M. Humboldt on the Sulphur Mountain oj Ticsan. 121 



found a little plain, where, in the seventeenth century, was si- 

 tuated the village of Ticsan. The ruins of the church of Pueblo 

 Viejo are still seen. An earthquake wholly local (for its effects 

 were confined to a very small s}:)ace of country) made the sur- 

 rounding hills sink down : a part of the village sunk; another 

 part was thrown into the air, as happened at Riobamba, 

 where I found the bones of the unfortunate inhabitants of the 

 town thrown on the Cerro de la Culca, to a height of several 

 hundred feet. The Indians of Ticsan who survived this ca- 

 tastrophe constructed their habitations more to the north, far 

 from the mountain of sulphur whose neighbourhood they 

 dreaded. It may be that the coincidence of these phaenomena 

 of explosion and of tlie position [gisement) of a substance easy 

 to be converted into elastic vapours has only been accidental : 

 but it may be also that ancient communications with the interior 

 of the globe, those upon which is formed by sublimation the 

 immense deposit of sulphur, become re-established from time 

 to time, and allow the volcanic forces to shake the surface of 

 the soil. Near the ruins of Pueblo Viejo of Ticsan I found a 

 hill of gypsum lying above the micaceous schist: as this hill is 

 not covered by other formations, it is difficult to decide whether 

 the gypsum, partly fibrous and mixed with clay, is primitive, 

 like that of Val Canaria, or transition, like the gypsum of the 

 Tarentaise. 



The abundance of sulphur in primitive countries is a very 

 important geological fact, in relation to the study of volcanos 

 and of rocks through which the subterraneous fire has opened 

 itself a passage. Before I had visited the Andes of Quito and 

 the mountain of Ticsan, sul]>hur was known only in the tran- 

 sition limestone and gypsum ; in the gypsums, marles and mu- 

 riatiferous clays of secondary countries, and in the rocks ex- 

 clusively called volcanic. These different geological situations, 

 to which may be added the tertiary districts, very ill explained 

 tiie frequency of the sulphureous vapours exhaled by the 

 mouths of the volcanos whose centre of action was placed (and 

 doubtless with })ropriety) very much below the secondary and 

 intermediate rocks. In proportion as we become acquainted 

 with a greater part of the globe we not only see positive geo- 

 gnosy, that is to say, the view of the formations and of the geo- 

 logical positions, extended ; but even gcogomj, or systematic geo- 

 gnosy, the conjectural science which investigates tlie causes of 

 phji-'noniena, begins to be founded on the analogy of more 

 certain facts. We may iiave been struck for some time past 

 with the little masses of native suljihur which are disseminated 

 in some metalliferous veins, and which traverse granitic rocks; 

 for example, in Schwnrzw.'ild, nciir iJicpoldsMu. The moiintiiin 



Vol. f)j. No. M'J2. Fill. J»2.'>. (^ of 



