Christopher J. Rolfe

Physical and Chemical Analyses of Sediments from around Star Carr as Indicators of Preservation

Abstract This paper presents results of a project focused on investigating the deterioration of organic sediments in the area adjacent to the Mesolithic site of Star Carr. Physical and geochemical analyses of sediment sequences from 15 boreholes have been used to assess preservation status and potential of the deposits. The results indicate that severe acidification as a result of chemical oxidation of sulphide to sulphate has occurred at various locations around the site. This has adversely affected the preservation potential of these sediments. The acidification is strongly associated with a well-developed iron-sulphur (Fe-S) zone within the archaeological sediments, and is closely linked to annually fluctuating water tables. In contrast, some sequences had constantly low water tables and were oxidised throughout, but others with perennially high ground water showed only modest acidification. This offers the possibility of at least some areas of the Mesolithic Star Carr palaeo-lake edge being better preserved, although perhaps vulnerable to changes in the hydrological regime.

Holocene, Weichselian Late-glacial and earlier Pleistocene deposits of the upper Cam valley at the Hinxton Genome Campus, Cambridgeshire, UK

A section through Pleistocene deposits and temporary exposures of valley-side and valley-fill Late-glacial and Holocene sediments in the upper Cam valley at Hinxton Genome Campus, Cambridgeshire, UK are described. Stratigraphy, radiocarbon dating and pollen analysis are used to create a model of sediment transport, landscape change and vegetation history at the site. This study offers a new understanding of the stratigraphy and context of the Holocene, Weichselian Late-glacial and earlier Pleistocene deposits of the upper Cam valley, and provides an insight into valley-side sediment transport processes and the three-dimensional sediment architecture of the valley-fill sediments.

Imaging Periglacial Stripes using Ground Penetrating Radar at the 'GRIM' training site, Grimes Graves, Breckland, Norfolk

The geological structure of periglacial patterned ground made visible by heather ‘tiger’ stripes at the GRIM Military Training Site, Breckland, Norfolk was investigated using Ground Penetrating Radar. A tripartite deposit model comprising an upper pellet chalk, a gravelly diamicton and a lower chalk rubble, overlying bedrock Upper Chalk is proposed. Frost cracks active during the Devensian Stage appear to have allowed the diamicton to ‘heave’ to the surface during solifluction. Coversand has been deposited in the gullies formed by the frostcracks during the Devensian. It is the acidic coversand that supports the growth of heather and makes this site of both geological and ecological interest.