The BGS Lexicon of Named Rock Units — Result Details

Red Crag Formation

Computer Code: RCG Preferred Map Code: RCg
Status Code: Full
Age range: Piacenzian Age (NC) — Thurnian Stage (QT)
Lithological Description: Coarse-grained, poorly sorted, cross-bedded, abundantly shelly sands (in East Anglia). Dark green and glauconitic when unoxidised, but typically oxidised to yellow or reddish brown with ferruginous concretions (iron pan). Basal bed of rounded flint pebbles. Offshore, fine- to medium-grained, muddy, calcareous, glauconitic sands.
Definition of Lower Boundary: Rests unconformably on the Coralline Crag Formation, Palaeogene formations and Chalk Group bedrock.
Definition of Upper Boundary: Onshore overlain unconformably by sands of the Norwich Crag Formation, which are less coarse-grained, better sorted, less shelly and generally paler in colour. Offshore overlain unconformably by early Pleistocene or Holocene sediments.
Thickness: 70m maximum offshore (Flemish Bight Sheet). Onshore commonly to 20m but thicker in coastal areas of east Norfolk and Suffolk and within the Stradbroke Trough, locally reaching c.40 to 45m.
Geographical Limits: Widespread in the Southern North Sea basin and onshore at depth beneath Norfolk and northeast Suffolk. Crops out in southeast Suffolk and extends into northern Essex. Can be traced farther inland in boreholes as far west as Stansted Mountfitchett and beyond in an isolated outlier at Rothampstead.
Parent Unit: Crag Group (CRAG)
Previous Name(s): Red Crag Series (-2993)
Red Crag Member (-2389)
Lower Crag (-484)
Red Crag (-485)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  The area around Aldeburgh and Sizewell, Suffolk, Zalasiewicz et al., 1988. 
Type Area  Walton-on-the-Naze, Essex. Type samples offshore in Borehole 81/51. 
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. 
Wood, S V. 1866. On the structure of the Red Crag. Quarterly Journal of the Geological Society of London, Vol.22, 538-552. 
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. 
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.] 
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. 
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 E208 E225 E175 E206 E207 E224 E242 E148 E162 E176 E190 E223