510 PROCEEDINGS OF THE GEOLOGICAL SOCIETF. [Julie 25, 



Two other small lake-basins in the same immediate neighbour- 

 hood are differently situated, yet also in positions which make it 

 impossible to attribute them to ice. One is called Loch Nanum, 

 the other Loch Shalaga. They are both on the very tops of gra- 

 nitic hills, one of them occupying the summit-level between Loch 

 Awe and Loch Fyne. These are comparatively shallow basins, 

 simply depressions in the granite, with low round knolls forming 

 the banks. These likewise are not in the path of any glacier, and 

 they are in positions in which it is difficult to conceive that ice of 

 any kind could have employed itself in digging holes. 



The last lake mentioned was a very peculiar one, called the 

 Dhu Loch. It lies in the valley near Inverary called Glen Shira, 

 and is separated from Loch Fyne by a mass of gravel filling up 

 the mouth of the valley. It is exactly on the level of half-tide, 

 so that at high-water Loch Fyne flows into the lake and makes the 

 water brackish. This lake is a depression in detrital matter, with 

 which the lower part of the valley and the lake are being rapidly 

 filled. This is a case, and the only case in the district, where, in 

 the author's opinion, the basin might be accounted for by glacier- 

 action. It is just such a hollow as might possibly be formed by 

 the weight and motion of a glacier coming down the valley from 

 Ben Buie, which lies at the head of it ; and the semicircular form 

 which the barrier of gravel has assumed, on its inward face, suggests 

 the idea of the action of the sea beating up against the point or 

 nose of a protruding glacier. It thus appears that of six lake- 

 basins, large and small, near Inverary, only one is marked by con- 

 ditions which seem to render it at all probable, or even possible, 

 that the formation has been due to the action of ice. 



Discussion. 



Prof. Ramsay dissented from those parts of His Grace's remarks 

 which might lead the hearers to suppose that he had attributed 

 all valleys and lake-basins, without exception, to glacial action. 

 On the contrary, he had always maintained that in many in- 

 stances original valleys were due to various agencies, both of super- 

 ficial denudation and of internal disturbance, and acting at all periods 

 of the earth's existence. These earlier inequalities had. often indeed 

 received their final configuration from the action of ice ; and it was 

 only to certain lake-basins that he assigned a purely glacial origin. 



He disclaimed many of the ideas popularly attributed to him, 

 regarding them as utterly irreconcilable with the phenomena of 

 nature. As to the sides of the basins, nowhere had he seen a case 

 in which he could regard the existence of a lake as merely due to a 

 fracture of the rocks. In the Highlands of Scotland it was well 

 known that most of the contortions of the rocks had taken place 

 before the deposition of the Old Bed Sandstone. He wished to 

 know whether during the ages that had passed since that time all 

 atmospheric agencies had been suspended. On the contrary, their 

 operation had been such that thousands and thousands of feet of 

 strata had by their means been removed. Nowhere was this prin- 



