88 



LYELL'S ELEMENTS GEOLOGY. 



Erratic Blocks drifted by Ice. 



head of all the sounds along the western coast of the southern 

 extremity of South America, in latitudes as low as 46«, and still 

 farther, the ice being covered with great fragments of rock. Al- 

 though these glaciers come down to the sea, the mountains from 

 which they descend have only half the altitude of the Alps, and 

 yet are equidistant from the equator. Portions of this South 

 American ice, charged with large blocks of granite, were seen in 

 Sir George Eyre's sound, in the same parallel of latitude as 

 Paris, floating outwards to the ocean.* 



It is therefore natural to suppose that masses of rock may fre- 

 quently be carried by icebergs from the foot of the Andes, in this 

 quarter of South America, across deep channels, and stranded 

 on adjacent islands in the Pacific, such as Chiloe, on which large 

 erratics from the Andes are actually seen ; and a general eleva- 

 tion of the mainland, together with the islands, accompanied by 

 the laying dry of the intervening sounds, might present to a 

 future geologist a problem respecting the transport of blocks, as 

 enigmatical as any which are now encountered in Europe. "f 



Icebergs then, detached from glaciers together with coast ice, 

 may convey, for hundreds of miles, pebbles, boulders, sand, and 

 mud, and let these fall wherever they may chance to melt, on 

 submarine hills and valleys. These, when the land emerges 

 from the deep, may constitute some of the far-transported allu- 

 vium which has been ascribed to diluvial agency.J 



* Darwin, p. 283. t Ibid, p. 286. 



t For speculations on the causes of a local and general change of climate, de- 

 pendent on fluctuations in physical geography, and proofs of the wide conversion 

 of sea into land in Europe, at periods comparatively modern, see Princ. of Geol. 

 book i. 



