Appendix Jiii Effects of past and present ploughing on the prehistoric monuments: the Wyke Down, Cranborne Chase, Dorset, case study. C A I French © C A I French, 2001 Oxford Archaeology May 2002 (revised December 2002) Effects of past and present ploughing on the prehistoric monuments: the Wyke Down, Cranborne Chase, Dorset, case study C A I French (6/12/2001) Introduction Palaeoenvironmental and geoarchaeological fieldwork focusing on the later Neolithic-earlier Bronze Age periods in the Wyke Down area of Cranborne Chase in Dorset (Figs. 1-3) is in the process of gathering new data with which to re-examine the landscape models put forward by Barrett et al. (1991a and b) and Barrett (1994) for Wessex. In the process, this project has revealed data relevant to the past and present erosion of prehistoric monuments which is ostensibly associated with past and present arable agriculture. To date a selection of prehistoric scheduled monuments on Wyke and Bottlebush Downs (Fig. 2) have been sample investigated to retrieve archaeological and palaeoenvironmental data. This has been combined with geomorphological survey of the Allen valley. Results Introduction Four barrows of the Wyke Down group (SAM 299 c, f, g & i) and a length of the Dorset Cursus on Bottlebush Down (SAM 310) have now been investigated through a combination of hand augering, topographical and geophysical surveys and sample excavation. The Wyke Down barrow group The main part of the Wyke Down barrow cemetery was evaluated by topographical and magnetometer surveys of about 1 hectare in extent (Figs. 4-6). These clearly show barrow 44 (bottom left) and 47 (top left) upstanding with evident internal features, but the remainder are ostensibly ploughed out with only ring-ditches surviving as earthfast features. The conventional topographical, magnetometer and resistivity surveys of barrows 34, 36, 41 and 44 pin-pointed with great accuracy the position of the ring-ditches, the extent of the surviving mounds, and areas of antiquarian and plough disturbance (Figs. 7-14) (GSB 1998, 1999 & 2001). Barrow 41 Barrow 41 was much destroyed and denuded, and to a large extent this had already occurred in the past. Today the monument survives as a small, low (c 80cm high), turf mound in the centre of the area enclosed by a ring-ditch (Fig. 7). The ring-ditch is about 3.5m wide, 1.6m deep, with an internal diameter of about 19m and an external diameter of about 26m. The inner third of ring-ditch backfill was composed of densely- packed, clean chalk rubble which would appear to be a deliberate backfill deposit. One could speculate that this chalk substrate material had acted as either a cap to the turf core, or as a circular bank on the inner edge of the ring-ditch, which had been deliberately put back into the ditch after a short period. Thus this barrow has probably previously been two slightly modified versions of a disc barrow. There is a difference of about 25cm between the level of the chalk on the outer edge of the ring-ditch and the chalk subsoil beneath the surviving mound (Table 1). The mound itself has become elongated along the east-west direction of the property boundary between the Shaftesbury Estate to the north and Martin Green’s land to the south (Figs. 7 & 8). Barrow 34 Barrow 34 was exhibited a more complicated and diverse sequence than barrow 41. Despite the presence of the large antiquarian trench on its northern side (which may be early 20th century in date, and is regrettably unrecorded), the mound of this barrow appears to be substantially intact and standing to a height of about 1.6m above the present day surface (Figs. 7-9 & 11). Sample excavation revealed that the site was comprised of at least two superimposed barrow monuments associated with first an inner and then an outer ring-ditch. First, a small (c 2 x 3m), sub-rectangular chalk cairn was erected on a thin (<10cm), truncated old land surface. This cairn would appear to mark the centre of the subsequent mounds and was covered by one or two layers of turf. The inner ring-ditch (of about 18m internal diameter) was then dug (or deepened), and the chalk subsoil upcast from this was used to make a primary chalk mound of about 16m diameter placed over the primary chalk and turf cairn. The surface of this chalk mound was initially left bare and underwent a period of weathering sufficient to discolour the upper 5-8cm of the chalk, and saw the accumulation of large quantities of worked flint, probably worked in situ. Then, a more substantial turf mound was created with its outer edge vertical sided and retained by a slight wooden revetment of stakes (slender fence post size, <10cm), with each stake placed about 40cm apart, presumably retaining a woven wattle-work fence, located about 1m in from the inner edge of the ring-ditch. The inner ring-ditch had become completely infilled by the time the outer, slighter, ring-ditch was dug (with a c 23m internal diameter, c 24.5m external diameter). The mixed upcast of turves, soil and chalk rubble produced by the digging of this ditch was thrown-up against the outside of the wattle fence around the first barrow, which was now leaning outwards, thus increasing the diameter of the barrow mound by about 3m and creating a gently sloping outer edge to the barrow, but still leaving a wide berm (2.5-3m). Apart from the antiquarian disturbance of the north-central part of the barrow mound, ploughing over different time periods has differentially affected its northern and southern sides (Figs. 7-9). The mound survives to a maximum height of 1.6m above the modern ground surface. On its northern side, the mound rises abruptly from the flat level of the present day ploughsoil where it has been ploughed for a 45 year period. In contrast, the southern side, which has not been ploughed for the past 15 years and is under established grassland, exhibits a more gentle sloping aspect between the edge of the surviving mound and the inner edge of the outer ring-ditch. This mound talus slope exhibits a 56cm thickness over a distance 6m (Table 1). Barrow 36 Sample excavation of barrow 36 revealed a thin rendsina soil profile (c 12-15cm thick) overlain by a thick turf core and substantial dumped chalk mound, as was indicated by the auger survey. The mound was about 25m across north-south and 23m across east-west, and has the best height survival at 2.45m. Essentially, the mound has become sub-square in plan (Figs. 12, 14-16). The single ring-ditch was about 2.5 m in width and 1.3m in depth. Significantly, the berm area between the inner edge of the ring-ditch and the outer edge of the surviving mound exhibited three steps in the upper level of the chalk subsoil. The first step was of 10cm between the outer and inner edges of the ring-ditch, then about 1.5m in from the inner edge of the ring-ditch there was a second step of 15cm and then another metre in there was a step of 27cm at the outer edge of the surviving mound. This gives a total figure of 52cm of truncation over a width of about 5m in the level of the chalk subsoil on the east side of the mound (Fig. 17; Table 1). The field in which this barrow sits is known to have been ploughed for 45 years (P Rymer and M Green, pers comm.), and has apparently caused the significant denudation and re-shaping of this mound. Barrow 44 Sample excavation of barrow 44 revealed very much the same picture as for barrow 36, but the mound and buried soil were less well preserved (Figs. 13, 14 & 18). The mound exhibits a diameter of about 27m across east-west and 18m across north-south, and has effectively become sub-rectangular in plan. The single ring-ditch was about 3.2m in width and 1.35m deep. This barrow mound survives to a maximum height of 1.33m and has suffered severe rabbit warrening and possibly an antiquarian trench being placed in its northwestern quadrant. As for barrow 36, it too exhibits three steps in the level of the chalk between the inner edge of the ring-ditch and the outer edge of the surviving edge of the barrow mound. In this case, there are steps of 7, 18 and 53cm giving a total figure of 78cm of denudation (Fig. 18; Table 1). The Dorset Cursus Four sample sections were excavated through the northern and southern cursus ditch and bank on the c 1km stretch leading to the Bottlebush Down terminal (Figs. 15, 16, 19 & 20). Unlike those sections previously excavated by Richard Bradley (Barrett et al. 1991: figs. 2.12 & 2.13), these new sections revealed fills that were mainly dominated by clean chalk rubble. Moreover, the surviving bank was much denuded in height (i.e. less than 30cm) and appeared to have been ploughed in pre-Roman times. From the 2001 field investigation it looks as if the Bottlebush Down length of both cursus banks was deliberately slighted back into the ditch shortly after the monument was constructed. This is in contrast to the other fill sequences observed further to the south in the same monument on Wyke Down and in Firtree Field by Bradley (ibid.) where the homogeneous organic silt loam and fine chalk rubble fills suggested a natural infilling over a lengthy time period.