106 MR DAVID MILNE HOME: MEMOIR ON THE 
The denuding agent of which Mr Jameson speaks, flowing over the hills 
at a height of 3055 feet, leaving great boulders on the top, but sweeping 
off all smaller fragments, can scarcely be conceived to be anything else than 
a sea loaded with floating ice. 
(2). With regard to the enormous mounds of gravel, and multitudes of 
boulders resting on them, situated in Glen Spean between the Rough Burn 
and Loch Treig, and which have been called the moraines of the Treig 
Glacier, I may observe, that any glacier which could ever have come from 
Loch Treig must have been far too insignificant to have produced effects on 
so large a scale. Moreover, several of the gravel mounds are at heights 
(viz., 1500 above the sea) which could never have been reached by any 
glacier flowing out of Glen Treig, where the waters of the lake are now only 
740 feet above the sea. 
In my last Memoir, I threw out a conjecture, that these so-called moraines 
were submarine banks, formed when the sea prevailed here, at a level of 2000 
or 3000 feet above its present level. 
This conjecture has been strengthened by a more special examination. At 
one end, viz., to the east of Loch Treig, the embankments run on lines nearly 
horizontal, and along the face of a hill, in an east and west direction, at a 
height of about 1500 feet above the sea. They then change their direction, 
and run first in a nearly north-east direction, and afterwards due north, forming 
two or more concentric crescents or curves, and about 200 yards apart, whose 
concave sides face down the valley of Glen Spean. They are even continued 
to the opposite side of the valley on the hill called Coinichte, situated to 
the north of Rough Burn. (See Map on Plate XLIII. of former Memoir.) 
These embankments are, in respect of continuity and shape, more numerous 
and distinct when they are above the level of Shelf 4, which is 856 feet above 
the sea. Below that shelf, they were of course covered by the waters of the 
old Glen Spean Lake ; and when that lake, or a large portion of it, rushed 
down Glen Spean, on the rupture of its blockage, the embankments in the 
central and lowest part of the valley would be to a great extent broken up; 
and cliffs or banks would be formed, approximately parallel with the axis of 
the valley. Such banks do occur along the course of the Spean, in the centre 
of the valley. 
If the idea of submarine banks be adopted, the sea at this place may have 
been from 1000 to 2000 feet deep. In that view there would be a narrow 
passage at the west end, viz., between Ben Chlinaig and Craig Dhu, with a 
strong current running through it from the west,—and at the east end, viz., near 
Mukkul, a similar narrow passage; whilst in the district between Treig and 
Rough Burn, there would be a wide basin, with little current, where the 
gravel banks would be formed by eddies, many examples of such occur in 

