The BGS Lexicon of Named Rock Units — Result Details

Acutistriatum-Comptoni Bed

Computer Code: ACCO Preferred Map Code: Ac
Status Code: Full
Age range: Callovian Age (JC) — Callovian Age (JC)
Lithological Description: Grey calcareous mudstone, becoming more shelly and shell-detrital upwards, grading into pyritic shell bed (Comptoni Bed), overlain by brownish grey shaly mudstone (at type section) or grey calcareous mudstone with pale grey ovoid argillaceous limestone nodules and burrowed top (from Bedfordshire south) ( Acutistriatum Bed). Comptoni Bed has rich fauna of oysters, nuculacean bivalves, belemnites, and ammonites (including Binatisphinctes comptoni). Acutistriatum Bed fauna is rich in forams, and includes ammonites, notably species of Kosmoceras, including K. acutistriatum
Definition of Lower Boundary: Passage up from relatively unfossiliferous brownish grey mudstone of undifferentiated Peterborough Member into shelly mudstone with fauna of Comptoni Bed as described under Lithology; base of Bed 37 in type section (Hudson and Martill, 1984, p.118).
Definition of Upper Boundary: Change up from brownish grey mudstone with fauna of Acutistriatum Bed, as described under Lithology, into greenish grey mudstone of undifferentiated Peterborough Member, top is burrowed; top of Bed 38 in type section (Hudson and Martill, 1994, p. 118).
Thickness: 0.3 to 0.6m; 0.45m at type section.
Geographical Limits: England; Dorset to Humberside.
Parent Unit: Peterborough Member (PET)
Previous Name(s): Acutistriatum Band (*840)
Comptoni Bed (-2557)
Acutistriatum Bed (-1943)
Alternative Name(s): Acutistriatum Band
Stratotypes:
Type Section  King's Dyke pit, Whittlesey, Peterborough. Hudson and Martill, 1984. 
Reference(s):
Horton, A, Shephard-Thorn, E R and Thurell, R G, 1974. The Geology of the new town of Milton Keynes. Report of the Institute of Geological Sciences, No 74/16. 
Callomon, J H, 1968. The Kellaways Beds and the Oxford clay. In Sylvester-Bradley, P C and Ford, T D. (Editors). The Geology of the East Midlands. (Leicester: Leicester University Press). 
Horton, A, Sumbler, M G, Cox, B M and Ambrose, K, 1995. Geology of the country around Thame. Memoir of the British Geological Survey, Sheet 237 (England and Wales). 
Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). 
Hudson, J D, and Martill, D M. 1994. The Peterborough Member (Callovian, Middle Jurassic) of the Oxford Clay Formation at Peterborough, UK. Journal of the Geological Society of London, Vol.151, 113-124. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E127