LETTER XVII. 



Natural History. 



Geology. — The whole of this archipelago is particu- 

 larly characterized by its igneous origin, and according to 

 the conjecture of many geologists, this, together with the 

 Azores, the Madeiras and the Cape de Verds, is the 

 remains of a submerged chain of mountains, probably the 

 ancient isle of Atlantis, which is in no way contradictory 

 to the acknowledged laws of nature. But to verify or 

 refute this conjecture will require more time than is allotted 

 to my task. 



The question has often been agitated, whether '' the 

 archipelago of the Canary Islands contains any rocks of 

 primitive or secondary formation ; or is there any produc- 

 tion observed, that has not been modified by fire ? " To 

 this interesting question, I Vv'ill reply that there are. On 

 the authority of Broussonet, the island of Gomera contains 

 mountains of granite and mica-slate; and on a hill above 

 Guimar in Teneriffe, fragments of the latter substance, 

 containing beautiful plates of specular iron, have been 

 found. In passing over Las Caiiadas, I repeatedly ob- 

 served masses of granitic lava which had evidently been 

 thrown from the crater of the Peak. From these facts, it 

 appears that in this archipelago, as well as the Andes of 

 Quito, in Auvergne, Greece, and a greater portion of the 

 globe, the subterranean fires have forced their way through 

 the rocks of primitive formation. 



From the information of several well-informed gentle- 

 men of this island, I learn that there are secondary forma- 

 tions in Grand Canary, Lanzarote, Fuerteventura, Gra- 

 ciosa, and Teneriffe. At Lanzarote, there are large quan- 

 tities of calcareous stone which the natives burn into lime. 



