128 PATAGONIA AND SHEEP-REARING 



pumilio) extends as far as the fringe of the Alpine 

 forests. The forest does not reach the eastern Umit of 

 the lakes. In the sub-Andean depression it is reduced 

 to thickets of nirre {Notofagus antarctica) and mayten 

 and clumps of calafate (something like myrtles). 



It is on the Alumine, about 39° S. lat., that we find 

 traces of glacial erosion, as they spread over the land- 

 scape. At present there is no ice on the mountain 

 except on the peaks of Lanin and Tronador, but 

 from the Rio Puelo onward (42° S. lat.), glaciers clothe 

 all the summits which rise above 6,500 feet. North 

 of the Aisen they form a narrow, but almost continuous, 

 line. From the Aisen to the Calen fiord, and 

 beyond the gap of the fiord as far as 52° S. lat., 

 the ice spreads in a considerable sheet which in some 

 places attains a breadth of eighty miles. The tongues 

 of the glaciers reach the Pacific below 46° S. lat., and 

 Lake San Martin on the Argentine slope below 49° S. 

 lat. In Tierra del Fuego the snow-line is at 2,300 feet, 

 and the glaciers which the snows feed, reach as far 

 as the fiords and Lake Fagnano. 



Lake Carri Lauquen, on the Barrancas (36° 20' S. 

 lat.), which was almost entirely drained in 1914 through 

 the breaking down of the natural dam of soft earth 

 which confined its waters, is not a glacial lake.^ 

 The chain of glacial lakes stretches from the Alumine 

 to the Seno de la Ultima Esperanza, and is continued 

 southward by Skyring Water, Otway Water, and 

 Useless Bay — genuine lakes in communication with 

 the Pacific by means of narrow channels. The lakes 

 sometimes lie in a narrow and deep glacial valley, 

 the bottom of which they fill ; sometimes they 

 branch out into the neighbouring valleys ; at other 

 times they advance eastward beyond the zone of the 

 mountains and spread into round basins surrounded 



* Pablo Groeber, Informe sobra las caitsas que han producido las 

 crecientes del Rio Colarado in 1914. Dir. Gen. de Minas, Geol. e 

 Hidrol., Bol. No. 11, series B, Geologia (Buenos Aires, 1916). 



