THE ANDES. 231 



THE MOUNTAINS. 



The Andes. Our knowledge of even the general character of the 

 southern Andean ranges is at present extremely limited and incomplete, 

 while no attempt has ever been made toward a detailed study of either 

 their structure or topography. Since the accomplishment of either of the 

 latter tasks would in itself alone require the services for many years of a 

 specially equipped corps of experts in each department of orography, the 

 southern Andes will no doubt long remain, as they are at present, among 

 the least perfectly known of the mountain systems within the habitable 

 area of the earth's surface. If the present writer is able to add but little 

 to our meagre knowledge of these mountains, he may perhaps be par- 

 doned for asking the indulgence of the reader on the score of the mag- 

 nitude and difficult nature of the work. Neither were the means at his 

 disposal adequate, nor his former training of a character which would 

 make him competent to undertake a task so difficult and so different 

 from that for which he visited Patagonia. Nevertheless, some observations 

 were made bearing directly upon the structure and age of the southern 

 Andes, which it is believed are worthy of record and of careful considera- 

 tion by future students and travellers in this region. 



The Andes in that part of Patagonia under discussion embrace practi- 

 cally all the region west of the seventy-first meridian of west longi- 

 tude, including the mainland and the adjoining islands. In this region 

 the mountain system has a nearly north and south trend, until the fifty- 

 second parallel of south latitude is reached, when its axis turns sharply to 

 the eastward and assumes an almost direct northwestern and southeastern 

 course, terminating in Navarin Island, north of Cape Horn. A glance at 

 any of the current maps of the western hemisphere will convince the reader 

 that these mountains are but the southernmost continuation of the single 

 mountain system that extends along the west coast of South America, 



That feature in connection with the structure of the southern Andes 

 which most strongly impressed the present writer during his travels in 

 those mountains, was the fact that, instead of one continuous range, they 

 were made up of three distinct and parallel, although not always continu- 

 ous, mountain ranges, separated by two deep and exceedingly irregular 

 longitudinal valleys. The middle one of these three ranges is everywhere 

 higher than the two lateral ranges and may be considered as the principal 



