Mwyngloddiau a Chreigiau Gwydyr

Site of Special Scientific Interest · 53.1168, -3.8273

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Clwyd County Eryri / Snowdonia National Park

Habitats

Calaminarian grassland, High montane heath and snow bed

Geology & landscape

Mining / Industrial: Calaminarian, Mine Spoil · Geological Period: Ordovician

Landscape processes: Volcanic / Igneous

Description

Description This site consists of a large number of isolated areas of disused mine workings and spoil heaps within the Gwydyr Forest near to Betws-y-Coed. The different sections of the site are located at around 200 to 300 m and many are closely surrounded by coniferous plantations. The different parts of the site are of special interest for their geological features, plant assemblages and their use by bat colonies as hibernation sites. The site includes two important geological conservation review sites, namely the outstanding exposures of Ordovician igneous rocks at Sarnau and the internationally important mineral deposits at Cae Coch Mine. Sarnau (Ordovician Igneous): Sarnau provides the best available exposures through the Ordovician Middle and Upper Crafnant Volcanic formations, which consist of the eruptive products from the youngest of three major volcanic centres which were active during the 2nd Eruptive Cycle in northern Snowdonia during Caradoc times. In contrast to the other major volcanic centres in Snowdonia, the Crafnant Centre is completely buried by younger rocks and its eruptive history and palaeoenvironmental setting can only be inferred from its outflow products. The outcrops at Sarnau are comparable in age to the Longvillian Snowdon Volcanic Group but differ from that group in facies association. The Middle Crafnant Volcanic Formation is characterized by an ordered sequence of acidic ash-flow tuffs integrated with flaggy, evenly bedded, remobilized tuffaceous to volcaniclastic sedimentary rocks which were derived from a volcanic centre tentatively located farther to the north and east. The Upper Crafnant Volcanic Formation comprises a massive heterogeneous unit of unsorted tuffaceous sedimentary rocks which is separated from the underlying Middle Crafnant Volcanic Formation by blue-black cleaved mudstones. The emplacement of these volcanogenic deposits into dark marine mudstones and siltstones suggests either deposition from high-density turbid flows or a deep-water submarine eruption through unlithified muds. Sarnau is a key site for studies of volcanic and volcaniclastic lithologies, sedimentary structures and eruptive and depositional environments. Cae Coch Mine (Mineralogy of Wales): The massive stratabound pyrite deposit at Cae Coch Mine is of national metallogenic interest but is also of international importance for the microbial ecosystem developed within the underground workings. The origin of the Cae Coch stratiform pyrite deposit is controversial, the most recent models invoking either contemporary volcanic exhaltative mineralization or a syndiagenetic inhalative replacement process involving the large-scale bacterial reduction of sulphate to sulphide in the presence of an iron-rich flux leached from underlying volcanic rocks. Extensive post-mining oxidation of the pyrite has produced copious quantities of iron sulphate minerals dominated by fibroferrite, and accompanied by melanterite and copiapite. The oxidation is largely bacteriogenic with acidophile autotrophic and heterotrophic bacteria forming in excess of 100m3 of gelatinous streamer-growths which result in acidic, iron-rich mine drainage. Biological Interest: The areas included are of special interest for the distinctive plant assemblages which occur on rocks and spoil which are contaminated by heavy metals and also for the bats which roost in the mine systems during the winter. The habitat formed on the mine spoil is considered to be a form of ‘Calaminarian Grassland’ habitat found on such sites in different parts of Europe. Various specialist metallophytic species are associated with abandoned heavy-metal mines such as those found in the Gwydyr Forest. As well as particular species (especially lichens and bryophytes), these include specially adapted variants of more widespread taxa. Extensive mining in the Gwydyr area took place in the 19th and 20th centuries, although there is evidence of mining before this time. Commercial mining took place from the late 1800s through to the middle of the Twentieth Century, when the majority of the ores had been removed and mining had become unviable. The principal ore mined in the Gwydyr region was sphalerite (zinc sulphide), although some galena (lead sulphide) was also removed. The methods of extraction employed at the mines have left the legacy of large amounts of waste spoil throughout the area. This spoil now forms an important habitat within the forest. Afforestation with conifers first took place at Gwydyr in 1921 around the time that many of the mines were closing, but much of the contaminated spoil remains free from tree cover allowing colonisation by specialist species. In particular, the lower plants (lichens and bryophytes) are of interest at the sites. Notable species present include the nationally rare moss Ditrichum plumbicola, and a nationally scarce liverwort Cephaloziella stellulifera. Nationally scarce ferns at the sites include, forked spleenwort Asplenium septentrionale, and lanceolate spleenwort Asplenium obovatum. Gyalidea subscutellaris, Vezdaea acicularis, V. rheocarpa, and Coppinsia minutissima are all nationally scarce lichens found at these mine sites. Flowering plants found at some sites include the nationally scarce alpine penny-cress Noccaea caerulescens, and the locally uncommon sea campion Silene uniflora. The abandoned mines are of importance for several species of bat as roosting sites, particularly when hibernating. Several of the mine systems in the forest support colonies of lesser horseshoe bat Rhinolophus hipposideros, which are considered to be rare in Europe. Other bat species which are found in the mine systems are Daubenton’s bat Myotis daubentonii, whiskered bat Myotis mystacinus, brown long-eared bat Plecotus auritus, pipistrelle bats Pipistrellus sp., and Natterer’s bat M. nattereri. Remarks: These sites support vegetation assignable to Calaminarian Grassland. This habitat type is listed on Annex I of the EC Habitats Directive (Directive 92/43/EEC on the Conservation of Natural Habitats and Wild Flora & Fauna). The lesser horseshoe bat is listed on Annex IIa of the Habitats Directive. Parts of this site form the Mwyngloddiau a Safleoedd Ystlumod Gwydyr / Gwydyr Mines and Bats Sites candidate Special Area of Conservation. Mwyngloddiau a Chreigiau Gwydyr SSSI is located within the Snowdonia National Park. Lesser horseshoe bat and pipistrelle bats are UK Biodiversity Action Plan species. D. plumbicola, lesser horseshoe bat, Natterer’s bat and pipistrelle bats are Snowdonia Local Biodiversity Action Plan species. Mines and mine wastes is a Snowdonia Local Biodiversity Action Plan Habitat.

Species mentioned

English name
search for this in other sites		 Latin name
search with Google		 IUCN / Red List Type Family
Daubenton's bat Myotis daubentonii LC bat vespertillonidae
whiskered bat Myotis mystacinus DD bat vespertillonidae
brown long-eared bat Plecotus auritus LC bat vespertillonidae
lesser horseshoe bat Rhinolophus hipposideros LC bat vespertillonidae
lanceolate spleenwort Asplenium obovatum LC herb aspleniaceae
forked spleenwort Asplenium septentrionale NT herb aspleniaceae
alpine pennycress Noccaea caerulescens VU herb brassicaceae
sea campion Silene uniflora LC herb carophyllaceae
Coppinsia minutissima LC lichen trapeliaceae
lichen Vezdaea acicularis LC lichen vezdaeaceae
red heath threadwort Cephaloziella stellulifera NT liverwort jungermanniales

Plant communities

CG12 — Alpine and subalpine calcareous grassland, High montane heath and snow bed

Festuca ovina-Alchemilla alpina-Silene acaulis dwarf-herb community

Empetrum nigrum, Calluna vulgaris, Kalmia procumbens, Vaccinium myrtillus, Salix herbacea, Carex bigelowii, Carex demissa, Carex panicea, Carex pilulifera, Carex pulicaris, Juncus trifidus, Juncus triglumis, Luzula campestris, Luzula multiflora, Luzula spicata, Luzula sylvatica, Diphasiastrum alpinum, Huperzia selago, Selaginella selaginoides, Andreaea alpina, Aulacomnium turgidum, Bartramia ithyphylla, Breutelia chrysocoma, Mnium hornum, Dicranum scoparium, Ditrichum flexicaule, Racomitrium canescens sens.lat., Racomitrium fasciculare, Racomitrium lanuginosum, Ctenidium molluscum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Hypnum hamulosum, Lescuraea incurvata, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Thuidium delicatulum, Thuidium tamariscinum, Pogonatum urnigerum, Polytrichastrum alpinum, Tortella tortuosa, Barbilophozia hatcheri, Barbilophozia lycopodioides, Diplophyllum albicans, Frullania tamarisci, Nardia scalaris, Plagiochila asplenioides, Ptilidium ciliare, Scapania subalpina, Tritomaria quinquedentata, Cetraria islandica, Cladonia arbuscula, Cladonia gracilis, Cladonia pyxidata, Cladonia uncialis, Peltigera canina, Achillea millefolium, Antennaria dioica, Gnaphalium supinum, Hieraclium spp., Scorzoneroides autumnalis, Solidago virgaurea, Taraxacum officianalis, Myosotis alpestris, Cardamine pratensis, Draba norvegica, Campanula rotundifolia, Succisa pratensis, Cerastium alpinum, Cerastium fontanum, Minuartia sedoides, Sagina saginoides, Silene acaulis, Sedum rosea, Vaccinium vitis-idaea, Thymus praecox, Linum catharticum, Epilobium anagallidifolium, Euphrasia frigida, Euphrasia officinalis, Oxalis acetosella, Plantago maritima, Veronica alpina, Veronica officinalis, Veronica serpyllifolia, Armeria maritima, Polygonum viviparum, Rumex acetosa, Anemone nemorosa, Ranunculus acris, Thalictrum alpinum, Trollius europaeus, Alchemilla alpina, Alchemilla filicaulis, Filipendula ulmaria, Geum rivale, Potentilla crantzii, Potentilla erecta, Sibbaldia procumbens, Galium boreale, Galium saxatile, Saxifraga aizoides, Saxifraga hypnoides, Saxifraga nivalis, Saxifraga oppositifolia, Saxifraga stellaris, Viola lutea, Viola palustris, Viola riviniana, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Festuca vivipara, Nardus stricta, Poa pratensis, Botrychium lunaria

OV37 — Calaminarian grassland

Festuca ovina-Minuartia verna community

Calluna vulgaris, Carex caryophyllea, Carex flacca, Bryum pallens, Pohlia nutans, Dicranum scoparium, Rhytidiadelphus squarrosus, Weissia controversa, Cladonia arbuscula, Cladonia chlorophaea, Cladonia furcata, Cladonia gracilis, Cladonia portentosa, Cladonia pyxidata, Cladonia rangiformis, Coelocaulon aculeatum, Parmelia saxatilis, Achillea millefolium, Cirsium vulgare, Jacobaea vulgaris, Pilosella officinarum, Noccaea caerulescens, Campanula rotundifolia, Cerastium fontanum, Minuartia verna, Anthyllis vulneraria, Lotus corniculatus, Trifolium repens, Geranium robertianum, Thymus praecox, Linum catharticum, Euphrasia officinalis, Plantago lanceolata, Rumex acetosa, Galium saxatile, Galium sterneri, Viola lutea, Agrostis capillaris, Agrostis stolonifera, Anthoxanthum odoratum, Arrhenatherum elatius, Avenula pratensis, Dactylis glomerata, Festuca ovina, Festuca rubra, Koeleria macrantha

U7 — High montane heath and snow bed

Nardus stricta-Carex bigelowii grass-heath

Empetrum nigrum, Calluna vulgaris, Vaccinium myrtillus, Vaccinium uliginosum, Salix herbacea, Carex bigelowii, Carex nigra, Carex panicea, Carex pilulifera, Eriophorum vaginatum, Trichophorum cespitosum, Juncus squarrosus, Juncus trifidus, Luzula multiflora, Luzula sylvatica, Diphasiastrum alpinum, Huperzia selago, Campylopus flexuosus, Dicranum fuscescens, Dicranum scoparium, Kiaeria starkei, Racomitrium lanuginosum, Hylocomium splendens, Hypnum cupressiforme, Plagiothecium undulatum, Pleurozium schreberi, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Polytrichastrum alpinum, Polytrichum commune, Polytrichum juniperinum, Polytrichum piliferum, Polytrichum strictum, Sphagnum capillifolium, Anastrepta orcadensis, Anastrophyllum donianum, Barbilophozia floerkei, Barbilophozia hatcheri, Bazzania tricrenata, Diplophyllum albicans, Lophozia sudetica, Pleurozia purpurea, Ptilidium ciliare, Scapania gracilis, Scapania nemorea, Cetraria delisei, Cetraria islandica, Cladonia arbuscula, Cladonia bellidiflora, Cladonia coccifera, Cladonia gracilis, Cladonia impexa, Cladonia leucophaea, Cladonia pyxidata, Cladonia rangiferina, Cladonia tenuis, Cladonia uncialis, Gnaphalium supinum, Solidago virgaurea, Cornus suecica, Vaccinium vitis-idaea, Thymus praecox, Narthecium ossifragum, Rumex acetosa, Alchemilla alpina, Potentilla erecta, Galium saxatile, Viola palustris, Agrostis capillaris, Agrostis vinealis, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Nardus stricta

U8 — High montane heath and snow bed

Carex bigelowii-Polytrichum alpinum sedge-heath

Vaccinium myrtillus, Salix herbacea, Carex bigelowii, Juncus trifidus, Luzula spicata, Huperzia selago, Pohlia nutans, Dicranum fuscescens, Dicranum scoparium, Racomitrium canescens sens.lat., Racomitrium fasciculare, Racomitrium lanuginosum, Hylocomium splendens, Pleurozium schreberi, Sanionia uncinata, Polytrichastrum alpinum, Sphagnum compactum, Ptilidium ciliare, Cetraria delisei, Cetraria islandica, Cladonia arbuscula, Cladonia bellidiflora, Cladonia coccifera, Cladonia floerkeana, Cladonia gracilis, Cladonia macrophylla, Cladonia pyxidata, Cladonia rangiferina, Cladonia squamosa, Cladonia uncialis, Cornicularia aculeata, Ochrolechia frigida, Galium saxatile, Saxifraga stellaris, Agrostis capillaris, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Nardus stricta

U9 — High montane heath and snow bed

Juncus trifidus-Racomitrium lanuginosum rush-heath

Empetrum nigrum, Kalmia procumbens, Vaccinium myrtillus, Vaccinium uliginosum, Salix herbacea, Carex bigelowii, Carex pilulifera, Juncus trifidus, Luzula spicata, Diphasiastrum alpinum, Huperzia selago, Dicranum fuscescens, Racomitrium lanuginosum, Pleurozium schreberi, Polytrichastrum alpinum, Polytrichum piliferum, Barbilophozia floerkei, Diplophyllum albicans, Ptilidium ciliare, Cetraria delisei, Cetraria islandica, Cetraria nivalis, Cladonia arbuscula, Cladonia bellidiflora, Cladonia coccifera, Cladonia crispata, Cladonia gracilis, Cladonia pyxidata, Cladonia rangiferina, Cladonia uncialis, Cornicularia aculeata, Ochrolechia frigida, Sphaerophorus globosus, Stereocaulon vesuvianum, Thamnolia vermicularis, Silene acaulis, Vaccinium vitis-idaea, Armeria maritima, Polygonum viviparum, Alchemilla alpina, Galium saxatile, Agrostis capillaris, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Nardus stricta, Nitella flexilis

U10 — High montane heath and snow bed, Lowland dry acid grassland, Upland dry heath

Carex bigelowii-Racomitrium lanuginosum moss-heath

Empetrum nigrum, Kalmia procumbens, Vaccinium myrtillus, Salix herbacea, Carex bigelowii, Carex panicea, Carex pilulifera, Juncus squarrosus, Juncus trifidus, Luzula spicata, Diphasiastrum alpinum, Huperzia selago, Selaginella selaginoides, Andreaea alpina, Aulacomnium turgidum, Pohlia nutans, Campylopus flexuosus, Dicranum fuscescens, Dicranum scoparium, Kiaeria starkei, Racomitrium fasciculare, Racomitrium heterostichum, Racomitrium lanuginosum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Hypnum hamulosum, Pleurozium schreberi, Rhytidiadelphus loreus, Sanionia uncinata, Polytrichastrum alpinum, Polytrichum juniperinum, Polytrichum longisetum, Polytrichum piliferum, Polytrichum strictum, Anastrepta orcadensis, Diplophyllum albicans, Nardia scalaris, Ptilidium ciliare, Alectoria nigricans, Cetraria islandica, Cladonia arbuscula, Cladonia cervicornis, Cladonia coccifera, Cladonia crispata, Cladonia furcata, Cladonia gracilis, Cladonia impexa, Cladonia pyxidata, Cladonia rangiferina, Cladonia squamosa, Cladonia uncialis, Cornicularia aculeata, Ochrolechia frigida, Peltigera canina, Sphaerophorus globosus, Thamnolia vermicularis, Achillea millefolium, Antennaria dioica, Gnaphalium supinum, Solidago virgaurea, Campanula rotundifolia, Succisa pratensis, Minuartia sedoides, Silene acaulis, Vaccinium vitis-idaea, Thymus praecox, Armeria maritima, Polygonum viviparum, Rumex acetosa, Alchemilla alpina, Potentilla erecta, Sibbaldia procumbens, Galium saxatile, Viola palustris, Viola riviniana, Agrostis capillaris, Agrostis vinealis, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Nardus stricta

U11 — High montane heath and snow bed, Lowland dry acid grassland, Upland dry heath

Polytrichum sexangulare-Kiaeria starkei snow-bed

Empetrum nigrum, Salix herbacea, Carex bigelowii, Juncus trifidus, Huperzia selago, Conostomum tetragonum, Pohlia drummondii, Pohlia ludwigii, Pohlia nutans, Dicranum fuscescens, Kiaeria falcata, Kiaeria starkei, Racomitrium canescens sens.lat., Racomitrium fasciculare, Racomitrium heterostichum, Racomitrium lanuginosum, Pleurozium schreberi, Rhytidiadelphus loreus, Oligotrichum hercynicum, Polytrichastrum alpinum, Polytrichastrum sexangulare, Anthelia juratzkana, Barbilophozia floerkei, Lophozia sudetica, Marsupella emarginata, Moerckia blyttii, Nardia scalaris, Pleurocladula albescens, Cetraria islandica, Cladonia bellidiflora, Cladonia pyxidata, Cladonia uncialis, Solorina crocea, Gnaphalium supinum, Cerastium cerastoides, Silene acaulis, Alchemilla alpina, Sibbaldia procumbens, Galium saxatile, Saxifraga stellaris, Viola palustris, Agrostis capillaris, Deschampsia cespitosa, Deschampsia flexuosa, Festuca vivipara, Nardus stricta, Cryptogramma crispa, Blechnum spicant, Athyrium distentifolium

U12 — High montane heath and snow bed, Upland dry heath

Salix herbacea-Racomitrium heterostichum snow-bed

Salix herbacea, Carex bigelowii, Juncus trifidus, Luzula spicata, Huperzia selago, Andreaea rupestris, Conostomum tetragonum, Pohlia nutans, Dicranum scoparium, Kiaeria starkei, Racomitrium fasciculare, Racomitrium heterostichum, Racomitrium lanuginosum, Oligotrichum hercynicum, Polytrichastrum alpinum, Polytrichastrum sexangulare, Polytrichum piliferum, Barbilophozia floerkei, Diplophyllum albicans, Gymnomitrion concinnatum, Gymnomitrion corallioides, Lophozia sudetica, Marsupella brevissima, Nardia scalaris, Cetraria delisei, Cetraria islandica, Cladonia bellidiflora, Cladonia coccifera, Cladonia gracilis, Cladonia pyxidata, Cladonia uncialis, Cornicularia aculeata, Ochrolechia frigida, Gnaphalium supinum, Silene acaulis, Alchemilla alpina, Galium saxatile, Agrostis canina, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Nardus stricta

U13 — High montane heath and snow bed, Upland dry heath

Deschampsia cespitosa-Galium saxatile grassland

Vaccinium myrtillus, Salix herbacea, Carex bigelowii, Carex pilulifera, Luzula multiflora, Luzula sylvatica, Diphasiastrum alpinum, Huperzia selago, Selaginella selaginoides, Pohlia nutans, Kiaeria starkei, Racomitrium lanuginosum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Plagiothecium undulatum, Pleurozium schreberi, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Polytrichastrum alpinum, Polytrichum commune, Sphagnum capillifolium, Sphagnum russowii, Anastrepta orcadensis, Barbilophozia floerkei, Barbilophozia lycopodioides, Nardia scalaris, Ptilidium ciliare, Cetraria islandica, Cladonia gracilis, Peltigera canina, Achillea millefolium, Gnaphalium supinum, Saussurea alpina, Campanula rotundifolia, Cerastium alpinum, Cerastium fontanum, Minuartia sedoides, Silene acaulis, Vaccinium vitis-idaea, Thymus praecox, Euphrasia frigida, Oxalis acetosella, Armeria maritima, Polygonum viviparum, Rumex acetosa, Ranunculus acris, Alchemilla alpina, Alchemilla filicaulis, Alchemilla glabra, Potentilla erecta, Sibbaldia procumbens, Galium saxatile, Saxifraga hypnoides, Saxifraga stellaris, Viola palustris, Viola riviniana, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Nardus stricta, Blechnum spicant, Dryopteris dilatata

U14 — High montane heath and snow bed, Upland dry heath

Alchemilla alpina-Sibbaldia procumbens dwarf-herb community

Vaccinium myrtillus, Salix herbacea, Carex bigelowii, Carex pilulifera, Juncus trifidus, Luzula multiflora, Luzula spicata, Diphasiastrum alpinum, Huperzia selago, Selaginella selaginoides, Andreaea alpina, Pohlia nutans, Dicranum scoparium, Racomitrium aquaticum, Racomitrium canescens sens.lat., Racomitrium fasciculare, Racomitrium heterostichum, Racomitrium lanuginosum, Ctenidium molluscum, Hylocomium splendens, Hypnum callichroum, Pleurozium schreberi, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Oligotrichum hercynicum, Pogonatum urnigerum, Polytrichastrum alpinum, Polytrichum piliferum, Barbilophozia floerkei, Diplophyllum albicans, Lophozia sudetica, Nardia scalaris, Ptilidium ciliare, Cetraria islandica, Cladonia arbuscula, Cladonia bellidiflora, Cladonia pyxidata, Achillea millefolium, Gnaphalium supinum, Scorzoneroides autumnalis, Campanula rotundifolia, Cerastium alpinum, Cerastium fontanum, Minuartia sedoides, Sagina saginoides, Silene acaulis, Thymus praecox, Euphrasia officinalis, Armeria maritima, Polygonum viviparum, Rumex acetosa, Ranunculus acris, Thalictrum alpinum, Trollius europaeus, Alchemilla alpina, Alchemilla filicaulis, Alchemilla glabra, Potentilla erecta, Sibbaldia procumbens, Galium saxatile, Saxifraga hypnoides, Saxifraga oppositifolia, Saxifraga stellaris, Viola palustris, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Nardus stricta, Blechnum spicant, Botrychium lunaria