184 VEGETATION OF THE PEAK DISTRICT [CH. 
fifteen feet (305 to 457 cm.) in depth, and rarely less than five 
feet (152 cm.). On rare occasions, as in local hollows and 
swamps, it may reach a depth of twenty feet (610 cms.) or more. 
The peat is usually saturated and frequently supersaturated 
with water, although the superficial layer occasionally becomes 
very dry in summer. 
Over many parts of the higher moors, Eriophorum vagin- 
atum is the dominant plant; and, wherever this plant occurs 
in quantity, the depth of the peat is being added to year 
by year and denudation of the peat is not taking place. At 
the present time, Hriophorum vaginatum probably forms peat 
at a more rapid rate and over wider stretches of English moor- 
lands than any other plant; and the statement, occasionally 
met with, that peat formation is a phenomenon of the past and 
not of the present is incorrect. 
Bog-mosses (Sphagnum spp.) are even rarer on the cotton- 
grass moors than on the heather moors, though a contrary 
opinion has gained credence; and the erroneous view is still 
met with that the dominance of Sphagnum is a necessary 
condition of peat formation. As a matter of fact, Sphagnum 
is invariably absent from the peat of true fens, and is by no 
means a necessary constituent of the peat of moors. One may 
walk many miles over the moors of this district without seeing 
any trace of Sphagnum ; and one may examine many sections of 
the peat of the district without finding any trace of its remains. 
The cotton-grass moors are extensive, dreary, and monotonous, 
Eriophorum vaginatum is frequently not merely the dominant 
but the only vascular plant which occurs. In late summer and 
early autumn, the dead green hue of the shoots of the cotton- 
grass is scarcely relieved by any other touch of colour. In late 
autumn and throughout the winter, the shoots fade to dull 
red; and the vegetation then presents a most forbidding aspect. 
A little life is infused into the area in April and May, when the 
dusky brown florets make their appearance; but only in June, 
when the pure white fruits of the cotton-grass appear like 
suspended snow-flakes, is the cotton-grass moor attractive to 
the eye (see figure 26). 
The monotony of the cotton-grass moor is, however, relieved 
by certain physiographical features to which the vegetation 
responds. A sandstone escarpment or outcrop causes a decrease 
