Ebbor Gorge

Also within

Somerset County Mendip Hills Scenic Area

Condition (Natural England)

Habitats

Ancient woodland, Coppiced woodland, Fast flowing river and stream

Geology & landscape

Geological Feature: Cave / Cavern, Gorge / Ravine · Geological Period: Carboniferous · Rock Type: Carboniferous Limestone, Limestone, Millstone Grit

Landscape processes: Fluvial, Karst

Description

Description Ebbor Gorge lies on the south west facing slope of the Mendip Hills and consists of a steep sided ravine cut into Carboniferous Limestone. A stream issuing to the west of the site runs down the tributary valley of Hope Wood before joining the main gorge. Millstone Grit and Lower Coal Measures form an impermeable floor to this valley. The soils are well drained, fine and silty from the Nordoch series or loamy of the Crwbin series. They are of very variable depth with frequent exposures of rock on brows and steep valley sides. The majority of the site consists of calcareous ash woodland with a varied age and canopy structure, currently maintained by rotational coppicing and selective felling. The canopy is dominated by ash Fraxinus excelsior with oak Quercus robur varying in density from co-dominant in Hope Wood to virtual absence from central areas of the Gorge. Local stands of beech Fagus sylvatica, field maple Acer campestre, whitebeam Sorbus sp and hornbeam Carpinus betulus occur throughout the site. hazel Corylus avellana dominates the under storey and has been coppiced over a wide area. A variety of associated species include dogwood Cornus sanguinea, spindle Euonymus europaeus, wayfaring tree Viburnum lantana and guelder rose Viburnum opulus and wild privet Ligustrum vulgare. The ground flora is indicative of the calcareous nature of the site, with dog's mercury Mercurialis perennis being locally dominant. Many of the associated species are characteristic of ancient woodland. wood anemone Anemone nemorosa and bluebell Hyacinthoides non-scripta are both locally abundant. sanicle Sanicula europaea, primrose Primula vulgaris, pignut Conopodium majus, wood sedge Carex sylvatica, moschatel Adoxa moschatellina and opposite leaved golden saxifrage Chrysosplenium oppositifolium are also present. The valley of the main gorge is humid and provides ideal conditions for fungi and ferns. It contains a substantial assemblage of bryophytes with over 120 species recorded including the nationally rare Bryum canariense and very rare Amblystegium confervoides. In addition, rich communities of lichens occur on limestone outcrops and as epiphytes on older trees giving the Gorge in excess of 150 lichen species. Extensive areas of unimproved, rabbit grazed grassland occur at the top of the Gorge supporting a typical calcareous flora of common rose Helianthemum nummularium, fairy flax Linum catharticum, marjoram Origanum vulgare, wild thyme Thymus polytrichus, large thyme T. pulegoides, common milkwort Polygala vulgaris, salad burnet Poterium sanguisorba, carline thistle Carlina vulgaris and quaking grass Briza media. Leaching on the upper slopes gives rise to more acid tolerant flora such as European gorse Ulex europaeus and bell heather Erica cinerea. The varied age and canopy structure of woodland encourages a high diversity of butterflies, nationally scarce species including the white-letter hairstreak Satyrium w-album and high brown fritillary Argynnis adippe, while species such as the chalkhill blue Polyommatus coridon and brown argus Aricia agestis occur on the limestone grassland. Greater horseshoe bats Rhinolophus ferrumequinum and lesser horseshoes Rhinolophus hipposideros regularly use sites in the Gorge as hibernacular roosts. Several caves occur within the Gorge, of which Bridged Pot provides one of the best presumed Late Devensian small mammal assemblages known from Britain. Most of the deposit remains in situ. The fauna includes steppe pika, arctic lemming, Norway lemming, various voles, red deer and reindeer. The small cave/rock shelter at Savoy's Hole contains largely undisturbed deposits likely to yield a similar assemblage of Devensian age.

Species mentioned

Plant communities