CLIMATE OF FUEGIA. 437 



number and magnitude of the crj^stalline streams discharging into the upland 

 gorges or lower valleys. 



Tierra del Fuego, forming a triangular mass projecting between the Atlantic 

 and Pacific Oceans, has a special climate corresponding to these conditions. 

 The advanced headlands present a rocky surf-beaten barrier to the cold polar 

 current with its huge icebergs torn from the antarctic glaciers and lowering the 

 temperature of the sea to about 39° or 40° Fahr. The larger portion of this 

 current, averaging about 300 miles in breadth, follows the direction of the coast- 

 line, first from south-east to north-west, and then from south to north. With a 

 mean velocity of 28 miles a day, reduced in some places to less than 12, or even 

 apparently neutralised by the north wind, the Humboldt current, as it is called, 

 follows the coasts of Chili and Peru, beyond which it is merged westwards in the 

 great equatorial current. 



On reaching the submerged scarp of the terminal plateau of South America, 

 this polar stream throws off to the right (east) a smaller branch, which, instead 

 of following the Patagonian and Argentine seaboard, sets due east in the 

 direction of the Cape of Good Hope. The deflection is due to the tepid waters of 

 the Atlantic equatorial current flowing south-westwards to the extremity of the 

 continent, and impinging upon the east branch of the Antarctic stream. Accord- 

 ing to Popper, the equatorial current maintains a temperature of 50° Fahr., with 

 a daily velocity of over 200 miles in the Fuegian waters. Thus there is a diffe- 

 rence of 10° Fahr. between the two streams setting along the shores of the archi- 

 pelago in opposite directions, the Humboldt from south to north on the west, 

 the equatorial from north to south on the east side. The result is a very marked 

 contrast between the climates of the opposite shores of Fuegia. 



The relatively cool atmosphere of the Pacific side, whose temperature is further 

 lowered by the mountain snows and by the polar winds, descends rapidly in the 

 direction of the east to replace the warmer and more rarefied air ascending into 

 the higher regions above the eastern shores of the archipelago. Thus arises the 

 fierce gale which sweeps the eastern plains of Fuegia, preventing the growth 

 of a single tree on the bare steppe, whereas in the west leafy forest growths 

 flourish under the shelter of the mountains in the glens unexposed to the 

 boisterous winds. 



The rainfall also diminishes gradually in the direction of the east. On the 

 south-western slopes the wet days, according to Popper, rise to at least 300 

 in the year, whereas there are scarcely as many hours of rain at San Sebastian 

 Bay on the Atlantic coast.* 



* Meteoroloojical conditions of some towns in Chili : — 



