310 M. Humbolcit on txvo Attempts to ascend Chimtorazo. 



satyrical, Italian traveller, Girolamo Benzoin", whose work was 

 printed in 1565. He says, that the Montagna di Chimbo, 40 

 miglia high, appeared to him strangely come una visione. The 

 natives of Quito knew, long before the arrival of the French 

 surveyors, that Chiraborazo was the highest snow-mountain in 

 all their country. They saw that it ascended highest above the 

 line of perpetual snow. It was just this consideration that 

 induced them to consider the now fallen in Capac Urcu as 

 higher than Chimborazo. 



Regarding the geognostical constitution of Chimborazo, I 

 here add only the general remark, that if, according to the im- 

 portant results which Leopold von Buch has laid down in his 

 classical memoir, " On Craters of Elevation and Volcanoes,*" 

 Trachyte is a mass containing Felspar, and Andesite a mass 

 with imbedded Albite ; the rock of Chimborazo is by no 

 means deserving of either name. That in Chimborazo, Augite 

 replaces Hornblende, the same intelligent geognost observed, 

 more than twenty years ago, when I requested him to ex- 

 amine, oryctognostically and with precision, the rocks brought 

 home by me from the Andes. This fact has been mentioned 

 in several parts of my " Essai geognostique sur le Gisement 

 des Rockers dans les deux Hemispheres^^ which appeared in tlie 

 year 1823. Besides this, my Siberian travelling companion, 

 Gustav Rose, who, by his excellent work on the minerals related 

 to felspar, and their association with augite and hornblende, has 

 opened new ways for geognostical research, finds in all my col- 

 lection of mountain-fragments from Chimborazo, neither albite 

 nor felspar. The whole formation of this celebrated summit of the 

 Andes, consists of labrador and augite ; both fossils recognisable 

 in distinct crystals. Chimborazo is, according to the nomencla- 

 ture of Gustav Rose, an augite-porphyry, a species of dolerite. 

 Obsidian and pumice stone are also wanting in it. Hornblende 

 occurs very sparingly. Chimborazo is thus, as taught by 

 Leopold von Buch''s and Elie de Beaumont's latest decisions, 

 analogous in its rock to Etna. With the ruins of the old city 

 of Riobamba, three geographical miles east of Chimborazo, there 



• Poffffcndorff's Aimalen, Band. 37. S. 188—190. Also Edinburgh New 

 Philosophical Journal, for translation of this memoir. 



