| Abstract: |
Wessex Archaeology was commissioned by AECOM on behalf of Linkconnex (a partnership between BAM Ritchies, AECOM, and MACE) and their client, National Highways, to undertake geoarchaeological monitoring of Ground Investigation (GI) works undertaken in advance of a proposed new A27 bypass to the south of Arundel (the Scheme). This report contains the results of this GI monitoring.
1.1.2 To fulfil the aims and objectives of the monitoring, all machine dug trial pits were subject to archaeological and geoarchaeological monitoring. In total 29 trial pits were subject to archaeological and geoarchaeological monitoring. Archaeological monitoring of topsoil stripping during compound set-up was carried out where there was a risk of impacting archaeological remains.
Prior to the commencement of GI works, and in consultation with West Sussex County Council and Historic England’s Science Advisor, the locations of proposed boreholes were subject to specialist geoarchaeological review. This review identified a range of boreholes suitable for monitoring, which would enable baseline assessment of the superficial deposits present across the Scheme. In total 57 boreholes were subject to geoarchaeological monitoring. The results of the on-site geoarchaeological monitoring have been combined with a geoarchaeological review of all 232 draft GI logs. No significant archaeology was identified during monitoring of GI works. However, the monitoring has enabled the Quaternary stratigraphy present across the route to be determined, and a baseline assessment of the archaeological and geoarchaeological potential of these deposits to be provided.
A geoarchaeological deposit model and associated Geoarchaeological Landscape Characterisation (GLC) of the Scheme is presented. The GLC subdivides the areas investigated by the GI into ten Geoarchaeological Characterisation Zones (GCZs) based on variation in the Quaternary sediments. An initial assessment of the archaeological and geoarchaeological potential of the deposits present in each GCZ has been developed. Additionally, monitoring recovered samples from key deposits suitable for palaeoenvironmental assessment.
Quaternary deposits within the Scheme encompass at least three, and possibly four, periods of Middle Pleistocene near-shore marine and estuarine sedimentation belonging to the Sussex and Hampshire coastal plain raised beach sequence, with deposits of the Westbourne/Arundel, Aldingbourne and Brighton/Norton Beaches delimited. Additionally, four Middle and Upper Pleistocene terraces of the River Arun, including previously unrecognised terraces beneath the Holocene floodplain, have been identified, as have extensive late Pleistocene and Holocene alluvial sequences in the Arun and two tributaries with the Binsted and Tortington Rifes. In the Arun Valley this includes a possible early Holocene peat.
Pleistocene deposits with possible Palaeolithic archaeological and geoarchaeological occur in most GCZs. Holocene sediments that may have archaeological and geoarchaeological potential occur within GCZs defined by the valleys of the Arun, Binsted Rife and Tortington Rife.
To fully established the risk of the Scheme impacting on deposits containing significant archaeological and geoarchaeological evidence, purposive archaeological and geoarchaeological works are likely to be required. The requirements and scope of these works can be guided and targeted by this baseline assessment, and through assessment of palaeoenvironmental samples recovered during GI monitoring. Recommendations for further works, including palaeoenvironmental assessment of selected samples recovered during monitoring, are provided. |
