| Farr, G, Graham, J, and Stratford, C. 2014. Survey, characterisation and condition assessment of Palustriella dominated springs 'H7220 Petrifying springs with tufa formation (Cratoneurion)' in Wales. British Geological Survey Internal Report, OR/14/043.
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A list of potential sites (see below) was provided by NRW based on the occurrence of Palustriella dominated vegetation, the presence of tufa or NVC M37 community, a vegetation type known to occur widely in Wales based on preliminary NRW surveys. Descriptions of the sites are provided in the following sub chapters.
Table 3 List of sites and geology
| Site
|
1:50K Geology
|
Tufa forming?
|
| Foel Fawr Site 1
|
Carboniferous Limestone — Dowlais Limestone Formation
|
Yes
|
| Foel Fawr Site 2
|
Carboniferous Limestone — Dowlais Limestone Formation
|
Yes
|
| Foel Fawr: Moel Gornach
|
Carboniferous Limestone — Dowlais Limestone Formation
|
v.small area
|
| Carboniferous Limestone — Dowlais Limestone Formation
|
Yes
|
| Pont Clydach
|
Lower Devonian Old Red Sandstone — Brownstones Formation
|
No
|
| Blaen Onnen
|
Carboniferous Limestone — Abercriban Oolite Subgroup
|
Yes
|
| Llyn y Fan Fach
|
Lower Devonian Old Red Sandstone — Brownstones Formation underlain by the Lower Devonian Senni Formation
|
v.small on one plant
|
| Cwm Clydach
|
Carboniferous Limestone — Castell Coch Limestone formation
|
Yes
|
| Waun Ddu/Craig y Cilau
|
Carboniferous Limestone sequence (Pembroke and Avon Group) overlying Devonian Qtz conglomerate and brownstones
|
No
|
| Tarren y Esgob
|
Lower Devonian Old Red Sandstone, Senni Formation calcrete horizon
|
Yes
|
| Hen Allt Common
|
Devonian Raglan Mudstone Formation calcrete horizon
|
Yes
|
| Cors Erdderiniog
|
Junction of Carboniferous Clwyd Limestone Group overlying the Lligwy Sandstone
|
Yes
|
| Fedw Fawr Beach
|
Carboniferous Clwyd Limestone Group Loggerheads Limestone formation (includes sandstone in cliff section)
|
Yes
|
| Ddol Uchaf
|
Quaternary Tufa Deposit underlain by Silurian Elwy formation
|
Yes
|
| Mc Walters Dingle
|
Carboniferous Pennine Lower Coal Measures Formation
|
Yes
|
| Nant Peris
|
Ordovician Snowdon Volcanic Group
|
No
|