Rit (Vísindafélag Íslendinga) - 01.06.1967, Side 161

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are present. Towards the east the faults grade into the NE-
SW fault system bordering the Langjökull belt and here the
displacements are greater. The relationship of this fault
swarm to the previously described fault zone north of Borg-
arfjördur is unclear.
As to the Langjökull-Reykjanes volcanic belt (probably
this equally applies to the eastern volcanic belt) there is geo-
logically no evidence definitely opposing a long history and
a considerable crustal drift. On the contrary the evidence
summarized here rather favours it. A value as high as 1 cm
per year may be regarded as reasonable in the light of recent
data (Vine 1966). The rate of 2 cm per year of the Reykja-
nes-Ridge postulated in this paper might be reached by both
branches of the central graben of Iceland together. Assum-
ing this rate the total horizontal displacement since the be-
ginning of the N2-period would amount to about 30 km in
the Reykjanes-Langjökull belt alone. This brings the paleo-
magnetic N2-series on both sides of the Langjökull-Reykja-
nes belt very dose together and a stationary volcanic belt
(Bödvarsson and Walker 1964), of similar widtli as today,
active throughout a long period, becomes probable.
It has been emphasized that the dip of the plateau basalts
in Iceland is by no means as regular towards the central vol-
canic zones as often stated (e.g. Trausti Einarsson 1965 and
this symposium). Indeed this applies to a large part of NW-
Iceland from Borgarfjördur northward to Eyjafjördur (except
the NW Peninsula) but nearest to both branches of the cen-
tral graben the dip is with few exceptions towards them.
Trausti Einarsson (1965) mentions the existence of such
structures as flexures, anticlines and synclines. This may be
of major importance in the interpretation of the structure
of Iceland. The youngest rocks outcrop in the synclines (two
of them are occupied by the two central volcanic belts). A
third is indicated with W-E or WSW-ENE trend near Snae-
fellsnes and possibly a fourth in Húnavatnssýsla. It is notice-
able that the Quaternary volcanism on the western part of