| Computer Code: |
PYBT |
Preferred Map Code: |
PYB |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Acid ash-flow tuffs interbedded with silty calcareous mudstone. |
| Definition of Lower Boundary: |
Member at top of Llyn Conwy Formation. Basal contact marked by acid ash-flow tuff. |
| Definition of Upper Boundary: |
Below mudstones of undivided Nant Ffrancon Group. |
| Thickness: |
75m |
| Geographical Limits: |
Northeast flanks of Harlech Dome. |
| Parent Unit: |
Aran Fawddwy Formation (AFM)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Pen y Bedw. |
| Reference(s): |
| Lynas, B D T, 1973. The Cambrian and Ordovician rocks of the Migneint area, North Wales. Journal of the Geological Society, London, Vol.129, 481-503. |
| Howells, M F and Smith, M. 1997. Geology of the country around Snowdon. Memoir of the British Geological Survey, Sheet 119 (England and Wales). (London: The Stationery Office). 104pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E119
|
