Enclosed sites or hillforts and ‘marsh forts’

Sutton Common

The unusual pair of enclosures either side of the former course of the Hampole Beck at Sutton Common near Askern are situated within low-lying, once marshy land on the edge of the Humberhead Levels. They survived as earthworks and were Scheduled in 1937, but in 1980 the larger enclosure (Enclosure A) was bulldozed and ploughed. It was once interpreted as a Roman camp (Surtees 1868), and several 19th and early 20th century small-scale investigations have left no surviving records or finds. Whiting directed the first published excavations during 1933-1935, with trenches in both enclosures. These revealed a plank-lined pit, a possible solid wooden wheel, and a human skull fragment next to a post alignment linking the enclosures (Whiting 1936-38: 57). Enclosure A had a drystone revetment wall on its western side, and a timber palisade underneath the rampart (ibid.: 79). Whiting also identified at least 34 so-called ‘huts’ (Surtees’ ‘tent mounds’), on top of the ramparts and within the interiors of both enclosures. Many were surrounded by shallow gullies, some had stone-flagged floors and internal post-settings and traces of decayed wood and thatch; but they yielded no dating evidence.

Trial trenching by SYAU in 1987-88 found waterlogged and worked wood in the ditches of Enclosures A and B, including a notched wooden ladder; with radiocarbon dates indicating activity between c. 550–200 BC (Parker Pearson and Sydes 1997: 229). Joint SYAU and University of Sheffield investigations in 1992–93 recorded a marked deterioration in the condition of the wood (ibid.: 225-6); and indicated Enclosure B’s rampart had consisted of a clay base with turves above. One small ‘hut’ in Enclosure B was excavated, and its shallow subrectangular gully contained one sherd of ‘later prehistoric’ pottery (ibid.: 230). Fragments of saddle querns were also recovered. Continued degradation of previously waterlogged deposits by drainage schemes led to further work by the Universities of Hull and Exeter in 1998–99 and 2002–3; including open-area excavation of Enclosure A, though only 10% of features were investigated. This work revealed details of box timber ramparts and two substantial wooden gateways of Enclosure A, and the wooden causeway linking Enclosures A and B. Dendrochronology established that rampart timbers were felled between 372 and 362 BC (Van de Noort, Chapman and Collis 2007: 175). Hundreds of postholes within Enclosure A represented at least 115 four-post structures, fences and other features, but no roundhouses or other buildings were identified.

Following a period of disuse when ramparts rotted and partially collapsed, sometime between c. 400–200 BC at least 12 small subrectangular and penannular gullies may have been used for the secondary deposition of cremated human and animal remains, though evidence is ambiguous (Chapman and Fletcher 2007: 153-5). Given the overlap in dates with the construction of the ramparts, and that some of these features overlay four-post structures, this implies the original occupation of the enclosure was relatively short in duration. Only five gullies were sampled, and very minimally, rather than being 100% excavated as is almost standard with suspected funerary features. Just a few concentrations of bone were found, with occasional fragments of cremated bone noted elsewhere. Late Iron Age glass beads were recovered from one of these features, and the gold bracelet or ingot fragment found (Hill 2007) may also have been associated with them. Sadly, of the c. 10% of internal features actually excavated, most were only half-sectioned. An extremely limited sample of Enclosure A’s eastern entrance ditch terminals recorded possible ‘placed’ deposits of two human skulls, a quern fragment, and an antler weaving comb. Enclosure B was targeted by magnetometry survey and interpreted as a largely empty enclosure with a cross-wall, banks and ditches (Payne 2007: 68-71; Van de Noort and Chapman 2007: 37), although most of the numerous features in Enclosure A were not visible prior to excavation, so this may be supposition. It is also unclear from these excavations what the small ‘huts’ on the banks were or how they fit into the chronological sequence, but presumably they were part of a later phase of occupation, after the ramparts ceased to be functioning structures.

Other lowland enclosed sites

Sutton Common might not be exceptional – there are other enclosures in South Yorkshire on slight rises in otherwise low-lying areas. At Croft Road, Finningley, excavation by MAP ahead of gravel quarrying revealed a large curvilinear ditch at least 180m in length, with a possible ‘entrance’ up to 25m wide. This relatively narrow and shallow feature, part of a much larger oval feature visible on cropmarks, was interpreted as a possible Neolithic henge ditch (MAP 2006a: 18, 46-47), but there is no stratigraphic, artefactual or scientific dating evidence to support this assertion. No external bank was indicated, and no finds were recovered from the ditch, though very few slots were excavated across it. An outer series of shallow, curvilinear gullies or palisade slots respected the line of the innermost ditch, but also created an additional space or annex to the north-east. These may represent several later phases of activity. There were five pits inside the inner ditch – one contained later Bronze Age or earlier Iron Age pottery, and further sherds of this date came from the fill of an adjacent ditch. The area within the oval enclosure at Finningley, and to the north-east of it, then became the setting for a series of subrectangular enclosures, pits and waterholes of Iron Age and Romano-British date – radiocarbon dates of the 1st century BC were obtained from another ditch, and a pit.

The rather poorly written and at times internally contradictory 2006 report not only used segments of text uncredited from other sources (e.g. MAP 2006a: 50, para. 7.14, is largely plagiarised from Chadwick 1997), but also claimed that pottery of 3rd and 2nd millennium BC date was recovered from the enclosure (ibid.: 48). This is contradicted by the ceramics report, however, which suggested a late Bronze Age or early to mid-Iron Age date instead (Manby 2010: 180). Indeed, a subsequent Updated Project Design (MAP 2006c) admitted that there was ‘no conclusive evidence’ to support a Neolithic date. On balance, a later Bronze Age or earlier Iron Age date seems much more likely. At least one later prehistoric vessel had carbonised residue on the inside (Manby 2010: 180), potentially suitable for future AMS dating. Oddly, the ceramics report is dated four years after the main report it is presented within (MAP 2006b). This important site has still not been published, though the UPD dates to 2006 (MAP 2006c). Dating and publication should be a matter of urgency. Much of the oval enclosure lies outside the development area, and there is clear potential for future research-led investigations. It is hoped that any future fieldwork and reporting will be monitored more closely to ensure that it is of a much higher standard than the MAP investigation.

At Moorhouse Farm, Tickhill, a double or triple-ditched enclosure visible as cropmarks now lies beneath a modern farm (Riley 1980: 49, 66, plate 15). At Potteric Carr, a large (c. 1.7ha) irregular enclosure now partly under trees had up to three lines of ditches (Deegan 2004: 8, fig. 4; Magilton 1977: plate 4; Riley 1980: 91), and extant earthworks in Beeston Plantation. At least two, possibly three circular features up to c. 25m in diameter are visible it within it on some aerial photographs. Two smaller enclosures appear to have abutted the triple-ditched example. To the south, a series of trapezoidal fields and enclosures developed from the later Iron Age onwards (see below). Near Brodsworth, there is a cropmark of an irregular univallate curvilinear enclosure (Roberts, Deegan and Berg 2010: 27, fig. 33).

Several potentially similar bivallate and univallate irregular enclosures have been identified just outside South Yorkshire near Babworth, Loundfield Farm, Forest House Farm, Flint Hill, and Willow Holt in Nottinghamshire (Riley 1980: 48-49, maps 16, 20, 23), all located on floodplains or on slight rises surrounded by low-lying peaty and alluviated valleys. There is also a multivallate enclosure less than a hundred metres over the county boundary between Norton in South Yorkshire and Little Smeaton in North Yorkshire, on the River Went floodplain (Manby 1988: 26; Riley 1973: 212; Roberts, Deegan and Berg 2010: 37, 46, figs. 49, 46). Several possible ring ditches or roundhouses are visible on cropmarks, and further enclosures and trackways are situated to the south of it, within South Yorkshire.

Riley described such sites as ‘marsh forts’ (Riley 1980: 66), but this term is problematic, and it is unclear if they were ever defensive or even contemporary with one another. They were likely communal and social foci, as the numerous four-post possible granaries at Sutton Common suggest; but it is a significant stretch to propose that their distribution reflected a socio-political boundary between the limestone hills north and west of the Rivers Don and Idle, and the gravel lowlands to the south and east (Parker Pearson and Sydes 1997: 254). Earlier researchers, however, also suggested that this north-east to southwest line across South Yorkshire and north Nottinghamshire represented a Brigantian and Corieltauvi/Coritani tribal boundary (Haselgrove 1984: 16; Preston 1950a: 91). There is no real evidence for this.


Encompassing an area of c. 1.1 hectares, Wincobank is classified as a univallate hillfort (Pastscape 314855), with just one large surrounding ditch; though there are surviving remnants of a counterscarp bank too. There were small-scale investigations of Wincobank in 1899, but most of the interior was not examined and the results never published, although some records are held in Sheffield Museum. A summary of these unpublished results describes burnt masonry ramparts with the remains of timber lacing (Preston 1950a, 1954). Four possible entrances were noted in the inner ramparts; though the only dating evidence was some 2nd century Roman greyware found in upper ditch fills. An old radiocarbon date of c. 500 BC obtained from an unpublished evaluation by Beswick in 1979 may be unreliable (Beswick 1985; Coutts 1999: 78); although it has been suggested that Wincobank was probably disused by the later Iron Age (Buckland 1986: 6). In the 18th and 19th centuries mineral extraction pits were dug nearby, and during the Second World War a searchlight and an anti-aircraft gun were sited on the ramparts (Whiteley 1993). An analytical earthwork survey identified gaps in the earthworks to the north-east and south-west as possible original entrances (Pouncett 2001), but any interior features are still completely unknown. The site would therefore benefit considerably from detailed geophysical survey using the latest techniques and equipment. Located within an urban environment, Wincobank continues to suffer from erosion and vandalism, burning, and other negative impacts.

Carl Wark

This unusual enclosure was broadly subrectangular in plan and c. 1.8 hectares in area, on a sloping Millstone Grit outcrop or promontory in moorland overlooking the Burbage valley. Along the northern and eastern sides of the enclosure the naturally steep-sided rock face provides an impressive facade, reinforced with some drystone walling. The southern slope of the outcrop is less steep, and the site is most accessible from the west. Along these two sides, unbonded drystone blocks were used to create imposing revetment walls up to three metres high, the western wall being up to eight metres wide at the base and reinforced with an earthen rampart. There is a single inturned entrance at the south-west, and the stones here are noticeably more regular and partly dressed. There are large earthfast boulders over much of the interior, though smaller stones inside and outside the walls appear to have been cleared and used in construction. No internal structures are visible. There was disturbance of the north-eastern side of Carl Wark during the 19th century by millstone quarrying. Erosion from walkers is an ongoing issue (Bevan 2006a).

Several antiquarian writers proposed that Carl Wark was a prehistoric stronghold (Gould 1903; Trustram 1911). During a survey in 1948, Stuart Piggott noted that the retaining wall and earthen bank resembled early medieval structures in Scotland. A small-scale trench by Simpson in 1950 found no dating evidence but revealed that the embankment was constructed of turves, thought to be another possible indicator of a ‘Dark Age’ date (Piggott 1951: 210-2). Despite its unusual form, however, it was accepted by several researchers as an Iron Age hillfort (Challis and Harding 1974: 47; Forde-Johnston 1976: 280-1); but it is very different to scarp-edge promontory forts or hillforts in the Peak District such as Comb’s Moss (Castle Naze), Fin Cop, and Mam Tor. Based on initial work at Gardom’s Edge, where a stone rubble bank enclosed a boulder-strewn area on a scarp edge, a Neolithic date for Carl Wark was proposed (Edmonds and Seabourne 2001: 73-4), but Gardom’s Edge has now been dated to 1400–800 BC or the later Bronze Age (Barnatt, Bevan and Edmonds 2017: 54). Work elsewhere in upland Britain suggests several other supposed Iron Age hillforts may in fact be Bronze Age in date (e.g. Jecock and Evans 2018). Though defensible in extremis, Carl Wark is a poor choice as a truly defensive structure, as it lacks a natural water source (Bevan 2006a: 8). Such sites may have instead fulfilled roles as community meeting places and ceremonial centres. Geophysical magnetometry survey at Carl Wark has been undertaken (Sykes and Brunning 2016), but with inconclusive or negative results. Further geophysical survey at the site may not be productive; but detailed 3-D laser scanning might prove useful.

Research questions

  • What were the functions of hillforts and analogous upland and lowland enclosed sites dating from this period, and how were these related to each other and to other settlements?
  • When were these enclosed sites constructed, are they all Iron Age in date, and were any contemporary with one another?
  • What internal features can be identified within these enclosed sites, and what subsistence and/or social practices were undertaken within them?

Priorities and implementation

  • Several upstanding sites (e.g. Carl Wark) have never had detailed analytical earthwork survey of them undertaken, and photogrammetry, lidar and laser scanning might also be useful techniques. This might reveal previously unrecorded details, and the use of Structure from Motion and similar technologies (Crutchley and Crow 2009; Historic England 2017) would also provide useful data such as 3-D Digital Terrain Models and Digital Elevation Models for future research and monument condition monitoring;
  • Viewshed analyses of enclosed sites and 3-D modelling of their position may help ascertain why earthworks and entrances were positioned in particular places (q.v. Driver 2007, 2018; Hamilton and Manley 2001);
  • Lowland enclosed sites such as Finningley, Moorhouse Farm and Potteric Carr would benefit from detailed air photo analysis, lidar analysis, and analytical earthwork survey (Bowden 2002; Historic England 2017);
  • All sites but especially Wincobank would benefit from detailed geophysical survey utilising the latest soil resistance survey, gradiometry and caesium magnetometry, and Ground Penetrating Radar equipment (David, Linford and Linford 2008). Survey work should concentrate on the interiors of these sites. This includes Enclosure B at Sutton Common, as geophysical survey and imaging technology has advanced since the last survey programme there;
  • At Carl Wark and Wincobank, watching briefs should be undertaken during future footpath or remediation work within or near Scheduled areas (Bevan 2006a: 103). Erosion should be closely monitored, and stewardship schemes implemented to take enclosed sites currently ploughed out of cultivation. At Sutton Common and Potteric Carr, water table levels should be closely monitored, to safeguard any surviving anaerobic waterlogged deposits (q.v. Douterelo, Goulder and Lillie 2010);
  • To characterise and date these sites, a programme of field investigation should be initiated. Old excavation trenches at Carl Wark and Wincobank could be re-opened and expanded to assess the condition of buried deposits, obtain artefacts and charcoal or organic material suitable for radiocarbon analyses, and find palaeo-environmental remains that would advance understanding of the local environment in and around these sites in the past. The turf layers at Carl Wark may yield such evidence. New targeted excavations at enclosed sites should also take place, to investigate specific research questions such as the date, nature and scale of any internal occupation. The coring and targeted sectioning of ditch sediments could also take place to obtain artefacts and ecofacts, but particularly charcoal and/or organic material suitable for scientific dating;