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DISCUSSION
Th. Sigurgeirsson: Have you found any connection between
seismic velocities and direction of the profile, indicating an-
other velocity along the fissure zone than at right angles
to it?
G. Pálmason: The profiles have been laid in different di-
rections, depending on local conditions. Surficial irregulari-
ties have some influence but I have not found any definite
correlation between the direction of profiles and the velo-
cities obtained.
Trausti Einarsson: Did both values of the velocity in lay-
er 3 ever occur in the same profile?
G. Pálmason: Both velocities have not been found in any
profile so far but they might be observed in longer refrac-
tion profiles.
S. Thorarinsson: It is necessary to learn more about the
petrography and chemical composition of the layers of diffe-
rent P-velocities in order to control the interpretations of the
geophysicists. In Iceland it seems to be possible to drill down
to interesting layers such as the P-velocity 6.5 km/sec layer
with a smaller cost than elsewhere and such a drilling was
recommended by the Ottawa symposium on drilling in 1966.
It was also suggested there that such a drilling be a joint
Nordic enterprise if Iceland could not afford to do it alone.
Trausti Einarsson: I think that the case for alteration as
the cause of the 2—3 seismic boundary is now stronger than
before. In addition to what I wrote earlier (Einarsson 1965),