Introduction
We were invited to evaluate the geoarchaeology of a site at Bath Road, Digliss, Worcester, to help the excavating archaeologists, both in understanding the origins of the deposits and in assessing the archaeological potential of the site.
Background
The bedrock of the area was known to be Triassic Eldersfield Mudstone Formation overlain by alluvial deposits, we found the soils on the site to be similar to nearby pelo-alluvial gley soils, these are mottled soils with moderately good drainage, which are periodically waterlogged by a fluctuating ground water table. The site lies near the middle of the former valley of the Frog Brook close to the centre of the historic town.
A complete sequence of deposits was recovered in 10cm diameter cores from a depth of 2.5 metres to the bedrock at 7.4 metres below the surface. Observations were also made during the excavation of trial pits to the east of Bath Road.
Findings
The Mudstone bedrock is weathered, and appears to have been broken up and disturbed under Devensian periglacial conditions, gravel and sand were then deposited in flowing water, and the stream flow reduced as vegetation stabilised in the early Holocene.
Conclusions
From our investigations, we were able to tell the client that the deposits studied were bedrock overlain by an accumulation of alluvium which was overlain in turn by made ground. The lower alluvium was deposited in stable wet conditions and may preserve pollen and other evidence which could be used to reconstruct the environmental history of the valley floor. It was also felt unlikely that the environmental sequence could be dated, as no material which could be reliably dated was found.