Geophysical Survey Report
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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 W E S T Land at Moons Hill Quarry, Stoke St Michael, Somerset Geophysical Survey (Magnetic) by Tim Dawson Site Code: MHQ12/56 (ST 6589 4541) Land at Moons Hill Quarry, Stoke St Michael, Somerset Geophysical Survey (Magnetic) Report For John Wainwright and Company Ltd byTimDawson ThamesValleyArchaeologicalServicesLtd Site Code MHQ 12/56 June 2014 Summary Site name: Land at Moons Hill Quarry, Stoke St Michael, Somerset Grid reference: ST 6589 4541 Site activity: Magnetometer survey Date and duration of project: 21st May - 9th June 2014 Project manager: Steve Ford Site supervisor: Tim Dawson Site code: MHQ 12/56 Area of site: Area B: 11.39ha, Area C: 9.83ha Summary of results: A sparse number of anomalies, some possibly of archaeological origin, were recorded across the whole site area, with the most convincing of these occurring in Area C Field 3. Despite the projected line of a Roman road crossing the southern part of the site no magnetic anomalies relating to such a structure were identified. Anomalies relating to existing landscape features, such as footpaths and tracks, were identified as were those reflecting the underlying geology of the site. 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 All TVAS unpublished fieldwork reports are available on our website: www.tvas.co.uk/reports/reports.asp. Report edited/checked by: Steve Ford 04.07.14 Andrew Mundin 04.07.14 i Thames Valley Archaeological Services Ltd, 47–49 De Beauvoir Road, Reading RG1 5NR Tel. (0118) 926 0552; Fax (0118) 926 0553; email [email protected]; website: www.tvas.co.uk Land at Moons Hill Quarry, Stoke St Michael, Somerset A Geophysical Survey (Magnetic) by Tim Dawson Report 12/56b Introduction This report documents the results of a geophysical survey (magnetic) carried out on six fields to the south of Moons Hill Quarry, Long Cross Bottom, Stoke St Michael, Somerset (ST 6589 4541) (Fig. 1). The project was commissioned by Mr Nick Dunn of Land & Mineral Management Ltd, The Roundhouse Cottages, Bridge Street, Frome, Somerset on behalf of John Wainwright and Company Limited, Moons Hill Quarry, Mendip Road, Stoke St Michael, Bath, Somerset, BA3 5JU. Planning permission is to be sought for the development of a new landscaped storage area for indigenous quarry wastes to the south of the present quarry workings. A geophysical survey was requested in order to inform the planning process. This is in accordance with the Department for Communities and Local Government’s National Planning Policy Framework (NPPF 2012) and the County’s policies on archaeology. The fieldwork was undertaken by Aiji Castle, Tim Dawson and Lizzi Lewins between 21st May and 9th June 2014 and the site code is MHQ 12/56. 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 to the south of the village of Stoke St Michael, in eastern Somerset between the towns of Shepton Mallet and Frome (Fig. 1). It consists of two survey areas, Area B and Area C in reference to a previous desk-based assessment (Dawson 2014). Area B (Pl. 1-2) comprises two main fields both containing scrub and pasture with their high points in the north and sloping down to the south. The western field has boggy patches across its area and is divided in three by wire fencing with a fenced-off enclosure for two covered reservoirs in the north, and a trackway and several pipes connecting this to the main road in the south. This field also contains earthworks which correspond to the projected line of a Roman road which crosses the southern proposal site. There are, however, no signs of such earthworks in the eastern field although there are signs of a hedgerow which once divided the field in two (west–east). The projected line of the Roman road also crosses the south- western corner of Area C where there appears to be a slight earthwork to reflect this. This area (Pl. 3-4) slopes 1 steeply uphill from a stream in the centre of the northern field towards Long Cross Farm to the east. All of the fields that make up this area are pasture with the majority of the area also containing dense patches of rushes, suggesting waterlogged ground conditions. Possibly as a result of this a bank has been built along the southern and western boundary of the area along with a causeway leading down the hillside from Long Cross Farm. Areas B and C cover areas of 11.39ha and 9.83ha respectively and are centred on NGRs ST 6570 4540 and ST 6611 4540. The site is located primarily on Portishead Formation sandstone with an area of mixed andesite and tuff/agglomerates immediately to the north, on which stands Moons Hill Quarry (BGS 2000). Both areas are on steeply sloping ground at maximum heights of between 273m in the west and 265m in the east sloping down to a valley in between at a height of c.230m above Ordnance Datum. The weather conditions during the survey period varied with dense fog, and later sun characterising Area B and sunny spells and periods of heavy rain during Area C. This left ground conditions soft although the sun baked a crust on exposed areas making walking in areas of rutting and cattle trample difficult. Site history and archaeological background A desk-based assessment has been compiled which details the site’s history and archaeological background of the area (Dawson 2014). In summary, cartographic evidence demonstrates that both sites have undergone very little change since 1760 therefore suggesting that any buried archaeological deposits are likely to have been preserved. Stoke St Michael lies on the southern edge of the Mendip Hills, an area from which Lower Palaeolithic flint artefacts and fossilized mammal bones carrying associated cut marks have been found, which may represent some of the earliest evidence for a human presence in Britain (Webster 2007, 34; Webster and Mayberry 2007, 18). Similar finds of tools and butchery marks in animal bones with dates throughout the Palaeolithic, Mesolithic and Neolithic periods have been identified in many cave sites across Mendip (Webster 2007, 34, 50). The Bronze Age is represented by a concentration of round barrows in the region (Adkins 1992, 15), many of which were investigated in a very rudimentary manner by Rev John Skinner and his team of Mendip coal miners in the early 19th century (Webster and Mayberry 2007, 8). The Iron Age and Roman archaeology of the area is dominated by Maesbury Castle, an Iron Age hillfort to the north of Shepton Mallet, the Iron Age and Roman settlements and pottery industry at Shepton Mallet (Gathercole 2003, 3; Webster and Mayberry 2007, 49; 53) and the Roman roads of the Fosse Way and Margary’s route 45b (Margary 1955, 74, 93). The two roads, the Fosse Way connecting Lincoln to Axmouth and route 45b connecting the lead mines at Charterhouse on the Mendips to Old Sarum, cross c.2km to the west of the survey site with the projected line of 2 route 45b crossing the southern edge of both Areas B and C. The extensive lead extraction industry began under military control in the AD 40s and continued until the 3rd century AD, producing a highly characteristic series of ingots, after which it passed to private interests and continued as a sizable industry well into the medieval period (Webster 2007, 154–5; 289). Mendip lead has been found on sites in Gaul and beyond, suggesting that the Mendip-Old Sarum road was an important link in the transport network (Webster 2007, 155). 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. Grids were aligned on a field by field basis following the longest straight edge of an area where possible in order to reduce the number of partial survey grids. The majority of the fields were aligned north-south. Obstructions were present in most of the survey areas with marsh and scrub being the most disruptive, particularly in Area B Fields 1 A-C and Area C Fields 2 and 3. The softness of the ground and the height of the vegetation prevented surveying from taking place in these areas. The Grad 601-2 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. 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.