ON ITS EXTERIOR. TOLC ANDES. 329 



Volcanoes of Iceland : Oerafa, Hecla, Eauda-Kamba, 

 &c. 



Volcano in the Island of Pico ( 47 ), one of the 

 Azores : great eruption of lava from 1st of May to 5th 

 of June 1800. 



Peak of Teneriffe. 



Volcano of Fogo ( 471 ), one of the Cape de Verde 

 Islands. 



Prehistoric volcanic activity. This kind of volcanic 

 activity is less definitely connected with particular 

 centres in Iceland than in other places. If, with Sar- 

 torius von Waltershausen, we divide the volcanoes of 

 Iceland into two classes, one of such as have had only a 

 single eruption, and the other of such as have repeatedly 

 poured forth streams of lava from the same principal 

 fissure, then the first class will include Eauda-Kamba, 

 Skapta, Ellidavatan, south-east of Eeykiavik, &c. ; 

 while to the second class, which shows a more perma- 

 nent individuality, belong the two highest volcanoes of 

 Iceland, Oerafa (fully 6,400 feet high), and Snaefiall, 

 Hecla, &c. Snaefiall has not been in eruption within 

 the memory of man ; while Oerafa is known for its 

 dreadful eruptions in 1362 and 1727. ^Sart. von 

 Waltershausen, Phys. geogr. Skizze von Island S. 108 

 and 112.) In Madeira ( 472 ), the two highest moun- 

 tains : the conical Pico Euivo, 6059 feet high, and 

 Pico de Torres, which is only a little lower, and which 

 have their steep declivities covered with scoriaceous 

 lavas, cannot be regarded as the central points of the 

 former volcanic activity of the entire island, as at many 

 other points, and, especially towards the coasts, orifices 

 of eruption have been found, and even a large crater, 



