Site Event/Activity record ECH7211 - A Geoarchaeological Assessment at Chelford Road, Henbury

A geoarchaeological assessment which was undertaken in 2021 on land situated at the north-eastern extent of Chelford Road, Henbury. The auger survey was undertaken using a hand-operated auger to investigate the character and extent of buried sediments that comprised organic deposits of significant depth. Particular focus was given to identifying the extent of organic-rich peat sediments which could represent areas of potential archaeological and/or palaeoenvironmental interest. A total of 37 auger survey points were investigated to test for the presence of organic-rich peat sediments and to build a peat deposit model. Of particular significance were two distinctive, steep-sided wetland basins that contained extensive organic deposits over 3m deep which overlay laminated post-glacial lacustrine clays and silts of an unknown extent. Overlying the post-glacial lacustrine clays and silts was a herbaceous peat which transitioned into a ligneous (woody) peat which contained significant quantities of roots, twigs, branches, and wooden fragments. One of these wooden fragments was identified as a relatively mature piece of alder (Alnus sp.), a wet-tolerant tree. The organic strata within these basins were very similar to one another and likely indicative of the same broad palaeoenvironmental processes. These peats are likely of significant age, the result of organic formation extending at least back to the early Holocene and potentially earlier to the immediate post-glacial period. A further, relatively thin, peat spread was identified during earlier geotechnical investigation (Ellis, 2017) but was not encountered during this assessment due to impenetrable overlying sediment. (1) Analysis of the peat samples recovered demonstrates that these peat-filled basins are palaeoenvironmental archives which specifically detail a history of local natural vegetation transition following the onset of the Holocene. Following the transition from post-glacial lacustrine clay deposition and onto organic sediment formation, a succession of woodland communities dominated the site. Dominant birch forest was eclipsed by hazel woodland during the early Holocene, this was superseded by mixed coniferous (pine) and deciduous woodland by the mid-Holocene and then by deciduous forest primarily composed of oak and alder. No evidence for human presence was identified by the palaeoenvironmental analysis. (2)