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is generally agreed, that Scotland, England, and Ireland was, 
during the Glacial period, submerged, so that most of our hills 
were covered ; and judging by the types of molluscs, and skeletons 
of seals (of a species existing only in an arctic sea) found in 
our clay beds, the submerging ocean must have been of an arctic 
character.* 
With reference, therefore, to such trainees of boulders, as have 
been found by Professor Heddle, among the Highland hills, the 
same explanation is, to say the least, admissible. 
Third . — But there are other districts covered with boulders 
to which this explanation is not applicable. I refer to the 
Western Islands and the Hebrides (Islay, Tiree, Barra, Uist, 
and Harris), all of which have numerous boulders on hill slopes 
facing the Atlantic, and which, judging by the peculiar position 
and attitude of many of them, clearly show that they have come 
from a westerly or north-westerly direction. On these islands, 
with no ranges of hills on them of the necessary height, local 
glaciers are out of the question. On the north-west coast of 
Argyleshire, there are, in like manner, boulders in positions which 
convinced the late Robert Chambers, the late Dr Bryce, the late 
Professor Nicol, and Mr Jameson of Ellon, all of whom personally 
examined them, that they also had come across the sea, and not 
from any inland district. 
But where in a direction west or north-west, is there any land 
from which these boulders could have come, and how could they 
have traversed the wide Atlantic? Though there are probably 
entire hills of granite and gneiss in Labrador and Greenland, it is 
hardly conceivable that any ice-bergs or ice-floes obtaining boulders 
there, could reach our shores to discharge their cargoes upon them, 
even though there had then been no Gulph-Stream to intercept and 
melt them. 
Is no other hypothesis possible ? 
(1.) There now exists, about 190 miles to the west of the 
Hebrides, a range of submarine granite hills, whose peak, called in 
our charts “ Rockallf stands above the sea-level to the height of 80 
feet ; and within about 2 miles from it, there are two rocks, 
* See an interesting article by Professor Turner of Edinburgh University, on 
these fossil seals, in “ Journal of Anatomy,” vol. iv. p. 270. 
