on the Rocks in the Environs of Edinburgh. 311 



mechanism of their formation clearly shews that they must 

 accommodate themselves at every possible angle, since the 

 position of the pebble, confined between the ice and the rock, 

 is continually changing. Actual observation upon the exist- 

 ing glaciers has often demonstrated this to all those who have 

 studied the phenomena among the Alps. 



Proofs of the existence of Ancient Marine Glaciers in the 

 Environs of Edinburgh. 



I shall now attempt accurately to demonstrate that all the 

 glacial phenomena in the neighbourhood of Edinburgh may 

 be explained on the hypothesis of the existence of ancient 

 glaciers which descended to the shores of the ocean, and 

 by slight changes of the level of the country since that 

 epoch. For the purpose of demonstrating this truth, I am 

 not obliged to suppose a general immersion of Scotland 

 below the ocean to a depth greater than that which is indi- 

 cated by the most elevated shell-beds, nor to admit that the 

 floating icebergs streaked the rocks, and that their striae are 

 identical with those of the existing glaciers. My proposi- 

 tion may be thus expressed — that at the glacial epoch, Scot- 

 land re as covered with glaciers, as Spitzbergen is at the present 

 time. Let us then consider if the facts confirm this compa- 

 rison and resemblance. 



The polished and striated rocks which I have examined at 

 Blackford Hill, at Corstorphine Hill, at St Margaret's works 

 (North British Railway), at the northern foot of Arthur 

 Seat, also at Granton, upon the Pentland Hills, round the 

 Gare Loch, near Glasgow, are all identical with those which 

 the existing ones now fabricating — so to speak — under our 

 eyes ; and they differ in no respect from those which I 

 have observed in Scandinavia, in the Alps, and in the Vos- 

 gian range. It is then assuredly both simple and natural to 

 attribute them to the action of glaciers, whose existence at 

 this period, in the mountains of Scotland, has been doubted 

 by none. But this is not all. My excellent friend Mr 

 Charles Maclaren, who has contributed so much to the elu- 

 cidation of this subject, directed my attention, in the neigh- 

 bourhood of Edinburgh, to a polished and striated rock, the 



