589 
of Edinburgh, Session 1879 - 80 . 
These striae seemed deeper at their west ends, as if the tools which 
cut them, had struck the rock first at these ends. 
The boulders on Loch Killesport appeared to me, from their posi- 
tions, to have all come from the westward. If they came on floating 
ice, the sea must at that time have stood at a high level to have 
floated ice of sufficient size to carry and deposit boulders of such 
weight as those above described. On that point there need be no 
difficulty, as there is abundant evidence that the sea prevailed over 
the Highlands of Scotland to a height of at least 2000 feet, and 
thereafter subsided, whether gradually or rapidly is not yet known. 
The sea-bottom on which the boulders were dropped, would of couise 
present a very different surface from what forms the present dry land. 
What are now valleys in the land would be formed (after the sea sub- 
sided) by the detritus which filled these hollows being scoured out by 
rivers; whilst the boulders which had occupied the old sea-bed, when 
too heavy to be moved by river floods, would remain in the newly 
formed valley, though sometimes at lower levels. In like manner, the 
boulders which are now on the shores of sea lochs, may in many 
cases have been undermined by the scouring out of detritus by tides 
and storms, and sunk to a lower level than they originally occupied. 
Hence it is that along the present line of high water the boulders are 
generally more numerous than elsewhere ; and the same circumstance 
occurs everywhere along the old sea-margin, as in Loch Killesport. 
10. Another place visited was Loch Svnn, an arm of the sea on the 
west coast of Argyleshire, about 16 miles west from Lochgilphead. 
Mr Alexander of Lochgilphead kindly accompanied me to this 
district also. At Keills , on the north bank of the loch, close to its 
mouth, there are several boulders of a light-coloured grey gneiss, and 
one or two of a fine-grained granite. The rocks on which they rest 
are a coarse dark-coloured Silurian. 
The first boulder examined was on the shore facing the island 
of Jura, here distant about 4 miles to the west. Its size was 
12 x 10 x 9 feet. It lay on a bank sloping down towards the sea 
at an angle of about 15° to the W.N.W. It rests on Silurian rock, 
at a height of about 50 feet above the sea, and about 100 yards 
from the beach. 
About a mile to the eastward, and not far from the old ruinous 
church of Keills, there is another grey gneiss boulder, 18x15x12 
