The BGS Lexicon of Named Rock Units — Result Details

Longthorpe Member

Computer Code: LONG Preferred Map Code: BwL
Status Code: Full
Age range: Bathonian Age (JN) — Bathonian Age (JN)
Lithological Description: Pale grey to off-white or brownish, more or less argillaceous packstones and wackestones, with grainstone intercalations, thin marls and mudstones, generally fossiliferous notably with Praeexogyra hebridica (Forbes),and bivalves such as Modiolus.
Definition of Lower Boundary: The base of the limestones described, overlying limestones with Kallihynchia sharpi, of the Roade Member.
Definition of Upper Boundary: Generally a sharp boundary with mudstone of the Blisworth Clay Formation.
Thickness: Typically from about 4 m to 7m thick (Cripps, 1986).
Geographical Limits: The Kettering to Stamford area.
Parent Unit: Blisworth Limestone Formation (BWL)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Longthorpe Road Cutting,Peterborough. Cripps, 1986. 
Reference Section  Primary reference section: Thrapston Quarry. Torrens,1968; Cripps,1986; Cox, B M, and Sumbler, M G. 2002. 
Reference Section  Spires Wood Quarry. Torrens,1967,1968; Cripps,1986. 
Reference(s):
Torrens, H S. 1968. The Great Oolite Series. 227-263 in Sylvester-Bradley, P C and Ford, T D (editors), The geology of the East Midlands. (Leicester: Leicester University Press.) 
Torrens, H S, 1967. The Great Oolite Limestone of the Midlands. Transactions of the Leicestershire Literary and Philosophical Society, Vol.61, 65-90. 
Cripps, D W. 1986. A facies analysis of Upper Great Oolite Group in Central and Eastern England. (University of Aston in Birmingham: Unpublished PhD thesis.) 
Cox, B M and Sumbler, M G. 2002. British Middle Jurassic Stratigraphy. Geological Conservation Review Series No.26. [Peterborough: Joint Nature Conservation Committee.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E157 E171