VOLCANIC CONES AND CRATERS. 



" Yues des Cordilleres," pi. XLIII., p. 239. Other examples are 

 presented by the small cones of the volcano of Awatscha, and of 

 the field of lava in Kamtsehatka, described by Erman. 



70. Around each mouth from which the fiery matter is pro- 

 jected, a cone' of cinders and ashes is formed by the return of the 

 matter which has been projected upwards. These cones vary 

 greatly in height and magnitude, and appear to have no relation 

 to the general elevation of the mountain, the smaller class of 

 volcanoes often producing the highest cones. One of the most 

 remarkable of these cones is that of the Volcano of Cotopaxi, in 

 the eastern Cordillera of the Andes, about 34 miles S.S.E. of 

 Quito. The general form of this remarkable mountain is that of 

 an immense cone, shaped with an accuracy almost geometrical. 

 The summit is about 19000 feet above the level of the sea, and 

 nearly 10000 above the adjacent table-land. The snow line is 

 at 4400 feet below the summit. The cone, therefore, above this 

 line is coated with perpetual snow, except at the times of erup- 

 tions, in which the solid sides of the cone becoming incandescent, 

 the snow suddenly melts, and descending in torrents down the 

 flanks of the mountain, leaves the conical summit uncovered. 

 " Of all' the volcanoes which I have seen," says Humboldt, " in 

 either hemisphere, the cone-formed Cotopaxi is at once the most 

 regular and the most picturesque. Before each great eruption, 

 the sudden fusion of the snow, which habitually invests its 

 vast cone, announces the coming catastrophe. Even before the 

 appearance of smoke issuing from its lofty crater, the sides of 

 the cone acquire a glowing temperature, and the mass of the 

 mountain assumes an aspect of most awful and portentous 

 blackness." 



71. It is difficult to imagine any spectacle more awfully grand 

 than the view of a crater in activity presented to an observer 

 stationed at the summit of the surrounding wall. The space 

 beneath him appears like the surface of agitated half-molten 

 matter contained in a colossal cauldron. The surface swells and 

 intumesces ; from the cracks and fissures vapours issue ; small 

 chasms here and there alternately open and close, showing within 

 them red hot molten matter ; burning fragments are from time 

 to time thrown up, and fall back upon the sides of the mounds 

 surrounding the mouths from which they have been vomited ; 

 each small eruption of this kind is regularly preceded and 

 announced by small earthquake shocks, which sensibly shake the 

 ground beneath the feet of the observer ; occasionally lava issues 

 in a fiery torrent from these fissures and mouths, but not in 

 sufficient quantity to break through the walls of the crater, but 

 sometimes the flow of this red hot pasty matter is so abundant 



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