Tunbridge Wells Sand Formation
Tunbridge Wells Sand Formation | |
---|---|
Stratigraphic range: Late | |
Type | Geological formation |
Unit of | Wealden Group |
Sub-units |
|
Underlies | Weald Clay |
Overlies | Wadhurst Clay Formation |
Thickness | Generally 75 m, but varies from 46 to 122 m |
Lithology | |
Primary | Sandstone, Siltstone |
Other | Mudstone, Limestone |
Location | |
Region | Europe |
Country | UK |
Extent | Weald Basin |
Type section | |
Named for | Royal Tunbridge Wells |
The Tunbridge Wells Sand Formation is a geological unit which forms part of the
The other component formations of the
Lithology
The Tunbridge Wells Sand Formation comprises complex cyclic sequences of siltstones with sandstones and clays, typically fining upwards, and is lithologically similar to the older Ashdown Formation.[2] It has a total thickness typically in the region of about 75 m.[1] However, near Haywards Heath borehole data has proven the formation to be up to 150m thick.[3]
In the western parts of the High Weald the Tunbridge Wells Sands can be divided into four separate divisions; the Lower Tunbridge Wells Sand, the Ardingly Sandstone Member, the Grinstead Clay Member, and the Upper Tunbridge Wells Sand.[3]
Lower Tunbridge Wells Sand
The Lower Tunbridge Wells Sand shows the best cyclic fining up sequences in the formation. The division comprises mainly interbedded siltstones and silty sandstones and occurs up to 27m thick.[4]
Ardingly Sandstone Member
A massive thick cross bedded fine to medium grained quartz sandstone separates the Tunbridge Wells Sands from the overlying Grinstead Clay. This horizon is known as the Ardingly Sandstone and occurs in thicknesses of up to 18m. It is particularly well exposed throughout the region between
Grinstead Clay Member
The Grinstead Clay comprises mudstones and silty mudstones with siltstone, ironstone and shelly limestone. This member is lithologically similar to the older
Upper Tunbridge Wells Sand
The Upper Tunbridge Wells Sand is similar to the Lower Tunbridge Wells Sand. It comprises soft red and grey mottled silts and clays in its lower part, and alternating silts and silty clays with thin beds of sandstones.
The base of the Tunbridge Wells Sand is marked by a distinct change from the predominantly argillaceous sediments of the
The top of the Tunbridge Wells Sand Formation is well defined in the southwest of East Sussex but is gradational elsewhere. In the area north of Brighton and west of Lewes the boundary is marked by a massive sandstone, though this is not seen anywhere else.[4]
Engineering Geology
Landslips often occur at or close to the lower boundary of the Tunbridge Wells Sands, between it and the underlying
When percolating groundwater in the permeable sandstones of the Tunbridge Wells Sands comes into contact with the upper impermeable clay beds of the
Paleobiota
Pterosaurs
Pterosaurs reported from the Tunbridge Wells Sands | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Serradraco | S. sagittirostris | St.-Leonards-on-Sea | Upper Tunbridge Wells Sands | Lower Jaw, vertebrae | An ornithocheiromorph
|
Crocodyliformes
Crocodyliformes reported from the Tunbridge Wells Sands | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Hulkepholis | H. willetti | Cuckfield | Grinstead Clay | |||
Goniopholis | Indeterminate | Pevensey Pit, Ashdown Brickworks | Lower Tunbridge Wells Sand |
Turtles
Turtles reported from the Tunbridge Wells Sands | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
“Helochelydra” | “Helochelydra” bakewelli | Cuckfield | Grinstead Clay | Shell fragments | A helochelydrid turtle, unclear whether it actually belongs to Helochelydra[6]
|
Dinosaurs
Dinosaurs reported from the Tunbridge Wells Sands | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Barilium | B. dawsoni[7] | Whiteman’s Green, Cuckfield | Grinstead Clay | Lower Jaw | An iguanodontian, originally given the name Kukufeldia
|
|
Regnosaurus[8] | R. northamptoni[8] | Tilgate Forest, Cuckfield | Grinstead Clay Member | Lower jaw | Nomen dubium.[8] | |
Hylaeosaurus[9] | H. armatus[9] | "Partial skull, skeleton, isolated postcrania."[10] | ||||
Suchosaurus | S. cultridens | Teeth | A spinosaurid | |||
Valdoraptor[8] | V. oweni[8] | Cuckfield | "Metatarsals."[11] | An ornithomimosaur
|
||
Pelorosaurus[9] | P. conybeari[8] | Cuckfield Quarry, Tilgate | " Humerus (Holotype) [and four] caudal vertebrae."[12] These were found separately and might belong to different taxa | A basal titanosauriform
|
Mammals
Mammals reported from the Tumbridge Wells Sands | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
?Aegialodon | ?A. dawsoni | Paddockhurst bone bed | Grinstead Clay | |||
Spalacotherium | S. taylori | |||||
Loxaulax | L. valdensis |
See also
- Hastings Beds
- Ashdown Formation
- Wadhurst Clay Formation
- Geology of East Sussex
References
- ^ a b Hopson, P.M., Wilkinson, I.P. and Woods, M.A. (2010) A stratigraphical framework for the Lower Cretaceous of England. Research Report RR/08/03. British Geological Survey, Keyworth.
- ^ a b c Codd, J.W. (2007) Analysis of the distribution and characteristics of landslips in the Weald of East Sussex. MSc dissertation, University of Brighton.
- ^ a b c Young, B. & Lake, R.D. (1988) Geology of the country around Brighton and Worthing: Memoir for 1:50,000 geological sheets 318 and 333. British Geological Survey, London.
- ^ a b Lake, R.D. & Shepard-Thorn, E.R. (1987) Geology of the country around Hastings and Dungeness: Memoir for 1:50,000 geological sheets 320 and 321. British Geological Survey, London.
- ^ Messenger, Alex (9 July 2011). "Southern Sandstone: guidelines". The British Mountaineering Council.
- S2CID 54982901. Retrieved July 9, 2017.
- ^ "10.19 East Sussex, England; 1. Hastings Beds" in Weishampel, et al. (2004). Page 559.
- ^ a b c d e f "10.18 West Sussex, England; 1. Hastings Beds" in Weishampel, et al. (2004). Page 559.
- ^ a b c "10.19 East Sussex, England; 1. Hastings Beds" and "10.18 West Sussex, England; 1. Hastings Beds" in Weishampel, et al. (2004). Page 559.
- ^ "Table 17.1," in Weishampel, et al. (2004). Page 366.
- ^ "Table 4.1," in Weishampel, et al. (2004). Page 77.
- ^ "Table 13.1," in Weishampel, et al. (2004). Page 266.