116 



ISLAND LIFE 



PAKT I 



It is evident that the change of climate requisite to 

 produce such marvellous effects in the British Isles could 

 not have been local, and we accordingly find strikingly 

 similar proofs that Scandinavia and all northern Europe 

 have also been covered with a huge ice-sheet ; while we 

 have already seen that a similar gigantic glacier buried the 

 Alps, carrying granitic blocks to the Jura, where it de- 

 posited them at a height of 3,450 feet above the sea; 

 while to the south, in the plains of Italy, the terminal 

 moraines left by the retreating glaciers have formed exten- 

 sive hills, those of Ivrea the work of the great glacier from 

 the Yal d'Aosta being fifteen miles across and from 700 to 

 1,500 feet high. 



Glacial Phenomena in North America. — In North 

 America the marks of glaciation are even more extensive 

 and striking than in Europe, stretching over the whole of 

 Canada and to the south of the great lakes as far as 

 latitude 39°. There is, in all these countries, a wide-spread 

 deposit like the " till " of Scotland, produced by the grind- 

 ing of the great ice-sheet when it was at its maximum 

 thickness ; and also extensive beds of moraine-matter, true 

 moraines, and travelled blocks, left by the glaciers as they 

 retreated towards the mountains and finally withdrew into 

 the upland valleys. There are, also, in Britain, Scandin- 

 avia, and North America, proofs of the submersion of the 

 land beneath the sea to a depth of upwards of a thousand 

 feet ; but this is a subject we need not here enter upon, as 

 our special object is to show the reality and amount of that 

 wonderful and comparatively recent change of climate 

 termed the glacial epoch. 



Many persons, even among scientific men, who have not 

 given much attention to the question, look upon the whole 

 subject of the glacial epoch as a geological theory made to 

 explain certain phenomena which are otherwise a puzzle ; 

 and they would not be much surprised if they were some 

 day told that it was all a delusion, and that Mr. So-and-so 

 had explained the whole thing in a much more simple way. 

 It is to prevent my readers being imposed upon by any such 

 statements or doubts, that I have given this very brief and 

 imperfect outline of the nature, extent, and completeness 



