1] INTRODUCTION 13 
Geological Strata Vegetation 
II. Pendleside Non-calcareous, ferru- Birch (Betula pubes- 
one rocks :— | ginous sands, gravels, and | cens) woods and scrub, 
A. Sandstones | shales, which at the sur- | oak (Quercus sessili- 
B. Shales face degenerate intoakind | fora) woods and 
III. Millstone Grit | of false clay, or which may | scrub, siliceous grass- 
rocks :— be mixed with much acidic | land, siliceous grass- 
A. Sandstones | humus: the colour varies | land with much hea- 
B. Shales from yellowish brown to | ther 
IV. Coal-measure | black according to the 
rocks :— amount of humus present 
A. Sandstones 
B. Shales 
V. Recent soils :— 
a. Glacial sands (a) Yellowish non-cal- (a) Oak (Quercus 
careous sands, often mixed } Robur) woods, scrub, 
with acidic humus siliceous grassland 
b. River gravels (61) Yellowish, non- (bi) Stream-side 
calcareous, sandy gravels | scrub and_ siliceous 
grassland 
(bii) Calcareous gra- (bii) Stream-side 
vels and tufa scrub and calcareous 
grassland 
c. Upland peat (c) Brown or black (c) Heather moors, 
' peat, of a depth of 15 feet | cotton-grass moors, 
(457 cm.) or more, and | bilberry moors, re- 
usually very wet _ trogressive moors 
SoILS AND THEIR CHARACTERISTIC PLANTS 
It will be seen that the soils of the southern Pennines fall 
into three main types, namely, calcareous soils, siliceous soils, 
and peaty soils. The ground waters of the calcareous soils are 
alkaline in reaction, those of the siliceous soils neutral or acid, 
and those of the peaty soils of this district always acid. The 
siliceous and peaty soils of the district are more closely related 
to each other than either is to the calcareous soils, not only 
by the acidity but also by their low, soluble mineral-content 
and by their floristic composition. There is also every stage of 
transition from acidic siliceous soils to the acidic peaty soils; 
and in the following table of plants characteristic of (though 
not in all cases absolutely confined to) each kind of soil, several 
species are necessarily given as characteristic both of siliceous 
and of peaty soils. 
