At the request of the English Heritage Inspector of Ancient Monuments for West Sussex, Judith Roebuck, a geophysical survey of approximately 0.15ha was conducted over part of the site of Boxgrove Priory (SU 907 075). The area to the northwest of the current parish church (once the priory church) contains the buried remains of the cloisters and other buildings. Although plans of these exist, the location, depth and state of preservation is unknown.

The Priory is a scheduled ancient monument (SAM WS26) in the guardianship of English Heritage and the purpose of the survey was to trace and define any buried structural remains to better inform future management of the site. In particular, with regard to a request for scheduled monument consent, it was important to identify any near-surface features that might be damaged by the erection of temporary marquees on the site.

Boxgrove Priory lies on well drained silty soils of the Charity 1 association (Soil Survey of England and Wales 1983) developed over Clayey gravel and Chalk (Institute of Geological Sciences 1996). At the time of the survey the field was under grass.

An earth resistance survey was conducted in an attempt to clarify the position of buried stone footings. Resistivity measurements were made with a Geoscan RM15 meter, MPX15 multiplexer and PA5 probe array, using the Twin Electrode probe configuration. Readings were collected using the standard method outlined in note 1 of Annex 1, with measurements taken at 0.5m intervals with mobile probe separations of 0.5m and 1.0m. Plots of the 0.5m mobile probe spacing data set are presented as both an X-Y traceplot and a linear greyscale, at a scale of 1:500 in Figures 2a and 2b. Figure 2c shows a linear greyscale of the data after a gaussian high-pass filter has been applied, to highlight anomalies less that 6m in width. Technical problems caused by inclement weather affected the 1.0m mobile probe spacing data. As a consequence, the worst affected sections of the data have been processed with a 0.75m gaussian low-pass filter to enhance its appearance for presentation as a linear greyscale in Figure 2d. Figure 2e shows a linear greyscale plot of the scaled resistance values from the 1.0m mobile probe spacing data subtracted from the corresponding value in the 0.5m mobile probe spacing data set. This treatment has the effect of accentuating near surface anomalies. Figure 3 depicts this same greyscale plot superimposed on the location plan.

Magnetometer survey was conducted over the same area using the standard method outlined in note 2 of Annex 1. Plots of the data set are presented as both an X-Y traceplot and a linear greyscale, at a scale of 1:500 in Figure 4. The only corrections made to the measured values displayed in the plots were to zero-mean each instrument traverse to remove heading errors and to ‘despike' the data through the application of a 2m by 2m thresholding median filter (Scollar et al 1990; 492) to reduce the detrimental effects produced by surface iron objects. In addition the lower and upper values of the data have been trimmed for presentation as a traceplot on Figure 4a.

A graphical summary of the anomalies discussed in the following text, superimposed on the location plan, is provided in Figure 5.

There are a number of high resistance anomalies that are likely to correlate with the remains of building foundations. The patterning at [1] probably relates to the building identified as the Brewhouse in the Sussex Archaeological Society plan of the site.

To the east of this is a probable rubble spread with some evidence for discrete features nearer the surface [2]. These may relate to a southern extension of the guest house. Running directly south of this (though not necessarily connected) is a linear high resistance anomaly [3], perhaps the western wall of the warming room (below the dorter). However, there is no obvious response from a corresponding eastern wall. It may be that the rubble spread containing some near surface anomalies at [4] is all that is left of the latter.

A further possible rubble spread, together with tentative linear responses [5], may relate to the frater. This association is only speculative, as the response is more subdued in this area.

Directly east of [4] lie a pair of very slight curvilinear anomalies [6] that do not appear to correlate with the rectilinear plan of the medieval religious buildings. They enclose an area approximately ten metres in diameter and only appear in the shallow data set The linear high resistance anomaly [7] running in a NE-SW is also without reciprocation in the plans of the Priory structures but appears similar in character to anomaly [3].

The low resistance linear anomaly [8] traversing the west of the site is likely to be a trench, probably dug for a service (see below).

The magnetic data exhibits a great deal of disturbance due to near-surface ferrous material, particularly at the edges of the survey where the boundary fencing incorporates iron posts or steel wire. The only obvious anomaly is the line of disturbed readings running NW-SE. This has a magnetic response typical of that caused by a modern service pipeline and corresponds with the location of resistivity anomaly [8] (see above).

The magnetometer survey does not appear to have revealed any clear anomalies of archaeological significance. This may be due to the survey area being small and partially confined within ferrous boundary fences. Furthermore, it would appear that the stone footings of the claustral remains do not exhibit a strong magnetic contrast with the surrounding soil.

However, as might be expected with this type of feature, the resistivity survey has been more successful. The remains of a structure lying to the north of and parallel to the church have been clearly defined. Other structural foundations across the site are less distinct, perhaps suggesting a poorer state of preservation. With the possible exception of [1] and [4], most of the anomalies exhibit their strongest response in the 0.5m mobile probe separation survey. This suggests that the majority of the remains are likely to be at only a shallow depth (~0.5 to 0.75m) beneath the current ground surface.

British Geological Survey, 1996, Chichester and Bognor, England and Wales Solid and Drift, Sheet 317/332, 1:50,000.

Scollar, I. Tabbagh, A. Hesse, A. and Herzog, I. (eds.), 1990, Archaeological Prospecting and Remote Sensing. Cambridge.

Soil Survey of England and Wales, 1983, Soils of England and Wales, Sheet 6, South East England.

Figure 1 Survey location plan (1:500).

Figure 2 Traceplot, linear greyscales and interpretation of resistivity data (1:500).

Figure 3 Linear greyscale plot of near-surface resistivity anomalies superimposed on location plan (1:500).

Figure 4 Traceplot and linear greyscale of magnetometer data (1:500).

Figure 5 Interpretation of geophysical surveys superimposed on location plan (1:500).