1996:370 - LISSENHALL, Tipperary

In the course of assessing No. 353, Excavations 1996 (Carrigatogher), a new site was discovered which would suffer badly during the construction of the Nenagh Bypass. This site was discovered due east of No. 353, just beyond a small stream and bridge. It took the form of a series of low linear banks, some of which were in the shape of squares or rectangles. First impressions suggested an extensive man-made site consisting of a series of possible house sites and platforms. The basal remains of an old stone farm dwelling were located among the earthworks, now wildly overgrown with trees and shrubbery. A small-scale assessment was carried out, concentrating on two areas of the field.

Three short trenches were excavated to the east of the stream, cutting primarily across the low banks.

Trenches 1 and 2 revealed that the upstanding banks were not man-made but solid, undisturbed white clay marl, 0.4m high and 1.5–2m wide, the upper surface of which had been the original ground level presumably across the field. The partial removal of this white clay marl in a linear fashion had created illusory banks. It was clear that we were no longer dealing with upstanding man-made banks but rather with a series of substantial linear, negative, fosse-type features. The extracted marl clay created fosse-type features up to 0.45m deep and around 1.2m wide. These features had almost completely filled up with a dark brown/black peat, a very thin layer of which covered the upper surface of the clay marl 'banks'. This peat was overlain with a thick grassy sod across both trenches.

Trench 3 was essentially a western extension of Trench 1 across a flat area of field. A thin layer of peat was uncovered below this grassy sod, which in turn lay directly on top of the white clay marl. No further negative features were uncovered in this trench.

Two longer trenches were opened up to the east of Trenches 1–3, again cutting across visible low upstanding banks. Again these banks were revealed to be undisturbed natural ridges of white clay marl left 'upstanding' after the selected extraction of the same marl in a linear fosse-type fashion.

Trench 4 concentrated mainly on the interior of one of the rectangular shapes. On excavation it was clear that the 'bank' was a ridge of natural white clay which enclosed a sunken area-again owing to the selected extraction of the same marl.

Trench 5 cut across two fosse-type features, 0.45m deep x 1.75m wide and 0.4m deep x 23m wide, leaving a natural ridge of white clay marl 0.45m high and 2.7m wide. Both fosse-type features were almost entirely infilled with a dark brown/black peat, again with only a very thin covering of this peat sealing the natural marl ridges. Over this peat a substantial grassy sod covered the trench, almost levelling up the features. Across the top of the marl ridge a metalled surface was laid down on top of the peat from which large sherds of modern farmhouse pottery were recovered. Probing on either side of the trench suggests that this metalled surface continues along the ridge. Although the stones were not densely packed, it is clear that a deliberate attempt to formalise a path or track-way had taken place in fairly recent times. This metalled surface is probably associated with the old farm building.

Elsewhere along the trench animal bone was recovered from the peat filling the eastern negative linear feature, while wheelthrown, internally glazed post-medieval pottery was recovered from the upper level of the same peat from the western negative linear feature.

To the very west of the trench, occurring naturally in the white clay marl, was a steep, almost vertically sided 'X' shape which had been infilled with the brown/black pear. Several more sherds of the internally glazed post-medieval pottery were recovered from the upper fill of these voids.

Results suggest that a concentrated and selective process of white clay extraction of an unknown period has resulted in the illusory linear banks and rectangles still visible today. The current landscape cannot be the results of agriculture-these are not the standard ridge and furrow pattern resulting from lazy beds; the apparent 'ridges and furrows' are much too wide for agriculture and there is very little evidence for the mixing of peat and clay marl that one would expect after ploughing this type of ground. The underlying geology cannot explain the regular pattern of linear negative features through subsidence or collapse; besides, this type of landscape occurs only in a very localised area and is not evident in the surrounding fields.

As the evidence stands, the only plausible explanation for the resulting linear patterns, both positive and negative, is the deliberate extraction of the white clay marl in a selected linear fashion at an undetermined date for a presumably industrial purpose.

Power House, Pigeon House Harbour, Dublin 4