SUTTON FARM, SUTTON-UPON-DERWENT, N. YORKSHIRE

Report on Geophysical Survey, December 1997

INTRODUCTION

A geophysical survey was carried out over an area southeast of Sutton Farm, Sutton-upon-Derwent (N. Yorkshire, centred around NGR SE 70 44) for inclusion in the Humber Wetlands Project (Centre for Wetlands Archaeology, University of Hull).

Situated on the northern floodplain of the old river Derwent, the site has yielded a number of Roman and Medieval pottery surface finds, and Roman drainpipes next to the river (Van de Noort and Ellis, in press). In addition, information supplied by the current landowners indicates possible building remains near the river; also, a stone coffin has been recovered from nearby within living memory (R. Van de Noort, pers. comm.).

Owing to the location of the site, the potential for the existence of waterlogged remains is good. The main aim of the survey was therefore to locate and confirm the existence of any buried archaeological features associated with the fieldwalkers' finds.

Three fields were partially surveyed (Figure 1); the east field was under low crop, and the west and south fields were under pasture. This area covered the main concentration of pottery finds.

The local geology consists of Triassic Sherwood Sandstone overlain by clayey alluvium.

METHOD

An initial grid of 30m x 30m squares was emplaced by the Humber Wetlands Project team from Hull University (Figure 1). This was aligned roughly with OS Grid North.

Because of time restrictions imposed on the project, the magnetic method was most suitable since it is capable of collecting data over large areas relatively quickly. The area was surveyed using 4 Geoscan FM36 gradiometers, recording data at 0.25m intervals along survey lines separated by 1m. Instrument traverses were made in the approximate N-S direction, allowing weaker magnetic anomalies to be displayed at their maximum amplitude.

On perusal of the preliminary data collected, the archaeological features appeared to extend eastward out of the area gridded by the HWP team, so more 30m x 30m grid squares were added in this direction.

Samples of topsoil were taken every 15m from transects across all the survey areas (Figure 1). Measurements of mass susceptibility were later made with a Bartington Magnetic Susceptibility MS1 Meter; results are shown in Figures 5 and 6.

RESULTS (Figures 2-6)

Gradiometer Data (Figures 2-4)

Figure 2 shows a traceplot of the raw data; final results of the survey are displayed in Figure 3 showing processing steps and optimal display parameters, and an interpretation diagram is shown in Figure 4.

Archaeological features have been detected very clearly over most of the survey area. They are most clearly defined in the east field, but continue into the west field; traces can be seen in the south field.

Immediately visible in the data is a series of anomalies indicating a complex of rectilinear enclosures situated on either side of, and in places overlapping, a central W-E road or trackway of width approximately 8m. At least two possible lateral roadways also seem to be present (eg A and B on Figure 4). The main W-E road deflects slightly to the north as it approaches The Beck and the Pocklington Canal (Shown in the SW corner of Figure 1).

Within and amongst the enclosures are groups of more intense magnetic anomalies of up to 45nT which might be indicative either of pits or thermoremanent features such as hearths or kilns. The intense anomalies that are most likely to be due to kilns are marked [ K ] on Figure 4. Although these are relatively weak when compared to kiln anomalies at other sites (typically with values of 100 - 150nT) the subdued response here may be due to damaged or deeply buried features. Weaker anomalies may be due to smaller hearths or to pits infilled with strongly magnetised material.

In places there is also evidence for internal subdivision of enclosures (eg C and D on Figure 4) and perhaps even the presence of buildings, although this can only be suggested very tentatively. In some cases (eg E on Figure 4) the enclosure ditches appear to be intermittent - perhaps due to an uneven infilling or to discrete dumps of more magnetic sediments or materials (eg ceramic debris).

At the eastern end of the survey, where the magnetic anomalies are at their most intense, there is evidence for broader but more weakly defined anomalies (approximately 6m wide) consistent with ridge and furrow. These anomalies share the same alignment as elements of the ditch system and it is a possibility that the latter influenced later cultivation practice.

Magnetic Susceptibility (Figures 5 and 6)

The MS measurements show that although the average values are low, there are clear contrasts in mass susceptibility across the site. The relatively high readings (up to 29.46 x10-8 m3/kg) for samples from the eastern part of the site correspond with the more prominent anomalies detected by the gradiometers there. To the north of the roadway, in an area where archaeological features appear to be sparser, there is a corresponding drop in MS values (similar to other `quiet' parts of the site to the south and west). These lower MS levels may indicate that the archaeological horizon is at greater depth - although it is unclear whether or not a partial alluvial cover is responsible. It is also possible that recent cultivation history has had the effect of subduing MS levels over the western and southern parts of the site (pasture) whilst emphasising values over parts of the east field (ploughed).

CONCLUSIONS

The gradiometer survey has amply confirmed the existence of archaeological features at this site. The main finding has been that of an axial roadway with arrays of enclosures to either side. Within some of the latter are anomalies consistent with pits and industrial features. Buildings may be present too, although the magnetic evidence on its own is not sufficient to identify these with certainty. The overlap and off-setting of enclosure ditch and roadway anomalies suggests that different phases of activity are represented. Also, it is clear that the survey has only covered part of a larger site which extends both to the north and south, and which may also have a focus further to the east.

A. Payne
N. Linford
P. Cottrell
E. Bray

E. Bray Date of Report: 13/2/1998

Archaeometry Branch
Ancient Monuments Laboratory
English Heritage

Reference

Van de Noort, R. and Ellis, S. (eds.) Wetland Heritage of the Vale of York, an Archaeological Survey; in print (Feb 1999).

List of Figures

Figure 1 Location of survey grids and MS sample positions
Figure 2 Trace plots of raw magnetometer data
Figure 3 Greyscale plot of filtered magnetometer data
Figure 4 Interpretation of data
Figure 5 Location of magnetometer data and MS measurements
Figure 6 Chart of MS measurements

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