320 Dr. Mac Culloch oa the Parallel Roads of Glen Roy. 



indeed be distinguished (but with more difficulty) if viewed in 

 profile. In the part which I am now describing the lines are narrow 

 and the declination of their surfaces from the horizontal plane is 

 considerable, as the profiles* will show. This ground is rocky and 

 irregular, the natural rock being visible in many places, while in 

 the rest of the glen it is but rarely seen ; and it may be remarked 

 that wherever the natural rock comes to light these marks or lines 

 are always least discernible, being of much smaller dimensions, and 

 having a much greater conformity in their slopes to the natural 

 slope of the hill. Whatever loose matter occurs here consists of 

 large fragments, which have evidently descended from the hill 

 above. That this is their origin and that they are not transported 

 materials is plain, since they are not rounded and since they exactly 

 resemble the natural rock, which is of a remarkable character, con- 

 sisting of mica slate traversed by numerous veins of red granite; a 

 rock which is limited to the upper part of the glen and is not 

 found in the neighbouring hills. The natural rock projects in 

 many parts of the line so as to interrupt it ; or it is wanting 

 wherever a solid mass of rock occurs in its course. As I am 

 here only describing the appearances, I will not anticipate the 

 arguments by asking whether the line has not been sometimes over- 

 whelmed by the fall of rubbish ; in many cases however its obscu- 

 rity evidently arises from the refractory nature of the materials on 

 which it is traced. Obscure marks of two similar lines are here 

 and there visible on the left hand side in this place, particularly on 

 certain projecting faces where the surface of the hill is, from its 

 outline, evidently covered with a coat of alluvial matter. Indepen- 

 dently of these fragments of the two principal lines, many short 

 indistinct traces are to be seen at different levels from those on 



* Plate 18, Profiles No. 3, fi. 



