The BGS Lexicon of Named Rock Units — Result Details

New Pit Chalk Formation

Computer Code: NPCH Preferred Map Code: NPCk
Status Code: Full
Age range: Turonian Age (KT) — Turonian Age (KT)
Lithological Description: Principally blocky, white firm to moderately hard chalk with numerous marls or paired marl seams. Flint occurs sporadically in the upper part in the deeper basin areas of the Southern Province. In some localities flint, in seams, occurs towards the base of the formation most notable over structural highs, towards the margins of the outcrop and within the "Transitional" Province.
Definition of Lower Boundary: The lower boundary is conformable at the bedding plane immediately below the Gun Gardens Main Marl (the Lulworth Marl of Gale, 1996) in the standard Sussex succession. The mapping boundary is placed at the highest shell-detrital chalk and at the incoming of sporadic flints. In the "Transitional" Province the top of these shell-detrital chalks is at the Odsey Marl (see Hopson et al., 1996).
Definition of Upper Boundary: The top is conformable at the base of Glynde Marl 1 in Sussex, but one of the higher marls elsewhere although invariably in the interval Glynde Marls to Southerham Marls in the Southern Province. The mapping boundary is placed at the appearance of nodular chalks and significant flint development within that range of marls. In the "Transitional" Province the formation expands in response to the later inception of nodularity and hardground development (characteristic of the Lewes Nodular Chalk Formation) such that the upper boundary is diachronous here and placed below the "Chalk Rock Member" at the Reed Marl (the lateral equivalent of the Bridgewick Marls of the Southern Province).
Thickness: Typically between 35 and 50m but is as little as 10 to 25m thick in Wiltshire, north Hampshire and Berkshire over synsedimentary structural highs. The formation expands in the "Transitional" Province where it is thought to be up to 75 to 80m thick.
Geographical Limits: Known throughout the Southern Province, within the Chilterns and northward into East Anglia in the "Transitional" Province. A number of laterally persistent and named marl and flint beds in Mortimore (1986) can be recognized over much of southern England.
Parent Unit: White Chalk Subgroup (WHCK)
Previous Name(s): Shakespear Cliff Member (-4223)
Aycliff Member (-2341)
Upper Holywell Beds And New Pit Beds (-2342)
New Pit Chalk Member (-1729)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Shillingstone Chalk pit on the north side of Shillingstone Hill, Dorset. Various exposures in quarry give full succession in thin development of the formation. 
Type Section  Cliff section east of Beachy Head, Sussex. Full succession available on foreshore and lower cliff at various states of the tide. 
Reference Section  Compton Bay cliff section, Isle of Wight. Full section visible at extreme low tide along cliff section towards Freshwater Bay. 
Reference Section  Akers Steps cliff section, Kent. Full succession available along coastal path. The section is used as the standard reference section for the foraminiferal biostratigraphy of the Turonian stage. 
Type Section  Gun Gardens, Eastbourne, Sussex. Full succession in numerous exposures along coastal path and foreshore below Gun Gardens. 
Reference(s):
Hopson, P M. 2005. A stratigraphical framework for the Upper Cretaceous Chalk of England and Scotland, with statements on the Chalk of Northern Ireland and the UK Offshore Sector. British Geological Survey Research Report RR/05/01 102pp. ISBN 0 852725175 
Bristow, C R, Barton, C M, Freshney, E C, Wood, C J, Evans, D J, Cox, B M and Woods, M A. 1999. The Wincanton district - a concise account of the geology. Memoir of the British Geological Survey, Sheet 297 (England and Wales). 
Bristow, C R. 1991. Geology of Sheet ST80NW and Sheet ST80SW (Turnworth-Milton Abbas, Dorset). British Geological Survey Technical Report, WA/92/20. 
Mortimore, R N. 1986. Stratigraphy of the Upper Cretaceous White Chalk of Sussex. Proceedings of the Geologists' Association, Vol.97(2), 97-139. 
Bristow, C R, Mortimore, R N and Wood C J. 1997. Lithostratigraphy for mapping the Chalk of southern England. Proceedings of the Geologists' Association, Vol.108(4), 293-315. 
Rawson, P F, Allen, P M and Gale, A. 2001. A revised lithostratigraphy for the Chalk Group. Geoscientist, Vol.11, p.21. 
Bristow, C R, 1989. Geology of the East Stour - Shaftesbury district (Dorset) British Geological Survey Technical Report WA/89/58. 
Bristow, C R, Barton, C M, Freshney, E C, Wood, C J, Evans, D J, Cox, B M, Ivimey-Cook, H C, and Taylor, R T. 1995. Geology of the country around Shaftesbury. Memoir of the British Geological Survey, Sheet 313 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E281 E300 E313 E314 E327 E341 E342 E343