YORKSHIRE PLANT ECOLOGY 23 



Cauldron Snout and passes over an irregular series of basaltic cliffs, 

 bordered by a ridge of Scar Limestone. These cliffs provide a contrast 

 and variety both in scenery and vegetation, and the limestone, at the 

 point of contact with the intrusive rock, has been changed into a coarsely 

 granular ' sugar ' limestone, on which many of the rare plants are found. 

 On the basalt is an extensive development of Juniper. 



Proceeding southwards, extensive moorlands are developed on the 

 non-calcareous Yoredale grits and shales. Sphagnum bogs cover a large 

 area and Sphagnum, is the chief peat-former ; at the base of the peat are 

 remains of trees, especially birch. Across Stainmore is a broad pass 

 between the Vales of Eden and Tees and the Vale of York, covered with 

 boulder clay. 



The north-western calcareous dales again offer a striking contrast, 

 and include the sources of the Swale, Ure, Nidd, Wharfe and Aire. 

 This is a deeply dissected area with only peaks of limited extent rising 

 above 2,000 ft., e.g. Whernside, Ingleborough and Penyghent. This 

 district almost rivals Teesdale in the interest of its flora, occurring chiefly 

 on the great limestone scars and pavements, as at Kettlewell, Arncliffe, 

 Malham, Gordale, Settle and Ingleborough. The higher ground, 

 capped with Millstone Grit, is covered with cottongrass moss, ling and 

 grass-heath predominating on the higher slopes and extending some 

 distance over the leached limestones below. A striking feature in the 

 landscape is the white limestone walls dividing pastures which provide 

 excellent grazing for sheep. 



The scar woods of the Mountain Limestone bear a rich flora ; ash is 

 the dominant tree, oak is rare in the dales except on the alluvial plains of 

 the rivers. There is much hazel as an undershrub, also Prunus spinosa, 

 P. padus, Holly, Cornus sanguinea, Viburnum Lantana, and Rubus saxatilis. 

 The more interesting plants of the ground flora are Aquilegia vulgaris, 

 Actcea spicata, Viola odorata, Spircea Filipendula, Geranium sylvaticum, 

 Saxifraga umbrosa, Galium boreale, Polemonium cosruleum, Melampyrum 

 sylvaticum, Lathrcea squamaria. Orchis apifera, Convallaria majalis and 

 Melica uniflora. In the scar woods of Upper Wharfedale occurs the 

 rare lady's slipper (Cypripedium Calceolus). In the neighbourhood of 

 Settle, Malham, and Gordale occur Actcea spicata, Potentilla alpestris, 

 Saxifraga stellaris, Ribes petrceum, Galium boreale, Hieracium crocatum, 

 Bartsia alpina. Primula farinosa, Polygonum viviparum, Aspidium Lonchitis 

 and Nephrodium rigidum. On Ingleborough occur Saxifraga oppositifolia, 

 S. aizoides, Sedum villosum, Epilohium alsinifolium, Salix herbacea, Carex 

 rigida, Poa alpina and P. rigida. 



A small area in the neighbourhood of Sedbergh is on the Silurian 

 slates, and on Howgill Fells and Cautley Crags occur Alchemilla alpina, 

 Saxifraga stellaris, Circcea alpina, Epilobium alsinifolium, Meum Athaman- 

 ticum, Pyrola secunda, Hymenophyllum unilaterale and Lycopodiutn alpinum. 



While the moors above 1,250 ft. are generally dominated by cotton- 

 grass, which forms peat five feet or more in depth, the moors west of the 

 Swale, from Masham Moor to Pately Moor, and further south, Burnsall 

 Moor, Blubberhouse Moor and Rombalds Moor have a shallower peat 

 and are dominated by Calluna, cottongrass being subordinate. It is 



