VULCANISM, ETC., IN ICELAND. 499 



syssel) from that of Eang.irvallii, are located two centers of eruption, 

 the EyjafjallajokuU and the Kaila. The neighborhood of this gronj) 

 consists of sandy deserts and bowlders, which have their origin in the 

 glacial movement and in volcanic eruptions. Tiie configuration cf 

 several districts have in this manner been entirely changed within his- 

 toric times. The combined power of the glacial movement and of the 

 volcanoes is plainly seen in many instances. At one place where for- 

 merly quite a considerable fjord existed, there is at present a desert, and 

 several small mountains which formerly rose from the coast are at 

 present quite a distance away from the sea. The Eyjalfjallnjoknll 

 (630 37' K Lat. and W. Long. 32° 16' 18"), to the west, is a truncated 

 cone of 1,706 meters in height. The principal crater, has tumbled in 

 and is tilled up with ice. The eruption of 1831 took place from a crevice 

 of about 50 meters, on the northwest slope of the mountain. The Katla 

 (63° 37' N. Lat., 31° 35' W. Long, is a deep crater, situated in the east- 

 ern portion of the M;^rdalsj6kull, and ordinarily filled with ice. It has 

 several times been attempted to closely examine this volcano, but always 

 in vain. 



From the Katla, descending to the base of the glacier, extend two 

 valleys, the one in a southeasterly direction, towards the M;frdalssandr, 

 beyond the isolated mountain Hafrsey, the other one in a southwesterly 

 direction, towards the Solheimasandr. The greater part of the water- 

 courses issuing from the glaciers at the time of the eruptions descend 

 through the valley to the southeast; still some few find their way 

 through the southwesterly valley. The eruptions which in the annals 

 have been ascribed to the M;^rdalsjokull, MidhdalsjokuU, Hefdhajokull, 

 Solheimajokull, and Katla, shouhl all be credited to the Katla, since 

 all these names have been given to the same volcano. Several districts 

 and a large number of farms have been destroyed by the eruptions of 

 the Katla. Neither the Katla nor the other ice-covered volcanoes in the 

 south of Iceland have ever emitted any lava. This, next to the Hecl;i, 

 is the most active volcano, twelve or thirteen eruptions having been 

 recorded within historic times. 



(5) Group of Yarmdrdalr. — The most violent eruptions ever recorded 

 in Iceland within historic times occurred in 1783, to the northeast of 

 the glacier of Myrdalr, in the neighborhood of the sources of the 

 Skaptd. These eruptions issued from a large number of craters, situ- 

 ated to the southwest, north, and east of Mont Laki (64<^ 2' X. Lat.), ami 

 throughout a valley named Varmardalr, and not' from the Skaptiirjo- 

 kull, as mentioned in most geological manuals, although it is not implied 

 that on other occasions eruptions have not taken place from craters in 

 that region of glaciers. The craters which occupy our nttention in tlu^ 

 present case are but imperfecitly known. Magnus Stephensen (1781) and 

 Sveinn Pallson (1704) examined several of them superficially. Those of 

 the valley of Varmardalr extend throughout a length of about 15 kilom- 

 eters. The currents of lava which were formed are the most extensive 



