Ladybridge Farm: Evaluation Trench (Intervention 27)
Intervention 27 was located centrally within Zone B and measured 100m x 4m, orientated north-south. The trench was positioned to contact an anomaly identified by magnetometer survey (Intervention 4, F24). Ground surface sloped down from c.41.60m AOD at the southern end of the trench to c.41.20m AOD at the northern end. The dark yellowish-brown ploughsoil (C1123) was found to be c.0.40m in depth throughout the trench and overlay a well-drained homogenous orangish-brown gravel and clayey silt natural subsoil (C1124) which was consistent throughout the trench.
Five features were defined within Intervention 27. A cluster of features, F20, F27, F28 and F29 were situated close to the northern end of the intervention and an isolated feature, F30, was situated at the southern end of the intervention and continued beyond the edge of excavation. F20 was defined initially as a large amorphous deposit of sterile clayey silt measuring 6.50m long by 2.90m minimum width, and disappeared beyond the eastern edge of the trench. The southwestern quadrant was excavated where it proved to be a poorly defined shallow gently sloping feature with an ill-defined base filled with a sterile gravelly clayey silt C1198. A single chert flake was recovered from C1198, although this is likely to be a surface find and inspection of the surrounding natural subsoil system suggested that C1198 represented a pocket of gravel within the natural subsoil of the area. This interpretation was confirmed by F27, which was identified on the western side of the intervention, and cut into the natural system represented by F20.
F27 was defined as a possibly sub-oval feature measuring 1.10m in width by a minimum 0.70m in length. Excavation revealed the feature to be a steep-sided cut with a concave base backfilled once with C1208, a gravel-rich (50%) dark greyish-brown clayey silt. The deposit was generally well-defined, although some merging with the subsoil interface was noted. F27 was interpreted as a small pit or posthole, and while no dateable material was contained within C1208, a fragment of large mammal long bone was recovered.
F28 was situated c.8.0m from the northern end of the intervention and appeared as a small circular deposit of greyish-brown gravelly silt, measuring c.0.70m in diameter. The feature was sectioned approximately NE-SW and the northwestern side was excavated, revealing an insubstantial feature up to 0.15m in depth. F28 had been backfilled once with C1209, which consisted of a dark greyish-brown silt with a high percentage of mixed gravel (75%) which appeared to be a redeposited subsoil. F28 was interpreted as either a truncated archaeological feature or a natural depression in the subsoil system; no dateable material was recovered during excavation.
F29 was situated c.3.20m to the northeast of F28 and appeared as a deposit of dark brown clayey silt. The feature was situated at the eastern side of the intervention and continued beyond the eastern edge of excavation. It appeared to be a sub-circular feature measuring c.2.20m in diameter. The feature was half-sectioned northsouth and the western half was removed. Excavation revealed the feature to be 0.50m deep with well-defined gently sloping sides and a concave base . The feature had been backfilled once with C1210, a sterile brown clayey silt with high percentage of gravel (45%). F29 was interpreted as a pit of unknown function; no dateable material was recovered during excavation.
F30 was situated at the southern end of the intervention and was only partially visible, disappearing beneath the southern western and eastern limits of the intervention. The feature appeared as a possible sub-circular deposit of sterile brown silt. The northeastern quadrant of the available area was excavated where the feature proved to have gently sloping sides to a depth of c.0.60m below the top of the feature becoming near-vertical thereafter. The feature was excavated to a depth of c.1.20m below the top of ploughsoil, and excavation was stepped in but only continued for another 0.20m; excavation was not taken further for health and safety reasons. The bottom of the feature was sought with an auger, an exercise which suggested a total depth of 2.50m.
Within the excavated sample a total of six deposits were encountered, C1211, C1216 to C1220 inclusive. The stratigraphically earliest fill to be encountered, C1217, consisted of a tipping deposit of grey clean sterile silt and proved to be homogenous and contained only gravel. C1217 was visible in both the east and west facing sections of F30, and was very similar to a band of gravelly coarse sand in the surrounding natural system at the same height as C1217. C1217 was overlain by a deposit of sterile gravel which contained black-coloured flecks which were thought to be manganese mineralisation (C1220). C1220 was overlain by a desiccated poorquality blocky peat with occasional veins of silver sand and mixed gravel throughout (C1219), which appeared to be tipping or ‘u’-shaped in profile. This deposit was overlain in turn by C1218 a tip of clean grey silt with rare charcoal flecks (2%), which was only visible in the north facing section of the feature. C1218 was overlain by another deposit with a tipping profile, C1216, which was a gravel-rich grey coarse sand. C1216 was defined as a clean sterile grey silt with rare mixed gravel inclusions measuring 0.50m thick within the excavated sample, although its full depth is unknown. This deposit was sealed by a ‘u’-shaped deposit of clean brown gravel-rich silt measuring up to c.1.00m in depth, which represented the latest fill of the feature (C1211).
The fill system of F30 consisted mainly of tipping deposits, at least one of which represented the slumping of the surrounding natural subsoil (C1217), and only one of which consisted of desiccated peat (C1219); F30 was consequently interpreted as a sink hole and corresponded with the position of F24 (Intervention 4).