Fróðskaparrit - 01.01.1998, Blaðsíða 258

264
EARLY HOLOCENEINVESTIGATIONS AT SAKSUNARDALUR
AND THE ORIGINS OF THE FAROESE BIOTA
was a brownish clayey layer 1.7 cm in
thickness and this was overlain by black
humified peat. High resolution sampling
with contiguous 2 mm thick layers was
conducted across the Saksunarvatn ash de-
posits. Beyond the close-sampled se-
quences, sample thicknesses of 10 mm
were employed with sampling intervals up
to 40 mm. Samples were pre-treated with
standard KOH, HCl, HF and acetolysis
methods (Faegri and Iversen, 1989). More
detailed discussion is given in Edwards and
Craigie (ms). Computation and diagram
construction were aided by the computer
programs TILIA and TILIA.GRAPH
(Grimm, 1991).
The pollen profile covers the monolith
thickness of 14 cm. Statistically acceptable
counts of pollen were not recovered from
the top of the ash layer, although estimates
of pollen concentration from five levels
within and around the visible ash layer (not
shown here) show a marked reduction.
Pollen and spores in the diagram (Fig. 3)
are expressed as percentages of a total land
pollen (TLP) sum which excludes the
pollen of taxa considered to represent off-
island species (i.e. Pinus sylvestris, Ulmus,
Quercus, Fraxinus excelsior, Alnus and
possibly Corylus avellana-type).
The pollen diagram is dominated by
Cyperaceae and Poaceae, which are, along
with Calluna vulgaris (present at <2 %
here), typical of blanket peat floras. Betula
pollen is well represented and size mea-
surements from similar contexts elsewhere
(Edwards and Craigie, 1998) suggest that
this derives from tree birch (cf. B. pubes-
cens) rather than the dwarf birch, B. nana.
It is not possible to say how much of the
birch pollen could originate from off-island
sources.
Empetrum nigrum, Vaccinium-type and
Potentilla-type are frequent in mires and
heaths, while the other pollen and spore
taxa present are of types referrable to
known plants and habitats in the Faroes
(Hansen, 1966) or are already known from
the fossil pollen record (Jóhansen, 1985)
(e.g. Filipendua, Sedum, Lamiaceae, Plan-
tago maritima, P. major/media (cf. P. ma-
jor), Saxifraga granulata-lype [cf. S.
rosacea and S. rivularis], Thalictrum, Eq-
uisetum, Huperzia selago, Selaginella se-
laginoides). Chrysosplenium is unknown in
the Faroes.
Discussion
The pre-landnám fauna of the Faroes shows
many similarities with that of Iceland
(Buckland, 1988), although it is somewhat
more diverse. It is apparent that by the ear
ly Holocene, the fauna already contained
many of those elements which became
characteristic of infield as well as outfield
areas after settlement. Othius punctulatus,
now alrnost entirely restricted to infield
sites and cliffs and shelves (Bengtson,
1981), and a likely candidate for anthro-
pochorous dispersal, appears in the two
preliminary samples (P1 & P2) and is also
known from the poorly dated, although nat-
ural succession on Mykines (Buckland et
al., 1998). An association with the eutroph-
ic areas of bird cliffs is probable, and it may
have been dipersed casually with migrating
birds. Whilst some species may have been
dispersed in this way, the majority of the