235 



or thrown out by the mouth of the Peak ; and 

 the absence of these rocks characterizes almost 

 every island of small extent, that has an unextin- 

 guished volcano. We know nothing positive of 

 the mountains of the Azores ; but it is certain, 

 that the island of Reunion % as well as that of 

 TenerifFe, exhibits only a heap of lavas and ba- 

 salts. No volcanic rock rears it's head, either on 

 the Gros Morne or on the volcano of Bour- 

 bon, or on the colossal pyramid of Cimandef, 

 which is perhaps more elevated than the Peak 

 of the Canary islands. 



It is nevertheless asserted that lavas includ- 

 ing fragments of grani te have been found on the 

 elevated plain of Retama. Mr. Broussonet in- 

 formed me, a short time before his death, that, 

 on a hill above Guimar, fragments of mica-slate, 

 containing beautiful plates of specular iron, had 

 been found. I can affirm nothing respecting the 

 accuracy of this observation, which it would be 

 so much the more important to verify, as Mr. 



* The Isle of Bourbon, 

 f Blocks of granite, thrown out probably by the ancien t 

 volcano of the Gros Morne, are found near the source of 

 Trois-Rivieres j and this fact is so much the more worthy at- 

 tention, as the neighbouring islands, known under the name of 

 Sechelles, are formed of granitic rocks. — Bory de St. Vincent, 

 Voy* aux lies d'Afrique, t, i, p. 338; t. ii, p. 35; t. iii, p. 

 146 et 246. 



X Bory de St. Vincent, Essai sur les lies Fortunees, p. 

 278. 



