212 



perhaps have never been perfectly liquified, but 

 which do not less belong to the domain of vol- 

 canoes. 



In the isle of TenerifFe strata of tufa, puzzo- 

 lana, and clay, separate the range of basaltic 

 hills from the currents of recent lithoid lavas, 

 and from the eruptions of the present volcano. 

 In the same manner as the eruptions of Epomeo 

 in the isle of Ischia, and those of Jorullo in 

 Mexico, have taken place in countries covered 

 with trappean porphyry, ancient basalt, and 

 volcanic ashes, so the Peak of Teyde has raised 

 itself amidst the wrecks of submarine volcanoes. 

 Notwithstanding the difference of composition in 

 the recent lavas of the Peak, there is a certain 

 regularity of position* which must strike the 

 naturalist the least skilled in geognosy. The 

 great elevated plain of Retama separates the 

 black, basaltic, and earthlike lava, from the vi- 

 treous and feldsparry lava, the basis of which is 

 obsidian, pitchstone, and phonolite. This phe- 

 nomenon is so much the more remarkable, as in 

 Bohemia, and other parts of Europe, the joor- 

 phyrschiefer with base of phonolite * covers 

 also the convex summits of the basaltic moun- 

 tains. 



as the domites of the Great-Sarcuy, of Puy-de-Dome, of the 

 Little-Cleirsou, and of one part of the Puy Chopine in Au- 

 vergne. 



* Klingstein. Werner, 



