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Coordinates: 51°24′N 1°06′E / 51.4°N 1.1°E / 51.4; 1.1
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| otherlithology = clay
| otherlithology = clay
| namedfor = [[Isle of Thanet]]
| namedfor = [[Isle of Thanet]]
| namedby =
| namedby =
| year_ts =
| region = southeastern [[England]]
| region = southeastern [[England]]
| country = [[United Kingdom]]
| country = {{UK}}
| coordinates =
| coordinates = {{coord|51.4|N|1.1|E|display=inline,title}}
| paleocoordinates = {{coord|45.9|N|1.0|E|display=inline}}
| unitof = [[Montrose Group]]
| unitof = [[Montrose Group]]
| subunits =
| subunits =
| underlies = [[Lambeth Group]]
| underlies = [[Lambeth Group]]
| overlies = [[Chalk Group]]
| overlies = [[Chalk Group]]
| thickness = 0-30 m
| thickness = {{convert|0|-|30|m|ft|abbr=on}}
| extent = [[London Basin]]
| extent = [[London Basin]]
| area =
| area =
| map =
| map = {{Location map+ | England
| relief = 1
| width = 250
| float = center
| places =
{{Location map~ | England
| lat_deg = 51.4
| lon_deg = 1.1
| mark = Orange pog.svg
| marksize = 10
}}
}}
| map_caption =
| map_caption =
}}
}}


The '''Thanet Formation''' is a [[Formation (geology)|geological formation]] found in the [[London Basin]] of southeastern [[England]]. It is of early to mid-[[Thanetian]] (late [[Paleocene]]) age and gave its name to that stratigraphic interval. It was previously known as the '''Thanet Beds''', the '''Thanet Sands''' and the '''Thanet Sand Formation'''. It was named after the [[Isle of Thanet]]. The [[type section]]s are [[Herne Bay, Kent|Herne Bay]] in [[Kent]] for the upper part of the formation and [[Pegwell Bay]] for the lower part.<ref name="Aldiss">{{cite web | url=http://nora.nerc.ac.uk/17121/ | title=The stratigraphical framework for the Palaeogene successions of the London Basin, UK | publisher=British Geological Survey | work=Open Report OR/14/008 | date=2014 | accessdate=30 July 2016 | author=Aldiss D.T. | pages=9–14}}</ref><ref name="BGS">{{cite web | url=http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=TAB | title=Thanet Formation | publisher=[[British Geological Survey]] | work=BGS Lexicon of Named Rock Units | accessdate=30 July 2016}}</ref> It lies [[unconformity|unconformably]] on the Late Cretaceous [[Chalk Group]]. It unconformably underlies the Lambeth Group, generally the Upnor Formation but in Essex it is the [[Reading Formation]].
The '''Thanet Formation''' is a [[Formation (geology)|geological formation]] found in the [[London Basin]] of southeastern [[England]].<ref name=FW>[http://www.fossilworks.org/cgi-bin/bridge.pl?action=displayStrata&geological_group=&formation=Thanet&group_formation_member=Thanet Thanet Formation] at [[Fossilworks]].org</ref> It is of early to mid-[[Thanetian]] (late [[Paleocene]]) age and gave its name to that stratigraphic interval. It was previously known as the '''Thanet Beds''', the '''Thanet Sands''' and the '''Thanet Sand Formation'''. It was named after the [[Isle of Thanet]]. The [[type section]]s are [[Herne Bay, Kent|Herne Bay]] in [[Kent]] for the upper part of the formation and [[Pegwell Bay]] for the lower part.<ref name="Aldiss">{{cite web | url=http://nora.nerc.ac.uk/17121/ | title=The stratigraphical framework for the Palaeogene successions of the London Basin, UK | publisher=British Geological Survey | work=Open Report OR/14/008 | date=2014 | accessdate=30 July 2016 | author=Aldiss D.T. | pages=9–14}}</ref><ref name="BGS">{{cite web | url=http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=TAB | title=Thanet Formation | publisher=[[British Geological Survey]] | work=BGS Lexicon of Named Rock Units | accessdate=30 July 2016}}</ref> It lies [[unconformity|unconformably]] on the Late Cretaceous [[Chalk Group]]. It unconformably underlies the Lambeth Group, generally the Upnor Formation but in Essex it is the [[Reading Formation]].


==Distribution==
== Distribution ==
The Thanet Formation is known at outcrop and in the subsurface over central and eastern parts of the London Basin. To the west it is missing, with the [[Lambeth Group]] lying directly on the Chalk, and to the north it is replaced by the Ormesby Clay Member.<ref name="Aldiss"/> It thins to the west and north of London. It reaches a maximum thickness of over 30 m in North Kent.
The Thanet Formation is known at outcrop and in the subsurface over central and eastern parts of the London Basin. To the west it is missing, with the [[Lambeth Group]] lying directly on the Chalk, and to the north it is replaced by the Ormesby Clay Member.<ref name="Aldiss"/> It thins to the west and north of London. It reaches a maximum thickness of over 30 m in North Kent.


==Lithology==
== Lithology ==
The predominant [[lithology]] is very pale grey or buff fine-grained [[glauconite|glauconitic]] sand. Particularly towards the base of the formation, the sand is interbedded with silts and clays. At the base of the formation a bed of flint pebbles is often developed with clasts up to [[Cobble (geology)|cobble]] size in a matrix of glauconitic clayey sand.<ref name="Aldiss"/>
The predominant [[lithology]] is very pale grey or buff fine-grained [[glauconite|glauconitic]] sand. Particularly towards the base of the formation, the sand is interbedded with silts and clays. At the base of the formation a bed of flint pebbles is often developed with clasts up to [[Cobble (geology)|cobble]] size in a matrix of glauconitic clayey sand.<ref name="Aldiss"/>


At Herne Bay the beds are divided as follows (top to bottom):<ref name=Holmes>{{cite web|url=http://jncc.defra.gov.uk/pdf/gcrdb/GCRsiteaccount2911.pdf|title=British Cenozoic fossil fishes sites Site: HERNE BAY (GCR ID: 2911)|last=Holmes|work=Volume 16: Fossil Fishes of Great Britain|publisher=Extracted from the Geological Conservation Review|pages=Chapter 14: pages 2 and 4|accessdate=9 April 2012}}</ref>
At Herne Bay the beds are divided as follows (top to bottom):<ref name=Holmes>{{cite web|url=http://jncc.defra.gov.uk/pdf/gcrdb/GCRsiteaccount2911.pdf|title=British Cenozoic fossil fishes sites Site: HERNE BAY (GCR ID: 2911)|last=Holmes|work=Volume 16: Fossil Fishes of Great Britain|publisher=Extracted from the Geological Conservation Review|pages=Chapter 14: pages 2 and 4|accessdate=9 April 2012}}</ref>


* A layer of concretionary blocks (‘doggers') of calcareous indurated sandstone of 0.3 metre thickness
* A layer of concretionary blocks (‘doggers') of calcareous indurated sandstone of 0.3 metre thickness
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* A bedded, clayey buff sand with many shells, seen to 0.9 metre thickness
* A bedded, clayey buff sand with many shells, seen to 0.9 metre thickness


==Depositional environment==
== Depositional environment ==
The Thanet Formation was deposited in open marine conditions. The water depth was relatively shallow, above normal wave-base, in an inner or outer [[continental shelf|shelf]] setting.<ref name="Aldiss"/>
The Thanet Formation was deposited in open marine conditions. The water depth was relatively shallow, above normal wave-base, in an inner or outer [[continental shelf|shelf]] setting.<ref name="Aldiss"/>


== Fossil content ==
==Fossils==
The sequence is known for its rich fossil content, particularly molluscs and fish. The fauna give somewhat contradictory evidence of the climate, with molluscs of both cold and warm water type being found and tropical to sub-tropical fish recognised. Overall a sub-tropical climate is indicated.<ref name=Holmes/>
The sequence is known for its rich fossil content, particularly molluscs and fish.<ref name=FW/> The fauna give somewhat contradictory evidence of the climate, with molluscs of both cold and warm water type being found and tropical to sub-tropical fish recognised. Overall, a sub-tropical climate is indicated.<ref name=Holmes/> The formation also has provided fossils of flora of ''[[Pinus macrocephalus]]'', ''[[Pinus prestwichi]]'', [[Palmae]] and ''[[Osmunda dowkeri]]''.<ref name=FW/>


==See also==
== See also ==
{{Portal|Earth sciences|England|Paleontology|Paleogene|Cenozoic}}
* [[List of fossiliferous stratigraphic units in England]]
* [[List of fossiliferous stratigraphic units in England]]
* [[:Category:Thanetian Stage|Thanetian formations]]
** [[Conglomérat de Cernay]]
** [[Tuffeau de St Omer]]
** [[Cerrejón Formation]]
** [[Danata Formation]]
** [[DeBeque Formation]]
** [[Willwood Formation]]


==References==
== References ==
{{Reflist}}
{{reflist}}
* {{cite web|title= Fossilworks: Gateway to the Paleobiology Database|author= Various Contributors to the Paleobiology Database|url= http://www.fossilworks.org/|accessdate= 8 July 2014}}


[[Category:Geology of London]]
[[Category:Paleogene England]]
[[Category:Geologic formations of England]]
[[Category:Geologic formations of England]]
[[Category:Paleocene Series of Europe]]
[[Category:Paleogene England]]
[[Category:Thanetian Stage| ]]
[[Category:Sandstone formations]]
[[Category:Open marine deposits]]
[[Category:Fossiliferous stratigraphic units of Europe]]
[[Category:Paleontology in England]]
[[Category:Geology of London]]

Latest revision as of 13:04, 12 June 2024

Thanet Formation
Stratigraphic range: Thanetian
Grey sands of the Thanet Formation in the cliffs just east of Herne Bay
TypFormation
Unit ofMontrose Group
UnderliesLambeth Group
OverliesChalk Group
Thickness0–30 m (0–98 ft)
Lithology
Primärefine-grained sand
Otherclay
Standort
Coordinates51°24′N 1°06′E / 51.4°N 1.1°E / 51.4; 1.1
Approximate paleocoordinates45°54′N 1°00′E / 45.9°N 1.0°E / 45.9; 1.0
Regionsoutheastern England
Land Vereinigtes Königreich
ExtentLondon Basin
Type section
Named forIsle of Thanet
Thanet Formation is located in England
Thanet Formation
Thanet Formation (England)

The Thanet Formation is a geological formation found in the London Basin of southeastern England.[1] It is of early to mid-Thanetian (late Paleocene) age and gave its name to that stratigraphic interval. It was previously known as the Thanet Beds, the Thanet Sands and the Thanet Sand Formation. It was named after the Isle of Thanet. The type sections are Herne Bay in Kent for the upper part of the formation and Pegwell Bay for the lower part.[2][3] It lies unconformably on the Late Cretaceous Chalk Group. It unconformably underlies the Lambeth Group, generally the Upnor Formation but in Essex it is the Reading Formation.

Distribution

[edit]

The Thanet Formation is known at outcrop and in the subsurface over central and eastern parts of the London Basin. To the west it is missing, with the Lambeth Group lying directly on the Chalk, and to the north it is replaced by the Ormesby Clay Member.[2] It thins to the west and north of London. It reaches a maximum thickness of over 30 m in North Kent.

Lithology

[edit]

The predominant lithology is very pale grey or buff fine-grained glauconitic sand. Particularly towards the base of the formation, the sand is interbedded with silts and clays. At the base of the formation a bed of flint pebbles is often developed with clasts up to cobble size in a matrix of glauconitic clayey sand.[2]

At Herne Bay the beds are divided as follows (top to bottom):[4]

  • A layer of concretionary blocks (‘doggers') of calcareous indurated sandstone of 0.3 metre thickness
  • A pale grey sandstone with abundant shells 2.6 metre thickness
  • A layer of calcareous sandstone doggers, 0.3 metre thickness
  • A bedded, clayey buff sand with many shells, seen to 0.9 metre thickness

Depositional environment

[edit]

The Thanet Formation was deposited in open marine conditions. The water depth was relatively shallow, above normal wave-base, in an inner or outer shelf setting.[2]

Fossil content

[edit]

The sequence is known for its rich fossil content, particularly molluscs and fish.[1] The fauna give somewhat contradictory evidence of the climate, with molluscs of both cold and warm water type being found and tropical to sub-tropical fish recognised. Overall, a sub-tropical climate is indicated.[4] The formation also has provided fossils of flora of Pinus macrocephalus, Pinus prestwichi, Palmae and Osmunda dowkeri.[1]

See also

[edit]

References

[edit]
  1. ^ a b c Thanet Formation at Fossilworks.org
  2. ^ a b c d Aldiss D.T. (2014). "The stratigraphical framework for the Palaeogene successions of the London Basin, UK". Open Report OR/14/008. British Geological Survey. pp. 9–14. Retrieved 30 July 2016.
  3. ^ "Thanet Formation". BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 30 July 2016.
  4. ^ a b Holmes. "British Cenozoic fossil fishes sites Site: HERNE BAY (GCR ID: 2911)" (PDF). Volume 16: Fossil Fishes of Great Britain. Extracted from the Geological Conservation Review. pp. Chapter 14: pages 2 and 4. Retrieved 9 April 2012.