Floras of Great Britain and Central Europe. 249 
The hard “ grit ” and the shales of the Carboniferous formation 
give rise to hills with slightly rounded summits to which the “ Peak” 
of Derbyshire belongs. We visited these hills between Crowden 
and Greenfield and between Greenfield and Huddersfield in south¬ 
west Yorkshire and here, where the water parting between the 
North Sea and the Irish Sea reaches a height of only 540 m., the 
immense difference between the zones of vegetation and those of 
Central Germany become very clear. Woodland stops at an 
astonishingly low level: dwarf shrubs and heath, with arctic-boreal 
elements, and also Nardetum, begin extremely soon: on screes 
Pteridium forms a pure association in full sun and extends to a high 
level, till it is replaced (about 350 m.) by a new association. The 
flat summits are covered with widely extended peat-moors, which 
are not situated in depressions surrounded by ridges and peaks, as 
on the German mountains, but are developed on the gently rolling 
summits themselves. On the edges of these highlying plateaux, 
the moor breaks off sharply into a steep slope covered with 
Vactinium Myrtillus , from which the rain-water flows out and 
collects into mountain streams. On the moor plateaux themselves 
the power of the water is seen in numerous rifts and channels 
dividing the vegetation of the “ Hochmoor ” into areas, from the 
sides of which the peat is worn away, and which form in dry 
weather most convenient passages between the plants of the moor 
scrub. 
This marked depression of all altitudinal limits is without any 
doubt the consequence of the damp rainy climate : although the 
last snowfalls may take place after Easter, the snow rarely lies 
continuously for many weeks during winter. In Germany also we 
have a depression of altitudinal limits towards the damper west. 
The moors of the Harz, whose vegetation of Myrtilleto-Empetretum 
with V. Vitis-idcea , Trichopliorum ccespitosum Stir pus ccespitosus) 
and Eriophorum vaginatum may be compared with the British, 
extend from 700 m. to 1080 m., but they lie in hollows which are 
covered with snow during the winter, or on the flat sides of the 
summits surrounded by woods of Picea. The difference of latitude 
from the Pennines is only 2°. 
Of the social species of the Pennine moors, Rubus Chamcemorus, 
which forms larger masses than I have ever seen in the best East 
Prussian “ Hochmoor,” is very noteworthy. This plant only reaches 
a few places of the German mountain moors in the Riesengebirge, 
at about 1000 m. 
