Rit (Vísindafélag Íslendinga) - 01.06.1976, Blaðsíða 163

origin. The mean deuterium content of these springs, 8D = — 65%0,
is practically the same as found in the hot spring Múli (sample No.
150), located on land approximately 32 km to the north-east. Con-
sequently the recharge area for the Breiðafjörður hot springs and
the hot spring Múli is very likely to he the southemmost part of the
Vestfirðir basaltic plateau.
The hot springs in ísafjörður (samples No. 151-156) all have
8D-values similar to that in the nearest mountains.
The few deuterium measurements carried out on thermal water
in the western or north-western part of the country suggest that the
thermal water in this part of the country is of an almost local ori-
gin. It obviously originates as precipitation in mountainous areas
near to the spring. The water, however, seems to descend to a depth
sufficiently great to heat it. The groundwater flow is obviously not
always limited to the coastal line but may continue under the bed
of the ocean.
15. 13 Húnavatnssýsla.
For a geological description of the thermal areas in northem Ice-
land discussed in the following section the reader is referred to
Einarsson (1942 and 1962).
Thermal water has been sampled from seven wells and hot
springs in Húnavatnssýsla in North Iceland (see Fig. 40, samples
No. 158-163 and No. 224).
The 8D-values of the water samples in this area vary considerably
within the area, indicating either that the water differs in its origin
or age or that it mixes with a variable amount of more local ground-
water. In his studies, however, Einarsson (1942) pointed out that
mixing with cold groundwater as the thermal water moves up to
the surface, is rather unlikely. In general, one can say that the
thermal water in Húnavatnssýsla all seems to originate in the west-
ern central part of the country, possibly in the glacier Langjökull.
15. 14 Skagafjörður.
The hot springs in Skagafjörður (see Fig. 40, samples No. 164-
177) vary considerably in their deuterium content 8D = — 83%0
to 8D = — 108%0. At present, values comparable to the lowest 8D-
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