to the Parallel Roads of Lochaber. 35 



sentation of a portion of the upper shelf. The eastern portion 

 is correctly represented as terminating at the south-west corner 

 of Glen Fintec ; but on the west side, the shelf, instead of ter- 

 minating as expressed on the map, is continued a considerable 

 distance southwards of the opening of Glen Fintec, from half 

 a mile to a mile, or perhaps more; at first less distinct than 

 usual, then more plainly marked, till coming against a rocky 

 projecting ledge on the hill side, it fails as usual to impress it, 

 and is seen no more. 



On referring lately to Sir T. D. Lauder's map accom- 

 panying his paper (Trans. Roy. Soc. Edinb. for 1817), which 

 I had not looked into before visiting the Parallel Roads, I 

 found that his representation of this portion of the district is 

 much more correct. Glen Giuoy is given in its true dimen- 

 sions; and the stream formed by the union of the Gluoy 

 and Fintec waters is laid down as turning, at a place called 

 Lowbridge, round the southern termination of the moun- 

 tainous ridge just described, and discharging into Loch Lochy, 

 nearly opposite to a village named Kyle-Rose in Mr. Cham- 

 bers's map. This representation is very near the truth ; but 

 perhaps too great extension is given to the southern part of 

 Loch Lochy. 



One of the principal objections which has been urged against 

 Mr. Milne's theory, is the absence from the district of a suffi- 

 cient quantity of detrital matter to account for the barriers at 

 the mouths of the glens, required by the theory. The force 

 of this objection would be very much diminished, if we could 

 receive Mr. Chambers's account of the hill of Oonchan as cor- 

 rect. It appears to me, however, that he quite over-estimates 

 the amount of detritus in this hill. 



After giving a full and accurate description of the other 

 principal detrital accumulations of the district, Mr. Chambers 

 thus notices the hill of Oonchan : — " By far the grandest delta 

 of the district is that hill which has been referred to under 

 the name of Unichan as occupying so much of the lower part 

 of Glen Spean. This is a mass of gravel 11 miles long by 

 perhaps 2 broad, and reaching an elevation of 612 feet. I 

 observed rock rising through it at one place; but it is mainly, 

 as has been said, a hill of gravel." He considers that " when 

 the sea stood somewhat above 622 feet (and there is evidence 

 of its having paused long at 628 or 630), the rivers descending 

 from the Ben Nevis group of mountains delivered their spoils 

 into the estuary filling Glen Spean : on the withdrawal of the 

 sea this mass was left." 



The high ground in question, part only of which is called 

 Oonchan, is an undulating ridge parallel to the main chain, 



D2 



