| Computer Code: |
TWY |
Preferred Map Code: |
TW |
| Status Code: |
Full |
| Age range: |
Arenig Series (OR)
— Arenig Series (OR) |
| Lithological Description: |
Thickly bedded pale weathering sandstones, bioturbated and fine-grained. |
| Definition of Lower Boundary: |
Gradational upward change from coarse-grained sandstones of the underlying Pared Mawr Member. |
| Definition of Upper Boundary: |
Conformable contact with the overlying cross-bedded, bioturbated muddy sandstones with granular clasts, of the Penrhyn Du Member. |
| Thickness: |
10-15m |
| Geographical Limits: |
Pwllheli area, northwest Wales. |
| Parent Unit: |
St Tudwal's Formation (STUD)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Porth Bach. Young, T P, Gibbons, W and McCarroll, D. 2002. |
| Reference Section |
Trwyn Llech-y-doll (upper part) coastal cliff exposure. Young, T P, Gibbons, W and McCarroll, D. 2002. |
| Reference Section |
Cliff section easy of Cilan Uchaf. Young, T P, Gibbons, W and McCarroll, D. 2002. |
| Type Section |
The headland of Trwyn-y-Wylfa. Young, T P, Gibbons, W and McCarroll, D. 2002. |
| 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: |
|
E134
|
