184 BATHYMETRICAL SURVEY OF 



The Assynt district furnishes impressive evidence of denudation by 

 the removal of a vast covering of Torridon Sandstone, by the persistent 

 eastward recession of that escarpment, by the stripping off of the 

 materials overlying the successive thrust-planes, and also by the 

 development of the present drainage system. It is a remarkable fact 

 that south of the mountainous region of Assynt the watershed lies to 

 the east of Cul Mor, Cul Beag, and the Coigach mountains in the less 

 elevated platform of the Moine schists. It is evident that the present 

 drainage system originated at a remote geological period, when the 

 eastern or Moine schists extended far to the west of their present 

 limits, and were arranged in the form of a dome round the displaced 

 masses which now form the mountainous region of Assynt. It is highly 

 probable, also, that before the glacial period the land stood relatively 

 higher than at present, and that the rivers on the west side of the 

 watershed occupy consequent valleys which extended far to the west 

 of the present coast-line. 



Everywhere throughout the Assynt district, and especially in the 

 mountainous region extending from Glas Bheinn to the Coigach area 

 and over the plateau of Archaean gneiss, there is conclusive evidence of 

 intense glaciation. Perhaps the most striking feature of the glacial 

 phenomena of Assynt is the evidence pointing to the conclusion that 

 during the maximum glaciation the ice-shed did not coincide with the 

 existing watershed. From an examination of the striae indicating the 

 direction of the ice-flow, and from the distribution of boulders, it 

 appears that the ice-parting lay to the east of the present watershed. 

 Indeed, the ice must have accumulated to a great thickness on the less 

 elevated plateau occupied by the Moine schists east of the Ben More 

 Assynt range and east of the Coigach mountains. 



The general movement of the ice at great elevations in this district 

 was in a westerly direction, sometimes to the north and sometimes 

 south of that point. For example, on Glas Bheinn, on one of the 

 exposures of Archaean gneiss, at a height exceeding 2000 feet, the 

 striae point W. 5 N. Again, on Beallach an Uidhe, between Glas 

 Bheinn and Beinn Uidhe, at an elevation of about 2000 feet, the 

 direction is west-south-west. East of Inchnadamph, on the quartzite 

 of Beinn an Fhurain, between the 2000- and 2250-feet contour-lines, 

 the striae run north of west. In the lofty pass crossing the Ben More 

 range, that leads into Corrie Mhadaidh, at a level of 2750 feet, the 

 direction is W. 10 S. or W.S.W. In like manner, on the long ridge 

 of Breabag that runs northward from the Beallach of Coniveall, the 

 average height of which is over 2000 feet, splendidly striated surfaces 

 have been recorded which indicate an ice-movement in a westerly 

 direction. 



Passing westwards to the mountains north and south of Loch 

 Assynt, we find similar evidence of a westerly movement during the 



