442 H, H. Howorth — Elevation of American Cordillera. 



enormous height) there are only slight traces to be found of ancient 

 glacial action, except in the length which separates Chili and Patagonia. 

 Excluding this length, there are hardly any scratched boulders, 

 roches moutonnees, or polished or striated surfaces which we can 

 assign to that vast ploughshare of ice which has left its mark so 

 plainly written on the flanks of the Alps and the Dovrefelds, the 

 granite wastes of Labrador and the North-Eastern parts of America. 

 Upon this point the best observers are unanimous. 



We will first turn to South America, 



It was Darwin who first drew attention to the distribution of 

 boulders in South America. Humboldt had argued that, inasmuch 

 as they are never found in the great intertropical plains of the 

 Eastern side of America, they are entirely absent from the whole 

 continent. Referring to this conclusion, Darwin says : " As far as I 

 am able to discover from the works of travellers, and from what I 

 have myself seen, the remark holds good in the countries on both 

 sides of the Cordillera as far south as Central Chile. Azara has 

 particularly stated such to be the case in Chaco. With respect to 

 the tributaries of the Amazons, nothing can more strongly prove it 

 than La Condamine's story " (Darwin's Narrative, p. 289). He says: 

 " Below Borja even for 400 or 500 leagues, a stone, even a single 

 flint, is as great a rarity as a diamond would be. The savages of 

 those countiies do not know what a stone is, and have not even a 

 notion of it. It is diversion enough to see some of them when 

 they come to Borja, and first meet with stones, express their 

 admiration at them with signs, and be eager to pick them up, load- 

 ing themselves therewith as with a valuable merchandize. . . . 

 Neither in the southern nor in the northern hemisphere do the frag- 

 ments, coming from the Polar regions, or from other mountain 

 groups, arrive within a considerable distance of the lines of the 

 tropics" (Darwin's Narrative, pp. 288-9). In the Appendix he 

 says : " The lowest latitude in South America, in which I found 

 large angular fragments, which must have been transported by ice 

 there formed, or bj' some unknown means, was in latitude 41°. 

 But as I did not examine the country immediately north of it, I am 

 not prepared to say that this is their extreme limit, but between 

 latitude 27° and 33° I found no appearance, on either side of the 

 Cordillera, which indicated a power of transportation of the kind 

 required to remove boulders from a distance. Thus we find that 

 the limit of their dispersion in the two Americas is nearly the 

 same " {id. p. 615). 



Darwin curiously compares the Andes with the Himalayas in 

 this respect. Thus he says: "We must couple the absence of erratic 

 blocks along that part of the Andes which is situated under a 

 warmer climate, with the similar non-occurrence, as I am informed 

 by Prof. Koyle, in Northern India round the flanks of the Himalaya, 

 those loftiest pinnacles on the face of the globe" [id. p. 289). 



What is true of South America is true of North America also. I 

 must not be misunderstood. I am only speaking of the Rocky 

 Mountains proper, which also are treated by Humboldt as in 



