Linear earthworks

Large ditches and associated earthen banks that extended for many kilometres are known from around Britain; and are notoriously difficult to date. Examples in East and North Yorkshire have been dated to the late Bronze Age and early Iron Age (e.g. Fenton-Thomas 2003, 2005; Giles 2007a; Spratt 1989; Stoertz 1997). In West Yorkshire, the Aberford Dykes complex was a series of linear earthworks located between the Rivers Aire and Wharfe, including features known as Grim’s Ditch, South Dyke, Becca Banks and The Rein. Grim’s Ditch produced radiocarbon dates of 777–396 BC, 790–400 BC and AD 86–335. Together with evidence for ditch re-cutting, this suggested construction during the earlier Iron Age, with redefinition in the late Iron Age, and/or during the late Roman period (Wheelhouse and Burgess 2001: 129). South Dyke yielded a date of 104 BC–AD 112 (ibid.: 132). The ditch was re-cut at least once, with secondary fills of the recut producing an amphora sherd and radiocarbon dates of AD 212–413 and AD 141–404 (ibid.: 135). Another intervention at South Dyke obtained a date of 740–390 BC from a pit underlying the bank (Gregory and Daniel 2013: 100-1), whilst the ditch produced a date of 370–160 BC. Some Iron Age or Romano-British field system boundaries in West Yorkshire clearly respected these earlier linear earthworks.

In South Yorkshire, the Roman Ridge or Roman Rig consisted of two lines of earthworks aligned south-west to north-east and totalling c. 27 kilometres in length, originating to the south-west of Wincobank hillfort and extending north-eastwards to Swinton Common and Mexborough, though the original limits of the banks and ditches are still unclear. The earthworks have been surveyed in the past (Preston 1950b) but are still undated despite several investigations (e.g. Atkinson 1994; Greene 1950; Greene and Preston 1957; Riley 1957). The Roman pottery recovered from secondary or tertiary ditch fills in excavated sections does not date the original construction; and it is not known if the two lines of earthworks were even contemporary. One investigation indicated that two stratigraphically earlier phases of ditch pre-dated at least one stretch of bank (Atkinson 1994: 47), suggesting that the earthworks have much more complex histories than is visible from the surface.

Ashbee (1957: 256-265) proposed that the Roman Rig was built hurriedly at the behest of the Brigantian leader Venutius in response to a deterioration in relation to Roman forces, as Alcock (1954) had posited for the Aberford Dykes; and that the earthworks thus formed part of an Iron Age defensive network along with Wincobank hillfort and the small earthwork enclosure of Caesar’s Camp at Scholes Coppice. This is highly problematic, however, not least because the linear earthworks never appear to have linked to either enclosed site. The hillfort and enclosure are also poorly dated, and a planned system of ‘defence in depth’ seems unlikely. The South Yorkshire linear earthworks have few if any clear relationships with field system boundaries visible on aerial photographs, so even their relative position in a landscape stratigraphy remains hard to establish.

Boldrini (1999: 103) also suggested an Iron Age date for the Rig, though admitted the earthworks could have been renewed in later periods. He believed that the banks and ditches were not defensive but social and territorial markers, marking the divide between Brigantian and Corieltauvian territories. Nonetheless, he considered it possible that they could also have dated to the 1st century AD, built as a reaction to the temporary Roman frontier between Chesterfield and Rossington. A post-Roman date has also been proposed (Cronk 2004), perhaps linked to the kingdoms of Elmet in the 5th to 6th century or Northumbria in the 7th to 9th century AD; but a Roman hoard of a brooch and 19 coins was discovered inserted into the Roman Rig in 1891 during railway construction (Addy 1893: 249), though it is possible that the earthworks were renewed in places in the early medieval period.

Such ideas may be trying to fit the evidence into too narrow a historical context, though overall an Iron Age origin (earlier or later) seems most likely. It is unlikely that the earthworks were defensive barriers – any overtly hostile forces could simply have outflanked them from the north-east and south-west. They may have been designed to be seen from the south-east though, helping to define territories and social identities, and perhaps channeling movements of livestock and people (Giles 2007a). The Roman Rig earthworks do have intriguing relationships with springs and streams, cutting across the line of many of these. Their construction would have required considerable time and labour from a significant proportion of the population. A more recent overview (Chadwick 2016a) stressed the dynamic and mutable nature of the Roman Rig earthworks and the need to establish the character of the relationships between banks and ditches, landscape, people, and materials as they were potentially understood in the past.

Shorter linear earthworks have also been identified in South Yorkshire. In Edlington Woods, the Double Dike earthwork is of at least post-Roman origin, and probably much later (Dolby 1973: 5-6; Ramm 1973: 28-31). It has a noticeable ‘kink’ in it where it respects an Iron Age or Romano-British earthwork enclosure. The full extent of the Double Dike is unclear, though Google Earth imagery suggests that it may have extended further to the east. There are also three possible curvilinear boundaries surviving as faint ploughed-out earthworks and cropmarks near Thrybergh Park (Deegan 2007: 25; Roberts, Deegan and Berg 2010: 47, fig. 60), following the contours and effectively cutting off an area between tributaries of the River Don – but unusually they curve inwards to the enclosed area, unlike promontory forts or cross-ridge dykes. One kilometre to the west at Ravenfield is what appears to be a curving multivallate defence work on the western side of the River Don valley (Deegan 2007: 25). It may be that they were a Corieltauvian counter to the Roman Rig earthworks. These undated features have never been surveyed in detail or excavated.

Research questions

  • Can we shed further light upon the development of field and boundary systems?
  • What were the economic, social or political roles of linear ditch systems?
  • What may we deduce from studies of linear boundaries with respect to changes in the agrarian landscape?

Priorities and implementation

  • Aerial photographs and lidar, detailed analytical earthwork survey, and geophysical survey would prove useful in helping to establish the original course of very subtle and degraded earthworks;
  • Targeted excavation and coring should be undertaken to try and resolve the chronological development of linear boundaries along with AMS dating of multiple securely stratified charcoal or bone samples; and where the geology is suitable, OSL dating. Pollen and soil micromorphology samples from targeted sections should be analysed for palaeo-environmental information, especially where the earthworks extend across potentially waterlogged ground, as at Blackburn Beck (P. Buckland pers. comm).
  • Such a research-led project presents ideal possibilities for collaborative work between Historic England and SYAS, university departments, and local societies and community volunteers.