| Computer Code: |
CRYC |
Preferred Map Code: |
Cryc |
| Status Code: |
Full |
| Age range: |
Frasnian Age (DR)
— Famennian Age (DA) |
| Lithological Description: |
Mainly quartz pebble conglomerates, with fine-grained quartzitic grey-green sandstones, pebbly sandstones and red-brown mudstones. |
| Definition of Lower Boundary: |
Topmost surface of a persistent calcrete, overlain by quartz pebble conglomerate, the latter appearing in the succession for the first time at this level (Lovell, 1978). |
| Definition of Upper Boundary: |
Surface cut in quartz pebble conglomerates, overlain by pale yellow to white micaceous sandstone of the Garn-gofen Formation (Lovell, 1978). |
| Thickness: |
5 m. to a maximum of about 12 m. |
| Geographical Limits: |
From Blaen Onneu area near Crickhowell, Gwent eastwards and southwards to Pontypool, Gwent, South Wales. |
| Parent Unit: |
Portishead Subgroup (POB)
|
| Previous Name(s): |
Quartz Pebble Conglomerate [Obsolete Name and Code: Use CRYC]
(-1463)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Exposures at Craig-y-cwm, about 3 km. south-east of Blaenavon, Gwent, South Wales. [Barclay, 1989]. |
| Reference(s): |
| Lovell, R W W. 1978a. The sedimentology and stratigraphy of the Upper Old Red Sandstone and Lower Limestone Shales of the South Wales Coalfield. Unpublished PhD thesis, University of Bristol. |
| Barclay, W J, Jackson, D I, Mitchell, M, Owen, B, Riley, N J, White, D E, Strong, G E, and Monkhouse, R A. 1989. Geology of the South Wales Coalfield, Part II, the country around Abergavenny. Memoir of the British Geological Survey. |
| Barclay, W J. 1975. Annual report for 1974, p. 26. Institute for Geological Sciences: London. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E232
|
