328 Dr. Mac Cul loch on the Parallel Roads of Glen Roy. 



alluvial flat for about three miles from the entrance of Glen Turit 

 downwards, and the terraces which are always found bordering this 

 flat, gradually disappear as the bottom of the glen contracts. A 

 few interruptions occur here and there, apparently connected with 

 the rockiness and irregularity of the ground, and these are most re- 

 markable on the right side ; but shortly before the glen turns to the 

 south, and until we arrive at Glen Fintec, all the three lines are 

 strongly marked on both sides. On the slope of a brown hill 

 in this place they are particularly worthy of remark, on account of 

 their continuity, preservation, and the almost absolute equality of 

 their dimensions, not only through the course of each individual 

 line, but respectively to each other.* This is easily accounted for 

 by the evenness both of the curvature and inclination of the plane 

 of the hill on which they are marked, as well as by the form of 

 its summit, which diverts the water courses in such a direction 

 as to preserve that surface from their action. It is important to 

 remark this equality, as it proves that the causes which produced 

 these lines, have been similar and equal, and that the irregularities 

 now to be met with are the result, not of irregularities in the action 

 of the power by which they were produced, but of inequalities in 

 the capacity of the ground on which these causes have acted. 



At this place an elevated glen opens into Glen Roy on the right. 

 No water enters into it from this valley, but the junction is formed 

 by a dry plain extending for some space, which, declining gradually 

 in the opposite direction, carries its waters towards Glen Gloy, 

 with which it also communicates. As the bottom of this glen is, 

 at its entrance, at a higher level than the lowermost of the lines, 

 this latter is here interrupted ; but the two upper ones enter it on 

 each hand, and are continued for some way along its sides. It is 



* PI. 16, 



