Dr. Mac Culloch on the Parallel Roads of Glen Roy. 331 



becomes again visible on hills below it of a slope precisely similar. 

 It must at present therefore be regarded as one of the numerous 

 difficulties attending this very difficult subject. 



The upper line becomes also invisible on the right opposite to 

 this place, and shortly after, the whole disappear on this side, 

 though no material alteration takes place in the form or structure of 

 the hills. About a mile before we arrive at the junction of the Roy 

 and Spean, the valley expands, and here the lowermost line again 

 makes its appearance, continuing its course round Meal Derig to 

 the side of Glen Spean, where it disappears. The same line shortly 

 after reappears on the right side, and from hence it can be traced 

 with more or less difficulty as far as Teindrish, over a various sur- 

 face of very slight inclination, until it finally vanishes. At Keppoch 

 the Roy falls into the Spean issuing from Loch Laggan, and here 

 it loses ics name ; while the Spean holds its course westward for a 

 space of five or six miles till it falls into the Lochy. 



On the left bank of the Spean, near the junction of the Roy, a 

 line is visible which is found by the spirit level to correspond with the 

 lowermost line of Glen Roy. It runs about three or four miles up the 

 valley over a surface of moderate inclination, yet although the cur- 

 vature and structure of the opposite hills which bound the Spean 

 are similar, it is not found on the right bank. It continues to hold 

 its course westward with more or less obscurity, from the junction 

 of the Roy and Spean along the declivities of the high mountains 

 Ben na 'chlianach, Scuir rinish, and Cam derig, which bound this 

 wide valley to the south, finally disappearing opposite to Teind- 

 rish, and nearly in the same meridional direction. The valley is 

 here of such dimensions that the opposite lines are about four miles 

 asunder. Its bottom is extremely irregular, offering rather an 

 accumulation of low hills than a valley properly so called. But in 



