Ch. VI.] 



PRIMARY ROCKS. 



103 



bearing this in mind, and making allowances for the spheroidal 

 tendency of the mass, and the curvatures of the layers, a regu- 

 larity may be generally detected, not inferior to that of the 

 crystalline schists. 



This structure is more or less visible in most published 

 sketches of granitic cliffs; more particularly if the sea has 

 excavated some portions of the perpendicular, layers, in con* 

 sequence of a different composition rendering them more sus- 

 ceptible of decay and degradation. We have attempted in 

 the subjoined figure to convey an idea of this arrangement, 

 having for this purpose intentionally exaggerated the regu- 

 larity of the lines. 



Fig. 4* 



The lines corresponding with the gentle declination of the 

 nearest hill towards the point, mark the manner in which the 

 inclined face of the rhomboid. slopes in one direction; while 

 the greater slope of the hill towards the cliff is denoted by 

 the lines on the sides of the indentations of the cliff, which run 

 parallel therewith. 



Concerning the structure of the primary schistose rocks a 

 few remarks will suffice. It may be divided, as in tlje case of 

 granite, into the concretionary and, the internal*; and the 



H 4 



