Siambre Ddu
Geology & landscape
Geological Feature: Cave / Cavern · Geological Period: Carboniferous · Rock Type: Carboniferous Limestone, Limestone, Millstone Grit
Landscape processes: Glacial, Karst
Description
Description Siambre Ddu is situated 5 kilometres south west of Abergavenny, at the head of Cwm Llan Wenarth. The site is at the top of a steep north west facing slope 400 metres above sea level. The site is of special earth science interest as a subsidence doline and is also an important hibernation roost site for lesser horseshoe bat Rhinolophus hipposideros. This site is unique in Britain in that it is the only accessible cave formed at the junction of the Millstone Grit and the Carboniferous Limestone. The Carboniferous Limestone has been dissolved to form a cavity below this junction. The weight of the overlying strata is such that collapse is taking place into the chamber below and a ‘subsidence doline’ (sink-hole) will eventually be formed. Such features, which are characteristically circular steep-sided depressions, are common throughout South Wales, but this site is unusual in that the process of formation can be observed from below ground level as well as from the surface. This site is also the third largest hibernation site in Gwent for the internationally endangered lesser horseshoe bat. In recent years, over 60 bats have been recorded in early winter. Remarks: Within Brecon Beacons National Park. Lesser horseshoe bat is listed in Annex 11a of Council Directive 92/43/EEC on the Conservation of Natural Habitats and Wild Flora and Fauna and in Schedule 5 of the Wildlife and Countryside Act 1981 (as amended).
Species mentioned
Show the 1 species mentioned in the description, with red-list status| English name search for this in other sites |
Latin name search with Google |
IUCN / Red List | Type | Family |
|---|---|---|---|---|
| lesser horseshoe bat | Rhinolophus hipposideros | LC | bat | vespertillonidae |