The BGS Lexicon of Named Rock Units — Result Details

Norwich Crag Formation

Computer Code: NCG Preferred Map Code: NCg
Status Code: Full
Age range: Pliocene Epoch (NP) — Early Pleistocene Epoch (QPE)
Lithological Description: The formation comprises a widespread sheet of well sorted, fine- to medium-grained micaceous, glauconitic, locally shelly sands (Chillesford Sand Member in southeast Suffolk), with localized beds of laminated silty clays (Chillesford Clay and Easton Bavents Clay members) and rounded flint gravels (Westleton Beds). The formation is marine, with the clay members being estuarine and the Westleton Beds representing beach-face gravels.
Definition of Lower Boundary: Rests with discontinuity on the Red Crag Formation and oversteps onto Coralline Crag Formation, Palaeogene formations and Chalk Group bedrock.
Definition of Upper Boundary: Overlain disconformably by Wroxham Crag Formation, unconformably by Kesgrave Valley Subgroup and Mid Pleistocene glacigenic deposits.
Thickness: c.70m
Geographical Limits: Restricted to East Anglia. Well defined throughout Suffolk and north Essex, as far as Stanstead Mountfichet. It continues north into Norfolk area and Ludham, but farther north it is cut out beneath the base of the Wroxham Crag Formation.
Parent Unit: Crag Group (CRAG)
Previous Name(s): Fluvio-Marine Crag (-1081)
Icenian Crag (-1721)
Mammaliferous Crag (-414)
Norwich Crag (-415)
Upper Crag (-3574)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  The area around Wickham Market and Aldeburgh, Suffolk (southern East Anglia). Mathers and Zalasiewicz, 1988. 
Reference(s):
Hamblin, R J O, Moorlock, B S P, Booth, S J, Jeffery, D H and Morigi, A N. 1997. The Red Crag and Norwich Crag formations in eastern Suffolk. Proceedings of the Geologists' Association, Vol.108, 11-23. 
Zalasiewicz, J A, Mathers, S J, Hughes, M J, Gibbard, P L, Peglar, S M, Harland, R, Nicholson, R A, Boulton, G S, Cambridge, P and Wealthall, G P. 1988. Stratigraphy and palaeoenvironments of the Red Crag and Norwich Crag formations between Aldeburgh and Sizewell, Suffolk, England. Philosophical Transactions of the Royal Society of London, Vol.B322, 221-272. 
Charlesworth, E. 1837. A notice of the remains of vertebrate animals found in the Tertiary beds of Norfolk and Suffolk. Report of the British Association for the Advancement of Science, (for 1836), Sections 84-86. 
Bell, A and Bell, R. 1871. The English Crags, and their stratigraphical divisions as indicated by their invertebrate fauna. Geological Magazine, Vol.108, 256-263. 
Harmer, F W. 1900. On a proposed new classification for the Plicocene deposits of the east of England. Report of the British Association for the Advancement of Science, (Dover), Transactions of Sections C, (for 1899), 751-753. 
Zalasiewicz, J A and Mathers, S J. 1985. Lithostratigraphy of the Red and Norwich crags of the Aldeburgh-Orford area. Southeast Suffolk Geological Magazine, Vol.122, 287-296. 
Funnell, B M and West, R G. 1977. Preglacial Pleistocene deposits of East Anglia. 247-265 in Shotton, F W (Editor), British Quaternary studies: recent advances. [Oxford: Clarendon Press.] 
Lyell, C. 1839. On the relative ages of the Teriary deposits commonly called 'Crag' in the counties of Norfolk and Suffolk. Magazine of Natural History, Series 2, Vol.3, 313-322. 
Mathers, S J and Zalasiewicz, J A. 1996. A gravel beach-ripchannel system - the Westleton Beds (Pleistocene) of Suffolk, England. Proceedings of the Geologists' Association, Vol.107, 57-67. 
Mathers, S J and Zalasiewicz, J A. 1988. The Red Crag and Norwich Crag formations of southern East Anglia. Proceedings of the Geologists Association, Vol.99, 261-278. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E191 E207 E162 E175