Jökull - 01.12.1956, Blaðsíða 7

Fig. 3. Soil profiles measured in Örcefi in Sept. 1955.
Profile De 18b was dug on the flat gravel
ridge immediately in front of Stóralda proper.
There we find the tephra layers already men-
tioned and besides, the black Katla tephra of
1918 and the greyish white rhyolitic (liparitic)
Öræfajökull tephra (pumice) of the great erup-
tion in Öræfajökull 1362. The pumice is here
mostly redeposited by wind and only the lower-
most part of the layer is still in situ. Beneath
that layer we find ab. 5 cm thick layer of med-
ium sand mixed with humus.
There seems to be no doubt that the ridge
on which profile De 18b was dug is practically
of the same age as Stóralda proper. Thus both
Stóralda proper and the ridges in front of it
are clearly older than 1362. The fact that onlv
a thin layer of humified sand is found be-
tween the 1362-layer and the underlying gravel
could be explained by the gravel being only a
little older than the 1362-layer. J. Thorkelsson
(1921, p. 267) was of the opinion that the farm
Svínafell had been destroyed shortly before 1343
by a jökulhlaup caused by an eruption in Ör-
æfajökull. In that case one could possibly re-
gard the Stóralda moraine complex as being
formed by a catastrophic advance of Svínafells-
jökull in connection with that jökulhlaup. But
the material in these moraines has no resem-
blance to a normal jökulhlaup sediment and
besides, it is very unlikely that Öræfajökull
erupted at all in historical time before 1362.
The tephrochronological studies of the 1362
tephra show that this eruption has been a typi-
cal initial eruption following a long period of
quiescence and the vague mentioning of fire
in “Knappa fells jökli” 1332 (Gottskálksannáll)
and in “Hnappa vallar iokli” 1341 (Skálholts-
annáll) is no proof of an eruption in Öræfa-