The BGS Lexicon of Named Rock Units — Result Details

Weald Clay Formation

Computer Code: WC Preferred Map Code: WC
Status Code: Full
Age range: Hauterivian Age (KH) — Barremian Age (KB)
Lithological Description: Dark grey thinly-bedded mudstones (shales) and mudstones with subordinate siltstones, fine- to medium-grained sandstones, including calcareous sandstone (e.g. Horsham Stone Member), shelly limestones (the so called "Paludina Limestones") and clay ironstones.
Definition of Lower Boundary: The lower boundary is generally poorly defined and gradational in complete successions, from the siltstones and silty fine-grained sandstones of the underlying Tunbridge Wells Sand Formation up into the mudstones of the Weald Clay Formation. Locally, the basal beds of the Weald Clay are weakly sideritised. Elsewhere, the boundary is erosive and unconformable, with the Weald Clay resting on beds down to the Grinstead Clay Member (e.g. southwestern part of the Maidstone Geological Sheet around Pearsons Green [TQ 694 433]).
Definition of Upper Boundary: The top is unconformable and sharp at the contact between the drab, ochre-brown mudstones of the upper part of the Weald Clay and the overlying "chocolate" (dark yellow brown) brown (dark grey or black when unweathered) mudstones of the basal Atherfield Clay Formation.
Thickness: Up to 460m around Guildford; 122m at Hythe; 240m south of Maidstone and 180m at Eastbourne.
Geographical Limits: The formation crops out in the Weald. Known in the subcrop but thins and is cut-out against the Hampshire-Dieppe High in the south and the London-Brabant Ridge in the north. Disappears westward in the subcrop of the Wessex Basin.
Parent Unit: Wealden Group (W)
Previous Name(s): Weald Clay (-2522)
Weald Clay Group (-4963)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  For lower 80% in the Western Weald: Blacknest Borehole (SU93NE/11). 
Reference Section  Babylon Tileworks, Hawkenbury [TQ 802 461] 
Reference Section  Clockhouse Brickworks, Capel [TQ 177 385] 
Reference Section  Ashpark Brickyard, Plaistow [TQ 993 316] 
Reference Section  Langhurstwood, Horsham [TQ 175 350] 
Reference Section  Smokejack Brickworks, Ockley [TQ 121 372] 
Reference Section  South Holmwood and Beare Green, Newdigate [TQ 186 423] 
Reference Section  Keymer Tileworks, Burgess Hill [TQ 334 192] 
Reference Section  Laybrook Brickworks, Thakenham [TQ 115 188] 
Reference Section  Rudgwick Brickworks, Rudgwick [TQ 083 343] 
Reference Section  Chailey Brickworks, Lewes [TQ 393 177] 
Type Area  The Weald, with numerous partial reference sections All are described within the BGS memoirs covering the Weald (see bibliography). 
Reference Section  Pluckley, nr. Ashford [TQ 918 433] 
Reference Section  Bookhurst Tileworks, Cranleigh [TQ 076 394] 
Reference Section  Baynards Brickworks, Horsham [TQ 068 353]. 
Reference(s):
Rawson, P F. 1992. Cretaceous, 355-388 in Duff, P McL D and Smith, A J (editors), Geology of England and Wales. (London: Geological Society.) 
Conybeare, W D and Phillips, W, 1822. Outlines of the Geology of England and Wales. Published by W. Phillips of London. 
Bristow, C R and Bazley, R A. 1972. Geology of the country around Royal Tunbridge Wells. Memoir of the Geological Survey of Great Britain, sheet 303 (England and Wales). 
Lake, R D and Shephard-Thorn, E R. 1987. Geology of the country around Hastings and Dungeness. Memoir of the British Geological Survey, Sheets 320 and 321 (England and Wales). 
Allen, P. 1976. The Wealden of the Weald. Proceedings of the Geologists' Association, Vol.86, 389-437. 
Gallois, R W and Worssam, B C. 1993. Geology of the country around Horsham. Memoir of the British Geological Survey, Sheet 302 (England and Wales). 130pp. 
Shephard-Thorn, E R, Smart, J G O, Bisson G and Edmonds, E A. 1966. Geology of the country around Tenterden. Memoir of the British Geological Survey, Sheet 304 (England and Wales). 
Worssam, B C. 1963. Geology of the country around Maidstone. Memoir of the Geological Survey of Great Britain, Sheet 288 (England and Wales). 
Young, B and Lake, R D. 1988. Geology of the country around Brighton and Worthing. Memoir of the British Geological Survey, Sheet 318 and 333 (England and Wales). 
Allen, P. 1949. Wealden Petrology: The Top Ashdown Pebble Bed and the Top Ashdown Sandstone. Quarterly Journal of the Geological Society of London, Vol.104, 257-321. 
Allen, P. 1962. The Hastings Beds deltas: Recent progress and Easter field meeting report. Proceedings of the Geologists' Association, Vol.73, 219-243. 
Thurrell, R G, Worssam, B C and Edmonds, E A. 1968. Geology of the country around Haslemere. Memoir of the British Geological Survey, sheet 301 (England and Wales). 
Dines, H G, Buchan, S, Holmes, S C A and Bristow, C R. 1969. Geology of the country around Sevenoaks and Tonbridge. Second edition. Memoir of the Institute of Geological Sciences, Sheet 287 (England and Wales). 
Lake, R D, Young, B, Wood, C J and Mortimore, R N. 1987. Geology of the country around Lewes. Memoir of the British Geological Survey, Sheet 319 (England and Wales). 
Lake, R D and Thurrell, R G. 1974. The sedimentary sequence of the Wealden Beds in boreholes near Cuckfield, Sussex. Report of the Institute of Geological Sciences, No.74/2. 
Smart, J G O, Bisson, G and Worssam, B C. 1966. Geology of the Country around Canterbury and Folkestone. Memoir of the Geological Survey of Great Britain, Sheets 289, 305 and 306 (England and Wales). 
Topley, W. 1875. The geology of the Weald. Memoir of the Geological Survey of England and Wales. 
Fitton, W H, 1836. Observations on some of the strata between the Chalk and the Oxford Oolite, in the south-east of England. Transactions of the Geological Society of London, Vol.4, 103-378, 379*-388*. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E285 E286 E287 E288 E289 E300 E301 E302 E304 E305 E317 E318 E319 E320 E332 E333 E334