PHYSICAL GEOGRAPHY. 297 



at Fernando Po, 4 30 north latitude, is repeated on the 

 coast of the Pacific at 18 15' south latitude, between the 

 Valley of Arica and the Morro de Juan Diaz, where the Peru- 

 vian coast suddenly changes the direction from south to north 

 which it had previously followed, and inclines to the north- 

 west. This change of direction extends in like manner to the 

 chain of the Andes, which is divided into two parallel branches, 

 affecting not only the littoral portions* but even the eastern 

 Cordilleras. In the latter, civilization had its earliest seat 

 in the South American plateaux, where the small Alpine lake 

 of Titicaca bathes the feet of the colossal mountains of Sorata 

 and Illimani. Further to the south, from Valdivia and Chiloe, 

 (40 to 42 south latitude,) through the Archipelago de los 

 Chonos to Terra del Fuego, we find repeated that singular 

 configuration of fiords (a blending of narrow and deeply 

 indented bays), which, in the Northern Hemisphere, charac- 

 terises the western shores of Norway and Scotland. 



These are the most general considerations suggested by the 

 study of the upper surface of our planet with reference to the 

 form of continents, and their expansion in a horizontal direc- 

 tion. We have collected facts and brought forward some 

 analogies of configuration in distant parts of the earth, but we 

 do not venture to regard them as fixed laws of form. When 

 the traveller on the declivity of an active volcano, as, for 

 instance, of Vesuvius, examines the frequent partial elevations 

 by which portions of the soil are often permanently upheaved 

 several feet above their former level, either immediately pre- 

 ceding or during the continuance of an eruption, thus forming- 

 roof-like or flattened summits, he is taught how accidental 

 conditions in the expression of the force of subterranean 

 vapours, and in the resistance to be overcome, may modify 

 the form and direction of the elevated portions. In this 

 manner, feeble perturbations in the equilibrium of the internal 



* Humboldt, in Poggendorff's Annalen der Pliysik, bd. xl. s. 171, 

 On the remarkable fiord formation at the south-east end of America, see 

 Darwin's Journal (Narrative of the Voyages of the Adventure and 

 Beagle, vol. iii.), 1839, p. 266. The parallelism of the two mountain 

 chains is maintained from 5 south to 5 north lat. The change in the 

 direction of the coast at Arica appears to be in consequence of the altered 

 course of the fissure, above which the Cordillera of the Andes has bee - 

 upheaved. 



