The BGS Lexicon of Named Rock Units — Result Details
Cefn Gwyn Tuff
| Computer Code: | CGTU | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Caradoc Series (O4) — Caradoc Series (O4) | ||
| Lithological Description: | Non-welded felsic ash-flow tuff. | ||
| Definition of Lower Boundary: | Conformable with silty mudstones and siltstones of the Ceiswyn Formation. | ||
| Definition of Upper Boundary: | Conformable with the Ceiswyn Formation; immediately overlain by rocks of the Glyn Gower Siltstones Member. | ||
| Thickness: | 0 to 4m | ||
| Geographical Limits: | Bala and Corwen districts, North Wales. | ||
| Parent Unit: | Ceiswyn Formation (CSW) | ||
| Previous Name(s): | Cwm Clwyd Tuff Formation [Obsolete Name And Code: Use CGTU]
(CCT)
Cwm Clwyd Tuff Formation [Obsolete Name and Code: Use CGTU] (*135) Cefn Gwyn Tuff Member [Obsolete Name and Code: Use CGTU] (*32) |
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| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Partial Type Section | The valley of Glyn Gower, 400m westnorthwest of Glyn Bach. Bassett, D A, Whittington, H B and Williams, A. 1966. | ||
| Reference(s): | |||
| Rushton, A W A and Howells, M F. 1998. Stratigraphical framework for the Ordovician of Snowdonia and the Lleyn Peninsula. British Geological Survey Research Report, RR/99/08. | |||
| British Geological Survey. 1993. Corwen, provisional. England and Wales sheet 120. Solid and drift, 1:50 000 (Southampton: Ordnance Survey for British Geological Survey.) | |||
| Bassett, D A, Whittington, H B, and Williams, A. 1966. The stratigraphy of the Bala district, Merionethshire. Quarterly Journal of the Geological Society of London, Vol. 122, 219-271. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E136 | |||