453 



CHAPTER XIX. 



Islands volcanic — ^Niimber of craters — Leafless bushes — Colony at Charles 

 Island — James Island — Salt-lake in crater — Character of vegetation — 

 Ornithology, curious finches — Great tortoises, habits of, paths to the 

 wells — Marine lizard feeds on sea-weed — Terrestrial species, burrowing 

 habits, herbivorous — Importance of reptiles in the Archipelago — Few 

 and minute insects — American type of organizat"on — Species confined to 

 certain islands — Tameness of birds — Falkland Islands — Fear of man 

 an acquired instinct. 



GALAPAGOS ARCHIPELAGO. 



September 15th. — The Beagle arrived at the southern- 

 most of the Galapagos islands. This archipelago consists 

 of ten principal islands^ of which five much exceed the others 

 in size. They are situated under the equatorial line^ and 

 between five and six hundred miles to the westward of the 

 coast of America. The constitution of the whole is volcanic. 

 With the exception of some ejected fragments of granite_, 

 which have been most curiously glazed and altered by the 

 heat, every part consists of lava^ or of sandstone resulting 

 from the attrition of such materials. The higher islands^ 

 (which attain an elevation of three, and even four thousand 

 feet) generally have one or more principal craters towards 

 their centre, and on their flanks smaller orifices. I have no 

 exact data from which to calculate, but I do not hesitate to 

 affirm, that there must be, in all the islands of the archi- 

 pelago, at least two thousand craters. These are of two 

 kinds ; one, as in ordinary cases, consisting of scoriee and 

 lava, the other of finely-stratified volcanic sandstone. The 

 latter in most instances have a form beautifully symmetrical : 

 their origin is due to the ejection of mud, — that is, fine vol- 

 canic ashes and w^ater, — without any lava. 



Considering that these islands are placed directly under 

 the equator, the climate is far from being excessively hot ; a 



