Intensive mapping and sampling of the Middle Pleistocene fluvial sedimentary units of the River Axe valley

The River Axe Valley is particularly important within the context of this project as it is the source of an anomalously high concentration of artefacts (Broom) and has anomalous geomorphological characteristics. The Axe valley will be used to calibrate GPR remote sensing techniques and to create systematic protocols which will subsequently be applied to the Exe and Otter river valley systems. It is clear that the Axe Valley lacks a classical terrace sequence in the manner of other UK fluvial systems such as the Thames, making the development of a terrace-based geochronology difficult. OSL sampling at new locations in the Axe Valley (e.g. at Kilmington and Chard Junction) will indicate whether all of the sampled aggregates deposits in the valley are of similar ages, or whether deposits of significantly varying ages are present at different locations. These data will help in the development of a robust geochronology and Axe Valley fluvial sequence, both of which are critical to an understanding of issues of assemblage formation and hominin occupation of the region.

Fieldwork will primarily target sites of known archaeological potential at the junction between paired (e.g. Kilmington and Broom) and non-paired terraces (e.g. Clapton, Colyton and Chard Junction), at which no GPR and/or OSL dating sampling has previously been undertaken.

The fieldwork programme will consist of the following activities:

1. desktop analysis of high resolution digital data sets within GIS to develop digital surface models and digital terrain models;
2. remote sensing of Pleistocene fluvial sediments utilising ground penetrating radar (GPR), differential GPS, and interferometric synthetic aperture radar (IFSAR) to create 3-dimensional and volumetric models;
3. machine-cutting (and coring where appropriate) of field sections at selected localities.

Where relevant, machine-cut field sections will be sampled for clast fabric and morphology, pollen, other palaeoenvironmental data, and archaeological artefacts. Sections will be recorded, producing field archives of lithostratigraphic logs, section drawings, and photography, and differential GPS topographic data.

All biological materials recovered during modules 4 and 5 will undergo preliminary assessment to determine the potential of the materials for further analysis. Any promising material will be fully assessed in Phase III of the project.

All palaeoenvironmental data recorded during the project fieldwork will be stored with the project GIS and ultimately disseminated to the regional Historic Environment Record offices (HERs).

The fieldwork will generate high resolution spatial and attribute data for the enhancement and development of the GIS model/relational database developed during the phase one desktop assessment. Fieldwork results will be used in phase three as the basis of predictive modelling of the archaeological potential and probable locations of secondary context assemblages in the River Axe valley.

Optically stimulated luminescence (OSL) dating will be undertaken for Axe Valley terrace gravel remnants at Chard Junction Pit, Kilmington New Pit, and the Broom pits (from the lower gravel units, previously unsampled due to issues of access), with the sampling targeting the laterally impersistent, sub-horizontal lenses of laminated sands and silts which occur within the terrace gravels at all three locations. Samples will also be taken from the sand lenses occurring within the Axe valley terrace gravel deposits at Clapton, while the terrace gravels at Colyford will be sampled from the matrix.

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