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 Druim Suardalain and Loch na Doire 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 Crocach and Loch an Tuirc are likewise shallow rock-basins on 

 the bare Archaean floor. The long axis of the former loch, which is 

 about 1^ 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 Veyatie and Fiotin Loch. These lakes lie in rock-basins in the 



