336 COSMOS. 



he has acutely investigated this region 30 years after myself 

 he insists upon the analogy which appears to him to be 

 presented by the geognostic relations of the eruption of 

 Ansango to Antisana, and those of Yana Urcu (of which 

 I made a particular plan) to Chimborazo. I was the less 

 inclined to believe in a direct upheaval upon fissures through- 

 out the entire linear extent of the tract of fragments at 

 Ansango, because this, as I have already repeatedly mentioned, 

 leads at its upper extremity, to the two chasms now filled 

 with water. Non-fragmentary, wall-like upheavals of great 

 length and uniform direction, are however not unknown to 

 me, as I have seen and described them in our hemisphere, 

 in Chinese Mongolia, in granite banks with a floetz-like 

 bedding 27 . 



Antisana had an eruption 28 in the year 1580, and 

 another in the beginning of the last century, probably in 

 1728. Near the summit, on the northnorth-east side, we 

 observe a black mass of rock, upon which even freshly 

 fallen snow does not adhere. At this point, a black column 

 of smoke was seen ascending for several days in the spring 

 of 1801, at a time when the summit was on all sides per- 

 fectly free from clouds. On the 16th March, 1802, Bon- 

 pland, Carlos Montufar, and myself reached a ridge of 

 rock, covered with pumice-stone, and black, basaltic scoriae 

 in the region of perpetual snow, at an elevation of 2837 

 toises (18,142 feet), and consequently 2358 feet higher than 

 Montblanc. The snow was firm enough to bear us on 



Bd. i, s. 200). With regard to the first origin of the opinion of the 

 upheaval of solid masses in the form of heaped-up blocks, see Acosta, 

 in the Viajes d los Andes Ecuatoriales par M. Boussingault, 1849, 

 pp. 222 223. The movement of the heaped-up fragments, induced by 

 earth-shocks and other causes, and the gradual filling up of the inter- 

 stices, may, according to the assumptions of the celebrated traveller, 

 produce a gradual sinking of volcanic mountain peaks. 



^ Humboldt, Asie Centrale, t. ii, pp. 296301 (Gustav Rose, mineral- 

 geognostische JReise nach dem Ural, dem Altai und dem Kasp. Meere, 

 Bd. i, s. 599). Narrow, much elongated granitic walls may have risen, 

 during the earliest foldings of the earth's crust, over fissures analo- 

 gous to the remarkable, still open ones, which are found at the foot of 

 the volcano of Pichincha: as the Guaycos of the city of Quito, of 30 

 40 feet in width (see my Kleinere Schriften, Bd. i, s. 24). 



28 La Gondamine, Mesure des trois premiers Degr$s du Meridien dant 

 Hemisphere Austral, 1751, p. 56. 



