(C) Historic Buildings & Monuments Commission for England.
Report on geophysical survey, 1997.
Ellerton Priory, Humberside, was founded before 1212 by William Fitz-Peter, and was a house of the Order of St. Gilbert of Sempringham. It had a hospital attached for 13 poor persons (Page 1913).
Geophysical survey was undertaken on the site of the Priory in response to a request from the Carstairs Countryside Trust (CCT). The aim of the survey was to obtain a better understanding of the full extent of the priory within the land owned by the CCT.
A similar survey (undertaken by Geophysical Surveys of Bradford (GSB) in 1995) over a limited area of the site had already demonstrated its suitability for magnetometer survey. A series of ditches with N-S and E-W orientation was located, also indications of buried structures and evidence of occupation near the present churchyard wall (GSB 19 95). Resistivity data collected revealed evidence of buried features in accordance with the magnetometer data, but it was felt that a relatively poor moisture contrast due to dry weather conditions may have depleted the amount of useful data collected. From the results obtained, it was clear that more extensive survey coverage would have the potential to produce highly informative results, and this led to a request for assistance from the Ancient Monuments Laboratory.
The site of Ellerton Priory is centred on NGR SE 70 39. The underlying geology consists of Pleistocene and recent sands overlying Bunter Sandstone; the western edge of the site has a cover of alluvium (Institute of Geological Sciences 1973). The ground already surveyed by GSB forms a slightly raised platform in the field - the rest of the area is lower, and subject to seasonal flooding by the River Derwent (GSB 19 95).
As the effectiveness of magnetometry had already been demonstrated, this technique was chosen as the principle method of survey. Although insufficient time was available to undertake a full resistivity survey, a 30m x 30m sample area was covered by this technique to compare the results with those obtained by GSB during difficult dry conditions. It was hoped that a greater soil moisture contrast would enhance the resistivity results and confirm whether a resurvey of the area under better conditions would be beneficial (the GSB survey was undertaken in July 1995, and the AML survey in March 1997).
A grid of 30m squares was established over the site (see Figure 1). Each of these squares was then surveyed using Geoscan FM36 fluxgate gradiometers; data were recorded at 0.25m intervals along traverses separated by 1m. The recorded data are presented here in the form of greyscale and graphical trace plots, treated with a localised median filter to reduce the intense response to modern ferrous litter (Scollar et al 1990).
RESULTS (Figures 2 - 5)
Immediately apparent in the greyscale plot (Figure 3) is a central area of magnetic disturbance (denoted on Figure 5 by shading). Around this, magnetic activity is more subdued but further anomalies demonstrate that archaeological features, especially ditches, extend to the periphery of the survey area. The two linear anomalies that run E-W at the eastern end of the northern and southern sides of the plot correspond with ditches marked on the OS map.
There are several strongly magnetic anomalies in the survey area (identified by black circles in Figure 5) which may represent features such as kilns, hearths or ovens. A group of strong anomalies ('A') on the northern edge of the central area may be industrial in origin, an activity which could have contributed to the extensive and exaggerated magnetic response from the adjacent ditch. Another group of industrial features may be represented by the irregularly shaped anomaly near the centre of the site. Exceptionally, the anomaly marked X, with an amplitude of 150nT, has a trace (Figure 4) that suggests the presence of ferrous metal. If not a modern intrusion, this may indicate a hearth, casting pit or furnace in a smithy comparable to that uncovered at Waltham Abbey, Essex (Coppack 1993).
The outline of the fishpond, beyond the western edge of the area surveyed by GSB, and marked as an earthwork on the OS map, is distinguishable on the greyscale as an elongated oval of slightly raised readings.
The resistivity data obtained in March 1997 does not allow a significantly improved definition of anomalies over that obtained previously, despite differing soil moisture conditions.
An interpretation of both the resistivity and magnetic surveys undertaken by GSB has already been reported upon (GSB 19 95).
From the results obtained by the magnetometer survey over the grounds of Ellerton Priory, it is clear that extensive remains of archaeological activity are present, possibly including several hearths, kilns and perhaps even a smithy.
The sample of resistivity data showed no significant improvement over that collected under the dryer conditions of 1995 and therefore re-survey of the remainder of the area already covered was not pursued.
Ancient Monuments Laboratory
Coppack, G 1993. English Heritage Book of Abbeys and Priories, Batsford.
GSB 19 95. Geophysical Survey Report No. 95/84, Ellerton Priory. Unpublished.
Institute of Geological Sciences (British Geological Survey) 1973 1:50 000 map, Geological Survey of Great Britain, Sheet 71, Selby - Solid and Drift.
Page, W 1913. Victoria County History of Yorkshire 3 , pp 251-252.
Scollar, I et al 1990 Topics in Remote Sensing 2: Archaeological Prospecting and Remote Sensing, Cambridge.
List of Figures
Figure 1 Location of survey grids
Figure 2 Location of magnetometer survey
Figure 3 Greyscale plot of filtered magnetometer data
Figure 4 Traceplot of raw magnetometer data
Figure 5 Interpretation diagram of magnetometer data