160 Sub-formation of the Older Limestones 



Associations of limestone 'pavements. 



A very striking feature of some of the summits of the 

 Carboniferous Limestone, as in the mid-Pennines^ and the 

 north Pennines, is the intricate maze of deep and narrow 

 clefts of the limestone rooks. Limestone rocks weathered 

 in this way are spoken of as "pavements." They are also 

 of great extent at low altitudes on the limestone plain of 

 Co. Clare, in west Ireland" (Plate XV). 



The exposed surface of the rock is very bare, and, 

 although rather rich in lichens and mosses, is extremely 

 poor as regards its Phanerogamic flora. Within the 

 clefts, however, ferns and flowering plants are abundant. 

 The clefts are sheltered from wind and sun ; and, there 



1 Smith and Rankin, 1903, p. 19 of separate. 

 - R. Lloyd Praeger, 1909, p. 50 et seq. 



