GRANITES OF NORTH CAROLINA 



379 



phenocrysts are marked in the different areas by idiomorphic out- 

 lines; and they are prevaihngly of large size, measuring in extreme 

 cases more than two inches long by one inch across. They are usually 

 white, with pinkish ones not uncommon, and, in most cases, they 

 contain more or less included biotite, frequently as large in size as 



Fig. 3- — Granite pinnacle on the west slope of Dunn's Mountain, near Salisbury, 

 North Carolina. Height of pinnacle more than twenty-five feet. 



that of the groundmass constituent. Under the microscope other 

 inclusions of the groundmass constituents are contained in some of 

 the phenocrysts. For this and other reasons elsewhere' stated by 

 me, the phenocrysts of the Carolina porphyritic granites are regarded 

 as having been formed largely, if not entirely, in place and not as 

 often urged of intrateUuric origin. 



Generally the phenocrysts do not grade into the similar ground- 

 mass constituent, but they are, in most cases, conspicuously developed 



I "On the Origin of the Phenocrysts in the Porphyritic Granites of Georgia," 

 Journal of Geology, Vol. IX (1901), pp. 97-122. 



