| Computer Code: |
PMN |
Preferred Map Code: |
Pm |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Basaltic trachyandesite lavas and tuffs and derived sediments. |
| Definition of Lower Boundary: |
Overlies mudstones and sandstones of the Dwyfach Formation. |
| Definition of Upper Boundary: |
Upward change from andesitic lavas and tuffs into rhyodacitic lavas and tuffs of the Foel Ddu Rhyodacitic Formation. |
| Thickness: |
300m |
| Geographical Limits: |
Pwllheli area, northwest Wales. |
| Parent Unit: |
Nant Ffrancon Subgroup (NFR)
|
| Previous Name(s): |
Penmaen Formation [Obsolete Name and Code: Use PMN]
(-3618)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Exposures near Pwllheli. |
| Reference(s): |
| Young, T P, Gibbons, W and McCarroll, D. 2002. Geology of the country around Pwllheli. Memoir of the British Geological Survey, Sheet 134 (England and Wales). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E119
E134
|
