l] INTRODUCTION 9 



Many of the plateaux marked on the geological maps as 

 consisting of limestone are capped by a layer of non-calcareous 

 chert (cf. Sibley, 1908); and such plateaux yield soils which 

 are essentially identical with those over the sandstones and 

 shales. Sometimes the soil contains a mixture of stones of the 

 limestone and of the non-calcareous chert ; and then lime-loving 

 plants occur. This agrees with the observations of Stebler 

 (1906) in Switzerland. 



Contemporaneous igneous rocks (cf. Arnold-Bemrose, 1907) 

 occur in the limestone area. Although of comparatively 

 limited extent, they are interesting locally. For example, a 

 small patch of bilberry (Vaccinium Myrtillus) and of other 

 lime-avoiding plants occurs on an outcrop of volcanic "toad- 

 stone" or basalt near Miller's Dale railway station, and is 

 surrounded by lime-loving plants, e.g., the salad burnet (Pote- 

 rium Sanguisorba) growing on the limestone soil. 



Of soils composed of recent deposits, there are the glacial 

 sands, the river alluvia, and the upland peat. 



The glacial drift of this district is confined to its western 

 boundary. Boulder clay scarcely occurs; but non-calcareous, 

 fluvio-glacial sands form rather extensive deposits, chiefly near 

 the confluence of the rivers Etherow and Goyt. These deep 

 and non-calcareous sands bring about a noteworthy change in 

 the vegetation, as, in this district, woods of the pedunculate oak 

 (Quercus Robur = Q. pedunculata) occur on this soil alone. The 

 sands do not appear to occur much higher than about 600 feet 

 (183 m.). To the west of the Peak District, on the plain of 

 Lancashire and Cheshire, extensive glacial deposits are found, 

 which consist largely of boulder clay, gravel, and sand. These 

 deposits occur intermittently up to the crests of the hills which 

 face the western plain, and also up the river valleys. For 

 example, glacial boulders are to be found on the summit of 

 Spond's Hill, at 1350 feet (411 m.) ; and they also occur in the 

 valley of the Goyt, on the watershed, and in the valleys of the 

 Wye and the Dove (cf. Dale, 1900, etc.). The boulders, however, 

 are local in their occurrence, and bring about no appreciable 

 change in the vegetation. Except on its western fringe, as on 

 Tintwistle Moor, near Glossop, the general moorland plateau 

 of the Pennines south of the Aire and Calder watershed is not 

 glaciated. No perched blocks occur, no striae, and no roches 



