HEIGHT OF THE SNOW-LINE. 315 



almost called tree-ferns ; and in these islands, and 

 even as far south as lat. 55'^ in the Macquarrie Isl- 

 ands, parrots abound. 



On, the Height of the Snoui-Une, and on the De- 

 scent of the Glaciers, i?i South A^nenca. — For the 

 detailed authorities for the following table I must 

 refer to the former edition : 



Latitude. "f'f'ow"lme.' Observer. 



Equatorial reg-ion . mean result 15,748 Humboldt. 



Bolivia, lat. 160 to l&o s. . . 17,000 Pentland. 



Central Chile, lat .330 S. . . 14,500 to 15,000 Gillies, and the Author. 



Chiloe, lat. 410 to 430 S. . . 6,000 j Officers of the Beagle, 



' ' \ and the Author. 



Tierra del Fuego, 54° S. . . 3,500 to 4,000 King. 



As the height of the plane of perpetual snow seems 

 chiefly to be determined by the exti-eme heat of 

 the summer rather than by the mean temperature 

 of the year, we ought not to be surprised at its de- 

 scent in the Strait of Magellan, where the summer 

 is so cool, to only 3500 or 4000 feet above the level 

 of the sea ; although in Norway we must travel to 

 between lat. 67° and 70° N., that is, about 14° 

 nearer the pole, to meet with perpetual snow at 

 this low level. The difference in height, namely, 

 about 9000 feet, between the snow-line on the Cor- 

 dillera behind Chiloe (with its highest points I'an- 

 ging from only 5600 to 7500 feet) and in central 

 Chile* (a distance of only 9° of latitude), is truly 

 wonderful The land from the southward of Chi- 

 loe to near Concepcion (lat. 37°), is hidden by one 

 dense forest dripping with moisture. The sky is 

 cloudy, and we have seen how badly the fruits of 

 Southern Europe succeed. In central Chile, on 

 the other hand, a little northward of Concepcion, 



* On the Cordillera of central Chile, I believe the snovv-jine 

 varies exceedingly in height in different summers. I was assured 

 that during one very dry and long summer all the snow disappear- 

 ed from Aconcagua, although it attains the prodigious height of 

 23,000 feet. It is probable that nmch of the snow at these great 

 heights is evaporated rather than thawed. 



