Langford Lane, Alchester, Oxfordshire: Archaeological Geophysical Survey and Trial Trench Evaluation Report

Throughout 2010 Oxford Archaeology undertook a two-stage field evaluation of land along the proposed route of a new access road and bridge crossing for Langford Lane around the perimeter of the Scheduled Monument of Alchester Roman Town. This took the form of a magnetometer and resistivity geophysical survey followed by
the excavation of 48 trial trenches. The trench arrangement was informed by previously identified cropmark features and by the current geophysical survey although this did not substantially add to the existing body of data.
The trial trench phase of the evaluation covered a cross section of the Roman landscape and confirmed the accuracy of the cropmark evidence. All targeted features were identified whilst Trenches 43-48 upon the high ground west of the floodplain and Trenches 6-18 where previous evidence was negative, failed to encounter any significant remains confirming this absence. However, some trenches
within the latter area were moved from their intended location and there is a hint that some of the enclosures to the west and north extend only very slightly into this area.
Each of the large enclosures aligned on the Dorchester road were identified although there was scant evidence of occupation and other substantial activity
within the interiors of these. Artefactual evidence was also reasonably limited although that which was encountered suggested a bias towards the 2nd century AD.
The recovery of charred processed cereals from a ditch in Trench 21 perhaps indicates a primary agricultural function for these enclosures. Settlement or increased densities of features associated with the roadside zones along the
Dorchester road were not encountered with any certainty although Trench 21 did produce the only posthole from the evaluation, suggesting that some form of
structure may be present.
Road surfaces were encountered in Trench 2 with an associated flanking ditch and a channel that probably diverted or canalised a stream alongside one of the roads.
Other localised areas of surfacing indicate roadside activity within this area although the nature of this could not be established within the confines of the evaluation. A
dense collection of ditches and possible other features/deposits was recorded in Trench 3 and the combined pottery assemblages indicate 1st century AD activity.
These features may have an origin or connection with the military phase of the occupation of Alchester.
Of more certain military association are the access road or track ditches leading to the military parade ground that were excavated within Trench 4. These were
generally unremarkable, although a single probable casket cremation burial was positioned adjacent to one of the ditches. This may also be military by association
although there were no characteristic traits to confirm this interpretation. Excellent palaeoenvironmental remains were recovered in the form of snails and
waterlogged plant and insect remains from selected ditches. Snail preservation was noted across a broad spatial and chronological range of features. Waterlogged
deposits are likely to exist reasonably regularly within the evaluation area as, although only a single occurrence was excavated, most deep features could not be
fully investigated due to the water table being encountered within the features.
All trenches upon the floodplain demonstrated only minimal or, in the case of Trenches 2 and 3, no post-Roman truncation or plough damage. The trenches within the arable fields to the west of the rail line did display a buried ploughsoil horizon across much of the field although this does not appear to have substantially affected the levels of archaeological preservation. Indeed, Trench 41 included a buried soil horizon that possibly predated a Roman boundary ditch with later alluvial layers infilling the upper part of the ditch and extending over the lower sequence of soils. However, it should be noted that no clear evidence for contemporary Roman land surfaces was identified. Likewise, within the area to the east of the rail line and within the pasture fields there was no evidence for deep ploughing damage with the
thin topsoil and turf directly overlying gravel and archaeological deposits across
most of this area. The clearest example of the excellent state of preservation of sealed deposits without any post-Roman intrusion was the presence of a road
surface only 0.2 m directly below the topsoil within Trench 2. This was also partly sealed by alluvial deposits that sealed pristine archaeological deposits to a greater
depth across the remainder of this trench and within Trench 3. The planning archaeologist for Oxfordshire County Council has requested that provision be made
within the design to ensure preservation in situ of this area due to the high quality and significance of these deposits.