Art. vii] Watson, Virgilina Copper District. loi 



west of the Virgilina area. The scattered areas lie principally 

 in Chatham and Orange counties, within short distances of Ra- 

 leigh and Chapel Hill. The close resemblance of certain ones 

 in structure and composition to the rhyolites of South Moun- 

 tain in Pennsylvania is noted. The localities were visited by 

 Professor George H. Williams, in company with Professor J. 

 A. Holmes, in the summer of 1893, and afterward discussed in 

 the Journal of Geology for 1894 by Williams.' They are re- 

 ferred to as pre-Cambrian in age, and are suggested as proba- 

 bly being contemporaneous with the somewhat analogous rocks 

 of the South mountain, in Maryland and Pennsylvania. 



In describing the Carolina Gold Belt area, situated in the 

 central Piedmont region and crossing the central part of the 

 state in a southwesterly direction, Nitze and Wilkens" again re- 

 fer to the kinds and distribution of the ancient volcanic rocks. 

 Their description follows : ^ 



"The volcanic rocks occupy irregular patches along the eastern 

 border of the belt, in close proximity to the western edges of the Jura- 

 Trias basins. They comprise both acid and basic types. The acid 

 rocks are generally devitrified to such an extent that their real charac- 

 ter is no longer recognizable to the naked eye, and they appear as or- 

 dinary cherts or hornstones, although flow structure is at times still 

 discernible. Microscopic examination shows them to belong to the 

 class of rhyolites and quartz porphyries. They are sometimes sheared 

 into schists, as for instance at the Haile mine, South Carolina. The 

 basic types are dark green in color and perhaps pyroxenic in composi- 

 tion ; they are sometimes massive porphyrites, but more generally 

 sheared into schists. The pyroclastic breccias consist of angular frag- 

 ments of the acid rhyolites and porphyries in a basic matrix. The age 

 of these ancient volcanics is believed to be pre-Cambrian. They seem 

 to be analogous to, and probably contemporaneous with, similar rocks 

 of the South mountain in Maryland and Pennsylvania, and other 

 points along the Atlantic coast." 



Professor George H. Williams^ published in 1894 a very 

 important paper on the distribution of the ancient volcanic 

 rocks along the Atlantic Coast region. Attention is directed 



1 Journal of Geology, 1894, Vol. II, pp. 1-31. 



^ Gold Mining in North Carolina, et cetera, N. C. Geol. Survey. Bulletin 

 No. 10, 1897, pp. 15, 16. 

 ' Ibid., p. 16. 

 * Journal of Geology, 1894, Vol- H. PP i~3'- 



