over the country, sometimes singly, but more frequently in groups, along 
lissures in the earth's crust. In and near the volcanic zone there is a 
considerable number of Solfataras and Mudvolcanoes, the fumes from 
which consist mainly of sulphuretted hydrogen, hydrogen, and carbonic 
acid gas. But in other places of the country the hot springs are mostly 
alkaline, the chief constituent of the (spring) gases being nitrogen. 
Most hot springs keep the same temperature all the year round irre- 
spective of the weather conditions. But all hot springs are not equally 
hot, the temperature varying from 10° C. to boiling point. No springs 
show more than 100° C. on the surface, while at the bottom of a 
deep well the heat may rise even to 120° C, 
Some of the hot springs in Iceland are intermittently eruptive, the 
best known being the Stéri Gepsir (i. e. the Great Geysir) in Hauka- 
dal (Hawksdale) in the south. Its eruptions have been very unequal 
in height, the highest yet known measuring 67 metres. At present the 
most powerful hot springs in Iceland are Nordurhver (Northspring) in 
Repkjahverfi (Reekie-Parish) in Thingeyjar district, throwing jets to a 
height of 11 metres; Smidur and Otherrishola (Wet-weather Hole) 
near Stéri Gevsir and Grila in Olfus. 
EARTHQUAKES 
Earthquakes (jardskjélftar) are frequent in Iceland, especially in the 
south-western and north-eastern parts of the country, and have at 
limes done a great amount of damage to property. As late as 1896 an 
earthquake, confined to the lowlands in the south, destroyed a great 
number of farm-houses. 
LAKES AND RIVERS 
Though there are a great many rivers in Iceland and some of them 
have a considerable volume of water, yet none are navigable on ac- 
count of their swift currents. Such rivers as are fed by glaciers are 
whitish-grey in colour, because they carry with them a large quantity 
of mineral dust, eroded by the glaciers from the rocks on which they 
vest. This water, charged as it is with minerals, has proved useful for 
irrigation purposes. In many of the rivers, where they leave the high- 
lands, there are lofty falls, the best known being the Gulifoss (The 
Goldforce) in the Hwiti (Whitewater) in the south, and Dettifoss in 
the Jokulsi in AxarfjorBur (Axefirth). In the spring thaws the waters 
in the rivers increase greatly, and the rushing streams carry with them 
quantities of gravel and loose stones. which. when the rivers quiet