| Computer Code: |
TNC |
Preferred Map Code: |
TnC |
| Status Code: |
Full |
| Age range: |
Fennian Stage (OF)
— Fennian Stage (OF) |
| Lithological Description: |
Grey, bioturbated, fine-grained laminated sandstones and subordinate siltstones, with large calcareous nodules that weather out. A structureless grey siliceous siltstone, possible representing a tuff, occurs in the upper part of the sequence. |
| Definition of Lower Boundary: |
Conformable and gradational with dark grey siltstones that form the main part of the Wig Bach Formation. |
| Definition of Upper Boundary: |
Conformably overlain by dark grey siltstones of the Wig Bach Formation. |
| Thickness: |
35m |
| Geographical Limits: |
Not yet recorded. |
| Parent Unit: |
Wig Bâch Formation (WGB)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Partial Type Section |
Coastal cliff section along 200m of the west side of Aberdaron Bay, south of the headland of Trwyn Cam. Gibbons, W and McCarroll, D. 1993. |
| 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. |
| Gibbons W and McCarroll D. 1993. Geology of the country around Aberdaron, including Bardsey Island. Memoir of the British Geological Survey, Sheet 133 (England and Wales). (London: H.M.S.O.). 88pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
