Archaeologia Islandica - 01.01.2002, Side 28

Timothy J. Horsley & Stephen J. Dockrjll
cutting (Friðriksson, pers. comm.).
Around the eastern perimeter of the farm
mound the ground is quite disturbed by
many well-formed thufur, and at the time
of survey this area stood out due to the
bright yellow flowers of numerous but-
tercups. The rest of the farm mound is
not mown due to the uneven ground, and
as a result is colonised by well-estab-
lished grasses. The westem edge of the
farm mound roughly coincides with the
modern track that passes over the top,
although it is not known whether buried
structures exist on this western side.
One of the archaeological aims of the
geophysical surveys was to attempt to
locate the remains of a church known to
have existed on the eastern side of the
farm mound. There are no surface indica-
tions for the location of this or a church-
yard.
Magnetometer results
A processed plot of the fluxgate gra-
diometer survey is presented in Figure 6.
The data was collected in the 'zig-zag'
fashion and as a result the plots suffer
from quite severe bunching effects. This
is especially noticed around the intense
anomalies caused by the background
geology. The data would be free of this
defect had a 'parallel' approach been
adopted, but it is the small-scale jumbled
noise detected which is of interest, and
the striping does not detract from this
archaeological information. Walking
'zig-zag' allowed a greater survey area to
be covered at Hofstaðir, however it is
recommended that future magnetometer
surveys be conducted in a different man-
ner.
As the previous surveys have shown,
the intense geological anomalies limit the
type of archaeological features that can
be detected, and it is oiiten the smaller
scale jumble of magnetic dipoles due to
individual rocks that provide useful
information. This is certainly true of
these results. During data processing, a
low-pass (Gaussian) fílter was employed
in an attempt to remove the bunching dis-
cussed above, however it was found that
this also reduced the small-scale detail,
resulting in a loss of information.
The interpretation (fíg. 6b) simply
indicates the areas of small-scale mag-
netic noise, and the identifiable anom-
alies of the modern track and two buried
pipes. The general area of magnetic noise
corresponds well to the area of the farm
mound, and it is interpreted that the more
dense areas are due to clusters of rocks,
and might therefore indicate the sites of
buried structural remains. Some rectilin-
ear features can be made out within the
noise, but it is difficult to make any firm
conclusions.
A large area to the east of the farm
mound is free of this noise, and while this
might be indicative of a lack of loose
rock debris in this area, it cannot be con-
cluded that it is free of any archaeologi-
cal activity. Subtle anomalies might be
present but are overwhelmed by the
igneous geology.
Earth resistance results
The results of the earth resistance survey
over the farm mound are presented in
Figure 7. The survey was conducted at
the high resolution of 0.5m x 0.5m to
record a maximum level of information.
26