CHAP. XIX. CONFIGURATION OF THE ANDES OF ECUADOR. 337 



Of the extinct Volcanoes, Oayambe, Antisana and Chimborazo 

 are the most important. There are lava-streams upon the flanks 

 of" all three mountains/ and I cannot doubt that they had craters 

 of considerable size, though none can now be seen. The space at 

 the summit of Antisana is sufficiently large to admit of one as 

 great as that of Cotopaxi, and I think it may be assumed that 

 under the snowy domes which now form the summits of Chim- 

 borazo there are rocky peaks which were formerly two of the 

 highest points around the rim of a crater. 



There are no records of eruptions of Chimborazo.'^ It must 

 have been an extinct volcano for many ages. The complete burial 

 of its crater, the thickness of the ice-cap at its summit and large 

 size of its glaciers, the ruin and erosion of its lava-streams, and the 

 height vegetation has attained upon its flanks are all indications 

 that its activity ceased at a remote period. It is less regularly 

 conical than Cotopaxi, Sangai or Tunguragua, and towards its 

 summits has sheer cliffs,^ that I have termed the Northern and 

 Southern Walls, which it seems to me can only have been formed 

 either by violent upheaval or by explosive blowing away of por- 

 tions of the exterior of the cone. The Southern Walls are shewn 

 in the illustrations facing pages 24, 64 and 76, and, more in detail, 

 in the accompanying plate. They are in two series, B, B, and D, D. 



1 In the matter of lava-streams I differ from Boussingault, who says that none 

 can be seen anywhere among the Volcanoes of Tropical America. "La masse du 

 Chimborazo est formee par I'accumulation de debris trachytiques, amonceles sans 

 aucun ordre. Ces fragmens trachytiques, d'un volume souvent enorme, ont ete 

 souleves a I'etat solide ; leurs angles sont toujours tranchans ; rien n'indique qu'il y 

 ait en fusion ou meme un simple etat de mollesse. Nulle part^ dans aucune des 

 volcans de Veqaateur, on n^ observe rien qui puisse faire presumer une coulee de laves^ 

 — Annates de Chimie et de Physique, tome Iviii, 2me serie, p. 175, Paris, 1835. 



1 find this difficult to comprehend, as Boussingault visited Cotopaxi and the 

 Hacienda of Antisana. See pages 138, 145, 187 and 189. 



2 "Chimborazo, Volcan (on ignore I'epoque de son eruption)."— La Condamine 

 in Hist, de VAcad. Royale des Sciences (annee 1746), Paris, 1751, pp. 650-1. 



3 There is some equally sheer cliff on the northern side of Cotopaxi, near the 

 summit. 



2X 



