Few sites illustrate coastal erosion, loss and environmental change more than the headland of Dinas Island and the village of Cwm yr Eglwys. The headland has been delineated from the mainland through glacial processes creating a narrow u-shaped valley, some 70 metres deep. The cluster of cottages at the northern end of the valley makes up the hamlet of Cwm yr Eglwys.
Most notable landmark in valley is the ruined church dedicated to St. Brynach which sites on a platform some 3 metres above and immediately behind the beach. It is surrounded by a handful of weathered headstones.
The church was damaged by storm of 1850 and 1851 destroying the chancel and removing the surface of the cemetery exposing human remains. The final straw came in the Royal Charter Storm of 1859 which demolished the walls and roof leading to its abandonment. Erosion has been stabilised for now by the construction of modern concrete sea walls, but it uncertain how future climate change and sea-level rise might impact the cove.