The Botany of Iceland - 01.12.1914, Qupperneq 47

PHYSICAL GEOGRAPHY
231
growlh. While plant-growth is abundant in the neighbourhood of
the alkaline hot springs, from the vicinity of the sulphur springs
it is almost absent. In places where surface-water or underground
water is found, mud-holes are formed, or Jarger or smaller sloughs,
in which clayey mud of various colours boils and bubbles; it is
sometimes ejected a few feet upwards, whereby crater-like mounds
are formed around the larger pits, bearing a weird resemblance to
Fig. 12. Solfataras of Krisuvík.
large cauldrons of boiling porridge. The majority of tlie sulpliur
springs occur on Reykjanes, in Hengill, near Krisuvík and at Cape
Reykjanes where the large slough of Gunna is well-known. More-
over, extensive sulphur-spring districts (Námufjall, Krafla, Fremri-
námur) occur near Mvvatn, and Iverlingarfjöll near Arnarfellsjökull
is another, upon the interior plateau. Carbonic acid springs
(ölkeldur) and Mofettes occur here and there, especially on Snæ-
fellsnes in western Iceland; the best-known carbonic acid spring
is found near Raudimelur in Hnappadal. Ores, metals and stones
of any great commercial value are not found in Iceland. Here and
there some lignite occurs which is utilized by the neighbouring
tnhabitants. The gathering of sulphur is no longer lucrative, but,