Limestone pavements and cliffs

The limestone pavements which are such a feature of the Yorkshire Dales are mostly found towards the south-west of the area, in Ribblesdale, Chapel-le-Dale and Kingsdale. Langstrothdale (upper Wharfedale), Wharfedale and Littondale host a secondary concentration, however, with the Great Scar Limestone exposures forming a habitat which is increasingly rare and valuable in Britain. The pavements often preserve woodland species which grew in the area before the trees disappeared, and form a safe haven away from grazing sheep, although rabbits can be a problem. Ferns found here include wall rue, maidenhair spleenwort and brittle bladder-fern. Hart's-tongue and hard shield-fern are also to be found.

High up in Wharfedale the scars and screes support a range of plants including the nationally scarce alpine cinquefoil and hoary whitlowgrass. Also to be found are lesser meadow-rue, goldenrod, small scabious and bloody crane's-bill with, occasionally, mountain melick. These screes were for centuries the home of the rare Lady's-slipper orchid and are also important for the nationally scarce limestone fern.

At the Helks, above Beckermonds, partially-exposed pavement provides an interesting refuge for hay meadow species such as wood crane's-bill and melancholy thistle. The exposed pavements nearby have more typical species, including lesser meadow-rue, green spleenwort, wall lettuce and hairy stonecrop.

Lower down the valley, Conistone Old Pasture has five nationally important limestone pavements. Sheep grazing confines the flora to the grikes, the cracks between the raised clints. They are rich in species including alpine cinquefoil, lily-of-the-valley, mountain melick and herb Paris.

At nearby Grass Wood the screes have developed local gleying and species usually associated with waterlogged situations occur, including common valerian and wild angelica. The limestone outcrops have several locally uncommon species including rock whitebeam and angular Solomon's Seal.

The 4933.9 hectares (12191.7 acres) of the Malham-Arncliffe SSSI include extensive areas of limestone pavements which are a habitat for several species usually confined to woodlands, such as dog's mercury, wood anemone and ramsons. Rarer species to be found in the grikes include baneberry, angular Solomon's-seal and downy currant. Ferns are at home in the safe, moist grikes and include limestone fern and rigid buckler-fern.

Some good pavements are to be found in Littondale. At Scoska Wood there is limestone scar and scree along the middle of the wood and this supports ferns such as maidenhair spleenwort and hard shield-fern, as well as the local baneberry. The limestone scar at Hawkswick Wood hosts trees and shrubs such as yew, rock whitebeam and spindle, with herbs including blue sesleria, small scabious and ferns such as hart's tongue, hard shield, wall rue and green spleenwort.

The pavement at Dale Head, near Pen-y-ghent, has green spleenwort, lesser meadow-rue and alternate-leaved golden-saxifrage. Where grazing has been limited the number of species is higher, with reed canary-grass and stone bramble.

Pen-y-ghent Gill has pavements which house green spleenwort and brittle bladder fern, and many other shade-tolerant species in the grikes. The scattered ash and sycamore in the valley bottom has baneberry among the understorey species.

The inaccessible cliffs of the upper Gill are damp and the ledge flora includes a wealth of mosses and liverworts, with Orthothecium rufescens, Pedinophyllum interruptum, Seligeria acutifolia and the very rare Zygodon gracilis. Bryologically it is one of the best upland limestone gills in the north of England. The ledges also support woodrush, polypody and water avens.

The high ledges of Pen-y-ghent itself are noted for arctic-alpine plants. These include purple saxifrage, yellow saxifrage, hoary whitlowgrass and roseroot.