Geology of North Carolina. 241 



resembles the Chlemsford granite, so much esteemed in Boston 

 for architectural purposes, recently appropriated to a noble use 

 in constructing the Bunker's Hill monument. It owes its soft- 

 ness to the intimate diffusion of the mica. The same kind of 

 granite is found at Louisburg, Warrenton, and near Halifax. 



Of the harder kinds of granite of coarse grain, which are 

 not susceptible of being dressed, a good example occurs at Dunn's 

 mountain, four miles east of Salisbury. The vast masses of hard 

 granite (boulders) which are here piled one upon another on 

 the summit of this hill, present a very striking and almost sub- 

 lime appearance, in a district of country so generally level and 

 sandy as the surrounding region. These globular masses rest 

 on a base of the same kind of rock which, being full of seams, 

 is easily divided into blocks or parallelopipeds of great regular- 

 ity^ of which a valuable use is made in the neighboring town. 

 They are likewise employed for millstones. 



In the counties of Stokes and Surry, and in several other 

 places of the western district, there is found a kind of granite 

 containing a large proportion of feldspar in a state of decompo- 

 sition, which gives it a loose shelly texture. It is by the de- 

 composition of this kind of granite, that the finest varieties of 

 porcelain clay are formed ; and accordingly, this is the region 

 where we may expect white clays of the most valuable kind ; 

 and veins, of fine clay are not unfrequently observed in the fore- 

 going rocks. White clays which result from the decomposition 

 of feldspar, are suitable for the finest kinds of pottery. It is es- 

 sential however, that they should burn white. Some white clays 

 contain so much iron as to lose their whiteness on calcination. 

 Among the varieties enumerated, that near the Pilot Mountain 

 appears to be most worthy of attention. 



The traveller, in going westward over the granite, meets 

 with alternate ridges of granite and greenstone, the latter of 

 which, Prof. O. supposes to constitute beds in the former. 

 Very interesting veins of a rock kindred to the greenstone, 

 and which the Report considers basalt, exist also in the gran- 

 ite. These constitute the celebrated natural walls of Row- 

 an — regarded for a great number of years as artificial, as the 

 work of some wonderful people, long since extinct. We 

 well recollect what full credence we gave in our boyish days 

 to this sapient suggestion, which we found in the geographies 

 of those times; and how very wisely our learned pedagogue 

 would descant upon the mighty people whose fortifications 

 still remained. But alas, science threw a ray of light upon 

 these structures, and the magic spell of the antiquary van- 



Voi, XIV.— No. 2. 5 



