330 cosxMos. 



another volcano, which in April, 1818, presented high erup- 

 tions of ashes every four months. 



The Beerenberg, 6874 feet in height, in the broad, north- 

 eastern part of Jan Mayen (lat. 71° 4 / ), is not known to be 

 a volcano.* 



Volcanoes of Iceland : Oerafa, Hecla, Rauda-Kamba . . . 



Volcano of the island of Pico,f in the Azores : a great 

 eruption of lava from the 1st May to the 5th June, 1800. 



The Peak of Teneriffe. 



Volcano of Fogo,| one of the Cape de Verd Islands. 



Pre-historic Volcanic Activity. — This on Iceland is less defin- 

 itely attached to certain centres. If we divide the volca- 

 noes of the island, with Sartorius von Waltershausen, into 

 two classes, of which those of the one have only had a sin- 

 gle eruption, while those of the other repeatedly emit lava 

 streams at the same principal fissure, we must refer to the 

 former, Rauda-Kamba, Scaptar, Ellidavatan, to the south- 

 east of Reykjavik . . . . ; to the second, which exhibits a per- 

 manent individuality, the two highest volcanoes of Iceland 

 Oerafa (more than 6390 feet) and Snaefiall, Hecla, etc. Snae- 

 fiall has not been in activity within the memory of man, while 

 Oerafa is known by the fearful eruptions of 1362 and 1727 

 (Sart. von Waltershausen, Skizze von Island, s. 108 and 112). 

 In Madeira,§ the two highest mountains, the conical Pico 

 Ruivo, 6060 feet in height, and the Pico de Torres, which is 

 but little known, covered on their steep declivities with sco- 

 riaceous lavas, can not be regarded as the central point of the 

 former volcanic activity on the whole island, as in many 

 parts of the latter, especially toward the coasts, eruptive ori- 

 fices, and even a large crater, that of the Lagoa, near Ma- 

 chico, are met with. The lavas, thickened by confluence, 

 can not be traced far as separate streams. Remains of an- 

 cient dicotyledonous and fern-like vegetation, carefully inves- 

 tigated by Charles Bunbury, are found buried in upheaved 



* Scoresby's Account of the Arctic Regions, vol. i., p. 155-169, tab. 

 v. and vi. 



f Leop. von Buch., Descr. cles lies Canaries, p. 357-369, and Land- 

 grebe, Naturgeschichte der Vulkane, 1855, bd. i., s. 121-136; and with 

 regard to the circumvallations of the craters of elevation (Caldeiras) 

 upon the islands of St. Michael, Fayal, and Terceira (from the maps 

 of Captain Vidal) (see page 216). The eruptions of Fayal (1672) and 

 Saint George (1580 and 1808) appear to be dependent upon the prin- 

 cipal volcano, the Pico. J See pages 236 and 249. 



§ Results of the observations upon Madeira, by Sir Charles Lyell 

 and Hartung, in the Manual of Geology, 1855, p. 515-525. 



