Chwarel Cwm Hirnant
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Geology & landscape
Mining / Industrial: Quarry · Geological Period: Ordovician · Rock Type: Limestone
Landscape processes: Glacial
Description
Description Chwarel Cwm Hirnant is located approximately 7 km south-south-east of Bala. It is of special scientific interest as the type locality for the Hirnant Limestone and is an internationally important biostratigraphical site for its fossil brachiopod assemblage which has facilitated long-range correlation. The small disused quarry on the western slope of Cwm Hirnant is the type locality of the Ashgill Hirnant Limestone with its characteristic ‘Hirnantia Community’. This assemblage of brachiopods is of profound international significance in the correlation of highest Ordovician shelly sequences, being found as far afield as Burma, eastern Europe and North America. The area of Cwm Hirnant gives its name to the highest stage of the Ashgill, the Hirnantian, which encompasses the Foel-y-ddinas Mudstones and the Hirnant Limestone. The site provides a critical section in the Ashgill of great Britain with international significance. Remarks: The site lies within Snowdonia National Park.