Rit (Vísindafélag Íslendinga) - 01.06.1967, Qupperneq 110

106
pretation by Vine (Vine et al. 1966) in accordance with the
geomagnetic time scale of Cox, Doell and Dalrymple (1964,
1966), i.e. an ocean floor spreading model. In my opinion
at least 3 other models of the ridge could be constructed by
taking into account that the whole ridge in this area is built
up of volcanic rocks and all of them would fit as well as the
ocean floor spreading model of Vine et al.
1) The ridge could have been built up of flat lying pillow
lavas during the last few million years. The youngest
lavas would lie on the crest but the older ones outcrop
on the flanks.
2) The ridge consists of pillow lavas which have subse-
quently been slightly folded resulting in a synclinal
structure, i.e. a structure similar to that of the so-called
“central graben” in northern Iceland. The youngest
rocks have been piled up in the synclinal troUgh but the
older rocks outcrop on the flanks of the ridge (Heirtzler
et al. 1966, fig. 11 drawn by Wensink).
In these models one has probably to assume that the vol-
canicity has migrated to the center of the ridge during the
last few million years, and also that the measured magnetic
anomalies are due to the surficial layers of some few hun-
dred meters thickness.
3) In my opinion the most acceptable model would be that
the surficial rocks of the ridge form elongated ridges of
pillow lavas piled up on top of volcanic fissures, just in
the same way as the subglacial móberg-ridges in Iceland.
The youngest móberg-ridges in Iceland have been built
up subglacially during the Brunhes geomagnetic-epoch.
There are also some ridges which have been piled up
during older geomagnetic-epochs, one of them is Búdar-
háls of Matuyama age between the rivers Thjórsá and
Kaldakvísl in southern Iceland, although most of the
older ridges are concealed by younger móberg-ridges and
interglacial lava flows.
In my opinion an aeromagnetic profile across Iceland from