252 R. Chambers, Esq., on Glacial Phenomena 



passage across the island in Ross-shire, — the dreary Dirry 

 More. 



It seems to me that the whole phenomena can only be ac- 

 counted for, by our supposing that there was, first, a general 

 sweeping of the surface of this district by a deep flow of mo- 

 bile ice, one great cause, if not the principal, of that enormous 

 denudation which has been described, but of which the spoils, 

 from the universality and power of the agent, were in a great 

 measure carried away. Second, local; and certainly subaerial 

 glaciers, occupying certain valleys in the more elevated moun- 

 tain systems, and producing moraines, composed of brown 

 clay, sand, and blocks. The small glaciers first pointed to 

 in this paper were perhaps of a still later date, when the 

 mean temperature was not much below its present point. 



The examples which have been cited do not, after all, refer 

 to a very extensive district ; but when we take a wider range 

 of observation, we find phenomena which are for the most 

 part in perfect harmony with those of the west coast of Assynt. 

 Passing northward to Rhiconich, we find near that place 

 stria) coming in from the coast, from the north-west, and 

 passing across a high moor, with no regard whatever to the 

 inequalities of the ground. A little farther north, at Loch 

 Laxford, a fine surface is marked with striation from the 

 north-west, being across the valley in which it occurs. At 

 an opening in the bold gneissic coast which looks out upon 

 the Pentland Firth, there is strong marking in a direction 

 from NNW. The high desolate tract called Moen, between 

 Loch Eribol and Tongue Bay, where there is nothing that 

 could restrain or guide the movement of the ice, exhibits 

 striation from N. 28° W. Stria?, in nearly the same direc- 

 tion, namely, N. 25° W , occur four miles to the east of 

 Tongue Bay. On perfectly free ground, at Armadale, the 

 markings point almost directly from the north. When we 

 pass on to Caithness, where the country generally is of that 

 rounded undulating character which speaks of glacial action, 

 we find a few traces of striation, still from points between 

 north and north-west, which is directly transverse to a line 

 pointing f<> the neighbouring hills. At the Clynelish quarry, 

 near Brora, in Sutherlandshire, the fine surface of smoothed 



