Si: RAH A of the GRAMPIANS. 7 



of the rock : they are formed of the fame materials with the 

 other parts of the (lone ; but into them the ferruginous flaming 

 matter has not apparently been able to penetrate, and they de- 

 rive their prefent greyifh appearance from the natural -colour of 

 its particles of quartz, which are here per fe of a bluifh-white 

 tint. This rock, in the plain, is perfectly horizontal in its pofi- 

 tion ; but upon its approach towards the undulated grounds, 

 which here form the lowed bafis of the Grampians, it begins to 

 rife from its horizontal bed, and, gradually increafing in its ac- 

 clivity towards the mountains, it at lad arrives at a pofition per- 

 fectly vertical. 



For the firft quarter of a mile from where this grit begins to 

 leave its horizontal pofition, the rife is very gradual ; but after 

 that diftance, it becomes more rapid, and in a mile it gains its 

 vertical pofition. 



Where this grit or fandftone rock is in its moft folid ftate, 

 and where its pofition is perfectly vertical, betwixt two beds or 

 layers of it, there occurs a bed of Whinflone forty feet broad. 



The main body of this bed of whin interfecls none of the 

 layers of grit, but ftands upright betwixt two of them, to both 

 of which it is clofely joined. The river, at this place, has, in its 

 paflage, worn down this bed of whin equally with that of the 

 adjoining grit, and a perpendicular face of it can be examined 

 upon each fide of the river, from fifty to fixty feet in height. 



Upon examining the feclion of this bed, I found upon the eafl 

 fide of the river two branches, which fprung from the main body 

 of the whin, nearly where the water of the river at prefent waflies 

 the bafe of its perpendicular furface. One of thofe branches 

 fprings from the right fide of the trunk, and the other fprings 

 from the left fide : they at firfl diverge from the trunk as they 

 afcend, and where they pufli out laterally, they interfecl: the con- 

 tiguous ftrata, and penetrate them in a zig-zag manner ; but at 

 laft, in a pofition betwixt two of the layers of the grit ; they con- 

 tinue 



