278 HE ACTION OF THE INTERIOR OF THE EARTH 



variety of the physical and geological views which shed 

 a lustre around the name of de Saussure, and around the 

 scenes of his untiring labours. External nature appears 

 to us clothed with the most grandeur where her direct 

 visible image is blended with its reflection from the in- 

 tellectual mirror of the human mind. 



The Peruvian and Bolivian series, also belonging 

 wholly to the equinoctial zone, and, according to Pent- 

 land, not covered with perpetual snow until the height 

 of nearly 17,000 feet is reached (Darwin, Journal, 

 1845, p. 244), attains its maximum elevation (22,350 

 feet) in about the middle of its length, in the Sahama 

 group, between 18 7' and 18 25' S. lat. At Arica, there 

 takes place a remarkable rounded inflection of the coast- 

 line, which corresponds to a sudden alteration in the 

 direction of the axes both of the chain of the Andes and 

 of the western volcanic line. From thence southwards 

 the direction of the coast, and at the same time of the 

 volcanic fissure, is no longer from N.W. to S.E., but from 

 north to south, which direction it maintains until near 

 the western entrance of the Straits of Magellan, over a 

 distance of more than two thousand geographical miles. 

 A map of the " Verzweigungen und Bergknoten der 

 Andeskette," which I published in 1831, shows many 

 similar correspondences between the outline of the 

 continent and the course of the Cordilleras near or dis- 

 tant. Thus, between the capes Aguja and San Lorenzo 

 (5J to 1 S. lat.), both the shore of the Pacific and the 

 Cordilleras run from south to north, after having 

 so long run from south-east to north-west between the 

 parallels of Arica and Caxamarca ; and thus, from the 

 mountain-node of Imbaburu near Quito to that of De 



