The BGS Lexicon of Named Rock Units — Result Details

Chercombe Bridge Limestone Formation

Computer Code: CBL Preferred Map Code: notEntered
Status Code: Full
Age range: Eifelian Age (DI) — Givetian Age (DV)
Lithological Description: Well bedded limestone, fine to medium grained, dark grey to bluish-black, with rich fauna including tabulate and rugose corals, dendroid stromatoporoids. Limestone locally contains shale partings, typically of red colour, and locally up to 50 mm thick (at Broadridge Wood Quarry [SX 8390 7112]. Dolomitisation and fissuring are seen locally; fissures at Bickleyball Quarry [SX 8850 7400] are filled with slipped Upper Greensand and flint gravel. Dip of the limestone beds is typically 20 degrees to the E-SE, although this varies over the area.
Definition of Lower Boundary: Chercombe Bridge Limestone of the Ugbrooke Unit (i.e. in the thickness of rock that is bound between the Bickington Thrust in the north and the Ware Barton Thrust in the south) has thrust contact with Carboniferous rocks around Bickington, and a thrust contact with Upper Devonian slate near to Telegraph Hill [SX 8082 7338]. Chercombe Bridge Limestone from the Ugbrooke - East Ogwell Succession conformably overlies the East Ogwell Limestone in an inverted succession at [SX 8850 7400].
Definition of Upper Boundary: Chercombe Bridge Limestone of the Ugbrooke Succession is locally faulted against the Kingsteignton Volcanic Group. In the Ugbrooke Unit (i.e. in the thickness of rock that is bound between the Bickington Thrust in the north and the Ware Barton Thrust in the south) the top of the formation is diachronous, with mid Frasnian ages at Chudleigh in the north [SS 8611 7793], and Givetian near Whiteway Barton [SX 8338 7090] in the south. In the Denbury and East Ogwell Successions, the upper boundary is a conformable one with the overlying Foxley Tuff.
Thickness: Up to 245 m.
Geographical Limits: South Devon.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Broadridge Wood Quarry. Selwood et al., 1984. 
Reference(s):
Selwood, E B, Edwards, R A, Simpson, S, Chesher, J A, Hamblin, R J O, Henson, M R, Riddolls, B W and Waters, R A. 1984. Geology of the countryside around Newton Abbot. Memoir of the British Geological Survey, Sheet 339 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E339