STRATA of the GRAMPIANS. 15 



fuch junctions are always to be much regretted in mineralogical 

 refearch. 



Having palled over this narrow plain, I advanced towards 

 a fecond range of hills, which here form the bans of the central 

 and higheft chain. It is at this place where the river fo fud- 

 denly changes its courfe from eaft to fouth, and where I Was un- 

 der the neceffity of leaving its bed, to continue my northern di- 

 rection towards Mount-Battoc. This, however, I was enabled 

 to do to great advantage, by following up the deep cut bed of a 

 winter torrent, which led me into the direction which I wilhed 

 to follow. 



Upon entering the bed of this torrent, I found that the bafis.^ 

 of the hills here entirely confilted of micaceous fhiftus, much 

 veined with quartz, and much twifled in its texture. The 

 ftretch of this rock is here nearly from welt to eait ; and it has 

 a foutherly dip of 45 degrees. 



In palling through among thofe hills towards the central 

 range, I found in feveral of the beds of the torrents large blocks 

 of reddilh-brown porphyry, with fcattered malTes of micaceous 

 fhiftus and granite. 



In tracing up one of thofe torrents, I faw the micaceous fhif- 

 tus rock and the porphyry both expofed to view, near to each 

 other ; and, foon after, in the bed of the fame torrent, I came to 

 a cafcade which had laid bare both thofe rocks at a point where 

 they are in contact j and near thofe a fecond bed of porphyry 

 made its appearance, in the front of a near hill. From my firft 

 view of thofe, and from their relative politions, I was led to ima- 

 gine, that they might here alternate in vertical polition j but up- 

 on more minute infpection, I found that the porphyry conftituted 

 vertical dikes, ftretching nearly from fouth to north - 3 which courfe 

 cuts the line of direction of the Grampians here almoft at right 

 angles : and, on the contrary, I found that the micaceous fhiflus 

 v?hich . flanked thofe dikes of porphyry, had a regular ftretch 



from 5 



