This collection comprises geophysical data and resulting images from a geophysical (magnetometer) survey, undertaken by Headland Archaeology (UK) Ltd, of 640 hectares on land between junctions 19 and 25 within the A12 Chelmsford to A120 Proposed Scheme (PS). the aim of the survey was to inform an archaeological assessment of the proposed road.

The survey has successfully evaluated the geophysical survey areas within the Proposed Scheme except in a small number of areas where ground conditions were deemed unsuitable for survey. Anomalies of either likely, or possible, archaeological potential have been identified.

Of high archaeological potential are a series of enclosures containing a ring ditch immediately south of the old Roman Road at area GP/13f, a discrete curvilinear enclosure of possible archaeological origin in GP/13a, small rectilinear enclosures on the edge of the Proposed Scheme in GP/13k and GP/13h and curvilinear and possible pit-like anomalies in GP/22e, GP/03h and GP/03g. Of particular significance are settlement anomalies to the north of the old Roman Road at Area 27, the remains of a possible Icehouse in Area 1, a possible kiln structure in Area 25, a ring-ditch in Area 29 and a large pit in Area 10. Other groups of linear and discrete anomalies, which might have an archaeological origin, have been identified in other areas as indicated in the results. Several dipolar anomalies have been detected which are consistent with modern activity such as buried service pipes, land drains, trackways, a former railway line, demolition rubble, and even a disused, Cold War observation post, backfilled pits and fences. Numerous linear anomalies, corresponding with field boundaries marked on historic Ordnance Survey maps, have also been identified throughout the survey areas. Several irregularly shaped low magnitude anomalies have been detected which are probably due to natural or geological causes. Overall, most of the PS contains no anomalies of any archaeological potential and therefore the PS is assessed as having low to moderate archaeological potential, although locally high in the vicinity of the clearly defined areas of archaeological activity.