310 REACTION OF THE INTERIOR OF THE EARTH 



heights above the level of the sea (regarded, perhaps 

 not quite correctly, as the mean level of the earth's 

 surface) are inconsiderable in relation to what we may 

 suppose to be the depth of the seat of volcanic activity, 

 and of the temperature required for the fusion of rocks. 

 The only phenomena resembling narrow flows of lava 

 which I ever discovered in the Cordilleras of Quito, are 

 those presented by the colossal Antisana, whose height I 

 determined by trigonometric measurement at 19,132 

 feet As in this case configuration affords us the best 

 criterion, I will avoid the systematic expression " lava," 

 as apt to convey too limited a sense in regard to origin, 

 and will use, in a purely objective sense terms equivalent 

 to the French expression "trainees de masses volca- 

 niques." The great mass of Antisana forms, at a height 

 of 13,455 feet, an almost oval plain, of which the 

 longest diameter is about 80,000 feet, and from which the 

 snow-covered portion of the volcano rises like an island. 

 The highest summit is rounded off into a dome, which 

 is connected by a short jagged ridge with a truncated 

 cone lying to the north of it. On this high plain, 

 which is partly desert and sandy, and partly covered 

 with grass, and on which dwell a very courageous race of 

 bulls (which, owing to the small amount of atmospheric 

 pressure, often bleed at the mouth or nostrils when 

 stimulated to any great muscular exertion), there is a 

 small hacienda, a single house, in which we passed four 

 days with a temperature varying between 38*7 and 

 48*2. The plain, which is not surrounded by any es- 

 carpment, as in craters of elevation, bears all the signs 

 of being an ancient lake-bottom. The Laguna Mica, 

 west of the Altos de la Moya, may be regarded as the 



