Introduction
We were invited to evaluate the geoarchaeology of a site at Alstone, Somerset, 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 the Lower Lias of the Lower Jurassic overlain by the Quaternary Burtle Beds, and we found the soils to be stagnogleyic brown earths. The site lies in an area of flat land, with a permanently high water table that was controlled by pumped drainage through ditches and sea defences. At the time of our visit the site was a grassed field within the village of Alstone.
A number of trenches had been dug across the site, and it was in these trenches that we examined deposits, visible in the sides of the trench, and took samples for later analysis.
Findings
The examination of the samples showed then to be a complicated sequence of Holocene deposits, due to the mixing of archaeological matter and destruction of boundaries by the action of worms and roots. In one sample, an olive green sandy deposit was found, which when the coarser sand element was examined and found to be rounded, indicated that it had been deposited by water.
Conclusions
From our investigations, we were able to tell the excavating archaeologists that the colour of the olive green sandy deposit, was the result of changes within the soil chemistry and variations within the local hydrology, and due to the amount of post-depositional mixing and alteration of the deposits, further analysis was unlikely to add much more to our understanding of the site.