Ffynnon Beuno and Cae Gwyn Caves

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Clwyd County BRYNIAU CLWYD A DYFFRYN DYFRDWY/CLWYDIAN RANGE AND DEE VALLEY Scenic Area

Geology & landscape

Geological Feature: Cave / Cavern · Geological Period: Carboniferous · Rock Type: Carboniferous Limestone, Glacial Till, Limestone

Landscape processes: Glacial, Karst

Description

Description This site is notified for its palaeontological interest and it's species interest, a winter roost of lesser horseshoe bat Rhinolophus hipposideros. The site is located on the east side of the Vale of Clwyd, 1⁄2 kilometre south of the village of Tremeirchion, 5 kilometres south east of St Asaph. It is at an altitude of 110-120 metres above mean sea level. The Vale of Clwyd contains towards its northern end numerous small caves in the outcrops of Carboniferous Limestone that occur along both sides of the valley. Such caves when left undisturbed have been shown to contain either important palaeontological deposits or to provide ideal conditions for the hibernation of bats or both. Ffynnon Beuno and Cae Gwyn Caves are the best site in Clwyd to encompass both of these interests. These are two important caves featuring deposits with potential for further research and excavation. Cae Gwyn Cave is a site of considerable historical interest in that it provided some of the earliest clear evidence of the association of human stone tools with the remains of extinct mammals. The vertebrate fauna which includes mammoth, woolly rhino and reindeer appears to date, at least in part, from immediately before the major glaciation of the area in the late Devensian, as one bone has a radiocarbon date of c. 18,000 years BP (Before Present). Of particular interest is the fact that when excavated the fossiliferous deposits were seen to be sealed by glacial till. Fynnon Beuno Cave has yielded a rich mammal fauna including mammoth, woolly rhino, spotted hyaena, lion and reindeer. As at Cae Gwyn, the fauna may immediately pre-date the major Devensian glaciation of the area. The site comprises two small caves which shelter a winter roost (hibernaculum) of lesser horseshoe bat Rhinolophus hipposideros. This is the third largest winter roost for this species in Clwyd, with annual counts exceeding 50 bats. Two other species of bat have also used these caves, Natterer's bat Myotis nattereri and brown long-eared bat Plecotus auritus.

Species mentioned