Ab6lr.ct Total-irtensity maCneiic anomalies observ€d i. a 1973 survey reflect @nlrasts in the struclure
of the $ulhem leladd shell respectively west and ea$ oI 2fW. The wesle.n part, which is Mdcr and
nore evenly slopi.g I h an the easte.n parl, h4 subdued n agnelic rel iel indicat d! b asene nt (baalI) de pth
of at leasl 400 n. On lhc caslc.n pdt ol lhe shell there occu pronouced edge anonalies, apparenrly due
to a ba*nent slep ol at least I kn nean $ickdess and ol nean widtn 3-4 kn. The distan@ Irom the upper
edge of this basenent step !o the bathynetic sheli edg€ id€reases lron 5 8 kn ar 19'W to 12-14 lm at
14!30'W. Tle baenent ha allernating nagnelic polarnies. Linear nagneti. anonalies a.e indistincl or
abcent in lhe surveyed region. ll is specnlale{t lhal the sharp b6ene.t step repre*nts the tru.e oI lhe
naxinun $ulherly €xtent of the easlern volenic zone ol lceland