# Gault

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{{Short description|Geological formation in England}}
{{about|the clay formation}}
{{Infobox rockunit
| name           = Gault Formation
| image          = Rocks and Rock Pools - geograph.org.uk - 906044.jpg
| caption        = An exposed surface of Gault clay on the foreshore near [Beachy Head](/source/Beachy_Head), [East Sussex](/source/East_Sussex)
| type           = [Geological formation](/source/Geological_formation)
| age            = [Albian](/source/Albian) {{Fossil range|112|100}}
| period         = Albian
| prilithology   = [Mudstone](/source/Mudstone), [clay](/source/clay)
| otherlithology = [Limestone](/source/Limestone)
| namedfor       = 
| namedby        =
| region         = [Southern England](/source/Southern_England)
| country        = England
| coordinates    =
| unitof         = [Selborne Group](/source/Selborne_Group)
| subunits       =
| underlies      = [Upper Greensand Formation](/source/Upper_Greensand_Formation), [Cambridge Greensand](/source/Cambridge_Greensand), [Chalk Group](/source/Chalk_Group)
| overlies       = [Monk's Bay Sandstone Formation](/source/Monk's_Bay_Sandstone_Formation),  [Folkestone Formation](/source/Folkestone_Formation), [Woburn Sands Formation](/source/Woburn_Sands_Formation), [Carstone Formation](/source/Carstone_Formation), overstepping of [Jurassic](/source/Jurassic) and [Triassic](/source/Triassic) rocks in Southern England
| thickness      = 2 m in Norfolk to 110 m in the Weald
| extent         =
| area           =
| map            =
| map_caption    =
| location_ts    = Copt Point, [Folkestone](/source/Folkestone)
}}
The '''Gault Formation''' is a [geological formation](/source/geological_formation) of stiff blue [clay](/source/clay) deposited in a calm, fairly deep-water marine environment during the Lower [Cretaceous](/source/Cretaceous) Period (Upper and Middle [Albian](/source/Albian)). It is well exposed in the coastal cliffs at [Copt Point](/source/Copt_Point) in [Folkestone](/source/Folkestone), [Kent](/source/Kent), [England](/source/England), where it overlays the [Lower Greensand](/source/Lower_Greensand) formation, and underlies the [Upper Greensand Formation](/source/Upper_Greensand_Formation).<ref>{{cite web |url=http://www.bgs.ac.uk/Lexicon/lexicon.cfm?pub=SELB |title=Selborne Group |work=The BGS Lexicon of Named Rock Units |publisher=British Geological Survey |access-date=6 April 2016}}</ref> These represent different [facies](/source/facies), 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.<ref>{{cite book |last1=Gallois |first1=R.W. |last2=Edmunds |first2=M.A. |edition=4th |date=1965 |title=The Wealden District |series=British Regional Geology series |publisher=British Geological Survey |isbn=0-11-884078-9}}</ref>

The etymology  of the name is uncertain and probably of local origin.<ref name="OED">{{Cite book |title=The Shorter Oxford English Dictionary |publisher=Clarendon Press |year=1973}}</ref>

==Distribution==
It is found in exposure on the south side of the [North Downs](/source/North_Downs) and the north side of the [South Downs](/source/South_Downs). It is also to be found beneath the [scarp](/source/escarpment) of the [Berkshire Downs](/source/Berkshire_Downs), in the [Vale of White Horse](/source/Vale_of_White_Horse), in [Oxfordshire](/source/Oxfordshire), England, and on the [Isle of Wight](/source/Isle_of_Wight) where it is known as Blue Slipper.<ref name="IOWBlueSlipper">{{cite news |url=http://www.iwcp.co.uk/news/news/men-rescued-from-mud-31920.aspx |title=Men rescued from mud |first=Martin |last=Neville |newspaper=[Isle of Wight County Press](/source/Isle_of_Wight_County_Press) |date=23 March 2010 |access-date=6 April 2016 |archive-date=17 April 2016 |archive-url=https://web.archive.org/web/20160417100236/http://www.iwcp.co.uk/news/news/men-rescued-from-mud-31920.aspx |url-status=dead }}</ref> Gault underlies the chalk beneath the [London Basin](/source/London_Basin), generally overlying eroded rocks of [Jurassic](/source/Jurassic) and [Devonian](/source/Devonian) 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](/source/marine_transgression) following erosion of the Lower Greensand. It is subdivided into two sections, the Upper Gault and the Lower Gault. The Upper Gault [onlap](/source/onlap)s onto the Lower Gault. The Gault Formation thins across the [London Platform](/source/London_Platform) and then terminates against the [Red Chalk](/source/Hunstanton_Formation) just to the south of [The Wash](/source/The_Wash) in [East Anglia](/source/East_Anglia).

The Gault exposure at Copt Point, which is the [type locality](/source/type_locality_(geology)) for the formation, is 40 m in thickness.

==Uses==
The clay has been used in several locations for making bricks, notably near [Dunton Green](/source/Dunton_Green) and near [Wye](/source/Wye%2C_Kent) in [Kent](/source/Kent).{{cn|date=January 2025}}

Gault often contains numerous phosphatic nodules, some thought to be [coprolites](/source/coprolites), and may also contain sand as well as small grains of the mineral [glauconite](/source/glauconite). Crystals of the mineral [selenite](/source/Selenite_(mineral)) are fairly common in places, as are nodules of [pyrite](/source/pyrite).

==Fossils==
[[File:Hamitidae Fossil in Wear Bay in Folkestone in England.jpg|thumb|[Hamitidae](/source/Hamitidae) fossil in Gault Clay on a beach in [Folkestone](/source/Folkestone), Kent]]
Gault yields abundant marine [fossil](/source/fossil)s, including [ammonite](/source/ammonite)s (such as ''Hoplites'', ''Hamites'', ''[Euhoplites](/source/Euhoplites)'', ''Anahoplites'', and ''Dimorphoplites''), [belemnites](/source/Belemnoidea) (such as ''Neohibolites''), [bivalves](/source/Bivalvia) (such as ''Birostrina'' and ''Pectinucula''), [gastropods](/source/Gastropoda) (such as ''Anchura''), solitary [coral](/source/coral)s, [fish](/source/fish) remains (including [shark](/source/shark) teeth), scattered [crinoid](/source/crinoid) remains, and [crustacean](/source/crustacean)s (such as the [crab](/source/crab) ''Notopocorystes''). Terrestrial fossils that have been found at Gault include fossil wood, a dinosaur (''[cf.](/source/cf.)'' ''[Acanthopholis](/source/Acanthopholis)''),<ref>{{cite book|last1=Lomax|first1=Dean R.|last2=Tamura|first2=Nobumichi|year=2014|title=Dinosaurs of the British Isles|publisher=Siri Scientific Press|isbn=9780957453050|at=367}}</ref> and [pterosaur](/source/pterosaur)s, including [azhdarchoids](/source/Azhdarchoidea), [ornithocheirids](/source/Ornithocheiridae), and the indeterminate [pterodactyloid](/source/Pterodactyloidea) "Pterodactylus" ''daviesii''.<ref>{{cite journal|last1=Smith|first1=Roy E.|last2=Martill|first2=David M.|year=2022|title=First occurrence of azhdarchoid pterosaurs in the Gault Formation (Lower Cretaceous, Albian) of England, United Kingdom with a brief review of Gault pterosaurs|journal=Proceedings of the Geologists' Association|volume=133|issue=6|pages=491–500|doi=10.1016/j.pgeola.2022.06.003 |bibcode=2022PrGA..133..491S }}</ref> Several pterosaur fossil remains from the overlying [Cambridge Greensand](/source/Cambridge_Greensand) may have been reworked from the underlying Gault.<ref>{{cite journal|last=Unwin|first=D.M.|date=2011-05-11|title=An overview of the pterosaur assemblage from the Cambridge Greensand (Cretaceous) of Eastern England|journal=Fossil Record|volume=4|pages=189–221|doi=10.1002/mmng.20010040112|doi-access=free}}</ref>

==See also==
*[Argiles du Gault](/source/Argiles_du_Gault)

==References==
{{reflist}}

==External links==
* [http://www.gaultammonite.co.uk/  Fossils of the Gault Clay]
* [http://www.discoveringfossils.co.uk/folkestone_fossils.htm Folkestone fossils and geology by Discovering Fossils]

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

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Adapted from the Wikipedia article [Gault](https://en.wikipedia.org/wiki/Gault) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Gault?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.