vit] MOORLAND ASSOCIATIONS 189 
way back have their banks (see figure 29) fringed with sloping 
banks of bare peat. In times of drought, the bed of these streams 
contains very little water which may temporarily disappear; but 
after heavy rain-storms, the stream is a rapid torrent of brown, 
peaty water. Every storm results in quantities of peat being 
carried away, in the stream winning its way further back into the 
peat, and in the channels becoming wider and deeper. Numerous 
tributary streams also are formed in course of time; and 
eventually the network of peaty channels at the head coalesces 
with a similar system belonging to the stream which flows 
down the opposite hill-side. The peat-moor which formerly 
_was the gathering ground of both rivers, is thus divided up 
into detached masses of peat, locally known as “ peat-hags” 
(figure 31); and the final disappearance of even these is merely 
a matter of time. 
It is obvious that this process results in a drying up of the 
peat of the original cotton-grass moor ; and it is most interesting 
to trace a series of degradation changes of the now decaying 
peat moor. The first change of importance of the vegetation 
appears to be the dying out of the more hydrophilous species, 
such as Hriophorum vaginatum and E. angustifolium, and the 
increase, on the summits of the peaty “islands” or “ peat-hags,” 
of plants, such as Vaccinium Myrtillus and Empetrum nigrum, 
which can tolerate the new and drier soil conditions. 
The composition of the upper layers of the peat of these 
retrogressive moors has, during the course of the present in- 
vestigation, been carefully examined; and it has been found 
that the peat consists in its upper layers almost wholly of the 
remains of Eriophorum. The succession therefore of cotton- 
grass moor to the series of retrogressive moors here being 
described, is established beyond doubt. 
THE PEAK OF DERBYSHIRE 
As the Peak of Derbyshire is covered by retrogressive 
moorland, a short description of this the most important 
topographical feature of the district will not be out of place 
at this juncture (cf. figure 32). 
The Peak is a plateau of Kinderscout sandstone varying in 
height from about 1750 feet (533 m.) at its eastern extremity 
