616 
Proceedings of the Royal Society 
of 1940 feet. A number of blocks of this rock were found by me 
at the west foot of Miall an Aodain, a hill situated to the east- 
ward. 
How these two sets of boulders have been carried to their present 
positions is a question on which I have yet formed no decided 
opinion. As perhaps bearing on that question, however, it is right 
to mention that the rocks near the fountain-tarn of the River Durer, 
at a height of 1940 feet, are much glaciated and apparently from the 
west. 
Striae occur on a clay-slate rock about J of a mile south from the 
place just mentioned, just before the ascent of Stob Coire Ruadli 
commences, and at a height of nearly 2000 feet, which show a 
movement from a little to the north of west. These facts seem to 
suggest that some powerful smoothing and striating agent had passed 
over this district from the west, and at a level exceeding 2000 feet 
above the sea. But west from the place where these smoothed and 
striated rocks occur, there are no hills so high as to produce a glacier, 
unless, indeed, a glacier had come through Glen Tarbert, which is a 
continuation of Loch Sunart, and crossed what is now the Linnhe 
Loch. Loch Sunart and Glen Tarbert occupy a hollow in the dis- 
trict which runs in a direction about W.N.W. and E.S.E. 
It is, however, proper to add, that on the rock where these W.N. W. 
striae occur, there are cross striae overlying and cutting into these, 
which cross striae indicate a movement from the S.W. These cross 
striae being more sharp and minute than those first made, indicate 
more recent and also less powerful action. Can it have been that a 
sea existed at a level exceeding 2000 feet above the present level, 
with ice in it which was floating about in eddying currents, among 
what are now high peaked hills, tearing rocks out of the shallows, 
and pushing them over what were then submarine reefs 1 
In regard to the boulders at Ivercreran and Fasnacloich, they 
manifestly have come from the particular hills above specified ; but 
whether dropped from floating ice, or carried by glaciers, it is with 
our present information impossible to say. 
The striae last mentioned, as occurring at the height of 2000 feet, 
pointing about W.N.W., bear on the top of Fraochaidh , a hill 2883 
feet high. 
But between that hill and the rock on which the striae appear, 
