782 Proceedings of the Royal Society 
have been formed, on which blocks could fall from Stob Phan, to 
be carried to Mullach nan Correan ? 
The detrital bank , “ containing mud, gravel, and small rounded 
stones ” at a height of 2904 feet, 100 yards long and 40 feet deep, 
seems more like a submarine bank than a moraine, especially as at 
that height, any glacier generated about Stob Bhan could have 
had no opportunity of collecting sufficient debris to form a 
moraine of such dimensions. 
The striations on the rocks of Ben Nevis do not necessarily imply 
glacier action, for striations have often been seen in localities, as in 
islands, where no glacier could have existed. 
Professor Duns in his notes avoids adoption of any theory, but 
he mentions some facts which seem to suggest explanation. Thus, 
in noticing the “ gravel heaps,” he says, that the blocks which occur 
in them, are “ subangular blocks of the immediate neighbourhood,” 
and that the blocks which are erratics , occur on the gravel heaps; 
meaning apparently, that the gravel had been deposited first by one 
agency, and the erratics afterwards by another agency. 
In referring to boulders occurring on “ the mountain slopes,” 
Professor Duns takes special notice of the remarkably precarious 
position of many large “ granite boulders lying on mica schist rocks, 
where the side of the mountain slopes down so steeply as to make 
it a puzzle to understand, how they can remain in position ” 
(pp. 23, 24). 
It is also a puzzle to conceive what kind of agent it was which 
could set these boulders upon the steep slope of a hill so gently and 
exactly, as enabled the boulders to occupy positions of stability. 
One large porphyry boulder is mentioned with the “ angle of its site 
to the horizon 35° ” (page 23). Having been brought from a distance 
on a glacier or on floating ice, a boulder must in either case have 
fallen with such violence, as, by the reaction of concussion, to have 
slipped down any slope even though far from steep. 
The only rational way, as it appears to me, of accounting for the 
position of these boulders is to suppose that the valleys became filled 
with detritus when the land was submerged, and that floating ice 
dropped boulders on the detritus. If the boulders were dropped 
near the side of a valley, the boulders, as the detritus was removed 
by rain and mountain streams, would slowly and gradually sink till 
