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BATHYMETRICAL SURVEY OF 
slightly oblique to the long axis of the loch, but almost parallel to 
that of the 50-feet basins. The latter in turn have their longer axes 
somewhat oblique to the strike of the Torridonian strata. 
Loch Gliiuragarstidh is a shallow loch lying along the strike of the 
Torridon Sandstone, with an exposure of Lewisian gneiss near its outlet, 
its greatest depth being 37 feet. A long ridge of sand and gravel, 
probably a moraine, occurs near its mouth, so that this lake may lie 
partly in drift and partly in rock. 
Loch Tollic is a true rock basin of very irregular shape, surrounded 
by Lewisian gneiss, the deepest sounding being 86 feet. This basin 
belongs to the shallow plateau type so common in the Archaean area 
in the west of Sutherland. Its irregularity is due to the folding and 
intense shearing of the component members of the Lewisian gneiss in 
that region. Glacial striae are met with at several localities round the 
loch, varying in direction from W. 10° N. to W. 41° N. The dominant 
strike of the foliation of the gneiss is west-north-west and east-south- 
east. The long axes of the bays in the loch are more in accordance 
with the direction of the ice-flow than with the strike of the foliation. 
Loch Glair lies partly in moraine drift and partly in thrust 
Torridonian strata. Drift occurs at the outlet and along its western 
margin, and all the islands are composed of moraines. 
Ijoch CouJin is separated from Loch Clair by an alluvial fan brought 
down by the Allt na Luib. The river Coulin has silted up the greater 
part of the upper end of the lake, and its limits have been still further 
restricted by detritus borne downwards by the streams on the north. 
