278 ICEL-\XD: ITS HISTORY AXD IXHABITAXTS. 



the geological conditions prevailing toward the close of the Glacial 

 epoch in Europe. 



Iceland is the center of a siiboceanic volcanic region, and no region 

 of the earth has an equal title to be called the " Land of Fire." It 

 owes its very existence to volcanic agency continued to-day and may 

 be truly called the abode of subterraneous heat. No spot on the sur- 

 face of the globe of its extent exhibits marks of fire in such a multi- 

 tude, in such a variety, and of such a magnitude. None contains an 

 equal number of volcanoes. Xowhere have eruptions of such magni- 

 tude occurred. Doctor Thoroddsen has counted 107 volcanoes, 83 of 

 which are a series of low craters or crater chains, 8 are of the Vesu- 

 vius shape, and 16 of the Sandwich Islands lava-cone shape. Five 

 thousand square miles of land are covered with lava. The post- 

 Glacial lava alone would cover Denmark with a laj'er 10 feet in thick- 

 ness. The largest lava desert is the Oda5ahraun, which covers an 

 area of 1.700 square miles and is from 1,000 to 3,500 feet above sea 

 level. This lava field has been formed by the eruptions of about 

 20 volcanoes. The cubic capacity of the lava ejected here would 

 make a solid cube, each side of which would measure about 50 miles. 

 The most frequent form of manifestation of volcanic eruption is the 

 formation of a series of low craters, often several miles in length, 

 along lines of cleavage in the crust of the earth. The longest is that 

 of Laki. 20 miles long, containing about 100 craters. Sometimes lava 

 has welled up out of fissures without craters. The largest of these 

 is Eldgja, north of Myrdalsjokull, 19 miles long, 434 feet deep — in 

 one place 050 feet deej^ — bottom 408 feet wide. The volcanoes are 

 not, as was formerly supposed, limited to the region of palagonite 

 breccia. On the Faxa-bay are many small volcanoes which have 

 broken through the basalt. About 25 volcanoes have been active in 

 historic times (900-1900). Vesuvius is dwarfed into insignificance, 

 for the lava flood of the last eruption in Iceland, in 1875, has Ijeen 

 comj^uted to contain 31,000 millions of cubic feet, while in the largest 

 eruption of Vesuvius on record, that in 1794, only about 730 millions 

 of cubic feet of lava were ejected. 



The lava field of the crater chain of Laki covers some 220 square 

 miles, and the lava current flowed 47 miles away from the place of 

 eruption. The longest flow of lava in Iceland is that from the craters 

 of Fiskivotn, 90 miles long. On March 12, 1875, a lava torrent forced 

 its way 620 j^ards up an incline of 0° 25'. On March 29, 1875, the 

 pumice ashes of Mount Askja were carried over 1.000 miles away to 

 Xorway in eleven hours fort}' minutes, and in another ten hours to 

 Stockholm. The column of ashes rising from Hekla was measured on 

 April 21, 1766, and was found to rise 16.500 feet above the top of the 

 mountain; on February 5, 1846, it rose 14,350 feet. On April 5, 



