Institute of Archaeology, Ucl
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INSTITUTE OF ARCHAEOLOGY, UCL ARCL 0027: Archaeological Surveying 2018-19 Year 2/3 Option, 15 credit module Topographic survey of a newly discovered burnt mound complex in Charlton Forest, East Dean, West Sussex. Co-ordinator and designer: Mark Roberts [email protected] Rm: 307. 0207 679 7535 Turnitin Code 3884042 Teachers: Mark Roberts and Alec Walker Contents 1/. Background 3 2/. The Survey Course (Specific) 25 3/. The Survey Course (General) 31 4/. Reading List and Bibliography 36 Appendix 1 Setting up the total station 41 Appendix 2 An example of an Historic Environment Record and scheduling description [The Waltham Down Barrow Group] 43 Appendix 3 Students attending the surveying course 44 Appendix 4 Useful telephone numbers and contacts 45 Appendix 5 Acknowledgements 45 Cover Page. The Downland block between the Cocking Gap and the head of the River Lavant, looking SW. Note the steep South Downs’ escarpment and the southern edge of the Weald, to the right of the image. Charlton Forest is located in the centre of the photograph. Rear Cover. Digital Terrain Model of Burnt Mound 2 on Bow Hill, made by students on the 2013 Surveying Course. 2 1/. Background The 2018 surveying course will take place in November, on land within the demesne of and owned by the Goodwood Estate, in West Sussex. This land 500m west of the East Dean and Upwaltham parishes, within Charlton Forest, is leased to the Forestry Commission. The survey area is situated at the eastern boundary of the estate, some 2km ENE of East Dean village and 0.9km south of the Downland scarp crest (Fig.1). The course will involve surveying the topography of, and monuments on, a c. 500 x 500m block of woodland on the dipslope of the South Downs, overlooking the valley of the River Lavant to the south and south-east (Fig. 2). An atypical burnt mound complex, marling pits, and field boundary banks and ditches are located in the survey area (Figs. 3, 4). Immediately around and within the survey area are located the lynchets of the late prehistoric/Romano-British field systems. These and a host of other features were revealed in their entirety by a Lidar survey, as part of the South Downs National Park “Secrets of the High Woods Project” (Manley 2016). Fig. 1. Charlton Forest in the area of Upwaltham. Blue square = 1km2. Red dot = site. 3 Fig. 2. Digital Terrain Model and location map East Dean Woods and major barrow groups in the study area. The three main geographical/geological provinces are also shown. As well as the academic teaching aims of the course (see below), the research aim is to provide an up to date topographic survey of the target monument, subsidiary monuments, and the immediate landscape setting. The data generated will be sent to the District Archaeologist, James Kenny, to be drawn up into a new Historic Environment Record, which may then be combined with that already compiled for the Waltham Down Barrow Group (HER) (Appendix 2). These data will then form part of a complete, integrated, topographic and monument survey of the downland block between Fairmile Bottom and the western margins of Bow Hill, which is an overarching aim of Survey Course in general. 4 The survey area An area of flint burning is visible on the ground which is more extensive than, and not restricted to, the depression (Fig. 5). Usually, the burnt area is disposed in a concentric arc of comminuted burnt flint nodules around part of the depression’s perimeter (Fig. 6). The Lidar image (Fig. 3), also shows the burnt mound to be part of an expanded feature rather than a stand-alone mound such as those on Bow Hill (Bliss 2015). The Lidar data also show the relationship of the burnt area to other archaeological and topographical features, such as those mentioned above. The aims of the work will be to carry out a detailed survey of the features to enhance and improve upon the data provided by Lidar, and to attempt to define the temporal and spatial relationship between the burnt mound complex and the field, and field systems, within which it sits, again through non-invasive detailed topographical investigation and analysis. The features surveyed will also be tied into the plans produced by the National Mapping Programme (NMP) (Figs. 7, 8) (Carpenter 2016), which overprinted and attempted interpretation of the features shown by Lidar. Fig. 3. LRM Lidar image of the area to the NW of the “Fiveways” crossroads. The burnt mound complex is in the southernmost of the fields in the field system (North to the top). 5 Fig. 4. Close up of the burnt mound complex shown in Fig. 3 The uppermost depression is a marling pit. Fig. 5. The main depression in the mound complex (see Figs. 3 & 4). 6 Fig. 6. Burnt Mound 1 on Bow Hill, note the crescentic mound composed of burnt flint. Fig. 7. NMP interpretation of the Lidar data, raised features in red, depressions in green. 7 Fig. 8. OS 1:25k map overlain by the Historic England’s interpretive feature mapping. The features to be surveyed are located within the Parish of East Dean, some 12.5km NNE of Chichester, the county town of West Sussex (Fig. 2) and 17.5km north of the current coastline of the English Channel at Bognor Regis. The survey area is on the gently southwards inclined dipslope of the South Downs, to the north over the scarp crest and face lies the Weald, and to the south the fertile flatlands of the Coastal Plain (Fig. 9). The burnt mound complex is situated on the Seaford Chalk Member, which constitutes part of the eroded Cretaceous Chalk surface of the southern limb of the Weald-Artois Anticlinorum (Figs. 10): this lithology intermixed with the Pleistocene loess mantle produces a Brown Rendzina soil (343i), which although thin on the higher ground and slopes, thickens considerably, as a consequence of gravitational slope movement into the dry valley systems. At and within the late prehistoric/Romano-British lynchets, remnants of the original Pleistocene loess cover are found; usually in a condition altered by prolonged cultivation (Macphail and Crowther 2016; pers comm). On this part of the downland block, the solid geology comprises the White Chalk sub-group of the Chalk Group that, with minor structural exceptions, young and dip southwards forming the downland dip slope (Aldiss 2002). In the Lavant feeder coombes such as Deep Coombe, Malecomb and Limekiln Bottom (Fig. 1), 8 Fig. 9. Digital terrain model of the downland block of the study area, looking NW. and in the Lavant itself, to the south of the study area, the older Chalks of the White Chalk sub- group, the Lewes, New Pit and Holywell Chalks, are exposed. To the north in the scarp face, at the junction of the South Downs and the Weald, a fuller range of the White and Grey Chalk sub-groups is exposed in a downward aging profile. At the base of the scarp, the older deposits of the Selbourne and Lower Greensand Groups exhibit a parallel disposition to the scarp face (Fig. 10). Younger deposits overlying the Chalk are the reworked Palaeogene cover known as “Clay-with-flints”; the aforementioned loess; valley sediments associated with the River Lavant, dry valleys and their feeders/tributaries; and mixed Head deposits which are preserved at the heads of some of the dipslope coombes, such as the Limekiln Bottom, a northern/right bank feeder of the Lavant Valley (Figs. 1, 2). These superficial head deposits are also found, albeit at a fraction of the volume of the dipslope material, at the base of the downland scarp slope extending out northwards onto the lithologies of the Selbourne Group. 9 Fig. 10. Geological map, showing structural features, drainage and the location of barrows on the South Downs and Folkestone Beds. The extant topography of the landscape across the South Downs, is largely the result of subaerial weathering on the gently uplifting solid geology (Figs. 9, 10). Initial uplift and exposure of the Chalk probably predated the major episodes of tectonism but it is the latter, orogenetically driven, events that are associated with the formation of the major anticlinal and synclinal structures of the region. Subsequent to these major tectonic pulses, the anticlinorum was breached and the sub-Chalk Cretaceous geology of the Weald exposed. During the Pleistocene Epoch, the final shaping of the downs took place, with most landscape contouring occurring at the end of glacial periods when snow and ice field melt carried vast amounts of material off the Downs and over the scarp and dip slopes (Figs. 9, 10). This process occurred as a result of blanket mass movement deposition and also sediment discharge through valley systems both fluvial and dry (coombes). 10 It is upon the post-Devensian Glacial Stage surface of the Downs, that the archaeological monuments of the past twelve thousand years were constructed and remain to this day, largely unaffected by natural processes (but see below) but greatly affected by anthropogenic activity, especially over the last hundred years. In the study area (Fig. 11), the Waltham Down spur is delineated by coombes to the north and south, Limekiln Bottom and Malecomb respectively; with the topographically impressive Deep Coombe immediately to the south, creating with Malecomb the spur of Oxen Down. Deep Coombe and Malecomb feed directly into the Lavant, whereas Limekiln Bottom is confluent with Stonepit Bottom, Brockhurst Bottom and the East Dean Woods’ coombe in the open fields at Lamb Lea (Fig. 1). Fig. 11. Overhead view of the Downs and the downland escarpment in the vicinity of the study area.