J. F. Campbell Collection > Additional memoir on the parallel roads of Lochaber

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 woukl cut out for itself lower channels as
the sea continued to subside.
VII. The Glacial Markings in Lochaher, and their hearing on the Parallel
Roads question.
Having explained the groinids on which I consider that the blockages
of the lakes were due to accumulation of detritus at the mouths of the
glens, it is i-ight 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
ujjper 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 Avorld's history long
antecedent to the formation of the Lochaber Lakes. It is quite evident that
the detritus now in the district mvist have come at a period subsequent to the
grinding and striation of the rocks ; — because, in numerous places, these rocks
are seen to bo covered by the detritus.*
Now, it Avas 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
l^roving that large glaciers must have existed to produce these Moraines.
which, when the ri.ame was given, came up to a point nut far from this? " Jl/Hr-/((;/7aH," situated
on the north hank of the supposed lake, signifies " hollow by the sea or lake," " Monessie, " or
" Mii)ie.wii_'," 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 Miiir, which
makes its genitive in Mum, is evidently the same word as the Latin Marc, the English Mere, the French
Mer, &c.
* See my last Jlenioir, p. 041, and Jameson, GcvI. Svc. J'roc. vol. xi.\. p. 241.