Jökull - 01.12.1960, Blaðsíða 14

that his own experience of glaciological pheno-
mena conflicts with his theories. Much rnore
than Ólafsson he is prepared to take the ex-
perience and view of the laymen of his country
into account. However, contrary to the views
of the local people he belives that the erup-
tion centre at Grímsvötn is the same as the
ice-dammed lake Grænalón, but in that case
the local people were right.
Pálsson’s morphological classification of gla-
ciers (op. cit. p. 429—432) is basecl on Fleischer
and Ólafsson. Pálsson denies emphatically that
glaciers of the type Ólafsson called Grunn-
Jöklar (cf. p. 9) exist in Iceland. He maintains
that there are only two main types of glaciers,
Hájöklar and Falljöklar.
Hájöklar are perpetually snow covered moun-
tains rising high above their surrounclings.
These glaciers, he writes, could also be called
Hjarnjöklar (firn glaciers) as they are coverecl
by hjarn (firn). They are in their turn of
three types: fjalljöklar (mountain glaciers),
which are rather steepsidecl cupolas, hveljöklar
(ice cupolas), which are more flat ancl exten-
sive, ancl toppjöklar (cone shaped glaciers).
Falljöklar (falling glaciers) are, according to
Pálsson heaps of snow that has glided from the
hájöklar and been transformed to ice, and
could thus be callecl ice glaciers in orde'r to
distinguish them from the firn glaciers. They
are also of tliree types: ]ökulvangar (ice cheeks),
skriðjöklar (creeping glaciers), and hrunjöklar
or jökulföll (icefalls). From Pálsson’s further
description it is clear that by jökulvangar he
means cirque glaciers ancl by skriðjöklar valley
glaciers of the type most common among the
southern outlets of Vatnajökull. On the whole
his classification fits well with the glacier types
found in Iceland.
Pálsson is one of the founders of the Plasticity
Theory of glacier movement. The idea that the
glaciers move as a plastic mass seems to have
struck him for the first time in the summer
of 1793, when he was studying the front of
Breidamerkurjökull. Having described the os-
cillations lre writes (p. 478):
“I cannot help mentioning liere an idea,
however absurd it may be, which struck me
when I was stuclying the eastern part of Breida-
merkurjökull before it advanced. It is well
known how fragile pitch is when it has been
well refined, but yet it has the nature of liquid
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materials even in cold weather, to the extent
that when it is placecl in a reclining position
it gradually, very slowly and almost invisibly
falls to a horizontal level under the force of
gravitation. If a few pieces of solid pitclr are
placed in reclining receptacle it will appear
after a while that the pitch has not only made
its way to the lowest point of the receptacle,
but all the pieces have nterged into one. The
possibility of a similar liquid nature of the ice
occurred to me, and if this idea is based on
facts we have found a new and contributory
cause of the formation of many ice-falls ancl
glaciers as well as of the disappearance of
glacier crevasses in a short time. There is no
conclusive evidence to support this theory,
however.”
A year later lie became still more convinced
of this idea, when on Aug. 11, 1794, he climbed
Iceland’s highest mountain, Öræfajökull, that
had never been climbed before. From the nu-
natak Hnappur he had a good view over the
glacier Fjallsárjökull ancl its ogives and he
writes in his diary:
‘‘I particularly noticed the above-mentioned
glacier, which has advanced just to the east
of Kvísker. Its surface seemed all to be covered
with curved stripes, lying right across the
glacier, especially near the main ice cap. The
top of the curves stretched towards the low-
lancl just as if this ice-fall hacl slicl down in
a halfmelted state or as a thick, semiliquid
material. Is this not evidence in support of the
theory that the ice is by nature — without
melting — partly liquid like various kinds ot'
resin, as I suggested in the above article?” (p.
495).
Little did Pálsson know that a similar idea
had struck a French naturalist, A.C.Bordier,
20 years earlier, although lie dicl not enforce
it so fully. In his work, Voyage Pittoresque aux
Glaciers de Savoye fait en 1772, Bordier writes
(p. 223) that the glaciers are “comme un amas
de matiére coagulée, ou comme de la cire amol-
lée fléxible & ductile jusqu’á un certain point”.
Bordier’s work lapsed into oblivion like Páls-
son’s treatise and was not unearthed until B.
Stucler did so in 1863.
Although not the first one to describe the
glaciers as a plastic mass Pálsson was certainly
the first one to state that convection plays a
greater role in the ablation on temperate gla-