1] 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, ¢.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 
