196 



VEGETATION OF THE PEAK DISTRICT 



[CH. 



34, c) is developed. The plateaux of the cotton-grass moor 

 either descend gradually into the zone of upland cultivation 

 (figures 83 and 34, e), in which case these two zones are 

 separated by a zone of heather moor (figures 33 and 34, d) ; 

 or they are terminated abruptly by steep shaly slopes, in which 

 case the zones of cotton-grass moor and upland cultivation are 

 separated by a zone of Nardus grassland (figures 33 and 34, d). 

 The relationships of the plant formation of the siliceous soils 

 and that of the moors may be seen in the following table : — 



Sub- Alpine Grassland 



OXODION - 



Bare Peat 



I Bilberry 



Retrogressive Moors 



Cotton-grass Moors. 

 Heather Moors 



Ridges 



bo 

 •a 



n 



Nardus Grassland 

 with much Heather, 



Molinia Grassland 



SiLIClON i 



Nardus Grassland Birch Woods {B. pubescens) 



Scrub 



1 



Oak Woods {Q. sessilijlora) 



List of Species of the Moor Formation 



The following species occur on the moor formation (cf. 

 Ostenfeld, 1908: 947 et 956) of the southern Pennines; and 

 their relative fi'equency in the three chief associations is also 

 indicated. The plants preceded by an obelisk have not been 

 recorded from the Peak District ; but they occur a few miles to 

 the north. 



