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Proceedings of the Royal Society 
IV. Conclusion. 
The facts which I have stated seem to warrant the theory, that 
when these rocks and boulders were striated, this part of Europe 
was submerged beneath a sea which reached to the tops of our 
highest hills, and that ice floated on this sea, carrying boulders 
and discharging them wherever the ice melted or was arrested 
by submarine obstructions. 
When the sea stood at a high level, effects would be produced on 
our hill tops and hill sides. As the sea subsided, similar effects 
would be produced at lower levels. 
During the whole period when Great Britain was submerged, we 
know that the sea was of so low a temperature as to be suited for 
floating ice. The shells found at a height of 1800 feet in the west 
of England contain several species of an arctic type. These arctic 
species occur likewise in Scotland, but at lower levels, when, 
therefore, probably the sea had greatly subsided. 
What all arctic voyagers report as having been seen by them 
may, therefore, have occurred in Scotland; for they saw rocks 
smoothed and striated, — and boulders occupying such positions, — as 
to satisfy them that icebergs, and floating ice in various forms, 
were the agents which had been, and were then, at work in these 
phenomena. 
With regard to the glacier theory, it seems to me that to account for 
the striated rocks and boulders in the valley of the Forth, that theory 
is attended with insuperable difficulties. If the striations on North 
Berwick Law, and in East Lothian generally, were due to a glacier, 
so must also have been the striations on Stirling Castle rock, the 
Abbot’s Craig, Torwood, and the Pentlancl Hills. This glacier, 
therefore, must have been of gigantic dimensions, filling the whole 
valley of the Forth, reaching to a height of 2000 feet above the 
present sea-level, and to a depth of at least a hundred feet below it, 
with a width of some 20 or 25 miles, when at the mouth of the 
present Firth of Forth. But where could be the birth-place of such 
a glacier] Certainly not in the valley of the Forth; for the head 
of the valley is only 220 feet above the sea, that being the height 
of the ridge which separates the valley of Loch Lomond from the 
valley of the Forth. 
