484 THE FRESH-WATER LOCHS OF SCOTLAND 
(3696 feet) on the confines of Ross-shire and Inverness-shire, two 
instances occur in a double corrie at a height of 2250 feet. They lie 
on a well-glaciated floor of hornblendic gneiss with prominent cliffs of 
muscovite-biotite gneiss rising behind them. 
Mr Harker has noted the occurrence of the following corrie rock- 
basins in the Cuillins : — Coir' a' Bhasteir at an altitude of 2250 feet ; 
Coir' SL Ghrunnda, 2220 feet; Coir' an Lochain, 1815 feet; Coire 
Labain, 1805 feet, which he ascribes to excessive ice-erosion in the 
head portions of the valleys. 
ROCK-BASINS ALONG SHATTER BELTS 
Reference has already been made to many rock-basins lying along 
lines of fault or shatter belts. The soundings of the Lake Survey 
show that, as a rule, they form simple basins with comparatively flat 
floors, and U-shaped in cross-section. Like the valley rock-basins 
free from shatter belts, they are an integral portion of the valley 
system in which they occur. The members of this group are of most 
common occurrence in the highly dissected plateaux where the 
normal valley and plateau basins are most abundant. In all those 
regions where valley rock-basins are absent the shatter belts are 
hollowed out relatively to the trunk streams which cross them. 
Loch Ness is perhaps one of the best examples of this group, for it 
lies along the line of fault traversing the Great Glen. It is ponded 
partly by glacial deposits and fluvio-glacial gravels, and partly by 
raised beaches ; but as it is deeper than any part of the bed of the 
North Sea between Scotland and the Norwegian Deep, there can be 
little doubt that it is a rock-basin. The soundings show that it possesses 
the typical form of a rock-basin. Like other depressions, it received 
great accessions of ice from either side, and was subjected to extreme 
erosion by the ice moving north-eastward towards the Moray Firth. 
In brief, a careful consideration of all the available evidence has 
led us to the conclusion that the distribution and form of Scottish 
rock -basins bear a direct relation to the geological structure, topog- 
raphy, and glaciation of the particular regions in which they occur, 
and that such basins merely represent a phase of the differential 
erosion of the whole country by the action of land ice. 
Ill the preparation of this paper and of the notes descriptive of the geological 
features of the rock-basins, we have freely availed ourselves of the information 
embodied in the maps and memoirs of the Geological Survey of Scotland. We 
desire further to acknowledge our obligations to the officers of the Geological 
Survey for valuable assistance rendered during the j^rogress of the Scottish Lake 
Kesearch investigations. 
In addition to the publications of the Geological Survey of Scotland, the more 
important works which have been consulted in the preparation of this paper are 
given in the subjoined list. 
