16 ME. T. P. JAMIESON SUPPLEMENTAKY 



to the Ordnance map, is only abont 8 feet in a mile or 1 in 660, , 

 which is insufficient to have caused the stream issuing out of a lake 

 to cut a groove of any kind, so that the conditions necessary for the 

 erosion of a vrell-marked channel are here wanting. Moreover, the 

 place is now overgrown with peat, which obscures any track that 

 might have been left. 



The Glen Glaster col is also in a flat-bottomed hollow now over- 

 grown with peat. A little to the eastward the glen is narrowed by 

 a low projecting spur from the hill on the north side, and here the 

 rocks have a remarkably bare, washed appearance, as if they had 

 been scoured by a rush of water passing eastward. Looking down 

 the course of the small rivulet which flows away to join the Hough 

 Eurn I observed that it ran along the middle, or rather to one side, 

 of a wide peat-overgrown channel, which seemed to have been at 

 one time the bed of a considerable stream. I followed the course 

 of the rivulet along the wide open glen all the way down to its 

 junction with the Eough Burn. Owing to the thick growth of 

 swampy turf the nature of the bottom in this old channel is hidden 

 for some distance, so that I could not discover whether it is pebbly 

 or not ; but a little farther eastward the appearances are more 

 distinct. A low escarpment is seen on the north side, and a stratum 

 or causeway of large waterivorn stones on the south, indicating the 

 former presence of a strong current, while the channel itself is about 

 70 yards broad and 12 feet deep in the middle. Big boulders of 

 the Glen Spean syenite, probably brought here by the Treig glacier, 

 are numerous all along the side of this hollow from the col down- 

 wards, and they occur also on the hills adjoining it up even to 

 heights of nearly 2000 feet. Erom the Glen Glaster col down to 

 the Eough Burn is a distance of about two miles, and the total fall 

 between these two points is 53 feet, or about 27 feet per mile, which 

 is equal to 1 in 195. The appearances down here of an old channel 

 are so clear that I can account for Nicol's statement only on the 

 supposition that he had confined his observations to the col itself, 

 and, had not walked down the glen to the eastward. To demand, 

 however, with him that we should find a long deep trench cut into 

 the hard solid rock, like what we see in some parts of the present 

 bed of the Eoy, is surely unreasonable. The Eoy has been cutting ll 

 away at its bed ever since the Glacial epoch, and perhaps before it, 

 whereas the outfall from the lake at the period of the middle line 

 existed only during the time the ice took to shrink back from the 

 mouth of Glen Glaster to Bohinia, about a mile and a half. How 

 long that may have taken, reckoned in years, we cannot tell, but 

 in comparison it must have been a very small fraction of time 

 indeed. I ought to mention that there is a mass of boulder clay 

 at the south side of the Glen Glaster col, which is probably the 

 remnant of a larger accumulation of moraine matter that had for- 

 merly occupied the hollow, and may have blocked it up to some 

 extent. 



As regards the col at Makoul, I have already in my previous paper 

 described the evidence of a river having passed out there. I shall 



