Jökull - 01.12.1966, Page 7

With the addition of these 30 m the level of
the maximum raised beaches would reach pre-
sent sea-level some 80 km outside the coast at
Eyjafjord, and some 100 km outside the middle
southern coast. Tlius the observable ancient
beaches, extending 50—60 km into the country,
lie well inside the region corresponding to the
hingeline zone in Scandinavia. Considering
iurther the smallness of the country compared
Fig. 4. Ice margins and Littorina zero. 1. Ice
margin about 27000 B.P. 2. margin about 14000
B.P. 3. Littorina zero = intersection of L-level
and present sea-level. After Sveriges geologi: p.
462 and 529.
4. mynd. Tvcer stöður ísjaðarsins (1, 2) og
skurðlína sjávar og Littorina flatarins.
Fig. 5. Schematic section through southern
margin of the Scandinavian glacier to illustrate
position of hingeline.
5. mynd. Skýringarmynd af suðurjaðri Skandi-
naviujökuls til að gera grein fyrir legu hverfi-
áss strandlinuflatanna.
with Scandinavia, we are justified to assume a
fully synchronous rise of the country, unless
some special reasons for the countrary were
found.
We also remark that the coast of Iceland
would fully correspond to a straight continental
coast in case the country had been unglaciated
— the correction due to the curvature of the
coast amounting to only about l/í> m — so dur-
ing glaciation elsewhere the relative sea-level
would in that case have dropped between 85
and 100 m. But as the oldest shorelines are
only about 11.000 years old the distinction be-
tween a yielding and an unyielding ocean floor
becomes unimportant.
The rapidity of post-glacial rise in Iceland,
already referred to, is Itorne out by two main
facts, using the latest material: 1) sea-level at
Stokkseyri on the south coast was as low as
now or lower 8000 B.P. This age rests on two
C14-ages of peat: 8065 ± 400 yr. and 8170 ± 300
yr. (Kjartansson 1964). 2) sea-level at Reykjavik
(Seltjörn) was practically as low as now 9000
B.P. The two C14-ages of peat give 9030 ± 280
yr. and 8780 ± 150 yr. (Thorarinsson 1964).
Full rise in observable parts of the country
appears to have been completed by 6000 B.P.
together with that of absolute sea-level.
These facts, combined with the age and
height of the raised beaches, enable us to con-
struct curves for the rise of various localities.
The age of about 11.000 years for the maximum
beaches is based on C14-ages of sea shells from
localities in Southern Iceland as shown in
Table I (Thorl. Einarsson 1964).
TABLE I.
Ages of sea shells from three localities.
Height of Age,
Locality locality, m Yr. B.P.
Reykjavík, Airfield .... 13 9940 ± 260
13 10450 ± 160
.... 13 10230 ± 190
.... 13 10310 ± 260
Spóastadir .... 55 9930 ± 190
Flellisholtslækur . .... 75 9580 ± 140
.... 75 9800 ± 150
Four different constructions of the curve of
rise for Reykjavik are shown in Fig. 6. The
JÖKULL 161