Chwarel Cambrian / Cambrian Quarry, Gwernymynydd

Also within

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

Habitats

Mixed scrub, Montane scrub

Geology & landscape

Mining / Industrial: Quarry · Geological Period: Cambrian, Carboniferous · Rock Type: Chert, Limestone, Sandstone

Birds & fish recorded

Fish

Description

Description Chwarel Cambrian/Cambrian Quarry, Gwernymynydd is of special biological interest for its large population of hibernating lesser horseshoe bats Rhinolophus hipposideros, one of the largest in north east Wales. Lesser horseshoe bats are considered to be rare and endangered in Europe and the population here is considered to be one of the most important hibernation sites for this species in Wales. Chwarel Cambrian/Cambrian Quarry, Gwernymynydd is situated to the south and above the village of Gwernymynydd, 3 km south west of Mold. The site lies at an altitude of 235 to 320 m AOD and is underlain by Carboniferous rocks comprising sandy limestone and pebbly to fine-grained quartzose sandstone, which are in turn overlain by chert. Significant parts of the site have been affected by quarrying and mining for silica sand, chert and limestone and the mining of heavy metals such as lead, which have left a legacy of open ground, quarry faces and benches and spoil heaps. The lesser horseshoe bats use the now disused silica sand/chert mine workings in Chwarel Cambrian/Cambrian Quarry itself. There are several entrance points to the workings used by these bats. This usage is predominantly for hibernation purposes, although small numbers of lesser horseshoe bats are present throughout the year. Although there is only one silica sand/chert mine, it appears to be effectively divided in two by a roof fall. Both parts of the mine are used by lesser horseshoe bats, although the more northerly part supports the larger numbers. The complex of underground workings provides a range of conditions suitable for bat hibernation. As well as supporting the lesser horseshoe bat, the site also functions as an important hibernation site for other species of bat including brown long-eared bat Plecotus auritus, Natterer’s bat Myotis nattereri, Daubenton’s bat Myotis daubentonii and whiskered/Brandt’ s bat Myotis mystacinus/brandtii. The site also includes woodland habitat, mainly mixed broadleaved in character, contiguous with these mine workings predominantly to their north, west and east. The woodland to the west extends in an arc on a steep west facing slope to the south. The broadleaved woodland provides typical foraging habitat for bats and is used by them for navigational purposes, as they follow well-developed tree lines when moving between roost sites and feeding areas. This is an important factor to the survival of this small species, which forages in wooded areas and usually avoids flying in the open. The mixed broadleaved woodlands, some of which have developed over former mineral workings, are characterised by trees such as ash Fraxinus excelsior, sycamore Acer pseudoplatanus, birch Betula spp and willows Salix spp. in the canopy, with shrubs such as hawthorn Crataegus monogyna, holly Ilex aquifolium, hazel Corylus avellana and mountain ash Sorbus aucuparia in the understorey. Parts of the woodlands have been planted or replanted and now support beech Fagus sylvatica, pine Pinus sp. and larch Larix sp. plantations. The woodland ground is frequently characterised by lime-loving species including dog’s mercury Mercurialis perennis, sanicle Sanicula europaea and common twayblade Neottia ovata. The site includes the whole of the quarry area, which now supports a range of habitats including open ground, grassland, scrub and small water bodies. The more open areas within the quarry, such as spoil heaps and floors support a range of herbs, grasses, sedges and woody scrub species including yellow-wort Blackstonia perfoliata, common spotted-orchid Dactylorhiza fuchsii, oxeye daisy Leucanthemum vulgare, fairy flax Linum catharticum, glaucous sedge Carex flacca and tufted hair-grass Deschampsia cespitosa. Other agricultural land overlying the underground mine passages is included to ensure the full extent of the underground silica sand/chert mine pillar and stall workings fall within the site. Other bats recorded foraging across the site include noctule Nyctalus noctula, common pipistrelle Pipistrellus pipistrellus and soprano pipistrelle Pipistrellus pygmaeus. The site also supports a population of great crested newt Triturus cristatus and other widespread amphibians including common toad Bufo bufo, smooth newt Lissotriton vulgaris and palmate newt Lissotriton helveticus. It also supports populations of the local grayling Hipparchia semele and dingy skipper Erynnis tages butterflies. Several other butterfly species have been recorded, including ringlet Aphantopus hyperantus. Remarks: The site lies mainly within the Clwydian Range Area of Outstanding Natural Beauty (AONB). All bat species and the great crested newt are listed on Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) and Annex II and IV (a) of the European Communities’ Habitats and Species Directive (92/43/EEC). The lesser horseshoe bat, the brown long-eared bat, the great crested newt, the common toad, the grayling and dingy skipper butterflies are listed as Welsh species of principal importance for the conservation of biological diversity under Section 42 of the Natural Environment and Rural Communities Act 2006. The lesser horseshoe bat is specifically listed in the Local Flintshire and Denbighshire Biodiversity Action Plans.

Species mentioned

Plant communities