308 Dr Ch. Martins on the Marks of Glacial Action 



were forced along the shore : he moreover imagined that the 

 boulders of trap which fell from the beach, are often im- 

 pacted into the ice and carried away along with it." It hap- 

 pens unfortunately then, that the explanation of the interest- 

 ing fact pointed out by Sir Charles Lyell, is derived from a 

 peasant who never confirmed it by direct observation, who 

 never had seeti the fragments of the trap infixed in the ice, 

 any more than he had seen the striation actually efi^ected ; 

 whilst at the same time the whole country being covered 

 with striated rocks which reach back as far as the glacier 

 epoch, doubts must necessarily exist concerning the re- 

 cent origin of those in question. We may add that the 

 striation of a soft sand-stone, by floating ice-blocks, would 

 be much more easily effected than that of hard rocks, such 

 as that of granite, trap, &c. This question then cannot 

 be determined : and hence w^e shall take the liberty of re- 

 commending the subject to the attention of those geologists 

 who inhabit the coasts of the gulf of Bothnia, and especially 

 to the learned professors of the University of Helsingfors. 



But to my apprehension there still exists another difficulty. 

 According to the acknowledgment of all competent observers, 

 the polished and striated mountain rocks present the same 

 appearances in the plains of Scotland, in the mountains 

 and in the valleys of Switzerland, and in the immediate 

 neighbourhood of the existing glaciers. I myself possess a 

 collection of polished and striated rocks procured from the 

 Alps of the Jura, from the Vosges, from the Pyrenees, from 

 Scotland, Scandinavia, and from North America, and the 

 whole of them are identical, as compared with each other, 

 and identical with those which I have detached from the 

 very ice of the glaciers themselves. It becomes necessary, 

 then, that the partizans of the theory of floating icebergs 

 proceed to demonstrate by direct observations. 1st, That the 

 floating ice-blocks proceeding from marine glaciers can striate 

 the hardest rocks. And, 2^, That the striae which tbey 

 produce are in every particular identical with those which 

 the existing glaciers effect. Unless I am very much deceived, 

 I am persuaded that, ere the first proposition be established, 

 it will be found that a difference exists between the traces 



