PARALLEL ROADS OF LOCHABER. 115 
4th. When the sea subsided to such a level as to expose hill ranges, the 
force of the N.W. current would increase by being more confined between these 
hill ranges,—as in the Great Glen of Scotland, and the strath which runs through 
Lochaber into Strath Spey. 
Then probably the detritus, previously forming beds more or less horizontal, 
would be formed into kaims or escars, whose direction would depend chiefly 
on the direction of the currents and tides. 
5th, In reference to the curved kaims or escars in the part of Glen Spean 
formerly described, it will be remembered that as these are (at one end) 1500 
feet above the sea; the sea must, when they were being formed, have been 
considerably above that height. On Ben Erin, one of the Glen Roy hills, there 
is a water line at a height of 1870 feet. At about the same height, there is a 
water line in Corry N’Eoin, on the rocky hill on the north side of the Glen. 
It was pointed out to me by Lord Abinger’s gamekeeper. 
A rapid current would at this time pass up Glen Spean, between Ben 
Chlinaig and Craig Dhu, both of which hills exceed 2000 feet in height, and 
this current would pass over into Strathspey. Glen Spean, whilst forming a 
narrow pass between Ben Chlinaig and Craig Dhu, opens out into the broad flat 
before described, occupied by the kaims and boulders. Just where the Glen 
so opens out, there stands a rocky hill called ‘“‘ Dun Dearg Mor,” well bared on 
all sides, and particularly the west, rising to a height of about 800 feet. 
This rocky hill might cause a division of the current, as it flowed eastward, the 
larger portion flowmg towards Treig, the smaller towards the Rough Burn. 
These streams, after curving past the adjoining hills, would unite farther east, 
and flow on through that part of the valley now occupied by Loch Laggan 
towards Strath Spey. 
6zh, Until the sea had subsided to a level below 1100 feet, none of the 
Lochaber lakes could have been formed. But in reference to materials for 
the blockage of these lakes, it is not unimportant to remember, that the 
extensive kaims just alluded to, consisting of detritus, exist at a level of 
1500 feet, which is more than 300 feet above the highest of the required 
blockages, and that on the hills near the Rough Burn, there are beds of 
detritus 1700 feet above the sea. 
In these circumstances, there is every reason to presume, that in the three 
valleys where blockages were required, viz. at 1170 and 856 feet, detritus must 
have jilled the glens to the requisite heights, and that they were removed by 
natural agencies before explained. 
7th, Lastly, I may observe, that whilst believing that the detrital theory is 
that which best explains how the lakes were dammed up, I can understand 
how other theories should have been suggested, and should have so long held 
their ground. The theory which ascribed the formation of the roads to the 
