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
