DESCRIPTION OF TINTO. 



127 



here supposed. The colour of the rock to which 

 I allude, is most generally greenish-grey. 



Over the conglomerate, which crops out at dif- 

 ferent heights along the base on the south side, 

 masses of clay stone, greenstone, and greenstone 

 passing into clinkstone and porphyry-slate, suc- 

 cessively appear, till we arrive at the summit of 

 the mountain, which is found to consist of com- 

 pact felspar, and felspar-porphyry, with crystals 

 of quartz, mica, felspar, and hornblende. The 

 felspar rocks also contain thin layers or beds of 

 reddish-coloured quartz. 



That these substances, composing the great body 

 of Tinto, are disposed in beds, is sufficiently pro- 

 bable ; but, it would be more than is warranted 

 by my observation, were I directly to assert the 

 fact, having been unable to do more than ascertain 

 their separate existence and relative position in 

 the order mentioned. So far as I could judge, 

 if the felspar is in beds, they are almost vertical, 

 and run nearly in the direction of north-east, and 

 south-west. 



The nature and characters of the felspar, which 

 in general may be described as slaty-compact, are 

 distinctly shewn by the cropping to be seen about 

 half a mile below the summit, towards the south- 

 west, where the surface over a great extent ex- 

 hibits this variety of the rock, both in situ and in 

 detached masses of all sizes, decomposing in plates 

 or layers of various thickness^ from a quarter of 

 an inch to half a foot. 



