382 J. F. KEMP GRANITES OF ATLANTIC COAST 



granites in the pre-Cambrian complex, but of their particular characters 

 the writer is unable to speak. The same is true of Alabama. 



Resume 



In resume, it may again be emphasized that there is a great and wide- 

 spread development of granites along the Atlantic coast or near it. The 

 granites have been intruded to our certain knowledge at several different 

 geological periods ; but allowing for the considerable variation that is 

 present in some regions, there is a striking predominance of l)iotite- 

 granites over all others, and among the rest there is a much greater 

 abundance of varieties allied to the biotite-granites than of those, such 

 as pure hornblende-granites, which are in contrast with them. 



It is also an impressive fact that throughout much the same region as 

 that which contains the granites, there is a great development of rocks of 

 the gabbro family and of diabases. While the surmise is quite purely 

 speculative the query may be raised as to whether in the long course of 

 geologic time some great parent magma has not given rise to these sev- 

 eral fractions, and also as to whether the abundant pre-Cambrian volcan- 

 ics of rhyolitic nature may not be the effusive products which correspond 

 to some of the deep-seated granites. 



