188 
BATHYMETRICAL SURVEY OF 
Glen Salach, is of pre-Torridonian age, and has no connection with the 
later post-Cambrian movements. It developed a line of weakness, 
which, when stripped of the overlying Torridon Sandstone and 
Cambrian strata, would aid erosion either by the action of running 
water or land ice. Several faults enter the lake on the south side 
between Tobeg and Rudh’ an Alttoir, which, trending in a north-east 
direction, are coincident with inlets at the margin. Indeed, it is not 
improbable that the sudden deflection of the lake between Loch Assynt 
Lodge and Little Assynt — its course there being south-west and north- 
east — may be due to faults in the same direction, entering the lake at 
Little Assynt. 
Loch Leitir Easaich.- — ^This is a shallow rock-basin on the Archaean 
plateau, which, as already indicated, was originally an arm of Loch 
Assynt. Its long axis, trending north-west, coincides in direction with 
that of the Glen Salach fault, but the deepest sounding — 70 feet — 
does not lie in the line of this pre-Torridonian dislocation, but in a 
small basin to the south of it. 
Loch Beannach is another shallow rock-basin on the Archaean gneiss 
with very irregular outlines, its greatest depth being 38 feet. Numerous 
rock knobs project above the surface of the water. The long arm 
trending north-west to Loch an Dubh Uidh coincides in direction with 
an epidiorite dyke and with a line of disruption, but the numerous 
small bays reflect the varying lithological characters of the Archaean 
gneiss. 
Loch Druini Suardalain and Loch na JDoire Daraich are two shallow 
rock-basins lying in the consequent valley of the Glen Canisp river 
(Amhainn na Clach Airidh). A chain of small lakes lies along this 
ancient valley, all of which are rock-basins now in course of being 
silted up. The greatest depth of Loch Druim Suardalain is 31 feet. 
Several small faults cross this lake in a north-east direction, which 
produce a slight displacement of the intrusive dykes, but they do not 
seem to have modified the floor of the loch as indicated by the 
soundings. Loch na Doire Daraich is only about 9 feet deep. 
Loch Grdcach and Loch an Tuirc are likewise shallow rock-basins on 
the bare Archaean floor. The long axis of the former loch, which is 
about miles in length, lies in the line of a well-marked fault which 
has been traced for miles across the Archaean plateau. There can be 
little doubt that the straight feature of the west shore is due to this 
dislocation. Numerous roches moutonnees rise above the surface of the 
lake towards the east side. Again, in the case of Loch an Tuirc, a 
fault which shifts the intrusive dykes enters the lake at its outlet, and 
crosses it in a -north-easterly direction. The straight feature on the 
south side coincides with a zone of newer shearing in the Archaean 
gneiss trending east and west. 
Loch V eyatie and Fionn Loch. — These lakes lie in rock-basins in the 
