Evaluation at Kiln Lane, Lacey Green, Buckinghamshire

Survey - The evaluation trench was located to sub metre accuracy by hand measuring from fixed points at the plot boundaries. Evaluation Trench - The trench was oriented WNW-ESE, 10m long and 1.80m wide, and positioned as close as possible to the central axis of the proposed building footprint (see figure 2). The trench was positioned approximately at right angles to the postulated alignment of Grim's Ditch rather than along the long axis of the proposed house. The trench was excavated using a JCB fitted with a toothless ditching blade. The mechanical excavator removed the overburden in 0.2m spits until the cut edge (004) of Grim's Ditch was visible. Following a site visit by Julia Wise on behalf of Buckinghamshire County Council, it was agreed that the trench should be extended by one metre at its east end, in accordance with the 10% contingency arrangement set out in the brief. The final dimensions of the evaluation trench were therefore 11m by 1.80m. A 0.5m wide slot was then hand dug across the ditch, beside the north baulk. The top of the baulk was stepped back to prevent it collapsing. On 12th April 2002, the slot was excavated to a maximum depth of 2.36m below the top of the section. It was not considered safe to continue beyond this. On 17th April 2002, the evaluation trench was inspected by staff from English Heritage, Network Archaeology, Buckinghamshire County Council and Stratfords. A soil sampling strategy for the recovery and assessment of pollen was discussed. It was also agreed that a further slot should be hand dug through what appeared to be the natural clay-with-flints on the west side of the ditch, to demonstrate that it was not bank material. By 26th June 2002, the north baulk had collapsed into the ditch section. The slot through the natural clay-with-flints (019) was excavated and much of the collapse was removed by hand. A hand auger was used in an attempt to profile the sides and base of the ditch, and to recover soil samples for pollen analysis and possible radiocarbon dating. In the event, the ditch was so deep and there were so many obstructions within its fills that the primary fill could not be reached and the ditch's profile could not be fully determined. Four samples (101 - 104) were, however, recovered from the ditch fills (see Appendix B). Immediately before the trench was backfilled on 31st July 2002, the JCB cleared the collapsed material from the ditch area to facilitate the use of an auger. The steep profile of the ditch meant that the auger reached natural in only two places, both close to the western edge of the cut. CONCLUSIONS The most significant discovery of the evaluation was the deep cut feature (004) at the eastern end of the trench. It is assumed to be part of Grim's Ditch, although this can not be certain due to the small size of the evaluation. Its presence suggests that the apparent gap in the course of Grim's Ditch in Lacey Green is not genuine. The narrowness of the evaluation trench meant that safety considerations made it impossible to record a complete profile or obtain a sample of the primary fill of the ditch. The single soil sample (104) submitted for pollen analysis contained well preserved and abundant pollen, but its date is uncertain and it may have come from a relatively late phase of ditch silting. It is, however, possible that the deep cut feature (004) is the side of a quarry pit, similar to others seen nearby. However, quarry pits are often deliberately backfilled whereas the lower fills of this feature appear to be natural accumulations. One edge of the cut feature (004) and the layer of possible associated bank material (006) were sealed below layers of post medieval build up. Brick making waste was confined to the upper fills of the ditch (004) and the layers above, suggesting that the ditch may have largely silted up before the local brick making industry was established.