The BGS Lexicon of Named Rock Units — Result Details
Bryn-Glas Formation
| Computer Code: | BGF | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Pending Upgrade | ||
| Age range: | Hirnantian Age (OH) — Hirnantian Age (OH) | ||
| Lithological Description: | Mid to dark grey massive mudstones, commonly slumped and destratified, with rafts and balled inclusions of sandstone; local thin-bedded siltstones. | ||
| Definition of Lower Boundary: | Overlies the Pencerrigtewion Member of the Drosgol Formation (Cave and Hains, 1986), with apparent conformity, although the boundary is likely to represent one or more syndepositional slide planes. Where the Pencerrigtewion Member disappears, the Formation cannot be distinguished from the underlying Drosgol Formation, and both have been grouped as the Garnedd-wen Formation. | ||
| Definition of Upper Boundary: | Conformably overlain by the anoxic hemipelagic mudstones of the Cwmere Formation. | ||
| Thickness: | 30 to 195m | ||
| Geographical Limits: | Not specified. | ||
| Parent Unit: | Not Available (!) | ||
| Previous Name(s): | Bryn-Glas Group [Obsolete Name and Code: Use BGF]
(-3846)
Bryn-Glas Mudstones [Obsolete Name and Code: Use BGF] (-1351) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| none recorded or not applicable | |||
| Reference(s): | |||
| Cave, R and Hains, B A. 1986. Geology of the country between Aberystwyth and Machynlleth. Memoir of the British Geological Survey, Sheet 163 [England and Wales]. [London: HMSO.]. 148pp. | |||
| Jones, O T. 1909. The Hartfell-Valentian succession in the district around Plynlimon and Pont Erwyd (north Cardiganshire). Quarterly Journal of the Geological Society of London, Vol.65, 463-536. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E149 | |||