224 THORODDSEN 



sheep's skins, and the hoofs of the sheep turned yellow when they 

 walked amongst them; while the rain which fell from the dust-clouds, 

 is said to have been so sharp and biting that it was painful where 

 it fell on the hands and face. The volcanic eruptions, on the whole, 

 have had a very injurious influence upon the plant -distribution 

 in the volcanic regions of Iceland. During the eruptions a great 

 number of sheep and cattle die from want of food or from its un- 

 wholesome nature, and of various diseases caused by the ashes eaten 

 with the fodder. No eruption has however been so disastrous as 

 the eruption of the Laki crater-rows in 1783. In the winter which 

 followed, and in the spring of 1784, the sheep and cattle suffered 

 from all kinds of diseases owing to the unwholesome food, and 

 died by scores. On many farmsteads the entire live-stock died out, 

 and the following year there died in the whole of Iceland 11,500 

 cattle, 28,000 ponies and 190,500 sheep about 53 per cent of all 

 the cattle, 77 per cent of the ponies and 82 per cent of the sheep. 

 Then came a famine, which carried off 9500 of the inhabitants, 

 about one-fifth of the total population of Iceland at that time. 



In Iceland there are several types of volcanoes. Usually, by a 

 volcano is understood a large hill or mountain, more or less conical 

 in form, which is ignivomous, discharging lava-streams and ejecting 

 ashes and fragments of lava. Volcanoes of this description occur 

 in Iceland, but are not common; seven or eight such volcanic moun- 

 tains are known, which resemble externally the well-known Italian 

 volcanoes of Vesuvius and Etna, without however being so regular 

 in form; they are built up of alternating layers of ashes, lava and 

 slag, and usually resemble truncated cones with a crater at the 

 top, and a considerable angle of inclination (at the base 8 15; 

 at the top 20 35); the majority of them have their summits 

 covered with snow and glaciers. Of these volcanoes the largest and 

 best known are Oraefajokull, Snsefellsjokull and Eyjafjallajokull. 

 Hekla is also built up of alternating layers of lava and tuff, but is 

 not conical. Its shape conforms to an elliptical ridge, rent down 

 its major axis, and studded with a row of craters along the line of 

 fissure. Another type of Icelandic volcano are the dome-shaped 

 u lava-cones" (dyngja, pi. dyngjur) larger or smaller volcanoes, 

 built up entirely of lava-streams, without any intermediate layers 

 of tuff or slag. Volcanoes of this description, which are also found 

 in the Sandwich Islands, are distinguishable from the country sur- 

 rounding them as shield-shaped cones, and their altitude is low 



