Archaeologia Islandica - 01.01.2002, Page 15

Geophysical Techniques
Currently no work has been done to
assess the effect of such periglacial phe-
nomenon as patterned ground, involu-
tions and frost hummocks (thufur) on
geophysical prospection.
Icelandic soils
For this project the available information
regarding Icelandic soil types was fairly
limited. This lack of pedological and
geological information does not prevent
geophysical survey, but is crucial in the
understanding and interpretation of the
results. It is hoped that details relevant to
geophysical surveys might have been
recorded during vegetation surveys, and
that this resource could be made use of in
future work.
Climatic conditions have a serious
effect on the soils in Iceland where they
slow down the rate of soil formation
(Gerrard 1985, 81). Coupled with preva-
lent soil erosion this obviously presents a
problem for the preservation of archaeo-
logical remains, and also for geophysical
prospection. In one place, soil erosion
might be so severe that wind erosion has
exposed the archaeology or removed it
altogether. Elsewhere, this soil will have
been deposited, possibly burying remains
beyond the detection limits of most
prospection techniques.
Icelandic archaeology
Iceland additionally provides an unusual
archaeological situation: geological
deposits may both predate and post-date
archaeology remains, since buried fea-
tures may be sandwiched between parent
material and tephra deposits. It is thus of
interest to leam the effect of these cir-
cumstances on archaeological prospec-
tion.
There is also the nature of the archae-
ology to consider. Many excavations
have revealed structures not built in
stone, but of turf sods, sometimes with
stone facings.
Is geophysical prospection capable of
detecting buried turf remains within the
collapse and back-fill of more turf and
soil? Surveys might only be able to iden-
tify areas of activity, such as hearths or
middens, but if combined with other evi-
dence such as earthwork analysis, this
would still be new and useful informa-
tion for site interpretation.
As stated in the introduction, only very
limited and certainly no systematic,
assessment of geophysical surveys for
the prospection of buried archaeology
has been conducted in Iceland. Indeed,
such methods have only been employed
in a handful of instances prior to this
study, in each case focussing solely on
answering specifíc archaeological ques-
tions, not to fulfil a systematic assess-
ment of the methods. One of the weak-
nesses of these targeting approaches has
been the lack of proper understanding of
the geophysical techniques employed
together with a high working knowledge
of geophysics and a sound appreciation
for the archaeological and geological
anomalies likely to be encountered.
It is important that the factors out-
lined above are fully understood before
such geophysical methods can effective-
ly be provided routinely and as a service.
It was the aim of this investigation to
provide a preliminary assessment of the
13