S E R V I C E S S O U T H. Land adjoining Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex. Geophysical Survey (Magnetic)

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1 T H A M E S V A L L E Y ARCHAEOLOGICAL S E R V I C E S S O U T H Land adjoining Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex Geophysical Survey (Magnetic) by Kyle Beaverstock and Tim Dawson Site Code TLH16/15 (TQ )

2 Land adjoining Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex Geophysical Survey (Magnetic) Report For Millwood Designer Homes Ltd by Tim Dawson and Kyle Beaverstock Thames Valley Archaeological Services Ltd Site Code TLH 16/15 November 2016

3 Summary Site name: Land adjoining Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex Grid reference: TQ Site activity: Magnetometer survey Date and duration of project: 16 th November 2016 Project manager: Steve Ford Site supervisor: Tim Dawson Site code: TLH 16/15 Area of site: 1.88ha (0.56ha surveyed) Summary of results: Several magnetic anomalies were recorded across the survey area. These represent a modern field boundary that is shown on 20 th century maps and areas with raised magnetic levels which may indicate ironworking activity. Location of archive: The archive is presently held at Thames Valley Archaeological Services, Reading in accordance with TVAS digital archiving policies. This report may be copied for bona fide research or planning purposes without the explicit permission of the copyright holder. All TVAS unpublished fieldwork reports are available on our website: Report edited/checked by: Steve Ford i Thames Valley Archaeological Services Ltd, De Beauvoir Road, Reading RG1 5NR Tel. (0118) ; Fax (0118) ; tvas@tvas.co.uk; website:

4 Introduction Land adjoining Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex A Geophysical Survey (Magnetic) by Tim Dawson and Kyle Beaverstock Report 16/15b This report documents the results of a geophysical survey (magnetic) carried out at land adjoining Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex TN21 0LS (TQ ) (Fig. 1). The work was commissioned by Mr Colin Viret of Millwood Designer Homes Ltd, Bordyke End, East Street, Tonbridge, Kent TN9 1HA. A planning application has been submitted to Wealden District Council (WD/2016/1877/MAJ) for the construction of 23 houses and associated access and landscaping. The decision on the application has been made subject to a condition which requires the implementation of an archaeological field evaluation. This is in accordance with the Department for Communities and Local Government s National Planning Policy Framework (NPPF 2012) and the District s policies on archaeology. The fieldwork was undertaken by Tim Dawson and Ellen McManus-Fry on 16 th November 2016 and the site code is TLH 16/15. The archive is presently held at Thames Valley Archaeological Services, Reading in accordance with TVAS digital archiving policies. Location, topography and geology The site is located on land adjoining Tilsmore Lodge, Mount Pleasant, on the western edge of Heathfield, East Sussex, and is centred on NGR TQ (Fig. 2). The site represents an irregular area of approximately 1.8ha, subdivided into three fields. This area is on the edge of a large wood (Tilsmore Wood) and is mainly grassland but with a tree belt along the western edge and numerous trees marking internal boundaries. The site occupies a spur between two small stream valleys and slopes from an elevation of approximately 145m above Ordnance Datum in the west to 132m aod in the east. According to the British Geological Survey (BGS 2006) the underlying geology consists of Ashdown Beds - Sandstone, Siltstone and Mudstone. Weather during the survey was dry and sunny although there had been rain overnight so the ground was wet with areas of standing water in the lower-lying areas of the site (Pl. 1-4). 1

5 Site history and archaeological background The archaeological background for the area in which the survey site lies has been explored in detail in a deskbased assessment (Bermingham 2016). In summary this concluded that there have been no below-ground archaeological investigations at this location and very few nearby. The apparent archaeological potential of the site, as reflected in previously recorded remains, is typically low for most periods. Given, however, that the site is located in a largely undeveloped area, the absence of archaeological sites is more likely to be due to a lack of archaeological investigation rather than a definitive absence of any past occupation. Where archaeological investigations have taken place recently on the Weald, they have tended to show that the absence of evidence can be misleading. Topographically, this particular site may not appear promising for early occupation, but it may lie next to a ridgeway and is close to two water sources, both factors potentially important for the location of early iron working. Cartographic evidence shows that the proposal site has not been built on but has been cultivated and forested in part from at least the 19 th century. It is possible that archaeological remains of prehistoric and/or later occupation, if present, would survive below ground within the proposed development area. Methodology Sample interval Data collection required a temporary grid to be established across the survey area using wooden pegs at 20m intervals with further subdivision where necessary. Readings were taken at 0.25m intervals along traverses 1m apart. This provides 1600 sampling points across a full 20m 20m grid (English Heritage 2008), providing an appropriate methodology balancing cost and time with resolution. The area around the site boundaries was mostly obstructed by trees and low hanging branches which prohibited surveying. Also, the ground was in general, uneven and in some areas deeply rutted. The Grad has a typical depth of penetration of 0.5m to 1.0m. This would be increased if strongly magnetic objects have been buried in the site. Under normal operating conditions it can be expected to identify buried features >0.5m in diameter. Features which can be detected include disturbed soil, such as the fill of a ditch, structures that have been heated to high temperatures (magnetic thermoremnance) and objects made from ferro-magnetic materials. The strength of the magnetic field is measured in nano Tesla (nt), equivalent to 10-9 Tesla, the SI unit of magnetic flux density. 2

6 Equipment The purpose of the survey was to identify geophysical anomalies that may be archaeological in origin in order to inform a targeted archaeological investigation of the site prior to development. The survey and report generally follow the recommendations and standards set out by both English Heritage (2008) and the Chartered Institute for Archaeologists (2002, 2011, 2014). Magnetometry was chosen as a survey method as it offers the most rapid ground coverage and responds to a wide range of anomalies caused by past human activity. These properties make it ideal for the fast yet detailed surveying of an area. The detailed magnetometry survey was carried out using a dual sensor Bartington Instruments Grad fluxgate gradiometer. The instrument consists of two fluxgates mounted 1m vertically apart with a second set positioned at 1m horizontal distance. This enables readings to be taken of both the general background magnetic field and any localised anomalies with the difference being plotted as either positive or negative buried features. All sensors are calibrated to cancel out the local magnetic field and react only to anomalies above or below this base line. On this basis, strong magnetic anomalies such as burnt features (kilns and hearths) will give a high response as will buried ferrous objects. More subtle anomalies such as pits and ditches, can be seen from their infilling soils containing higher proportions of humic material, rich in ferrous oxides, compared to the undisturbed subsoil. This will stand out in relation to the background magnetic readings and appear in plan following the course of a linear feature or within a discrete area. A Trimble Geo7x handheld GPS system with sub-decimetre real-time accuracy was used to tie the site grid into the Ordnance Survey national grid. This unit offers both real-time correction and post-survey processing; enabling a high level of accuracy to be obtained both in the field and in the final post-processed data. Data gathered in the field was processed using the TerraSurveyor software package. This allows the survey data to be collated and manipulated to enhance the visibility of anomalies, particularly those likely to be of archaeological origin. The table below lists the processes applied to this survey, full survey and data information is recorded in Appendix 1. Process Clip from to 2.20 nt Interpolate: y doubled De-stripe: median, all sensors Effect Enhance the contrast of the image to improve the appearance of possible archaeological anomalies. Increases the resolution of the readings in the y axis, enhancing the shape of anomalies. Removes the striping effect caused by differences in sensor calibration, enhancing the visibility of potential archaeological anomalies. 3

7 De-spike: threshold 1, window size 3 3 Compresses outlying magnetic points caused by interference of metal objects within the survey area. De-stagger: all grids, both by -1 intervals Cancels out effects of site s topography on irregularities in the traverse speed. The raw data plot is presented as a greyscale plot shown in relation to the site (Fig. 3) with the processed data then presented as a second figure (Fig. 4), followed by a third plan to present the abstraction and interpretation of the magnetic anomalies (Fig. 5). Anomalies are shown as colour-coded lines, points and polygons. The grid layout and georeferencing information (Fig. 2) is prepared in EasyCAD v , producing a.fc7 file format, and printed as a.pdf for inclusion in the final report. The greyscale plot of the processed data is exported from TerraSurveyor in a georeferenced portable network graphics (.PNG) format, a raster image format chosen for its lossless data compression and support for transparent pixels, enabling it to easily be overlaid onto an existing site plan. The data plot is combined with grid and site plans in QGIS and exported again in.png format in order to present them in figure templates in Adobe InDesign CS5.5, creating.indd file formats. Once the figures are finalised they are exported in.pdf format for inclusion within the finished report. Results Within the area surveyed a few anomalies were detected which may represent possible deposits of archaeological interest pertaining to ironworking as outlined in the desk-based assessment (Bermingham 2016). These areas [1, 2] in the north-east and north-west of the site are represented by strong dipolar responses which is likely to signify a spread of ferrous debris of a yet undetermined date. The most likely cut feature on the site is a positive linear anomaly [3] in the north-east of the site which is aligned north-west to south-east and runs for approximately 43.5m. This linear anomaly is most likely the remains of the boundary ditch recorded on the 1931 Ordnance Survey map (Bermingham 2016). Directly to the north-west of positive linear [3] are several strong dipolar anomalies [4] which are likely to have been caused by buried ferrous objects. To the south of these are three strong dipolar anomalies [5] which may represent a post-lined fence. There are four discrete positive anomalies in the south-western area which may indicate the presence of buried cut features (pits) of archaeological interest [6]. It is possible, however, that these may just represent tree throws and be of no archaeological significance. 4

8 Conclusion In conclusion, there is little evidence for cut features other than a single possible linear which is likely to be the same linear recorded on the 1931 Ordnance Survey map but none earlier than this and is therefore likely to be modern. The area(s) of magnetic debris may represent deposits relating to ironworking known to have been common in the region. The remaining dipolar anomalies are most likely ferrous objects and may be related to the possible ironworking or a post-built fence. References Bermingham, N, 2016, Land adjacent to Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex: An archaeological desk-based assessment, Thames Valley Archaeological Services report 16/15, Reading BGS, 2006, British Geological Survey, 1:50,000, Sheet 319/334, Solid and Drift Edition, Keyworth CIfA, 2002, The Use of Geophysical Techniques in Archaeological Evaluation, IFA Paper No. 6, Reading CIfA, 2011, Standard and Guidance: for archaeological geophysical survey, Reading CIfA, 2014, Standard and Guidance: for archaeological geophysical survey, Reading English Heritage, 2008, Geophysical Survey in Archaeological Field Evaluation, English Heritage, Portsmouth (2nd edn) NPPF, 2012, National Planning Policy Framework, Dept Communities and Local Government, London 5

9 Appendix 1. Survey and data information Programme: Name: TerraSurveyor Version: East Field Raw data Survey corner coordinates (X/Y): Northwest corner: , m Southeast corner: , m Direction of 1st Traverse: deg Collection Method: ZigZag Sensors: 1.00 m spacing. Dummy Value: Dimensions Composite Size (readings): 240 x 100 Survey Size (meters): 60 m x 100 m Grid Size: 20 m x 20 m X Interval: 0.25 m Y Interval: 1 m Stats Max: Min: Std Dev: 4.90 Mean: 0.26 Median: 0.14 Composite Area: 0.6 ha Surveyed Area: ha Source Grids: 12 1 Col:0 Row:0 Field1\01.xgd 2 Col:0 Row:1 Field1\02.xgd 3 Col:0 Row:2 Field1\03.xgd 4 Col:0 Row:3 Field1\04.xgd 5 Col:0 Row:4 Field1\05.xgd 6 Col:1 Row:1 Field1\06.xgd 7 Col:1 Row:2 Field1\08.xgd 8 Col:1 Row:3 Field1\09.xgd 9 Col:1 Row:4 Field1\10.xgd 10 Col:2 Row:0 Field1\11.xgd 11 Col:2 Row:1 Field1\12.xgd 12 Col:2 Row:2 Field1\13.xgd Processed data Stats Max: 2.20 Min: Std Dev: 0.78 Mean: 0.00 Median: 0.01 Processes: 6 1 Base Layer 2 DeStripe Median Sensors: Grids: All 3 De Stagger: Grids: All Mode: Both By: -2 intervals 4 Despike Threshold: 1 Window size: 3x3 5 Interpolate: Y Doubled. 6 Clip from to 2.20 nt West Field Raw data Survey corner coordinates (X/Y): Northwest corner: , m Southeast corner: , m Direction of 1st Traverse: deg Collection Method: ZigZag Sensors: 1.00 m spacing. Dummy Value: Dimensions Composite Size (readings): 320 x 60 Survey Size (meters): 80 m x 60 m Grid Size: 20 m x 20 m X Interval: 0.25 m Y Interval: 1 m Stats Max: Min: Std Dev: Mean: Median: Composite Area: 0.48 ha Surveyed Area: ha Source Grids: 11 1 Col:0 Row:1 Field2\01.xgd 2 Col:0 Row:2 Field2\02.xgd 3 Col:1 Row:0 Field2\03.xgd 4 Col:1 Row:1 Field2\04.xgd 5 Col:1 Row:2 Field2\05.xgd 6 Col:2 Row:0 Field2\06.xgd 7 Col:2 Row:1 Field2\07.xgd 8 Col:2 Row:2 Field2\08.xgd 9 Col:3 Row:0 Field2\09.xgd 10 Col:3 Row:1 Field2\10.xgd 11 Col:3 Row:2 Field2\11.xgd Processed data Stats Max: 2.20 Min: Std Dev: 1.11 Mean: 0.03 Median: 0.02 Processes: 6 1 Base Layer 2 DeStripe Median Sensors: Grids: All 3 De Stagger: Grids: All Mode: Both By: -1 intervals 4 Despike Threshold: 1 Window size: 3x3 5 Interpolate: Y Doubled. 6 Clip from to 2.20 nt 6

10 SITE Uckfield Battle Lewes Bexhill Hastings BRIGHTON Eastbourne SITE TQ Land adjacent to Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex, 2016 Geophysical Survey (Magnetic) Figure 1. Location of site within Heathfield and East Sussex. TLH 16/15b Reproduced from Ordnance Survey Explorer digital mapping at 1:12500 Ordnance Survey Licence

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12 SITE TQ N Land adjacent to Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex, 2016 Geophysical Survey (Magnetic) Figure 3. Plot of raw gradiometer data nt TLH 16/15b 0m 100m -100 nt

13 SITE TQ N Land adjacent to Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex, 2016 Geophysical Survey (Magnetic) Figure 4. Plot of minimally processed gradiometer data nt TLH 16/15b 0m 100m -1.8 nt

14 SITE Legend Positive anomaly - possible cut feature (archaeology) Weak positive anomaly - possible cut feature Negative anomaly - possible earthwork (archaeology) Positive anomaly - probably of geological origin Positive anomaly - probably of agricultural origin Ferrous spike - probable ferrous object Magnetic disturbance caused by nearby metal objects/services Scattered ferromagnetic debris TQ N Land adjacent to Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex, 2016 Geophysical Survey (Magnetic) Figure 5. Interpretation plot. TLH 16/15b 0m 100m

15 Plate 1. North-western field, looking north-east. Plate 2. North-western field, looking east. Plate 3. South-western field, looking west. Plate 4. Eastern field, looking north showing rutted surface in foreground. Land adjacent to Tilsmore Lodge, Mount Pleasant, Heathfield, East Sussex, 2016 Geophysical Survey (Magnetic) Plates 1-4. TLH 16/15b

16 TIME CHART Calendar Years Modern AD 1901 Victorian AD 1837 Post Medieval AD 1500 Medieval AD 1066 Saxon AD 410 Roman AD 43 BC/AD Iron Age 750 BC Bronze Age: Late Bronze Age: Middle Bronze Age: Early 1300 BC 1700 BC 2100 BC Neolithic: Late Neolithic: Early 3300 BC 4300 BC Mesolithic: Late Mesolithic: Early 6000 BC BC Palaeolithic: Upper Palaeolithic: Middle Palaeolithic: Lower BC BC 2,000,000 BC

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