| Computer Code: |
HDCI |
Preferred Map Code: |
HdC |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Oolitic ironstone. |
| Definition of Lower Boundary: |
Overlies dark grey mudstone, with minor sandstone and siltstone, of the Llanengan Formation. Boundary is probably a disconformity or non-sequence. |
| Definition of Upper Boundary: |
Overlain by mudstones and siltstones, with sandstones, of the Trygarn Formation, or undivided Nant Ffrancon Subgroup siltstones and fine-grained sandstones. |
| Thickness: |
4-6m |
| Geographical Limits: |
Pwllheli area, northwest Wales. |
| Parent Unit: |
Nant Ffrancon Subgroup (NFR)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Hen-dy-Capel Quarry. |
| Reference Section |
Small quarry at Llanengan. 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). |
| Young, T P, 1991. A revision of the age of the Hen-dy-capel Ooidal Ironstone (Ordovician), Llanengan, North Wales. Geological Journal, Vol.26, 317-327. |
| Trythell, R J B, Eccles, C, Molyneux, S G and Taylor, W E G, 1987. Age and controls on ironstone deposition (Ordovician) North Wales. Geological Journal, Vol.22, 31-43. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E134
|
