DART is a Science and Heritage project funded by the AHRC and EPSRC

DART methodology: from field to laboratory and monitoring

Keith Wilkinson

Plan

• The study areas and sites• Initial geophysical and borehole surveys (January-March 2011)• Excavation, sampling and monitoring station installation at

Harnhill (April 2011)• Proposed investigation strategy of Diddington (May 2011)• Geoarchaeological/geotechnical analyses planned for monolith

samples (June 2011 +)• Data to be collected by monitoring equipment• Future geophysical surveys• Vegetation and spectro-radiometer surveys• Questions

The sites: Harnhill (Cherry Copse), Cirencester

Fluxgate gradiometer survey carried out of Cherry Copse, Harnhill in January 2011

The sites: Harnhill (Quarry Field), Cirencester

Fluxgate gradiometer survey carried out of Quarry Field, Harnhill in January 2011

The sites: Diddington, St Neots

Fieldwork at Harnhill (April 2011)

Trenches manually excavated and recorded prior to sampling and probe installation

Excavation of a boundary ditch at Cherry Copse

Fieldwork at Harnhill

Not everything went as planned! Pipes in ditch at Quarry Field

….. but samples were collected and probes installed at both Quarry Field and Cherry Copse

Fieldwork at Harnhill (installation of monitoring equipment)

The monitoring equipment under construction

Inserting a probe into the (non-archaeological) part of the section in Quarry Field

Machine excavated trench

Ditch

Plan view

Cross section view

Planned excavation and probe installation strategy for Diddington

Present soil

‘Geology’ ‘Geology’Ditch fill

Step 1. Trench surveyed in and present soil removed by machine to the level of the underlying geology / top of the uppermost ditch fill. Artefacts are recovered.

c. 0.30m

Machine excavated trench

Ditch

Plan view

Cross section view

Present soil

‘Geology’ ‘Geology’

Ditch fills

Step 2. Ditch fills are removed separately by hand until the ‘geology’ is reached. Artefacts recovered from each ditch fill are kept separate. Total station/GPS measurements are taken on the surface of the ‘geology’ to produce a surface model. Cores collected.

Hand excavate ditch fills

Cores outside ditch

Cores inside ditchStrategy for Diddington

c. 1.00mc. 0.30m

Machine excavated trench

Ditch

Plan view

Cross section view

Present soil

‘Geology’ Ditch fills

Step 3. Machine excavate trench to 1.2m depth across its entire area.

1.2m

Strategy for Diddington

c. 0.30mc. 1.00m

Hand and machine excavated trench

Ditch

Plan view

Cross section view

Present soil

‘Geology’

Step 4. Draw and photograph both long sections. Collect geoarchaeological and geotechnical samples. Mark sample locations on section drawing and photograph in situ.

1.2m

Monolith samples

Strategy for Diddington

Machine excavated trench

Ditch

Plan view

Cross section view

Present soil

‘Geology’

Step 5. Install monitoring equipment (on opposite long section from the monolith samples)Step 6. Machine backfill trench and compact

1.2mData logger, batteries etc. Sensors

Strategy for Diddington

Post fieldwork geoarchaeological and geotechnical studies (Birmingham and Winchester)

Monolith samples collected from the sites will be used for:• Magnetic susceptibility measurement• Moisture content measurement• Bulk density measurement• Atterberg limit tests• Grain size measurements• Organic carbon measurements• Geochemistry

Cores collected at three monthly intervals will be used for:• Moisture content measurement

The probe arrays and weather stations will provide sub-hourly :• Temperature (soil and air) measurements • Moisture contents and precipitation measurements

Geophysical studies (Bradford)

The following geophysical methods will be applied at monthly intervals on a 15x15 or 20x20m grid around the sampling point at each site:• Ground penetrating radar• Magnetometry• Resistivity• Electrical Resistance Tomography

Vegetation and spectro-radiometry (Leeds and Nottingham)

Six 10-20m long transects perpendicular to archaeological features will be studied at two-weekly to monthly intervals at each test site and the following measurements obtained :• Field spectro-radiometry• Laboratory spectro-radiometry of vegetation samples (3/metre

of transect)• Leaf litter-soil ratio• Surface moisture• Vegetation coverage (via vertical photographs obtained from

pole-mounted cameras)• Chlorophyll content• Plant height

DART is a Science and Heritage project funded by the AHRC and EPSRC

Thank you for your attention.

Questions?