Rit (Vísindafélag Íslendinga) - 01.06.1967, Síða 108
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must be concentrated into several swarms, surrounded by
lavas with a different polarity of the TRM. Another possi-
bility would be a process on the same lines as described in
connection with the magnetic anomalies of the mid-ocean
ridges, new dykes being injected at a fairly constant rate.
The last explanation and also that of the dipping layers
imply that the anomalies would to some extent reflect the
geomagnetic time scale. The ratio between distances in the
EW direction and time would be of the order of 1 mm/year.
We do not know the age of the magnetized rocks, but there
seems not to be any striking similarity between the observed
anomalies and the pattem of reversal times published by
Heirtzler et al. (1967). This need not mean that neither
hypothesis is true as there would be plenty of sensible ex-
planations for a poor fit.
The conclusion of this discussion is that there are large
magnetic anomalies in Ljósavatnsskard, some of which at
least are strictly linear, and we do not know how to explain
them. Confirmation of any of the possibilities suggested here
would add a good deal to our knowledge of Icelandic geology.
Additional information can be obtained by more profiles
parallel to the road and perhaps also by following some of
the boundaries between magnetized layers in case they be-
come exposed on the surface. Other magnetic work in Ice-
land could also be of help, especially systematic studies of
the polarities of dykes.
REFERENCES
Cox, A., R. R. Doell and G. B. Dalrymple, 1964: Reversals of the earth’s
magnetic field. Science 144, 1537—1543.
Dietz, R. S., 1961: Continent and ocean basin evolution by spreading of
the sea-floor. Nature 190, 854—857.
Doell, R. R. and G. B. Dalrymple, 1966: Geomagnetic polarity epochs.
Science 152, 1060—1061.
Einarsson, Trausti, 1960: The plateau basalt areas in Iceland. In: On the
Geology and Geophysics of Iceland. Int. Geol. Congr. Norden 1960,
5-20.