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of Edinburgh^ Session 1877 - 78 . 
murchan, and Mull, which are described in my paper. I think 
there is no room to doubt it was derived from one of these localities 
— the rock is so peculiar and well characterised. 
“ Fast lacloich Boulders , Nos. 2, 3, 4, are very ordinary gabbros, 
such as form great mountain masses in Skye, Ardnamurchan, and 
Mull. These rocks are of a striking character, and differ from any 
which I know of on the mainland. I think it is certain, they were 
derived from the Western Isles.” 
Professor Judd, in his paper on the ancient volcanoes of Mull, 
Skye, and Ardnamurchan, refers to proofs that these volcanoes 
reached a greater height above the sea-level than any of the 
existing Scotch mountains, perhaps even to the height of 14,500 
feet,* and that “ denudation” had acted to an enormous extent in 
breaking up the old volcanic rocks and lowering their height. 
Professor Judd does not particularly specify the nature of the 
denuding agent which he supposed produced this effect. But if the 
sea with ice floating in it, at a height of say 2000 or 3000 feet above 
the present level, be allowed to be a denuding agent, it is easy to 
see how the boulders of Appin and Fasnacloich, if derived from Mull 
or Ardnamurchan, might have reached their present positions. 
The distance of Appin and Fasnacloich from Mull and Ardna- 
murchan is about 30 miles. The intervening sea has in some 
places a depth of 100 fathoms. The island of Lismore, which is 
in this part of the Linnhe Loch, at one spot only reaches a height 
of 420 feet. A sea current flowing across Mull and Ardnamurchan, 
towards and through what is now known as “ Glen na Albin,” with 
mountains on each side of the Glen reaching to 2000 feet above the 
present sea-level, might, by floating ice, have carried boulders and 
lodged them in lateral valleys, such as Loch Creran. 
11. Crinan Canal . — At the summit level, about half-way between 
the two extremes, there is a large accumulation of boulders, chiefly 
angular in shape. On the west side of the canal at the “ locks” a 
body of rock stands up, whose surfaces facing the north present 
marks of abrasion as if caused by some body or bodies passing over 
from the north. On the south side of this rocky knoll, lie a num- 
ber of boulders which, if they came from the north on floating ice, 
may have been projected over the knoll by its intercepting the ice 
* Quarterly Journal of the Geological Society for August 1874, page 259. 
