford. The county is a centre of research and development, primarily ...

, England, and on the Isle of Wight where it is known as Blue Slipper. Gault underlies the chalk beneath the London Basin, generally overlying eroded rocks of Jurassic and

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

age; lower gault is present only below the outer parts of the basin and is absent under central London. The Gault Formation represents a marine transgression following erosion of the Lower Greensand. It is subdivided into two sections, the Upper Gault and the Lower Gault. The Upper Gault onlaps onto the Lower Gault. The Gault Formation thins across the

London Platform The London Basin is an elongated, roughly triangular sedimentary basin approximately long which underlies London and a large area of south east England, south eastern East Anglia and the adjacent North Sea. The basin formed as a result of thrust ...

and then terminates against the Red Chalk just to the south of The Wash in

East Anglia East Anglia is an area in the East of England, often defined as including the counties of Norfolk, Suffolk and Cambridgeshire. The name derives from the Anglo-Saxon kingdom of the East Angles, a people whose name originated in Anglia, in ...

. The Gault exposure at Copt Point, which is the

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

for the formation, is 40 m in thickness.

Uses

The clay has been used in several locations for making bricks, notably near Dunton Green and Wye in Kent. Gault often contains numerous phosphatic nodules, some thought to be coprolites, and may also contain sand as well as small grains of the mineral glauconite. Crystals of the mineral

selenite Selenite may refer to: Substances containing selenium *A selenium-containing anion or ionic compound with the SeO32− anion: **Selenite (ion), anion is a selenium oxoanion with the chemical formula SeO32− ***Selenous acid, the conjugate acid, w ...

are fairly common in places, as are nodules of pyrite.

Fossils

Hamitidae Fossil in Wear Bay in Folkestone in England

Gault yields abundant marine fossils, including

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

s (such as ''Hoplites'', ''Hamites'', '' Euhoplites'', ''Anahoplites'', and ''Dimorphoplites''),

belemnites Belemnites may refer to: *Belemnitida Belemnitida (or the belemnite) is an extinct order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous. Unlike squid, belemnites had an internal skeleton that made up the cone. ...

(such as ''Neohibolites''),

bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

(such as ''Birostrina'' and ''Pectinucula''), gastropods (such as ''Anchura''), solitary corals, fish remains (including shark teeth), scattered crinoid remains, and crustaceans (such as the

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

''Notopocorystes''). Occasional fragments of fossil wood may also be found, and a dinosaur ('' cf.'' '' Acanthopholis'') has also been found.Lomax, D. & Tamura, N. (2014). "Dinosaurs of the British Isles", ''Siri Scientific Press'' pg. 367

References

{{reflist

External links

Fossils of the Gault Clay

Sedimentary rocks Cretaceous paleontological sites of Europe Geology of England Geology of Kent Geology of Oxfordshire Albian Stage Lower Cretaceous Series of Europe