Náttúrufræðingurinn - 1964, Blaðsíða 51

NÁTTÚ RU F RÆÐINGURINN
145
flected, the Betula-íorest decreases rapidly, and there is a sharp increase
of Graminae as well as the appearance o£ cultural indicators.
Tiie pollen analytical studies in Iceland are greatly faciliated by the numer-
ous radiocarbon datecl tephra layers in the bog profiles. In tlie lowest part of
tlie bog profiles, older than H5, 6600 B. P., tephra layers are lacking due to
the effusive character of volcanism in Iceland during late glacial and early
Holocene times. Radiocarbon datings at the bottom o£ submerged peat in
Seltjörn by Reykjavik seems to fix the age of the transition of pollen zone A
t.o pollen zone B at 9000 B. P. in southern Iceland.
For the purpose of correlating the transition of pollen zone A and B in
southern and northern Iceland, a peat sample was taken from a bog profile at
Moldhaugar, Eyjafjörður, N-Iceland. The sample is from the deepest part of
pollen zonc B. The radiocarbon age of this sample (II 404/370) is 7920 ± 170
ycars B. P. and seems to be a little lower than the age estimated frorn the
pollen diagrams.
Other Radiocarbon Age Determinations in Iceland
by Gudmundur Kjartansson
Museum of Natural History, Department of Geology, Reykjavik.
Pcat from the base of thc lava-flow Elliðaárhraun (1)
5300 ± 340 years (Chicago)
Sampled and submitted by J. Hospers.
Peat, in all probahility underlying the Iava-flow Grábrókarhraun (4)
3700 ± 120 years (H 146/124)
Sampled and submitted by Martin Schwarzbach.
Submerged peat from the beach of Stokksnes (10)
6510 ± 100 yeai-s (U 2)
Sampled and submitted by Jón Jónsson.
Lump of peat washed out from below the snout of the glacier Skeiðarárjökull (11)
4970 ± 100 years (U 77)
Sampled and submitted by Jón Jónsson.
Tree trunks from soil on the lava Landbrotshraun (12)
1710 ± 120 years and
1910 ± 120 years (U 3)
Sampled and submitted by Jón Jónsson.
Carbonized trunks under the lava-flow Nesjahraun (21)
1880 ± 65 years (H 1716-1240)
Sampled and submitted by Kristján Sæmundsson.