134 Proceedings of the Royal Societ 
3. Hear Lach Castle valley, i.e., about 1-J mile south of it, and 
about 2 miles north of Borve, a striated rock was observed on the 
roadside. It had recently been uncovered by the removal of road 
materials. The rock was Silurian. It was well smoothed, and 
sloped gently to the west. The striae were minute, but quite dis- 
cernible, and running H.W. The rock was on the H.W. side of 
the hill called in the Admiralty chart Carron Hill, and close to the 
sea, which was all open toward the H.W. As Carron Hill, with a 
height of 786 feet, was to the S. and S.E., the presumption 
afforded by the surrounding land features was that the striating 
agent had come from the north. 
4. Lach Castle bay and valley is shown on figs. 25 and 26. 
When the tide is out, the road between Borve and Tarbert crosses a 
sandy flat ; but when the tide is up, the margin of the land is indi- 
cated by the dotted line. There is an immense accumulation of 
boulders on the S.E. side of the hill marked A, where Carron Hill, 
above referred to, is situated. The X on the fig. indicates the spot 
where the striated rock was observed. 
If, when the sea stood say 1000 feet or more above its present 
level, boulders were brought by a current from the H.W., the facts 
observable in this Lach Castle valley could be explained. 
In that case, the current would flow through the valley, pressing 
most upon the range of hills on the east side, and smoothing its 
rocks; whilst the rocks on the west side of the valley would remain 
rough. This is found to be the case on an examination of the two 
sides of the valley. 
Icebergs or floe ice carrying boulders may have flowed up the 
valley from the north, discharging them chiefly on the hills along 
the east side of the valley. These hills bear on their sides and 
ridges numerous boulders, some of large size. Several of these were 
examined, and one or two gave indubitable proof, by their sites 
and by their own positions, that they had come from the north 
or H.W. 
In the centre of the valley there is an elongated ridge (as shown 
on fig. 25, l.c.) which bears far more boulders than the depressed 
portions between it and the sides of the valley. There may be two 
ways of accounting for this. If the valley was originally of its 
present form, any ice borne on a current flowing through the valley 
