of Edinburgh, Session 1879 - 80 . 579 
gneiss and mica schist. I measured several, the largest contains 
about 150 tons. 
The Old Red Sandstone formation occupies the west coast for 
some miles. It is well covered by detritus, and on the detritus, 
especially when it slopes to the west, there are many boulders of 
granite and gneiss, which from their position appear to have come 
from the X.W. 
Fig. 1, plate XVII., represents a bank of gravel, at a height of 
about 50 feet above the sea, and sloping to the sea in a X.X.W. 
direction at an angle of about 25°, well covered with gneiss 
boulders, of which three are represented. There was no rocky cliff 
from which they could have fallen. They were true erratics. Thick 
turf had formed on the bank, which partly covered the boulders. 
Fig. 2, plate XVII., represents, near the above spot, another boulder 
of gneiss, at a height of about 40 feet above the sea, lying on a 
mass of reddish coloured mica schist, blocked at its south end. Its 
longer axis lay X. by E. and S. by W. It had apparently come 
from the north, and been stopped in its further progress by the 
rocks at its south end. 
On the shore, I found a boulder partially in a fissure which 
cuts through the mica schist strata, here forming tablets or sheets 
nearly horizontal. Figs. 3 and 4, plate XVII., represent a fissure 
running X.W. and S.E., about 6 feet wide. The boulder, 
very hard gneiss, 10 x 5 x 4 feet, was sticking in this fissure. Fig. 
3 represents the fissure running N.W. and S.E., and the upper part 
of the boulder projecting above it. Fig. 4 represents the interior 
of the fissure partially filled with pebbles, and the boulder resting 
partly on them and partly on the S.W. wall of the fissure, whilst 
the other end of the boulder, outside and above, was resting on the 
X.E. edge. The boulder had clearly been pushed from the north- 
ward (from B in figs. 3 and 4), and on reaching the fissure had 
partially fallen into it, and become jammed there. 
If the idea of a sea-current from the north, with ice floating in it, 
be entertained, there seems to be no difficulty in explaining the 
above facts. The weight of the boulder was about 15 tons. 
On the same part of the shore, there were many other hard gneiss 
boulders. The largest measured was 12x6x6 feet, its longer axis 
pointing north and south, 
