Creigiau Abergwaun (Fishguard Cliffs)

Site of Special Scientific Interest · 51.9993, -4.9736

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Also within

Dyfed County Arfordir Penfro / Pembrokeshire Coast National Park

Geology & landscape

Geological Period: Ordovician · Rock Type: Shale

Landscape processes: Volcanic / Igneous

Description

Description The cliffs at Abergwaun offer the best opportunity to examine the Ordovician Fishguard Volcanic ‘Series’ (Llanvirn Series) in association with dateable sedimentary rocks. Interbedded with the volcanic tuffs, ashes and rarer lavas, including the pillow lavas of Lampit Cliffs, are several shale horizons yielding the Llanvirn zonal index Didymograptus bifidus. This occurrence places a definite Upper Llanvirn age on the very substantial volcanic outpourings which affected ‘Pembrokeshire’ in Lower Ordovician times.