Site 379 - Geophysics GPR Survey Report Heritage Non-intrusive Survey Reports Group 025

The survey was undertaken using the SIR (Subsurface Interface Radar) System-4000 manufactured by Geophysical Survey Systems Inc. The serial no. of the equipment used was system 1: SIR serial number 1814 and antenna 2584, and system 2: SIR serial number 1791 and antenna 2457. The layout of the geophysical survey is shown in Figure 1. The GPR survey was conducted by collecting data long a series of closely spaced parallel survey lines at 0.5m spacing across the whole area as access allowed. The survey lines were collected in a single direction. Due to shape and size of the survey area and a number of fences crossing the area the grids have been oriented to the best fit of the section. The location of each survey lines and measurement points was surveyed using a Leica SmartRover, providing accurate location data referenced to the Ordnance Survey OSGB36 National Grid system. The main findings of the survey include a series of faint high amplitude linear anomalies in the northern corner of the site which may be of archaeological origin. These anomalies appear similar in form and share an alignment with other GPR anomalies identified as possibly archaeological in origin and marking the extension of a DMV north of Gonsley Green Farm c.250m to the west. However, the anomalies also partly share an alignment with other linear anomalies identifying field drains and/or agricultural trends and reside at the boundary of changes in the geological superficial deposits and soils overlying the site and so a natural cause also remains plausible. Two further anomalies in the south-west of the site close to the railway might also be of possible archaeological origin. Both anomalies are identified in the 0.25m depth slice and relate to a high amplitude rectangular anomaly and a vague semi-circular anomaly close the edge of the survey area. Generally, there is little evidence to support that these anomalies could be associated with a nearby DMV and is perhaps more likely they map local near surface variations in the upper soil horizons. Elsewhere, linear anomalies were recorded across the site likely reflecting recent or historic agricultural use of the field or may relate to drainage required for the ponds in the north-east section of the site. Several higher amplitude areas were observed which may relate to changes in soil horizons or compaction of the soil.