GLENTILT. 365 



river, about two miles below the Lodge. Here 

 it is accompanied with a bed of coarse quartz/ 

 rock. It afterwards appears laid bare by the 

 action of the stream at different places farther up, 

 till we pass the Lodge ; and every where, particu- 

 larly at the bridge, its structure is curious, and 

 its aspect striking. Nor does this substance ter- 

 [ rninate here, but may be traced, through a dis- 

 tance of eight or ten miles, along the course of 

 the water to the head of Glen-Tilt, ; where also 

 we still find the quartzy material just mentioned. 



By taking the bearings of its successive por- 

 tions in the neighbourhood of the Lodge, this 

 singular and indestructible rock is found to 

 consist, not of six different veins, as has been 

 stated, but of one vast conformable mass, 

 which prevades the great formation, in a direc- 

 tion that is uniform, and nearly the same with 

 what is common to all the strata ; and of which 

 the out-going at some places intersects the chan- 

 nel of the Tilt, though it is covered for the most 

 part with soil or debris. The continuity of the 

 mass, in the general direction of its cropping out, 

 is a fact of which there can be no doubt. But I 

 had not data for completely satisfying myself, 

 whether in reality it is a bed ; or a vein lying 

 nearly in the direction of the strata ; or possibly a 

 long ridge of rock, previously formed and laid 

 bare, from the subsequently deposited strata, in 

 the course of decomposition and waste. The great 

 presumption, that it is a bed, rests on the confor- 



