| Computer Code: |
GAG |
Preferred Map Code: |
GaG |
| Status Code: |
Full |
| Age range: |
Arenig Series (OR)
— Arenig Series (OR) |
| Lithological Description: |
Quartzose conglomeratic sandstone. |
| Definition of Lower Boundary: |
Unconformity on siltstones of Dol-cyn-Afon Formation or mudstones of Dolgellau Formation (both in Mawddach Group): forms the basal unit of the Allt Lwyd Formation. |
| Definition of Upper Boundary: |
At base of siltstones and sandstones of the undivided Allt Lwyd Formation. |
| Thickness: |
0 to 70m |
| Geographical Limits: |
South central Snowdonia. |
| Parent Unit: |
Allt Lwyd Formation (ALL)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
North of Tanygrisiau Dam. Howells and Smith, 1997. |
| Reference(s): |
| 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. |
| Allen, P M, and Jackson, A A. 1985. Geology of the country around Harlech. Memoir of the British Geological Survey, Sheet 135 with part of Sheet 149 (England and Wales). (London: HMSO.) 112 pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E119
E136
E135
|
