Jökull - 01.12.1960, Blaðsíða 16

ciers than radiation. He writes (p. 433): “I also
venture to affirm that the rays of the sun do
not play as much part in melting the firn
of the plateau ices, not even in calrn weather
when they fall direct on them, as misty weather
without precipitation does. It would, indeed,
seem quite natural that the large ice caps re-
flected the sun rays without their being able
to affect the firn of the plateau ices to any
appreciable extent.” Not until thorough abla-
tion measurements were carried out by the
Swedish-Icelandic Vatnajökull Expeditions in
1936—37—38, was this view fully confirmed.
Pálsson also discusses the formation of super-
imposed ice (p. 434). His descriptions of glacier
rivers and their behaviour, formation of under-
water ice etc, is thorough and so are his de-
scriptions of glacier bursts. He distinguished
between glacier bursts, caused by the tapping
of ice dammed lakes, ancl those caused by sub-
glacial volcanism. Some volcano-glacial bursts
before his time had been excellently described by
eye-witnesses, e.g. the Ivatla bursts of 1625, 1660,
1721, and 1755. Pálsson is the first to differen-
tiate clearly between volcanogen and climatogen
oscillations of the Vatnajökull outlets. He says
of the volcanogen oscillations that “it is not
known if this apparent forward and backward
movement of the glaciers in this country is de-
finitely periodical. Something of the kind is
certainly said in respect of Skeidarárjökull, but
no conclusions can be drawn from that for
lack of reliable information” (p. 454—455). As
regards the climatically conditioned variations
he stresses that “like the climate itself they
certainly are periodical to some degree” (p. 455).
He also discusses the Föhn effect of Vatna-
jökull (p. 457), but on the whole he goes too
far in stressing the ameliorating influence of
glaciers on the climate of Iceland. He reallv
seems to have loved his glaciers.
Pálsson describes in detail many individual
glaciers and he has drawn maps and profiles of
most of the plateau ices. By far the best of these
maps is that of Vatnajökull (Fig. 6), which is
amazingly correct for its time. The representa-
tion of the glacier’s northern margin is parti-
cularly good. That part of the map is based
on information which Pálsson received from a
young Icelander, Pétur Brynjólfsson, who had
crossed the northern highland from E to W,
short N of Vatnajökull, in the summer of 1794.
The map of the southern margin of Vatna-
jökull is probably partly based on the Danish
geodecist Th. H. Knopf’s map of that area,
surveyed by him in 1732.
Although Sveinn Pálsson lived until 1840 he
belongs to the 18th century as a glaciologist..
What he wrote on Natural History after 1800
chiefly concerns some of its other branches. His
treatise on glaciers constitutes the last phase
and the culmination ol a glaciology which may
be called Icelandic in the sense that it was
principally based on knowledge of Icelandic
glaciers. To a large extent that knowledge was
common to the country people who lived along
the southern margin of Vatnajökull, in close
contact with its advancing glaciers, glacier rivers
and sandurs, knowledge which had gradually
accumulated during 9 centuries because these
people were in a large measure endowed with
“man’s nature to wish to see and experience
the things that he has heard about and thus
to learn whether the facts are as told or not”.
ÁGRIP:
ÞEKKING ÍSLENDINGA Á JÖKLUM
FRAM TIL 1800
Því hefur löngum verið á lofti haldið, og
ekki að ástceðulausu, að Islendingar hafi bceði
fyrr og siðar afrekað miklu á sviði húman-
istiskra bókmennta og frceða. Hitt hefur legið
meira i þagnargildi, hverju þeir hafa áorkað á
sviði náttúruvísinda, enda virðist það i fljótu
bragði a. m. k. ncesta fátceklegt í samanburði við
afrek skáldanna okkar. Hér munu ytri aðstceður
þó hafa ráðið meiru en skortur á hcefileikurn
til náttúrufrceðilegra iðkana. Náttúruvísindin
eru háðari ýmsum ytri aðslceðum en húmanistisk
frceði. Það er hcegt að þeysa á Pegasusi berbaka
og við einteyming, en ný frumefni verða trauð-
lega fundin i fjósbaðstofu. Flestar greinar nátt-
úruvísinda geta ekki þróazt nema að vissu marki
án visindatœkja.
En i sumum greinum náttúrufrceðinnar hafa
íslendingar þó haft góð skilyrði til að ná nokkr-
um árangri. Þar hefur landið sjálft lagt þeim
verkefnin upp i hendurnar og verið þeim, sem
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