98 R. Chambers, Esq., on Glacial Phenomena 



presence of valley glaciers in our chief mountain systems, the 

 detritus of which was of a lighter, looser, and coarser texture, 

 indeed identical in character with the moraines of existing 

 Alpine glaciers. The latter glacial operation I considered as 

 for certain taking place without the presence of the sea, and 

 in circumstances which admitted of a constant drainage from 

 the body of the glaciers. The former I deemed as showing, 

 in its effects, that either the sea was present, or that the ice, 

 covering a large surface of country, and consequently having 

 no drainage comparable to that of a valley glacier, retained 

 its own water within or about itself, so that the circumstances 

 were not greatly different from what we might expect in large 

 floods of sea-borne ice. It must remain an obscure problem 

 how ice can move over large surfaces of country ; but that its 

 so moving is a fact of nature, has, since the preparation of my 

 paper, been remarkably confirmed by the observations of Dr H. 

 Rink of Copenhagen in the west of North Greenland, where 

 he has found what may be called a continental glacier of 

 vast thickness, continually advancing from the interior of the 

 country to the coast, and there breaking off in icebergs. 



I have been able this summer to make a few observations 

 tending further to illustrate the distinction which I endea- 

 voured to establish between the compact boulder clay, as a 

 memorial of early, general, and watery glaciation, and the 

 coarse brown drift, as a monument of subaerial valley glacia- 

 tion, exactly resembling that seen in the Alps. 



True moraines had been scarcely detected in Scotland before 

 Mr Maclaren described that of Glenmessan, in Argyleshire, to 

 the geological section of the British Association in 1850. The 

 only examples adverted to before that period were those pointed 

 out by Sir Charles Lyell, as forming the dams of Lochs Brandy 

 and Whorral, two mountain tarns, placed high on the eastern 

 skirts of the Grampians, and one or two specimens observed 

 by Professor James Forbes on the skirts of the Cuhullin hills, 

 in Skye. In the paper just adverted to, I described some ex- 

 amples of moraines which I had discovered in the wilds of 

 Skye, of Sutherlandshire, and Ross-shire. Since then, some 

 others have come under my attention, and I am able to put 

 this kind of phenomena under a certain degree of classification. 



In at least two of the valleys descending from the skirts of 



