The BGS Lexicon of Named Rock Units — Result Details

Crediton Breccia Formation

Computer Code: CRBR Preferred Map Code: CrBr
Status Code: Full
Age range: Permian Period (P) — Permian Period (P)
Lithological Description: Reddish brown, poorly to moderately cemented breccia with a silt, sand and clay matrix. Clasts mostly less than 4cm. Clasts of sandstone, siltstone, slate, shale, hornfells, chert, acid lava and tuff, quartz-porphyry, vein quartz, and a variety of tournalinised rocks. Poorly developed bedding in units mostly over 1m thick. Thin interbedded or lenses of red mudstone throughout.
Definition of Lower Boundary: Overlies unconformably early Permian formations - Knowle Sandstone, Bow Breccia, Cadbury Breccia, Thorverton Sandstone, except in Crediton area, where the Creedy Park Sandstone intervenes.
Definition of Upper Boundary: Overlain by Newton St Cyres Breccia fairly sharply, with feature locally developed at the junction. East of Shute [SS 890 001] overlain by the Shute Sandstone.
Thickness: Up to 240m
Geographical Limits: Extends from Nymet Tracey [SS 728 006] in Okehampton District (as part of the 'Crediton Conglomerates' of Edmonds, E A, et al, 1968), into the Exeter district at Knowle [SS 783 015], and thence to Crediton, eastwards through Shobrooke [SS 863 011] to south of Raddon [SS 910 010], east of there, passed into Yellowford Formation.
Parent Unit: Exeter Group (EXE)
Previous Name(s): Crediton Beds (-1456)
Crediton Conglomerates (-817)
Yenpacott Breccia (-818)
Crediton Breccias [Obsolete Code: Use CRBR] (CRCG)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Town of Crediton, Devon. 
Reference(s):
Hutchins, P F, 1963. The Lower New Red Sandstone of the Crediton Valley. Geological Magazine, Vol.100, 107-128. 
Edmonds, E A, Wright, J E, Beer, K E, Hawkes, J R, Fenning, P J, Freshney, E C, Lovelock, P E R, McKeown, M C, Ramsbottom, W H C and Williams, M. 1968. Geology of the country around Okehampton. Memoir of the Geological Survey of Great Britain, Sheet 324 (England and Wales). 
Scrivener, R C. 1988. Geology of the Newton St Cyres district (Devon). 1:10,000 Sheet SX89NE. British Geological Survey Technical Report, WA/88/5/ 
Laming, D J C, 1982. The New Red Sandstone. "In" Durrance, E M and Laming, D J C, (Editors). The Geology of Devon, p.148-177. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable