ELEVATION OF JORULLA. 195 
deck, and several tons' weight of it must have been 
thrown overboard ; for, though an impalpable pow- 
der when it fell, when compressed it had consider- 
able weight, a pint measure of it weighing twelve 
ounces and three quarters." 
During this eruption many thousand inhabitants 
were destroyed; vegetation was completely killed; 
the sea rose twelve feet higher than it was ever 
known to do before, and violent whirlwinds pros- 
trated everything before them. 
In May, 1759, the plain on which the volcano of 
Jorulla now stands was highly cultivated, and cov- 
ered with indigo and sugar-canes. In June follow- 
ing, hollow subterranean noises were heard, ac- 
companied by earthquakes, which lasted fifty or 
sixty days. By the month of September tranquilli- 
ty seemed established, but on the 28th and 29th of 
this month the subterranean noises again began, and 
the ground, over an area of three or four square 
miles, according to Humboldt, rose up like a blad- 
der to a height of 524 feet towards the centre of the 
present volcanic district. Fragments of rock were 
thrown to a great height ; ashes were scattered far 
and wide ; and the light emitted was seen at a 
great distance. Two streams of water which ran 
through the plain precipitated themselves into the 
volcanic vent, and assisted, by the decomposition 
of their waters, the fury of the eruption. 
Submarine Volcanoes. — The whole of Iceland is 
believed to be a volcanic mass which has been 
projected from beneath the ocean. In January, 
1783, a volcanic eruption, attended with flame, rose 
through the sea about thirty miles from Iceland ; 
several islands were formed, and a reef of rocks 
now exists where they were formerly situated. 
The flame lasted several months, during which vast 
quantities of pumice and light slags were washed 
on shore. Another submarine eruption occurred 
near the same island in June, 1830, which resulted 
in the formation of an island 
