Dr. Mac Culloch on the Geology of Glen Tilt. 295 



Cumstances connected with the schist which forms the bed of the 

 river throughout this space, they were concealed from me. The 

 channel becomes so deep and the «ides so clothed with wood, that 

 it is scarcely possible to examine the banks ; and the bed of the 

 river itself may safely be called inaccessible during nearly the 

 whole of its remaining course to Blair. Within about two miles 

 of Blair, however, at a point which is marked by a cascade 

 and a small bridge, a large mass of yellow marble is seen crossing 

 the river. It is, like that before described, of an uniform ochre 

 colour, and like it, applicable to architectural uses. Lower down, 

 near the junction of the Fender, where there is again access for a 

 short space, the great body of blue limestone is found. This 

 may be traced across the grounds of Blair, and in the bed of the 

 Banavie, where it exhibits those minute reticulations of siliceous 

 matter which I have already described. From hence it is again 

 to be traced to the opposite side of the Garry, where it forms a 

 great part of the green hill of TuUoch. On this hill, at Invervach, 

 many of the beds are white, and resemble those already described 

 at Gow's bridge, being interlaminated in a similar manner with 

 steatitical clay, and accompanied by mica. But I have passed my 

 proposed boundary. 



Having anticipated no more of the description of the two ridges 

 which bound Glen Tilt, than was necessary to understand the 

 nature of the rocks which are seen in the bed of the river, I must 

 now return to them, taking up the right hand ridge, or north 

 side of the glen, at the place where I have now stopped. 



That portion of the ridge which lies from Blair to Gow's bridge 

 is so encumbered with wood in some places, and offers so little 

 interest in others, that I am content to pass it by in a superficial 

 manner, particularly as its more minute examination would throw 



