Neolithic and Bronze Age Landscapes of North Mayo: Report 2011

Iron probes of varying lengths had for long been used to locate fallen timbers and to establish the
length and bulk of trees and their depth in the bog. Similar probes had been used to a limited extent
when surveying the original Behy/Glenulra fields and at Belderg Beg. Noel Dunne who had worked
on the Belderg Beg excavations from 1975 and on the Erris survey now combined the use of probes
of different lengths with short bamboos to locate walls in deep uncut bog as he concentrated on
part of the Erris survey for a Master’s thesis. T-headed probes made from standard building site rod
iron of lengths from 1.5 to 4.0 metres were used depending on the depth of the bog and short
bamboos were inserted beside the top of the probe before it was extracted from the bog. In this
way, the profile of the pre-bog surface and the walls built on that surface even when under four
metres of bog could be transferred to the surface in a few minutes. It is this very basic method
which has been in use since then.
The Céide Fields Survey
The Behy/Glenulra plan was first published in 1978 (Caulfield, 1978). By the early 1980s the plan
had been republished in a number of papers and books on early agriculture by a number of
archaeologists writing on early agriculture. The Neolithic date and the scale of such early fields was
often commented on. Yet it was obvious that what had been mapped was only that part of the
fields which happened to be exposed by modern turf cutting and that all the long parallel walls on
the plan did not terminate but instead disappeared into uncut bog. In September 1983 the writer
returned to the Behy/Glenulra area with a group of UCD undergraduates to attempt to extend the
long parallels under the bog. In teams of three with iron probes from 1.5 to 4.0 metres in length
and short bamboos the teams located the position of the walls from where they entered the uncut
bog. Moving forward about five metres along the projected line of the wall from its last identified
location and then moving approximately four metres at right angles, a transect was probed across
the projected line. The probe was inserted at every 30cm in order to establish the ground level
beneath the bog. As the probe crossed the line of the wall the marker bamboos stand higher than
those marking ground level. Even though the feel of the probe hitting on stone is more firm than
when it hits the mineral soil and the sound of metal on stone can also be heard, only a raised profile
with lower ground level on either side delineated by the template of the bamboos indicates with
certainty where the wall is. Once the midpoint of the wall is located a bamboo is left in situ and the
team move forward a further five metres. In a short four week programme the long parallels were
traced as far again under the bog, doubling the originally mapped area of the Behy/Glenulra system.
That system comprised a series of xx parallel walls running inland from the cliff and following the
axis of Céide hill, a spur which runs northwards from the plateau of Maumakeogh mountain. Over
one and a half kilometres inland from the cliffs some of the walls curve to link with the adjacent
parallel closing off the strips with a rounded end. The two most easterly parallel walls of the
original Behy/Glenulra field system ran to the summit of Céide hill where they rounded off to link
the two parallels together. The most easterly wall also forked to the left in a curve which then
became a straight line but which was not parallel to the other walls and was over the crest of the
Céide ridge looking eastwards into Glenulra valley. The closest comparison for these large fields
were the very extensive fields of the Dartmoor reaves but in one element there was a major
contrast. Where the Dartmoor parallel reaves appear to run up to a previously constructed terminal
reave at right angles to the parallels, the Behy/Glenulra parallels have no such common boundary.
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