Jökull - 01.12.1978, Blaðsíða 50

Fig. 7. Boomer tracks
in the area with dots
indicating position fixes.
Broken lines are iso-
pachs in milliseconds of
the wedge-shaped de-
posit discussed in the
text. Outlines of rock
floor are indicated.
Mynd 7. Siglingalínur
með setþykktarmœli (slitnar
línur með þunktum) ásamt
jajnþykktarlínum sets, þar
sem þykkt er mœld í milli-
sekúndum. Utlínur harða
botnsins eru dregnar á kortið.
expected to be considerably faster due to
shallower water depths.
The bay is open to the west, and as waves
from that direction have the longest fetch, it is
to be expected that they are the likeliest to
cause water motion of geological importance.
Storm waves entering the bay have been ob-
served to break on the submerged rocks of the
“hraun” areas (Vigfússon et al. 1974).
Sediment transþort. The information available
on water motion in Faxaflói is not sufficient to
show whether currents will periodically reach
sufficient velocities to transport sediments in
the area. Tidal currents appear to be weak,
although peak velocities are not known. By
analogy with studies of the British shelf it
seems highly likely, however, that wave-
induced currents, combined perhaps with
tidal currents, could frequently move sedi-
ment of sand-size or even coarser. Hadley’s
(1964) estimate of oscillatory bottom currents
in the Celtic Sea and Draper’s (1967) results for
various areas around the British Isles indicate
that wave-induced oscillatory currents
frequently reach velocities of geological sig-
nificance. Later estimates by Ewing (1973) in-
dicate that the two authors may even have
underestimated the importance of wave oscil-
lations.
Fig. 8. Boomer profile of
sediment wedge in the
easternmoust part of the
area. Vertical scale in
milliseconds.
Mynd 8. Þykkt set ofan á
föstu bergi. Lóðréttur kvarði í
millisekúndum. Setþykktar-
mæling frá Sviðsbrún. Orku-
stofnun.
48 JÖKULL 28. ÁR