an uniform texture, which seems at first sight in 

 its characters and fracture to resemble basalt. 



Struck with this unlooked for appearance, and 

 comparing it with what I afterwards found at the 

 • summit, I conceived at first, and for some time, 

 that the observation thus made was the discovery 

 of a flcetz- formation, consisting of clinkstone over 

 porphyry-slate and basalt, and resting immediately 

 on sienite. I therefore applied myself with eager- 

 ness to find out what might be considered as the 

 junction or line where the transition takes place. 

 But the intermediate space, the bed of the rivulet, 

 and tHe surrounding acclivity in every direction, are 

 so completely covered with fragments, that the 

 line sought cannot be discovered hereabouts. So 

 that, after spending a long time, and returning on 

 purpose another day to prosecute the search, I was 

 obliged to abandon it without success. 



At the same time, although on this face of the 

 mountain, the quantity of debris from the high- 

 er rocks is prodigious, and descends probably a 

 little below the upper part of the sienitic mass, 

 the experienced eye can easily trace the horizon- 

 tal line, where the fragments of the subjacent 

 felspar-porphyry begin to mix with those of the 

 overlying dark-coloured substance. It runs along 

 the acclivity towards the north shoulder, and is 

 evidently but a small distance under the presum- 

 ed junction. I may further observe, that all the 

 rocks at this part of the ascent, are so little unco- 



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