288 



TIERRA DEL FUEGO. 



June, 1834. 



subsequently to the interior ones, so as to protect a coast 

 hitherto exposed, or that overwhelming deluges had swept 

 down the valleys, and in some manner produced, in one day, 

 the effects of attrition which on ordinary occasions require 

 the prolonged action of centuries. 



If we could at the present day submerge the greater part 

 of Tierra del Fuego, or leave unelevated that which we know 

 has recently been gained, an island with a few small out- 

 liers would be formed, similar to Georgia, and situated in 

 exactly the same latitude. Have we in such case the slightest 

 right to deny the probability that the snow-line would de- 

 scend nearly to the water^s edge, and that every valley 

 would be ^'^ terminated by a wall of ice,^^ and that " in winter 

 masses would be broken off and dispersed over the sea V — all 

 of which circumstances are now happening in Georgia. The 

 currents, which always set from the westward towards the 

 east, would drift these floating masses through the channels 

 towards the eastern side. And as we know that icebergs at 

 the present day, in both hemispheres, occasionally transport 

 fragments of rock, so we cannot deny that those of Tierra del 

 Fuego might formerly have done so. When the land was 

 elevated, the fragments of rock would be found deposited on 

 the eastern side of the continent, in bands representing the 

 ancient channels. Whether or not the hypothesis of their 

 transport be true, such is the position of the erratic blocks 

 in Tierra del Fuego. 



With respect to the general theory of the transport by 

 great fragments of ice, especially of such as are angular, I 

 may add a few remarks. Humboldt having observed that 

 none occurred over the vast intertropical plains of the eastern 

 side of South America, believed that they were entirely 

 absent from the whole continent. As far as I am able to 

 discover from the works of travellers, and from what I have 

 myself seen, the remark holds good in the countries on both 

 sides of the Cordillera as far south as central Chile. Azara has 

 particularly stated such to be the case in Chaco. With 

 respect to the tributaries of the Amazons, nothing can more 



