500 SCIENTIFIC RECORD FOR 1885. 



ever produced in the world in any single eruption within historic times. 

 They cover a track of 397i square kilometers, and in several places are 

 from 157 to 188 meters thick. The lava spread towards the south in 

 two branches, the westerly one, 83 kilometers long, into the bed of 

 the Skapt4, and the easterly one, 38 kilometers long, into that of the 

 Hoerf^sflj6t. According to Lyell its volume is considerably larger 

 than that of Mont Blanc;, its mean inclination, according to Elie de 

 Beaumont, is 0° 30' ; but in the absence of exact measurements these 

 figures can be relied on only approximately. 



(6) Group of volcanoes south of the Vatnajokull. — On tbe south side of 

 the Vatnajokull, in an unknown desert, are several volcanoes, but none 

 of them have as yet been examined, and even their exact location is not 

 known, with the exception of the highest mountain in Iceland, the 

 OrcqfajdJcull, or Hnappafellsjokull (64© 0' 48" N. Lat. and 29° 20' 10" 

 Loug. west of Copenhagen), which rises like a promontory on the south 

 brink of the Vatnajokull to a height of 1,960 meters. Formerly human 

 habitations extended to the foot of the glacier, but these regious have 

 been completely devastated by the eruption of 1349. Palsson ascended 

 the Orsefajokull in 1793. From all sides extend large glaciers down to 

 the low lands. To the west of the Oriefajokull is the glacier of Skei- 

 (Ihardrjokull, and still farther to the west that of SidhujokuJl; between 

 these is the lake of Grtmsvdtn. The annals mention several eruptions 

 in this region, but exact data are wanting. 



(7) Group of volcanoes of Odddhahraun. — To the north of the Vatna- 

 jokull is the grand lava current of Odddhahraun, covering a surface of 

 3,400 square kilometers, and on which a considerable number of craters 

 and volcanoes are located, the greater part of which are still unexplored. 

 The height of the Odddahraun, above the sea, at the foot of the Vatnajo- 

 kull, is 942 meters, but on the inner side only 471 meters. To the north 

 of the Vatnajokull, in W. Long. 29° 30', is the volcano Kverkfjall, from 

 which eruptions took place in 1717 and 1873, and likely quite frequently 

 within historic times. To the northwest of the Kverkfjall rises, at an 

 elevation of 1,400 meters above the sea level, the volcanic group of 

 D'ljngjufjall, explored by F. Jonstrup in 1876. These mountains encircle 

 the valley of Askja^ which has a surface of about 57 square kilometers, 

 and an altitude of 1,100 to 1,200 meters. The ground is covered with 

 iava beds having, in the east, towards the opening of the valley, an in- 

 clination of 1° 26'. In the southeast angle of Askja an abyss of 230 

 meters depth has formed, in the middle of which is found a circular 

 lake of 1,200 meters in diameter, with a water temperature, in 1876, of 

 22° 0. On the sides of this pit are craters which erupted in 1875. 



To the north of the Dyngjutjall mountains, to the west of Jokulsii i 

 Axarfirdhi, in a flat and sterile jilain, named M^vatnsoraefi, in which 

 there are some ancient craters, an eruption took place in 1875 in the 

 «'revice of Sveinagjd, in the midst of a grassy i)lain, whereby a current of 

 lava was created, 23,000 meters long and 1,900 meters wide, the volume 



