146 PLANT-LIFE ON LAND [ch. 



The links of the sea coast ma}^ be as various in 

 conformation as the coast itself. In point of fact 

 the rock-sculpture which underlies the surface gives 

 them their primary characters. However thickly 

 covered by sand and soil and varied vegetation, 

 sooner or later the solid rock would be reached 

 by boring, and it is in the inlets of the coast-line, 

 and the depressions of this rock-surface, that the 

 materials collect to form the links themselves. These 

 may take the form either of towering Dunes, built 

 up by agencies explained in the preceding chapter, 

 or of more level sand-fields originating in various 

 ways, but still owing their outlines primaril}^ to 

 the underlying rocks. Though often out of sight 

 the rocky skeleton has thus been the prime factor 

 in the shaping of the links, and the broader features 

 of the course may for the most part be properly 

 traced back to it. 



Apart from the general conformation of the links 

 thus defined by their rocky skeleton, the detailed 

 characters, whether of contour or of surface, arise 

 from the agencies which afiect the transfer and 

 lodgement of wind-borne sand. The mere existence 

 of an inlet or hollow in the framework would tend 

 to detain some of the sand blown upwards from the 

 beach. But much more effective is the influence of 

 perennial vegetation. Wherever this has obtained 

 a footing sand-aggregates collect, and grow with its 



