HO appearances of cavities from which these glohular 

 masses have fallen, from the want of support. 



Again, there are no appearances of these pebbles at 

 the bottom or base of these rocks, at which they must 

 have fallen, nor in their fissures, from whence they 

 could not be removed by either winds or rain. More- 

 over, I could find no signs of them in the little streams 

 that glided slowly round the fragments that had fallen 

 from the rocks above. 



But the most convincing proof that these rocks are 

 not in a progressive state of decomposition, except in a 

 very slight degree, is, that notwithstanding all the 

 changes of temperature to which they have been ex- 

 posed for ages, they retain all their points and angles, 

 and every feature of a rude and craggy aspect, such, 

 doubtless as nature first impressed upon them. 



4thly. The real porphyry also occurs upon this 

 mountain, and some other rocks, which it may not be 

 uninteresting to notice in this view. 



A very fine and beautiful porphyry occurs at Nichol- 

 son's Gap, in Pennsylvania, about half way across the 

 mountain, and immediately on the road. It is of a pale 

 red, brown, and purple colour, handsomely spotted 

 with crystals of felspar. 



This beautiful species of rock, in this, and I believe 

 all other places, discovers but little, if any signs of de- 

 composition. All the points and angles appear as 

 sharp and entire as when first broken, although ex- 

 posed in their present situation ever since they were 

 formed. Nay, if we consider the firm and compact 



