48 



CHAPTER XXYII. 



YOLCAXTC ERUPTIONS — concluded. 



VOLCANIC EBITPTION IN ICELAND IN 1783 NEW ISLAND THROWN TIP— LATA 



CURIiENTS OF SKAPTAR JOKUL, IN SAME YEAR THEIR IMMENSE VOLrME 



ERUPTION OF JORL'LLO IN MEXICO — HUMDOLDT's THEORY OF THE CONVEXITY 



OF THE PLAIN OF MALPAIS ERUPTION OF GALONGOON IN JAVA — SUBMARINE 



VOLCANOS — GRAHAM ISLAND, FOR^MED IN 1831— VOLCANIC ARCHIPELAGOS- 

 SUBMARINE ERUPTIONS IN MID-ATLANTIC THE CANARIES — CONES THROWN UP 



IN LANCEROTE, 1730-36 — SANTORIN AND ITS VOLCANIC ERUPTIONS— BARREN 



ISLAND IN THE BAY OF BENGAL IMUD VOLCANOS — MINERAL COMPOSITION OF 



VOLCANIC PRODUCTS. 



Vol c J NIC eruptions in Iceland. — Witli tlie exception of 



Etna and Vesuvius, tlie most complete clironological records 

 of a series of eruptions are those of Iceland, for their history 

 reaches as far back as the ninth century of our era; and, 

 from the beginning of the twelfth century, there is clear 

 evidence that, during the v^hole period, there has never been 

 an interval of more than forty, and very rarely one of twenty 

 years, without either an eruption or a great earthquake. So 

 intense is the energy of the volcanic action in this region, 

 that some eruptions of Hecla have lasted six years without 

 ceasing. Earthquakes have often shaken the whole island 

 at once, causing great changes in the interior, such as the 

 sinking down of hills, the rending of mountains, the desertion 

 by rivers of their channels, and the appearance of neAV lakes."^ 

 New islands have often been thrown up near the coast, some 

 of which still exist; while others have disappeared, either by 

 subsidences or the action of the waves. 



In the interval between eruptions, innumerable hot springs 

 afford vent to the subterranean heat, and solfataras discharge 

 copious streams of inflammable matter. The volcanos in 

 different parts of this island are observed, like those of the 



^ Von HofF, vol. li. p. 393. 



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