OTHER PLANT FORMATIONS 47 
culty is heightened by the fact that while the physical 
conditions show no contrasts so marked as those 
which we have been considering, the formations which 
can be distinguished are several, and each contains 
several associations—often a woodland, a scrub, and 
a grassland type. Thus, the formation which occupies 
calcareous soils exhibits characteristic woodlands— 
woods of Ash (Fraxinus excelsior), for instance, and 
on the downs peculiar woods or scrub of Box (Burrus 
sempervirens), Juniper (Juniperus communis), Yew 
(Taxus baccata), or Hazel, as on Farleton Fell. It 
also bears some very marked types of grassland, as 
on the chalk downs; and the limestone pavement of 
Farleton Fell is a special variant of this. Similarly, 
clays and loams, sands, and siliceous soils possess 
similar characteristic types of vegetation. But the con- 
sideration of these would occupy more space and lead 
us into more technical detail than the scope of this 
book warrants. For an account of these associations, 
written by botanists who have made a special study 
of them, the reader is referred to Tansley’s “Types 
of British Vegetation.” 
