The BGS Lexicon of Named Rock Units — Result Details
Hughes Member
| Computer Code: | H | Preferred Map Code: | H |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Asturian Substage (CAS) — Asturian Substage (CAS) | ||
| Lithological Description: | Green-grey, lithic arenites ('Pennant sandstones'), with thin mudstone/siltstone and seatearth interbeds, and mainly thin coals. Age Asturian. | ||
| Definition of Lower Boundary: | The base is placed at the base of the Hughes Coal or its equivalent (Cefn Glas, Wenallt, Bettws Four-Feet, Ty-du, etc.) in a predominantly arenaceous sequence of the Pennant Sandstone Formation, where the coal rests on mudstone/siltstone seatearth at the top of the Brithdir Member. | ||
| Definition of Upper Boundary: | The top is placed at the base of the Golden Seam or its equivalent (Swansea Three-Feet, Graigola) at the base of a predominantly arenaceous sequence of the Swansea Member, where the coal rests on mudstones/siltstone and seatearth at the top of the Hughes Member. In the east of the coalfield, the top is placed at the base of the Mynyddislwyn Coal. | ||
| Thickness: | From 45 m near Pontypool [SO 250 150] thickening westwards to 270 m near Swansea [SS 570 960]. | ||
| Geographical Limits: | Widespread outcrop throughout the South Wales Coalfield, from Llanelli [SN 49 02] to near Pontypool [ST 268 980]. | ||
| Parent Unit: | Pennant Sandstone Formation (PES) | ||
| Previous Name(s): | Hughes Formation [Obsolete Name and Code: Use H]
(-2226)
Hughes Beds [Obsolete Name and Code: Use H] (-946) |
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| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Reference Section | There is no designated type area, the Member being named after the basal coal, the Hughes Seam of the Swansea - Gower area of the South Wales Coalfield (Woodland et al., 1957). A reference section is provided by exposures in a disused mineral railway cutting at Tir-Evan-Llwyd [SS 765 951], south-east of Neath, in which 7.6 m of 'Pennant' sandstone contains lenticular mudstone beds (Barclay 2011). | ||
| Reference(s): | |||
| Woodland, A W, Evans, W B and Stephens, J V. 1957. Classification of the Coal Measures of South Wales with Special reference to the Upper Coal Measures. Bulletin of the Geological Survey of Great Britain, No. 13, 39-60. | |||
| Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009. Lithostratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/09/01. 184pp. | |||
| Barclay, W J. 2011. Geology of the Swansea district: a brief explanation of the geological map. Sheet Description of the British Geological Survey. 1:50 000 Sheet 247 Swansea (England and Wales). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E247 E232 E231 E230 E229 E246 | |||