176 



which follows the end of an eruption. Fron 

 the lapse of time, and the action of the vapors 

 the inside walls are detached, and have covered 

 the basin with great blocks of lithoid lavas. 



We reached the bottom of the Caldera with- 

 out danger. In a volcano, the activity of which 

 is principally directed towards the summit, such 

 as Vesuvius, the depth of the crater varies be- 

 fore and after each eruption ; but at the Peak of 

 TenerifFe, the depth appears to have remained 

 the same for a long time. Eden, in 1715, esti- 

 mated it at 115 feet; Cordier, in 1803, at 110 

 feet. Judging by mere inspection, I should have 

 thought the funnel of still less depth. It's pre- 

 sent state is that of a solfatara ; and it is rather 

 an object of curious investigation, than of tre- 

 mendous aspect. The majesty of the site con- 

 sists in it's elevation above the level of the ocean, 

 in the profound solitude of these lofty regions, 

 and the immense space over which the eye ranges 

 from the summit of the mountain. 



The wall of compact lava which forms the 

 enclosure of the Caldera, is snow ^vhite at it's 

 surface. The same colour prevails in the inside 

 of the solfatara of Puzzuoli. When we break 

 these lavas, which might be taken at some dis- 

 tance for calcareous stone, we find in them a 

 blackish brown nucleus. Porphyry with basis 

 of pitch stone is whitened externally by the slow 

 action of the vapors of sulphurous acid gas. 



