South Cadbury Environs Project

Test Pits

The excavation of 1m squares down to the geological surface every 100m within sampled areas, regular test-pitting, was at once the most revolutionary and the most generally informative technique introduced by the project, providing a relatively small but very high quality prehistoric ceramic database. The link between test pits and geophysical data was established more firmly by the introduction of targeted test-pitting aimed at key geophysical anomalies at the expense of ploughzone sampling.

Distribution Map of Test Pitss superimposed on Topography

Regular (black) and targeted (grey) test pits superimposed on topography

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The programme of regular test pitting was introduced in a pilot study on the Sigwells plateau in February 1998. It was so successful that it became, with geophysical survey, the core technique of the project. Originally intended as a test of the relationship between surface and the subsurface finds, it became the principal means for dating the distribution of activity within the prehistoric and Romano-British landscapes.

Test pits were dug until natural deposits were exposed. Colluvium was counted as archaeological as it frequently sealed lower archaeological deposits. Depths of excavation varied greatly. The shallow test pit shown below was on a low plateau and illustrates extreme plough damage. The surface of the field was littered with stone where natural rock had been shattered and churned up by the plough. During the Neolithic the soil would have been 40cm or more deeper.

Photograph showing Natural Rock at Base of Test Pit at Woolston 2006

Natural rock at the base of a shallow plateau test pit, Woolston, 2006

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In some instances the geological surface was below a depth to which it was considered safe to dig. The image below shows one of the deepest regular test pits to reach the geological surface. The gravely layers are partly for Medieval and Roman track metalling and partly from re-deposited natural. Below them are Bronze Age hillwashes including charcoal flecks (colluvium) sealing an earlier soil.

Photograph showing Romano-British track metalling and Bronze Colluvium, Milborne Valley, 2005

Romano-British track metalling, Bronze Age colluvium and an earlier buried soil above the base of a 2 metre deep test pit, Milborne Valley, 2005

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When surface collection methods were rejected targeted test pits replaced them. They introduced a substantial bias into the sampling but made it possible to date extensive boundary systems detected by geophysical survey.

Photograph showing community volunteers excavating a test pit

Regular volunteer, Tony Dickinson, excavating a 3 x 3 m test pit with the help of visitors in Great Cowleaze, Woolston. Cadbury Castle is in the central background.

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