Jökull - 01.12.1990, Page 40

age of this glacier advance has now been determined
between 10,205 ± 80 B.P. (T-4467) and 12,135 ±
150 B.P. (T-4470), a period that covers the Younger
Dryas, Allerpd and Older Dryas Chronozones (Péturs-
son, 1986; 1991). Hence, instead of an Older Dryas
age, Pétursson year has on lithostratigraphical and
chronological grounds inferred a Younger Dryas age
for this glacier advance. These results imply that dur-
ing the Younger Dryas the glaciers in the Melrakka-
slétta area were much more extensive than previously
suggested. Furthermore, data from Hvalvík in westem
Melrakkaslétta (Pétursson, 1986; 1991) may indicate
that a marine transgression up to 40-60 m a.s.l. and a
contemporaneous glacier advance occurred at 12,655
± 90 B.P. (T-4468) in these parts of Northeast Iceland
(Fig. 6).
Hjartarson et al. (1981) have described terraces
at about 90 m a.s.l. in the innermost parts of the
Vopnafjörður area, presumably formed when relative
sea-level reached 80-90 m a.s.l. and glaciers advanced
down into the southem part of the area. Later, Norð-
dahl and Hjort, (1987), not recognizing the 90 m ma-
rine level, concluded that raised marine features at
about 60 m a.s.l. in the outerparts of the Vopnafjörður
area were formed in close relation to glaciers that ter-
minated at the mouth of Hofsárdalur and Selárdalur
(Fig. 6). Furthermore, standstills or glacierreadvances
have been recognized farther south in Hofsárdalur and
Vesturárdalur.
Fossiliferous marine sediments in these valleys
postdate a glacier retreat from the outermost parts of
the valleys, and probably date relative sea-level at
about 35 m a.s.l. and a glacier readvance in Hofs-
árdalur and Vesturárdalur. Two samples of subfossil
molluscs collected from the marine silt in Hofsárdalur
have yielded ages of 9,615 ± 70 B.P. (Lu-2673) and
9,865 ± 90 B.P. (Lu-2674), and one sample collected
from the sediments in Vesturárdalur has yielded an age
of 9,685 ± 90 B.P. (Lu-2675) (Norðdahl and Hjort
1987). The results from the Vopnafjörður area indi-
cate that the glaciers in this part of Northeast Iceland
were much more extensive in early Preboreal time
and possibly in late Younger Dryas time too, than was
previously indicated by the DAD-model.
Figure 7. Late Weichselian and early Holocene
end-moraines and marine-limit features in East
Iceland. Legend: a) Fáskrúðsfjörður stage moraines.
b) Breiðdalsvík stage moraines. c) Berufjörður stage
moraines. — Jökulgarðar og sjávarborðsmenjar frá
síðjökultíma og upphafi nútíma á Austurlandi. Tákn:
a) Jökulgarðar Fáskrúðsfjarðarstigs. b) Jökulgarðar
Breiðdalsvíkurstigs. c) Jökulgarðar Berufjarðarstigs.
EAST ICELAND
Surveys of moraines and marine limits in East Ice-
land (Fig. 7) by Hjartarson et al. (1981) and by Norð-
dahl and Einarsson (1988), have clarified the course of
Late Weichselian deglaciation and sea-level changes
in this part of the country.
Hjartarson et al. (1981) divided the deglaciation
history of East Iceland into two stages; an older
stage of readvance called the Valley-glacier stage and
a younger Cirque-glacier stage. Subsequent to the
Valley-glacier stage relative sea-level reached the re-
38 JÖKULL,No. 40, 1990