MUD VOLCANOES. 



263 



been increased in intensity, and a passage been opened near the 

 summit, through which streams of lava and showers of scoriae had 

 been projected, we should have had a crater of elevation, though its 

 structure and mode of formation might have been concealed by vol- 

 canic substances covering the original rock. Von Buch and Hum- 

 boldt have been challenged to discover a single volcanic cone com- 

 posed exclusively of marine or of freshwater strata ; but surely this 

 is overlooking the conditions under which such a cone must be form- 

 ed : the eruptions from the crater, when once open, would cover a 

 great part of the external cone with lava and volcanic matter. The 

 above eminent geologists might show Crich Cliff and Wren's Nest 

 Hill, as presenting a triumphant confirmation of the theory of eleva- 

 tion ; a confirmation not the less satisfactory, because the volcanic 

 action had been arrested precisely at the point, where the truth of 

 the theory was rendered most apparent. 



The island called the New Kamenoi, raised near St. Erini during 

 a submarine eruption in the year 1707, was composed partly of lime- 

 stone, and covered with living shells, which prove that the rock was 

 upraised in a solid mass. Volcanic islands, of great elevation, have 

 been raised, in the present century, in the group called Aleutian 

 Islands ; and as they remain permanent, with little diminution of 

 height, it is supposed by Von Buch that they consist of solid rock. 



The marine limestone on the sides of ^tna, offers confirmatory 

 evidence of the truth of the theory of elevation, though the strata 

 may have been subsequently disturbed, and dip in different direc- 

 tions. I have in my possession an enormous marine shell, or gigantic 

 cerithium. According to the notice written upon it by the late Fau- 

 jas St. Fond, it was obtained from the Peak of Teneriffe, which in- 

 dicates that this vast volcanic mountain, was originally a crater of el- 

 evation raised from the sea. 



Some volcanoes in Europe, and many in the Andes, throw out 

 aqueous torrents, intermixed with mud and stones; indeed, the Amer- 

 ican volcanoes more frequently eject mud than lava. Eruptions of 

 water from jEtna and Vesuvius are rare, and some which have been 

 described as flowing from the crater of the former, have been mere- 

 ly the torrents of melted water from snow on its summit. The vol- 

 cano of Macaluba, in Sicily, presents the phenomena of mud, water, 

 and stones thrown out of the crater. Ferrara describes an alarming 

 eruption which took place on the 29th of September, 1777: — 

 " Dreadful noises were heard all round ; and from the midst of the 

 plain, in which was formed a vast gulf, an immense column of mud 

 arose to the height of about one hundred feet, which, abandoned by 

 the impulsive force, assumed the appearance of a large tree at the 

 top. In the middle, stones of all kinds and sizes were darted vio- 

 lently and vertically, within the body of the column. This terrible 

 explosion lasted half an hour, when it became quiet ; but after a few 

 minutes resumed its course, and with these intermissions continued 



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