ON ITS EXTERIOR. VOLCANOES. 317 



a height of 18,141 feet, therefore 2358 feet higher than 

 Mont Blanc. The snow near the rock was, at several 

 places, solid enough to bear our weight, a circumstance 

 which is very rare within the tropics. (The temperature 

 of the air was from 28'8 to 34*5.) On the southern 

 declivity, by which we did not ascend, at the Piedro de 

 Azufre, where the rock scales off from the effects of 

 weathering, masses of pure sulphur, ten or twelve 

 feet long and two feet thick, are found : there are no 

 sulphur springs in the neighbourhood. 



Although in the eastern Cordillera, Antisana, and 

 especially its western declivity (from Ansango and 

 Pinantura towards the little village of Pedregal), is 

 separated from Cotopaxi by the extinct volcano of Pas- 

 suchoa ( 453 ) (with its crater, la Peila, recognisable at a 

 great distance), by the Nevado Sinchulahua, and by the 

 less lofty Ruminaui ; yet there is a certain similarity in 

 the rocks of which these two great volcanoes are com- 

 posed. Beginning from el Quinche, the whole eastern 

 Cordillera has produced obsidian, and yet el Quinche, 

 Antisana, and Passuchoa belong to the basin in which 

 the city of Quito is situated, while Cotopaxi bounds 

 another basin, that of Lactacunga, Hambato, and 

 Riobamba. These two basins are divided from each 

 other by the little mountain knot of the Altos of 

 Chisinche, and the small dimensions of this dividing 

 wall renders more striking the circumstance, that the 

 waters of the northern side of Chisinche flow through 

 the Eios de San Pedro, de Pita, and de Guallabamba, 

 into the Pacific, while the waters of the southern side 

 flow through the Rio Alaques, and the Rio de San 

 Felipe into the Amazons and the Atlantic Ocean. The 



