Jökull - 01.12.1964, Blaðsíða 15

Fig. 9. Tlie area in front
of Hálsajökull. To the
right the big block in
front of the recent termi-
nal moraine (cf. Fig 10);
to the left a piece of that
block is resting on the
old terminal moraine.
Photo: S. Thorarinsson,
July 25, 1964.
even in their distal parts. Immediately in front
of them is a large block, dark in colour (figs.
9—10), which appears to be composed of some
pitchstone breccia (I did not take a close look
at it). It has obviously fallen down somewhere
from the nearby vertical walls of the névé area
of Hálsajökull, and smaller parts of it are
found farther down the slope (fig. 9).
About 160 m in front of the recent terminal
moraine there is a terminal moraine (cf. figs.
8 and 9) of similar type, but obviously much
older. It has a steep distal front, about 4 m
high. This moraine is vegetation-covered, and
in a small depression just inside the distal
front I measured the soil section shown as Cf
18a on fig. 5, together with a section dug about
3 km farther south (Cf 18b), and another (Cf
17) dug at our camping place 10 km N of Snæ-
fell and 1 km NW of Saudafell. In the last
mentioned section we can identify most of the
layers identified in section Cf 16a in Kringils-
árrani. In the sections E of Snæfell, however,
I found only one rhyolitic layer, viz. Ö 1362.
Comparing Cf 18a with Cf 17 and Cf 18b,
which represent the entire postglacial soil-
formation in this area, we are led to the con-
clusion that Cf 18a represents in all probability
JÖKULL 1964
a considerably shorter period. On the other
hand it is obvious that the old terminal
moraine in front of Hálsajökull is rnore than
1000 years older than Ö 1362. In my opinion
there is little doubt that this old terminal
moraine dates back to lte begi'nning of the
Subatlantic Tirne.
Thus the climatic deterioration, which
brought a sudden end to the relatively warm
subboreal climate, brought this steep glacier to
a position a little more advanced than it
reached during the “Little Ice Age” 1550—1890,
whereas the flat lobe-shaped Brúarjökull reach-
ed its maximum postglacial extension during
the 1810 ancl 1890 advances. This is in very
good agreement with the conclusion I have
formerly reached regarding the southern out-
lets of Vatnajökull—Öræfajökull (Thorarinsson
1956), viz. that the rising of the firn line dur-
ing the Postglacial Warm Period had a greater
effect of the big outlets of Vatnajökull proper,
with their relatively flat intake areas, than it
had on the steep alpine Öræfajökull outlets,
which consequently had inore advanced start-
ing position when the climatic deterioration
began. I have formerly proved by tephrochrono-
logy that the Hagafell glaciers of Langjökull,
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