Fróðskaparrit - 01.01.1998, Blaðsíða 219

MANNAÁRIN í TJØRNUVÍK í FØROYUM
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Sagina procumbens, a large Rumex sp. (R.
obtusifolius or R. longifolius) and Grami-
neae which is likely to be as a consequence
of the laying out of hay fields in addition to
crop cultivation, as suggested by Jóhansen
(1971; 1985) (3) Recovery of Hordeum-
type pollen at the same time as large wild
grass pollen grains, and associated with mi-
crocharcoal (<30 pm). Together these re-
sults indicate permanent settlement, intro-
duction of anthropogenic plants, clearance
and crop cultivation. In addition, the in-
crease in pollen concentration at 209 cm is
likely to also be an indirect consequence of
human impact. This may be as a result of
depleted vegetation on the slopes surround-
ing the valley, with the effect of increasing
the catchment area for pollen recruitment to
the site, leading to a steep increase in pollen
concentration.
The level from which the sample for
AMS radiocarbon dating was taken was
stratigraphically very precise, and the ter-
restrial plant macrofossils that were dated
had been dried immediately after sorting.
The result confirmed the earlier fmdings at
this site. However, the precise dating of this
important horizon, is hampered by the ra-
diocarbon plateau. The pilot microtephra
analysis at Tjømuvík shows that several
tephra horizons including the basaltic
phase of the ‘Landnám’ tephra occur
around the time of settlement. The two dif-
ferent populations of rhyolitic tephra may
indicate two ash-fall events, or a geochem-
ical evolution during the same emption
(Table 3). As yet, the number of analyses is
insufficient to allow a secure correlation
with tephra horizons on Iceland or in the
British Isles but it is likely that the Tjørnu-
vík A Tephra represents an eruption from
the Hekla Volcanic system. A more precise
chronology for the first permanent settle-
ment can be achieved at a better site in
which the tephra layers are well separated
stratigraphically, as many dated tephra
horizons reported in the literature occur
during this time interval (Hafliðason et al.,
1992; Gronvold et al., 1995; Pilcher et al.,
1995; Zielinski etal., 1997).
The basaltic shard analysed shows a geo-
chemistry which matches well with the
basaltic phase of the ‘Landnám’ tephra in
Iceland (Table 4) where slightly elevated
MgO concentrations have also been report-
ed (up to 7.4 %; Boygle, 1994). While re-
working cannot be mled out when dealing
with a single shard, the biostratigraphic ev-
idence does not support this theory. Fur-
thermore, as basaltic tephra shards are
more likely to be retrieved if sodium poly-
tungstate with a density of between 2.75
and 3.00 g/cm3 is used (Turney, 1998), it is
significant that this shard was found. The
geochemical identification of this shard
and correlation to the basaltic phase of the
‘Landnám’ tephra is also noteworthy, as
basaltic tephra is related to less explosive
volcanism than rhyolitic tephra, and is nor-
mally not carried as far as the British Isles
and Scandinavia (Dugmore et al., 1995).
Despite the fact that Buckland (1990) re-
gards early settlement unproved at Tjørnu-
vík due to the absence of the dung beetle
Aphodius lapponum, at the settlement hori-
zon, an AMS radiocarbon date (1-16,535)
on collagen from sheep/goat bones from a
house foundation in the village of Gøtu on