Archaeologia Islandica - 01.01.2010, Síða 25

ON FARM MOUNDS
further away from the site itself.
Yet another set of variables is the vol-
ume of refuse that can accumulate on a
site. This is primarily significant in the
case of fuel residues. The mineral content
of such residues - and therefore total vol-
ume - varies considerably with the type
of fuel used. Wood has very little mineral
content compared to peat or turf and so it
should be expected that farm-mounds
accumulate more rapidly at sites where
peat or turf were the main fuels than on
sites where wood was the principal fuel.
As already mentioned accumulations of
peat ash in excess of 2 metres thick were
observed at Bessastaðir (Guðmundur
Olafsson pers. comm. - see also fig. 5)
and these no doubt contributed signifí-
cantly to the build-up of that enormously
large mound.
There are therefore several local fac-
tors which can contribute to the build-up
of farm-mounds or check such a build-up
to a considerable degree. Some of these,
like soil quality and organic chemistry
are not well understood and need basic
research before their significance in this
context can be assessed.
It is clear from this overview of fac-
tors contributing to the build-up of farm-
mounds that a number of conditions need
to be met before a farm-mound can
develop. The combination of sub-arctic
climate and turf architecture are the basic
reasons - the technology no doubt large-
ly an effect of the environmental condi-
tions. Local factors like soil conditions
and landscape morphology can then
influence how fast a farm-mound will
accumulate in particular locations.
Non-accumulation of farm-
mounds
While it is necessary to keep them in
mind, the factors listed above do in fact
not explain adequately all the known
cases of slow or rapid farm-mound accu-
mulation. It is especially the cases of slow
accumulation which seem curious. About
these there may however be more than
meets the eye. At Hofstaðir in NE-Iceland
the late medieval and early modem farm-
mound appears very low with a visible
elevation above the surrounding field of
less than 1 m (Fig. 7). The mound is clear-
ly quite extensive, measuring 65x35 m,
much larger than the last turf-farm which
was ca. 20x20 m. Excavations of a chapel
with cemetery in the north-eastem edge of
the mound have revealed secular building
remains at a depth of -1,6 m below the
highest point of the mound (Hildur
Gestsdóttir pers.comm.). This suggests
that mounds that appear low can in fact
contain deep stratigraphies and have vol-
umes of a similar order of magnitude as
visibly high mounds. The Hofstaðir
mound may be ca. 3500 m3 compared to
Stóraborg’s c. 4500 m3, a difference
which may be explained simply by the
former being in the drier North whereas
the latter is in the wetter South. That dif-
ference does however not explain the
greater area of the Hofstaðir mound so
there is clearly more to this than just the
climatic factor. The Hofstaðir mound is
not as discrete and merges more gradually
with the surrounding homefield, suggest-
ing perhaps that there was a greater
degree of horizontal development of
buildings at the Hofstaðir type of mound
than in the Stóraborg type.
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