Sedgeford Historical and Archaeological Research Project
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Sedgeford Historical and Archaeological Research Project Eaton Barn Field NHER 11263 – Non Invasive Techniques Survey Andy Black, Megan Dennis, Peter Eyre, James Grogan, John Hensby, Gabe Moshenska, Clive Sheppard and Heather Smith. Introduction Between the 7th and 12th of August 2005 a non invasive techniques survey of the southern part of Eaton Barn Field to the east of the barn (TF 696 363, NHER 11263) was carried out by the above authors. It was self financed by the Sedgeford Historical and Archaeological Research Project (SHARP) and was carried out by the kind permission of Ken Hill Estate. The survey was carried out as a small research project and as training during the SHARP Non Invasive Techniques (NITS) course. Topography and Geology The focus of the study was a small part of Eaton Barn Field. Figure 1 – Study Area in Eaton Barn Field This field is a gentle north facing slope on the south side of the Heacham Valley. It is under pasture but the north part of the field, closer to the river is waterlogged sedge and carr woodland. The underlying geology is chalk. 1 Historical and Archaeological Background Previous research in the area was mostly carried out by the Smithdon Hundred Research Group led by local historian Janet Hammond. This research had concentrated on three main techniques – the use of early maps and field books, a molehill survey in adjoining land and observations and personal records collected over a long period of time. Early maps and field books dating the 16th century show that Eaton had a significantly different pattern of land ownership to Sedgeford from an early period. The area lies close to the parish boundary and some documentary sources record it as being within Heacham parish (notably the Lewes Priory Chartulary collated in the 15th century). The molehill survey which recovered and plotted artefacts found in molehills carried out on adjoining land found pottery which is evidence for activity from the Iron Age to the post medieval period. The personal knowledge and observations gained from Janet Hammond were invaluable for knowledge of Eaton in more recent times. Documentary Evidence A visit was made to the Norfolk Records Office in Norwich. It was an opportunity to make searches on the office records and find anything that could throw light on the Eaton area. Amongst the documents that were examined were the following - A tithe map and apportionment from 1840 for Sedgeford. An enclosure map from 1797, a 1630 Estate Map, priory records (considerable amounts of land were held by Lewes or Norwich priories), poll books. Searches at the records office produced a considerable number of documents of various kinds for example land conveyances and wills, however it was never possible to know just how useful a document might be until it arrived from the archive. When the documents were examined most were found to be indecipherable. The writing was often too elaborate to follow or else the language could not be translated. Maps were perhaps the most easy to use of all documents. Maps are obviously graphic and so the problems associated with reading archaic writing is avoided. Several books in the archive library proved a useful resource. There were books on families from the local area e.g. the Rolfes and the Le Stranges. Away from our work at the records office, we drew on information from the Smithdon Hundred Local History Forum (a group of local historians). Janet Hammond another local historian would bring more information to the groups attention later in the week, when she made a visit and talked about her work and personal knowledge of the area. Shovel Test Pits Our group decided to do shovel test pits because the field had not been ploughed and so the grass was very long and hid the ground and the soil had not been disturbed greatly and so any archaeology would still be below the soil on the surface. We felt that shovel test pits was a suitable alternative to fieldwalking, because although it was intrusive, we still dug down to a depth, which was above the depth of soil that would have been ploughed. 2 We created a grid 70 metres by 40 metres using the corner of the barn as a fixed point of reference. We placed the sticks every ten metres. We placed three sticks in line with the corner of the barn going northwards down the slope of the field, with the first stick being placed just in front of the corner of the barn. We then placed 18 more sticks going east across the field with six sticks in line with each of the first three sticks going north. Later on, we placed 7 more sticks going east, south of the first row of sticks. When we had set up our grid, we then dug a pit that was 1 cubic foot at each of the sticks we had placed in the ground. First, we removed the turf above the pit so that we could place it back over the pit when we finished. When we removed the soil from the pit, we placed it into a sieve that was above a bucket. We broke up the soil so that in went through the sieve and so we were only left with the bigger objects that could not go through the sieve. We then checked these objects, took out any artefacts and ecofacts, and placed them into bags. Finally, we passed a metal detector over the pit and our spoil to see if we missed anything. When the pit had been refilled, we placed the turf back on top. We then took our finds to the finds hut where we cleaned, identified and recorded them. This enabled us to create some distribution maps that helped us to see where there might be large areas of finds and possible archaeological sites. Figure 2 – Distribution Maps of Shovel Test Pit Finds 3 The artefacts, ecofacts, bulk finds sheets and distribution maps were then placed into the archive. 4 Resistivity Survey A resistivity survey of the pre-surveyed area East of the barn of 60m x 30m was performed on 10/8/2005, with the purpose of evaluating any evidence of settlement at Eaton Barn field (TF 696 363) and training NILA students. The resistivity equipment used was a fixed twin-probe array with 500mm probe separation. 1m traverses were performed and readings taken at 1m intervals. Recent weather had been showery, and conditions during the survey were mainly bright with a few light showers during the afternoon session. The soil was sandy and damp, becoming increasingly chalky with increasing depth. During the survey, the background readings averaged around 50mΩ. The highest readings were 100mΩ and the lowest 30mΩ. Figure 3 – Resistivity Plot White areas are low resistivity, dark areas have high resistivity. North is at the top of the figure and the survey was carried out over the area of the grid marked in figure 1. The most obvious features apparent on the resultant resistivity plot were: 1) A linear, low resistivity region, extending from the NW corner (B3) to halfway along the Eastern border (H2). This is consistent with a visible surface animal track. 2) A possibly linear region of high resistivity is apparent in the easternmost northern quadrant, extending from approximately E3 to G2. 5 3) There was also an area of scattered higher resistance (C1-H1) in the southern half of the plot. On the ground, this region is a level area, possibly terraced. However this higher background activity could be an artefact due to the topography. The field slopes gently towards the river valley lying to the North. This slope is more pronounced towards the NW corner. The lower resistance in this corner could therefore be the result of the soil being more waterlogged here due to the slope. Survey The area of investigation was surveyed with two methods: a) electronic distance measurer (EDM) and b) dumpy level. A bench mark datum had been marked on the south wall of the barn. This was replicated on the south east corner so that it could be sited from a position east of the barn. Electronic measuring device This instrument operates by emitting a light beam which is reflected from the measuring pole back to the instrument. The instrument calculates northing, eastings and height. The instrument was set up on the datum bench mark sited directly over the south west corner of the grid (10 m square previously set up for the shovel test pits) and now extended for the geophysics by 10m to the east. This survey was extended north to include the ditch. The south west corner (origin) was given the co-ordinates of 0,0 so that the actual grid references could be later inserted into the plan mapping. Measurements were taken along the line of the main east west ditch and a path detected during the geophysical survey. Points were taken at each side and in the centre of the ditch and on both sides of the path. The EDM was sighted on the measuring pole at each measuring station and when the reflecting mirror was in the centre of the sight the ‘measure’ button was pressed and the EDM calculated the northings, eastings and height. These were recorded and plotted on tracing paper. Dumpy level Heights relative to the barn benchmark were measured at 2m intervals by laying a cloth tape north south starting a metre north of the field fence bordering Eaton Drove Road on grid lines ‘C’ and ‘G’. the dumpy level was set up in an area where the backsight to the benchmark and foresights to the points we wanted to be measured could both be seen.