252 Proceedings of the Royal Society 
In making a short tour across the adjoining hills, I found many 
other boulders of grey granite, and mostly on hill slopes facing the 
north. One of these boulders, 6x4x4 feet, lay on a sort of shelf 
blocked at its S.E. end. 
4. At Dunstaffnage, about 5 miles JST.E. of Oban, there is a con- 
glomerate rock on which the old castle stands, as shown on fig. 3. 
The rock at the west end is about 30 feet above the general level of 
the land, and it extends horizontally for about 50 yards. On its 
east side the rock, though extremely tough, and full of large pebbles 
of quartz and other hard rocks, has been well smoothed by some 
agent of great weight and power which has come from the eastward. 
The conglomerate rocks on the beach below the castle, present 
similar smooth surfaces facing the east. 
Having learnt from the keeper of the castle, that smooth rock 
surfaces occur on a small island a few hundred yards to the east of 
Dunstaffnage, I procured a boat, and found two high knolls of con- 
glomerate rock, as shown in fig. 4, smoothed in a similar manner. 
Fig. 4. 
In going along the south bank of Loch Etive, one sees at numerous 
places great sheets of similarly smoothed rock, indicating, apparently, 
the action of a glacier which had moved down the valley now occu- 
pied by the loch. In the Fifth Report of the Committee (page 45), 
notice is taken of the Airde Point, on the west side of Loch Etive, 
where the rocks facing the south, i.e. up the glen, were found 
smoothed up to a height of 276 feet above the sea. 
