104 MR DAVID MILNE HOME: MEMOIR ON THE 
When the sea began to retire, the river discharging from the lake would 
acquire more power of erosion, and would cut out for itself lower channels as 
the sea continued to subside. 
VII. The Glacial Markings in Lochaber, and their bearing on the Parallel 
Roads question. 
Having explained the grounds on which I consider that the blockages 
of the lakes were due to accumulation of detritus at the mouths of the 
glens, it is right that I should advert to the ground on which the ice theory 
rests. 
There are undoubtedly marks of land ice in several of the glens. The 
upper part of Corry N’Eoin, at a height of about 1350 feet above the sea, 
is exceedingly narrow,—not more than a few hundred yards wide, with 
rocky sides, almost perpendicular. The floor of the valley is also rock; 
and in one part shows evidence of ice having moved down the valley, 
by long groovings and striations, in a direction parallel with the axis of the 
valley. 
So also at and below the mouth of Loch Treig, there are rocks smoothed 
and striated, which seem to show, though not so unequivocally as in Corry 
N’Eoin, that ice has passed over these rocks—from Treig Valley. 
But neither of these valleys is of sufficient size, as regards width, length, 
or depth, to have generated glaciers, even in the most favourable climate, of 
the dimensions required for the alleged ice barriers, and still less for reaching 
the sites of these barriers. 
Independently, however, of this difficulty, it is important to observe at what 
period these glaciers existed. It was at a period in the world’s history long 
antecedent to the formation of the Lochaber Lakes. It is quite evident that 
the detritus now in the district must have come at a period subsequent to the 
grinding and striation of the rocks ;—because, in numerous places, these rocks 
are seen to be covered by the detritus.* 
Now, it was not till after this detritus had been deposited, that the Parallel 
Roads were formed, because it is on the detritus that they were formed, as 
every geologist who has visited Lochaber, allows. 
Moraines, it is alleged, occur in Glen Spean, and they are referred to as 
proving that large glaciers must have existed to produce these Moraines. 
which, when the name was given, came up to a point not far from this? ‘‘ Mur-laggan,” situated 
on the north bank of the supposed lake, signifies “hollow by the sea or lake,” ‘‘ Monessie,” or 
“ Munessie,” situated at the lower or west end of the supposed lake, signifies the plain by the waterfall. 
Was this the waterfall from the lake over the ridge or barrier of the lake? The word Muir, which 
makes its genitive in Mara, is evidently the same word as the Latin Mare, the English Mere, the French 
Mer, &e. 
* See my last Memoir, p, 641, and JAMESON, Geol. Soc. Proc, vol. xix, p. 241. 

