286 



TIERRA DEL FUEGO. 



June, 1834. 



found mucli further northward : and considering the immense 

 size of the one just described, it is extremely improbable 

 that it should be the last. On the island of Chiloe, which 

 fronts the Cordillera as the Jura does the Alps, many angu- 

 lar fragments of granite, of an enormous size, which appear 

 to have crossed the inland arm of sea, lie scattered at 

 different heights over the country. Although situated be- 

 tween the parallels of 41° and 43°, I know of no sound 

 objection to the supposition that these might formerly have 

 been floated across, on icebergs produced by the fall of glaciers. 

 We are not bound to suppose that the latitude 46° 40' has 

 always been the northern limit of such phenomena, even if it 

 should be so at present. We have endeavoured to show that 

 the snow-line in the parallel of Chiloe has an elevation of 

 about 6000 feet ; and since on Mont Blanc the glaciers de- 

 scend 5160 feet beneath the line of perpetual snow, we might 

 at present expect to find them in front of Chiloe at a very 

 small altitude above the level of the sea. 



With respect to the position of the glaciers, they seem 

 to occur only within the deep sounds which penetrate the 

 central Cordillera. This may be attributed chiefly to the 

 subordinate elevation of the outer lines. When we consider 

 the vast dimensions and number of these glaciers, the efl"ect 

 produced on the land must be very great. Every one has 

 heard of the mass of rubbish propelled by the glaciers of 

 Switzerland, as they slowly creep onwards. In the same 

 manner in Tierra del Fuego, on a still night the cracking and 

 groaningof the great moving mass may be distinctly heard. The 

 same force, which is known to uproot whole forests of lofty 

 trees, must, when grating over the surface, tear from the 

 flanks of the mountain many huge fragments of rock. Be- 

 neath each glacier, also, a roaring torrent drains the upper 

 part of the ice. To these eff'ects, which are common to all 

 cases, there must be added, in this country, the wear and 

 tear of the waves produced by each successive fall. Nor can 

 this agency be inconsiderable, when we remember that it 

 goes on night and day, century after century. We must look 



