Computer Code: |
IRCH |
Preferred Map Code: |
BwL |
Status Code: |
Full |
Age range: |
Bathonian Age (JN)
— Bathonian Age (JN) |
Lithological Description: |
A pale grey to off- white or yellowish limestone with thin marls and mudstones, fossiliferous, bioturbated peloidal, ooidal and shell-fragmental more or less argillaceous packstones and wackestones, with subordinate cross-bedded, ooidal, shell-fragmental grainstones, containing a fauna mainly of bivalves, and locally brachiopods, such as Digonella digonoides, described as the Digonoides Beds of Torrens, 1967. |
Definition of Lower Boundary: |
Generally a sharp boundary with the underlying Roade Member comprising ofsimilar limestones generally containing K sharpi, or else a marl or mudstone bed at this level, which may prove a reliable marker, such as the mudstone at the base of the equivalent Ardley Member of the White Limestone Formation in Bucks-Oxon. |
Definition of Upper Boundary: |
Generally a sharp boundary of the limestones with mudstones of the Blisworth Clay Formation. |
Thickness: |
Typically from 5 m to 7 m thick, measured as 6.15 m in type section. |
Geographical Limits: |
The Towcester district to Kettering district, Northants, passings outh-west into the equivalent Ardley Member of the White Limestone Formation, and passing north into the equivalent Longthorpe Member of the Blisworth Limestone Formation. |
Parent Unit: |
Blisworth Limestone Formation (BWL)
|
Previous Name(s): |
Great Oolite Limestone [Obsolete Name And Code: Use BWL, GOG or CFDO]
(GOL)
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Type Section |
Irchester Old Lodge Pit, which is now entirely infilled. Cripps,1986; Cox, B M, and Sumbler, M G. 2002. |
Reference Section |
Irchester Country Park, a comparable section is located in the adjacent ironstone quarry. See Torrens, 1967; Cripps, 1986; and Cox, B M, and Sumbler, M G. 2002; for additional reference sections. |
Reference(s): |
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 (University of Aston in Birmingham: Unpublished PhD thesis.) |
Torrens, H S, 1967. The Great Oolite Limestone of the Midlands. Transactions of the Leicestershire Literary and Philosophical Society, Vol.61, 65-90. |
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: |
E171
E185
E186
E202
E203
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