248 LATEST GLACIAL CHANGES IN SCOTLAND. CHAP. xui. 



Latest Changes produced by Glaciers in Scotland. 



We may next consider the state of Scotland after its 

 emergence from the glacial sea, when we cannot fail to 

 be approaching the time when man coexisted with the 

 mammoth and other mammalia now extinct. In a paper 

 which I published in 1840, on the ancient glaciers of Forfar- 

 shire, I endeavoured to show that some of these existed after 

 the mountains and glens had acquired precisely their present 

 shape,* and had left moraines even in the minor valleys, just 

 where they would now leave them were the snow and ice 

 again to gain ground. I described also one remarkable 

 transverse mound, evidently the terminal moraine of a 

 retreating glacier, which crosses the valley of the South Esk, 

 a few miles above the point where it issues from the 

 Grampians, and about six miles below the town of Clova. It 

 is situated at a place called Grlenairn (perhaps 700 feet 

 above the level of the sea), where the valley is half a mile 

 broad and is bounded by steep and lofty mountains. The 

 valley immediately above this transverse barrier expands 

 into a wide alluvial plain, which has evidently once been a 

 lake. The barrier itself, nearly 200 feet high, consists in its 

 lower part of till with boulders, 80 feet thick, precisely resem 

 bling the moraine of a Swiss glacier, above which there is a 

 mass of stratified sand 100 feet thick, which has the appear 

 ance of consisting of the materials of the moraine re-arranged 

 in a stratified form, possibly by the waters of a glacier lake. 

 The structure of the entire barrier has been laid open by the 

 Esk, which has cut through it a deep passage about 300 yards 

 wide. 



I have also given an account of another striking feature in 

 the physical geography of Perthshire and Forfarshire, which I 



* Proceedings of the Geological Society, vol. iii. p. 337. 



