Ceunant Aberderfel
Also within
Geology & landscape
Geological Period: Ordovician · Rock Type: Limestone, Mudstone
Description
Description Ceunant Aberderfel is of special scientific interest because it contains the type locality of the Derfel Limestone, an important calcareous mudstone unit of Upper Ordovician (Caradoc Series) age, and is also the type locality for several species of brachiopod. The site is located approximately 8 km north-west of Bala and incorporates rocks exposed along the bed and banks of a 100 m long section of the Nant Aberderfel extending upstream from its confluence with Llyn Celyn. Ceunant Aberderfel is the type locality and most fossiliferous development of the Lower Caradoc Derfel Limestone. This historically important locality has yielding an extensive fauna of triobites and is type locality of ten species of brachiopod. The fossil assemblage clearly demonstrates the faunal dissimilarities between the Bala area and the type- Caradoc area of south Shropshire just 65 km to the east. The Kullervo- Palaeostrophomena-Nicolella (now Nicolella) brachiopod association, which is of wide international sigificance, was first recognised at this locality. Remarks: The site lies within Snowdonia National Park.