xxxviii Tliysical and Geognostic Suggestions, 



and platinum coast of the Choco, near San Buenaventura, 

 so as to proceed thence to Popayan, and afterwards return 

 to the volcanoes of the province of Pasto, which are highly 

 important, and so on to Quito, by way of Guachucal, Tulcan, 

 and Villa de Ibarra, rejoining the frigate only at Guayaquil. 

 I believe, however, it would be more advisable to select 

 Quito as the starting-point, whence to examine the important 

 elevated volcanic region De los Pastos (between 2° 20' and 

 0° 56' N.), containing the volcano of the town of Pasto, the 

 volcanoes of Tuguerres, Chiles and Cumbal, and the Azufral 

 de Pasto, and not to land at any port of the Choco coast, 

 not even from the Bahia de Cupica, which for half a century 

 I have recommended in vain on account of its vicinity to the 

 Rio Naipi, one of the tributaries of the Atrato. In draw- 

 ing up a list of names of the volcanoes of the renowned lofty 

 plateau of Quito, I may include, Imbaburu, Cotocachi, Rucu, 

 Pichincha, Antisana, the much-disputed question of the stony 

 walls like streams of lava, on the east slope of Tana Volcan, 

 and Reventazon de Ausango ; Cotopaxi, with its strange 

 inexplicable quarries of pumice, of Guapecho and Zum- 

 balica, in the neighbourhood of Llactacunga and San Felipe, 

 the pumice containing oligoclase, not glassy felspar, deposited 

 in strata, milike any rock in situ for a considerable dis- 

 tance on all sides of Cotopaxi ; Tunguragua (mica slate), 

 studded with garnets, and beds of granite, which dip under 

 the former, and have themselves been pierced by the trachytes 

 of Tungurahua at Rio Pullo and the Hacienda de Ganace ; 



