Introduction
We were invited to evaluate the geoarchaeology of a site at Union St, Bristol, 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 site was known to be red Triassic sandstone overlain by Holocene alluvium, and we found the soils to be Typical Alluvial Gley or Pelo-Alluvial Gley soils. The site lay in the built-up city centre of Bristol, within a low-lying valley bottom subject to waterlogging due to the changing ground water table. The deposits were examined in the sides of trenches and samples were taken for later analysis.
Findings
The samples collected represented three profiles, which showed the gradual accumulation of archaeological deposits over natural alluvium, near the centre and towards the edge of the River Frome.
Conclusions
From our investigations, we were able to tell the excavating archaeologists that the three profiles represented parts of a range of deposits across the site, from a location close to the centre of the former estuarine river channel, to the higher margins of the channel. These were deposits that told a story of gradual human intervention and of the archaeological deposition of coarser deposits over silt and clay alluvium.