Chwarel Gelli-grin
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Geology & landscape
Rock Type: Limestone
Description
Description Chwareli Gelli-grin is of special scientific interest because this site is the type locality for the Gelli-grin Calcareous Ashes, and it also contains the type locality of the Cymerig Limestone, a unit which has facilitated regional biostratigraphical correlation. The site is situated approximately 2.5 km south-east of Bala and incorporates natural rock outcrops and a series of disused quarries located immediately south-west of Gelli-grin farm. This site lies within the type area of the Longvillian Gelli-grin Calcareous Ashes in the classical Bala area and contains the type locality of the Cymerig Limestone, an important marker horizon which is internationally famous for its brachiopod fauna. The limestone is of great historical interest, being Sedgwick’s ‘Bala Limestone’, mistakenly thought (by Elles) to represent three stratigraphical horizons. The brachiopod fauna, represented by 30 species, serves to illustrate the distinctive nature of the Bala Caradoc faunas when compared to those of the Welsh Borders. The Cymerig Limestone is the type locality for a large number of brachiopods. Remarks: The site lies within Snowdonia National Park.