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The upper 7m of the primary shaft filling consisted of chalk rubble interspersed with ten main dark organic-rich soil lenses which contained no diagnostic artefacts. The skeletons of two young roe deer were uncovered within the chalk rubble that had accumulated from the weathering and eroding sides of the shaft. They had probably fallen in accidentally, died, and their bodies been covered by the gradual natural infilling. Two seams of poor nodular flint outcropped in the side of the shaft at 3.5 and 5m. Some loose nodules from these seams had been tested for knapping suitability, but this appears to have been an incidental activity taking place when the shaft was already substantially filled. Below the lowest black soily lens at nearly 10m from the surface, a further 3m of degraded chalk rubble bands, devoid of artefacts, were encountered before a layer of much larger chalk blocks was reached and this is where excavation was abandoned. Augering showed the soft waterlogged chalk continuing for another 12m.
The rate of accumulation given by the radiocarbon dates is very fast and clearly shows the date of the fills of the excavated portion of the feature dates to the late Mesolithic. But how was it formed? A human agency is most unlikely and there is no evidence of either human production of the shaft, nor of any debris discarded during its excavation. We can only conclude that it must a have natural origin. Solution hollows and dolines are widespread on the chalk. In Dorset most originate by water percolating though overlying acid clays and soils, dissolving the chalk and enlarging already weak fissures. Elsewhere in Dorset, even where these clays have been eroded away, substantial residues and clay-rich deposits are found in these features.
No trace of any such clay or residue was found within, or close to our shaft. However, the shaft does lie within a few metres of deeper
Coombe Deposits, in which lie the naleds. The naleds were created towards the end of the Ice Age and it is possible that the water unleashed by thawing ice may have percolated deep into the chalk and eroded fissures and channels producing 'cave systems'. Subsequent partial collapse of these systems could account for local subsidence and the creation of features such as the shaft. Although its origin still remains open to speculation, the feature has provided a long, dated and unprecedented environmental sequence spanning not only the Mesolithic/Neolithic transition but also the Neolithic/Bronze Age one as well: a sequence unique for the chalklands of western Europe.
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