GRANITES OF NORTH CAROLINA 383 



limits of the former, the thin veneer of loose unconsolidated sands and 

 gravel has been stripped from the surface, mainly along the streams, 

 exposing comparatively small, irregular, somewhat elongate areas of 

 the crystalline rocks, composed either in part or in whole of granite. 

 In such areas the general nature of the granite exposures is in the 

 form of ledge and bowlder outcrops, and as flat-surface masses a 

 short distance back from the streams. 



The inliers of crystalline rocks mark the eastward extension of the 

 Piedmont crystalHnes beneath the Coastal Plain sediments. Some 

 of the schists and gneisses composing parts of these areas are the 

 metamorphosed equivalents of original igneous masses. They 

 include both acid and basic types. 



The principal granite areas of the Coastal Plain are exposed in 

 Wilson, Edgecombe, and Nash counties to the east of Raleigh, and 

 in Anson and Richmond counties in the vicinity of Wadesboro near 

 the South Carolina line. They are composed of massive biotite gran- 

 ites, in one instance hornblende-bearing, which vary from fine even- 

 granular to coarse porphyritic rocks of gray to pink color. The area 

 to the north of Elm City, in the extreme northern part of Wilson 

 county, contains some hornblende in additioa to the biotite. 



LITHOLOGICAL CHARACTERS OF THE GRANITES. 



The Coastal Plain granites are described separately by areas in 

 order to bring out more clearly their close similarity to the granites of 

 the Piedmont region. 



The Wilson pink granite area. — The rock is uniformly coarse- 

 textured, of moderate pinkish-red color, and displays a pronounced 

 porphyritic tendency. Feldspar is greatly in excess of the other 

 minerals. The largest feldspar individuals measure one to two 

 inches long. They are pinkish-red in color, exhibiting good cleavage 

 development and twinned on the Carlsbad law. Microscopically the 

 feldspar and quartz make up not less than 95 per cent, of the rock. A 

 rough estimate indicates about 80 per cent, of the former and 15 per 

 cent, of the latter. Of the feldspathic content about 50 per cent, is 

 potash feldspar, most of which is orthoclase, with but little microcHne; 

 and 30 per cent, is plagioclase in very large, finely striated laths, whose 

 extinction angles measured against the twinning bands indicate 



