Oolite Member
***Honeycombed Sandstone Member
**Dowlais Limestone Formation
**Abercriban Oolite Subgroup & Clydach Valley Subgroup
*Avon Group
**Cwmyniscoy Mudstone Formation
**Castell Coch Limestone Formation (lowermost/oldest)

The limestone found north of the Wales-London-Brabant Massif and south of the emergent Southern Uplands block is identified as a separate northern province. It is characterised by the presence of numerous