TRUE VOLCANOES. 331 



The only phenomena resembling narrow lava-eruptions 

 which I discovered in the Cordilleras of Quito, are those 

 presented by the colossal mountain Antisana, the height of 

 which I determined to be 19,137 feet (5833 metres), by a 

 trigonometrical measurement. As the structure furnishes 

 the most important criterion here, I will avoid the systematic 

 denomination lava, which confines the idea of the mode of 

 production within too narrow limits, and make use, but 

 quite provisionally, of the names "rock-debris " (Felstrum- 

 inern) or " detritus dykes" (Schuttivallen, trainees de masses 

 volcaniques). The mighty mountain of Antisana, at an ele- 

 vation of 13,458 feet, forms a nearly oval plain, more than 

 12,5(30 toises (79,950 feet) in long diameter, from which the 

 portion of the mountain covered with perpetual snow rises 

 like an island. The highest summit is rounded off and 

 dome-shaped. The dome is united by a short jagged ridge 

 with a truncated cone lying towards the north. In the 

 plateau, partly desert and sandy, partly covered with grass 

 (the dwelling-place of a very spirited race of cattle, which, 

 owing to the slight atmospheric pressure, easily expel blood 

 from the mouth and nostrils when excited to any great mus- 

 cular exertion), is situated a small farm (Hacienda), a single 

 house in which we passed four days in a temperature varying 

 between 38'6and 48 C *2. The great plain, which is bynomeans 

 circumvallated as in craters of elevation, bears the traces of an 

 ancient sea-bottom. The Laguna Mica, to the westward of the 

 Altos de la Moya, is to be regarded as the residue of the old 

 covering of water. At the margin of the limit of perpetual 

 snow, the Rio Tinajillas bursts forth, subsequently, under the 

 name of Rio de Quixos, becoming a tributary of the Maspa, 

 the Napo, and the Amazon. Two narrow, wall-like dykes, or 

 elevations, which I have indicated upon the plan of Anti- 

 sana, drawn by me, as coulees de laves, and which are called 

 by the natives Volcan de la Hacienda and Yana Yolcan 

 ( Tana signifies black or brown in the Qquechhua language), 

 pass like bands from the foot of the volcano at the lower 

 margin of the perpetual snow-line, and extend, apparently 

 with a very moderate declivity, in a direction N.E. S.W., 

 for more than 2000 toises (12,792 feet) into the plain. 

 With very little breadth they have probably an elevation 

 of 192 to 213 feet above the soil of the Llanos de la Ha- 



