244 Geology of North Carolina. 



ally of a bright cherry red, but sometimes of a silvery white 

 color. These beds occur throughout a space not less than three 

 fourths of a mile wide and ten miles long. To this extent I have 

 myselfobserved.it; but a land surveyor informed me that he 

 had followed it eighteen miles, and found its bearing to be south 

 ten degrees east. I have no reason however to suppose, that 

 the limits of the plumbago, have been as yet accurately defined. 

 I have never read of any mine of plumbago which can com- 

 pare in extent with this, but have reason to believe that it is the 

 largest mine on record. 



The plumbago may be obtained in large masses unmixed 

 with any foreign ingredients 5 but it is frequently more or less 

 blended with the rock in which it lies. From this, however, on 

 account of its softness and friability, the Plumbago may be easily 

 separated by pulverising and washing ; although, probably, a 

 sufficient quantity of that which is pure may be obtained to sup- 

 ply the market. It would be favorable to the reputation of the 

 ore, to have that which is offered for sale well assorted, accor- 

 ding to the different qualities. This practice is strictly maintain- 

 ed at the celebrated mine in England. 



From Prof. Olmsted's descriptions, and from an inspection 

 of specimens in our possession, we are persuaded that an 

 important part of what is denominated mica slate in the He- 

 port, is the quartz rock of Macculloch. Indeed, as Dr. M. 

 calls all those aggregates of quartz and mica, quartz rock, in 

 which the quartz predominates, we have no hesitation in 

 saying that this is one of the most common rocks of our 

 country. We could refer, if it were necessary, to several 

 localities, and in almost all of them this rock occupies a 

 place next higher, and therefore newer, in the series, than 

 mica slate : indeed, it passes insensibly into mica slate, and 

 our geologists have hitherto described it as such, except that 

 small portion of it which consists of granular quartz alone. 



The flexible sandstone of North Carolina appears to us to 

 be a variety of quartz rock. But the most interesting spot 

 where quartz rock occurs, is in the pinnacle of Pilot Moun- 

 tain, and several adjacent eminences, whose description in 

 the Report is too interesting to be omitted. 



The Pilot and Sawratown Mountains. 



In the first glimpse we catch of the Pilot in Rockingham, it 

 resembles a magnificent temple with a superb cupola, not un- 

 like the picture of St. Peter's at Rome. The uncommon sym- 

 metry of its structure is preserved on a much nearer view. 



