Neolithic and Bronze Age Landscapes of North Mayo: Report 2011

Rathlackan
As a result of a lack of GPS survey points for the excavations at Rathlackan the base-plan for the site
has been georeferenced using values derived from the OSI online mapping service and translated
from ITM to NGR values. Following subsequent cross-checking against 1 metre resolution aerial
photographs an error of 5-10 metres must be taken into account for the Rathlackan excavation base
plan. A total of forty-four excavation plans from twelve separate cuttings have been georectified and
the vast majority of these have been digitised. As the base plan was used to georectify each of the
plans for the individual excavation cuttings the error of 5-10 metres is systematic and all plans are
internally consistent. The error could be corrected easily in the future by using high-grade survey.
Additional Datasets
A series of additional datasets derived from a number of contexts (SMR, EPA, GSI etc.) have been
incorporated into the GIS. This data has been simplified and displayed at a variety of scales to allow
outputs of value to the NBNM project. Figure X shows the relationship of fieldwalls, megalithic
monuments as recorded in the SMR and land use. This clearly demonstrates that fieldwalls do not
survive in areas of modern cultivation (green) although monuments do. The presence of both
fieldwalls and monuments in areas of bog (brown) suggests that walls and megaliths should be
found together and this implies that fieldwalls once covered the land suitable for cultivation as well.
In passing it should be noted that the SMR locations are not accurate for many monuments and that,
regardless of the errors noted above for the fieldwalls, they are more accurately located than most
of the SMR sites.
Figure 7: Land use and the survival of different aspects of the Neoltihic and Bronze Age
Landscapes of North Mayo
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