The BGS Lexicon of Named Rock Units — Result Details
Bow Breccia Formation
| Computer Code: | BOB | Preferred Map Code: | BwBr |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Permian Period (P) — Permian Period (P) | ||
| Lithological Description: | Breccia, reddish-brown, silty and sandy, with pebbles of sandstone, slate, shale, hornfels, acid lava, vein-quartz and quartz porphyry. Middle Devonian limestone clasts present at Solland (SS 615 021) and Westacott (SS 685 022). (Hutchins, 1958). Lamprophyres and basalts present near north Tawton, on southern side of trough. | ||
| Definition of Lower Boundary: | Rests directly on Upper Carboniferous Bude Formation, from Lower Creedy (SS 843 027) westwards to western edge of Exeter district, although thin Cadbury Breccia may locally intervene. East of Bradley Farm (SS 855 023) apparently overlies Cadbury Breccia. | ||
| Definition of Upper Boundary: | Passes gradationally up into the Knowle Sandstone Formation by gradual increase in the proportion of breccia. | ||
| Thickness: | Up to 140 (Crediton area). 430m (Bow). 380m (north Tawton). 180m+ (Sampford Chapple). 150m+ (Hatherleigh-Exbourne). | ||
| Geographical Limits: | Occupy the whole width of the Crediton Trough to the west of Bow (in the Okehampton district). In the Exeter district, present along the northern side of the trough from near Elston (SS 785 026) in the west, through Sandford to Bradley Farm (SS 855 023). | ||
| Parent Unit: | Exeter Group (EXE) | ||
| Previous Name(s): | Bow Conglomerates [Obsolete Name And Code: Use BOB]
(BWCG)
Bow Beds [Obsolete Name and Code: Use BOB] (-1374) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Reference Section | River Okement stream section, near Jacobstowe. Detailed section in Edmonds, et al, 1968, p 154. | ||
| Type Area | Village of Bow (SS 723 017), Devon. | ||
| Reference(s): | |||
| Scrivener, R C and Edwards, R A, 1991. Geology of the Shobrooke district (Devon). 1:10 000 Sheet SS80SE. British Geological Survey Technical Report, WA/90/24. | |||
| 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). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E324 E323 | |||