Náttúrufræðingurinn - 1993, Blaðsíða 39

cone produced the volcanics in question and
itself formed a barrier to the glacier burst that
prevented the flood from flowing south. The
volcanic products now in the area are thought
to be among the last or the last that issued
from the cone. In the eruption in question the
cone exploded and left a large cut that the
glacier on the upper side of the Öræfajökull
then fdled. This gave birth to the Kvíárjökull
glacier. There are two possible explanations
for this huge explosion in the volcanic cone:
I) Seawater, as the cone was located at the
coast, came into contact with the magma
through fissures or during an eruption that
opened a path to the magma, which then led
to hydromagmatic explosions.
2) The southern slope of the mountain
collapsed as instability was built up by the
intrusion of viscous magma into the cone. The
collapse may have been triggered by earth-
quakes. The accompanying sudden release of
pressure caused a series of magmatic
explosions.
There is a strong probability that this huge
eruption occurred at the end of the Ice Age
and that it was the source of some of those
extensive tephra layers that are to be found in
neighbouring countries, and at the bottom of
the North Allantic, the origin of which has
been difficult to trace.
33