The BGS Lexicon of Named Rock Units — Result Details
Bryn Brith Member
| Computer Code: | BYN | Preferred Map Code: | BnB |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Abereiddian Stage (O2) — Abereiddian Stage (O2) | ||
| Lithological Description: | Massive lenticular beds of disturbed mafic tuff, tuffite and tuffaceous sandstone, with subordinate thin mudstones. | ||
| Definition of Lower Boundary: | Conformable on the felsic ash-flow tuffs of the Offrwm Volcanic Formation or within the lowermost mudstones of the Cregennen Formation. | ||
| Definition of Upper Boundary: | Conformable within the mudstones of the Cregennen Formation. | ||
| Thickness: | To 65m, and might be locally up to 150m. | ||
| Geographical Limits: | Cadair Idris district. | ||
| Parent Unit: | Cregennen Formation (CREN) | ||
| Previous Name(s): | Bryn Brith Beds [Obsolete Name and Code: Use BYN]
(-3889)
Bryn Brith Grits (-742) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Section | Crags of Bryn Brith. Pratt, W T, Woodhall, D G and Howells, M F. 1995. | ||
| Reference(s): | |||
| Cox, A H, and Wells, A K. 1927. The geology of the Dolgelley district, Merionethshire. Proceedings of the Geologists' Association, Vol. 38, 265-318. | |||
| Cox, A H, and Wells, A K. 1921. The Lower Palaeozoic rocks of the Arthog-Dolgellau district (Merionethshire). Quarterly Journal of the Geological Society, London, Vol. 76, p. 254-324. | |||
| Pratt, W T, Woodhall, D G and Howells, M F. 1995. Geology of the country around Cadair Idris. Memoir of the British Geological Survey, Sheet 149. (England and Wales). (London: HMSO), 111pp | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E149 | |||