On the Great Terrace of Erosion in Scotland. 103 



pact than the former, contains a greater number of blocks, 

 and these reaching a much greater size, and many of them 

 smoothed and striated— a peculiarity I could not detect in 

 any of those which rest in the deep mass of detritus nearer the 

 summit of the pass. It is possible that that mass, then, may 

 be composed of washings from the adjacent hill sides, effected 

 at a time when this valley was a sound ; but I incline rather 

 to class it with such phenomena as Professor Ramsay has 

 found in Wales, and myself in Scotland, and which I regard 

 as relics of an old clay, due to a general glacial action over 

 the surface of the country, and which has been removed and 

 replaced by a looser material in all parts possessed of the re- 

 quisites for ordinary local glaciation, namely a certain eleva- 

 tion, and the existence of high valleys or bosoms of the hills 

 sufficiently wide to serve as the oerceaux of glaciers. 



On the Great Terrace of Erosion in Scotland, and its Rela- 

 tive Date and Connection with Glacial Phenomena. By 

 R. Chambers, F.R.S.E. 



A terrace of erosion is very conspicuous along the coasts of 

 Scotland, at between twenty and thirty feet above the present 

 level of the sea. It is well marked along the Firth of Clyde, 

 including the islands of Bute and Arran, and generally on 

 the coasts of Argyleshire. On the east coasts of Scotland, 

 which are well known to be of so much less bold a character 

 than those of the west, it is less remarkable ; yet it has been 

 traced on the Firths of Dornoch and Cromarty, while it may 

 be said to have an equivalent in the Firth of Forth, in the 

 well-known bench of land, of about the same elevation, which 

 stretches along both sides of that estuary. Everywhere, as is 

 well known, shells of the present epoch are found on this terrace, 



On the western coasts of Scotland, the breach which it 

 makes in the outline of the land is very striking. Generally 

 the hills slope in a smooth line to the sea, and very often we 

 find this slope but little broken even where the sea is now in 

 contact with the land. But between the slope above and the 

 only somewhat more broken slope of the existing beach below 3 

 this line of erosion forms generally a well-defined rectangular 



