90 WALKS AND TALKS. 



canopy several hundred miles in width. It covered the plains 

 for a distance of twenty-five miles, with a layer of dust six- 

 teen feet thick. The headland was advanced 787 feet into 

 the. bay. Two new islands were formed from the ashes and 

 stones. The wind carried the dust westward more than forty 

 degrees of longitude, and a layer of pumice was formed at that 

 distance which vessels penetrated with difficulty. On the 

 east, the fall of ashes extended to Jamaica, 800 miles. The 

 area covered by the fall was one and a half million square 

 miles ; and the total volume of matter which escaped was not 

 less than 65J billions of cubic yards. The sound of the ex- 

 plosion was heard at Bogota, 1,025 miles distant. Impenetra- 

 ble darkness reigned for forty-three hours throughout the re- 

 gion of the eruption. 



The amount of lava from Kilau-e'-a in 1840 exceeded 

 six billion five hundred and fifty million cubic yards. That 

 from Mauna Loa, in 1835, flowed seventy-six miles from the 

 crater. The volcano of Skaptar Jokul, in Iceland, was cleft 

 asunder in 1783, and gave vent to two rivers of fire, each of 

 which filled up a valley; one attained a length of fifty miles, 

 with a breadth of fifteen miles; the other was of less dimen- 

 sions, but the depth of the mass was in some places as much 

 as four hundred and ninety-two feet. The whole volume of 

 lava erupted on this occasion was not less than six hundred 

 and fifty-five billions of cubic yards a volume equivalent to 

 that of the whole mass of Mont Blanc. 



Many thrilling narratives of volcanic violence might be 

 cited ; but these must serve as examples. They demonstrate 

 the existence of enormous reservoirs of molten rock within 

 the earth, and the exertion of such inconceivable forces as 

 suffice to burst mountains, to hurl rock-fragments a mile into 

 the atmosphere ; to blow into atoms, while escaping with 

 steam and gases, sufficient matter to bury thousands of square 

 miles in ashes. It appears that isolated volcanic cones, like 

 Vesuvius, JEtna, and Shasta, are composed generally of piles 

 of ejected materials, inaugurated by the escape of matter 

 through an initial fissure. The volcanic cone is hollow above, 



