420 OBSERVATIONS ON THE GEOLOGY 



perhaps might with propriety be called the transition Dolomite, 

 in many places veins and irregular masses of silex, variously 

 coloured (mostly black) run through it, and considerable beds 

 of fine grained white marble, fit for the statuary, occur. 



Limestone spar runs in veins and detached masses, through 

 the whole of this formation, both it, and the grey wacke- 

 slate contain quantities of cubic pyrites; galena has likewise 

 been found near Lancaster, and many veins of the sulphate 

 of barytes traverse this formation, which runs about 25 to 30 

 miles south east, and nearly parallel to the great transition for- 

 mation. A similar formation, about fifteen miles long, and two 

 to three miles wide, occurs on the north fork of the Catabaw 

 river, running along Linville and John's mountains, near to the 

 Blue ridge; a bed of transition rock, commencing on Green 

 pond mountain, Jersey, runs through Suckasunny plains, in- 

 creasing in width as the primitive range decreases, until it joins 

 the great transition formation between Easton and Reading. — 

 On the west side of this partial transition formation, from the 

 Potomac to the Cataba, between it and the great western tran- 

 sition range, a series of primitive rocks intervenes, something 

 different from the common primitive, having the structure of 

 g?ieiss; with little mica, the scales of which are detached and 

 not contiguous; much felspar, rather granular than crystallized; 

 mica-slate, with small quantities of scaly mica; clay-slate, rather 

 soft and without lustre, the whole having a dull earthy fracture, 

 and gritty texture, partaking of transition and primitive, but 

 not properly belonging to either; this rock is always foui'd on 

 the edge of the primitive, before you come upon the transition, 

 but no where in such quantities as in this range; there are ma- 

 ny varieties of it, so that it imitates almost every species of the 

 common primitive rocks, but differing from them, by having 

 a dull earthy fracture, gritty texture, and little or no crystalli- 

 zation. 



About ten or twelve miles west of Richmond, in Virginia, 

 there is an independent coaljoi mation, twenty to twenty five miles 

 long, and about ten miles wide, it appears to be not far distant 

 from the range of the red sandstone formation, it is situated in an 

 oblong bason accompanied by whitish jreesione, slaty clay, &c. 



