128 PATAGONIA AND SHEEP-REARING 



pumilio) extends as far as the fringe of the Alpine 

 forests. The forest does not reach the eastern limit 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. 1 

 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 



1 Pablo Groeber, Informe sobra las causas que han producido las 

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

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



