The Thieves' Dikes: prehistoric linear boundaries and associated features


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:
Date of most recent amendment:


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The building or site itself may lie within the boundary of more than one authority.

North Yorkshire
Scarborough (District Authority)
North Yorkshire
Scarborough (District Authority)
National Park:
National Grid Reference:
SE 97126 93307, SE 97232 92942, SE 97619 92662, SE 97791 92877

Reasons for Designation

Linear boundaries are substantial earthwork features comprising single or multiple ditches and banks which may extend over distances varying between less than 1km to over 10km. They survive as earthworks or as linear features visible as cropmarks on aerial photographs or as a combination of both. The evidence of excavation and study of associated monuments demonstrate that their construction spans the millennium from the Middle Bronze Age, although they may have been re-used later. The scale of many linear boundaries has been taken to indicate that they were constructed by large social groups and were used to mark important boundaries in the landscape; their impressive scale displaying the corporate prestige of their builders. They would have been powerful symbols, often with religious associations, used to define and order the territorial holdings of those groups who constructed them. Linear earthworks are of considerable importance for the analysis of settlement and land use in the Bronze Age; all well preserved examples will normally merit statutory protection.

Round barrows are funerary monuments dating from the Late Neolithic period to the Late Bronze Age, with most examples belonging to the period 2400-1500 BC. They were constructed as earthen or rubble mounds, sometimes ditched, which covered single or multiple burials. They occur either in isolation or grouped as cemeteries and often acted as a focus for burials in later periods. Often superficially similar, although differing widely in size, they exhibit regional variations in form and a diversity of burial practices. There are over 10,000 surviving examples recorded nationally (many more have already been destroyed), occurring across most of Britain, including the Wessex area where it is often possible to classify them more closely, for example as bowl or bell barrows. Often occupying prominent locations, they are a major historic element in the modern landscape and their considerable variation of form and longevity as a monument type provide important information on the diversity of beliefs and social organisation amongst early prehistoric communities. They are particularly representative of their period and a substantial proportion of surviving examples are considered worthy of protection. Square barrows are funerary monuments of the Middle Iron Age, mostly dating from the period between c.500 BC and c.50 BC. The majority of these monuments are found between the Humber Estuary and the southern slopes of the North York Moors, but a wider distribution has also been identified, principally through aerial photography, spreading through the river valleys of the Midlands and south Essex. Around 200 square barrow cemeteries have been recorded; in addition, a further 250 sites consisting of single barrows or small groups of barrows have been identified. Square barrows were constructed as earthen mounds surrounded by a ditch and covering one or more bodies. Slight banks around the outer edge of the ditch have been noted in some examples. Despite the term `square', barrows can vary in shape. The majority are truly square, although many have rounded corners and some are more rectangular in plan. A few, however, occurring both in square barrow cemeteries and individually, are actually round in plan, but distinguishable from earlier Bronze Age round barrows by their smaller size. The main burial is normally central and carefully placed in a rectangular or oval grave pit, although burials placed on the ground surface below the mound are also known. A number of different types of burials have been identified, accompanied by grave goods which vary greatly in range and type. The most elaborate include the dismantled parts of a two-wheeled vehicle placed in the grave with the body of the deceased. Some Iron Age barrows have been associated with an unusual burial ritual of `spearing the corpse'. Ploughing and intensive land use since prehistoric times have eroded and levelled most square barrows and very few remain as upstanding monuments, although the ditches and the grave pits, with their contents, will survive beneath the ground surface. The different forms of burial and the variations in the type and range of artefacts placed in the graves provide important information on the beliefs, social organisation and material culture of these Iron Age communities and their development over time. All examples of square barrows which survive as upstanding earthworks, and a significant proportion of the remainder, are considered to be of national importance and worthy of protection. This square barrow is a rare example of one surviving as an upstanding earthwork, and it will preserve a range of evidence within and upon the flat-topped mound which does not survive on the plough-flattened examples elsewhere. It is one of only a few to be identified on the Hackness Hills, although there is a greater concentration on the Tabular Hills to the south west. The Hackness square barrows form an important group of this monument type which will provide valuable insight into cultural development during the Iron Age. Despite limited disturbance, it has survived well and will preserve significant information about its original form, the burials placed beneath it and any rituals associated with its construction and use. Evidence for earlier land use and the contemporary environment will also survive beneath the barrow mound and within the buried ditch. Despite limited disturbance, the earthwork sections of the Thieves' Dikes are in a good state of preservation. Stratigraphic relationships between the components of the multiple dyke sections will survive and provide evidence for the sequence of construction and development of the boundary system. Important environmental evidence which can be used to date the boundaries and determine contemporary land use will be preserved within the lowest ditch fills. Evidence for earlier land use will be preserved in the old ground surface beneath the banks. The lowest ditch fills of the plough-levelled boundaries will also preserve valuable environmental evidence. The Thieves' Dikes are thought to represent a system of territorial land division which was constructed to augment natural topographical divisions of the landscape. Many more such groups are found on the Tabular Hills. The close association of these boundaries and their relationships with the Bronze and Iron Age burial monuments in the landscape surrounding them will provide valuable insight into the division and use of the landscape for social, ritual and agricultural purposes during the later prehistoric period. The reuse of the boundaries in the Anglo-Saxon and medieval periods provides important evidence for the continuity of land division from the prehistoric period onwards.


The monument includes five prehistoric linear boundaries situated in Broxa Forest, on a level plateau at the top of the eastern scarp edge of the Hackness Hills. Also included are a round barrow, a square barrow and an area of intersecting hollow ways adjacent to the linear boundaries. The monument is divided into four separate areas of protection. The most northern of the linear boundaries runs in a south west to north east direction, between the head of Breaday Gill and the head of a stream gully at the top of Surgate Brow. In the centre it changes direction to run towards the ENE for the eastern part. It has a steep-sided `V'shaped ditch which runs between two parallel earth and stone banks and an overall maximum width of 13m. The east end of the boundary has been truncated by the construction of a modern road and a forestry track. Towards the west end, the upstanding earthworks have been levelled and the ditch infilled by forestry activities for a 46m length; for a further 40m the earthworks survive with a reduced profile. There are three other breaks which post-date the boundary, where pathways running in a north to south direction have broken through the earthworks. To the south, the second linear boundary runs in a WNW to ESE direction, from the top edge of the southern side of Breaday Gill to the north east side of Thirlsey Plantation. At the western end it turns slightly to the north west and towards the eastern end it changes direction to run south east. The boundary has a steep-sided `V' shaped ditch which runs between two parallel earth and stone banks and has an overall width of 14m, increasing to 19m at the eastern end. Arable ploughing has truncated parts of the banks and in places largely levelled them: for the western part, the southern bank has been levelled except for its northern edge, surviving in a modern field boundary, and for the eastern part, the northern bank has been reduced in width. On the north side of the northern bank there are fragmentary stretches of up to four additional shallower ditches and banks on the same orientation, which have an overall maximum width of 18m. Originally these would have been continuous along the length of the boundary, but over the years they have become levelled and infilled by forestry activities and, at the eastern end, by arable ploughing, so that now only short stretches are visible. The eastern end of the linear boundary has been truncated by a field entrance. There are a number of other breaks in the boundary: the public road from Silpho passes through the centre in a south west to north east direction and forks, and to the west of it there are three further breaches caused by field entrances and paths, now disused. At the western end of the WNW to ESE boundary, the third linear boundary runs SSW to NNE along the contours at the top of Breaday Gill as far as the rocky edge at the head of the southern spur of the Gill, where it turns more to the north east. It has a ditch of similar proportions and profile to the other two linear boundaries, which also runs between two earth and stone banks and it has a maximum width of 12m. In places, particularly at each end of the boundary, the banks have been partly levelled by forestry operations so that they are no longer visible as earthworks. On the east side of the eastern bank and parallel to it there are two additional shallower ditches and banks which have an overall width of up to 12m. However, these have been segmented by a modern footpath which runs along them and partly levelled by forestry activities so that they are no longer continuous along the length of the boundary. At the eastern end of the WNW to ESE boundary there is another linear boundary continuing in the same direction. This boundary has been ploughed level over the years and survives largely as a crop mark visible on aerial photographs, which show it to have turned to the south at the eastern end. In common with the linear boundaries to the north, it would have had a ditch between two parallel banks and would have had an overall width of 14m. Fragments of the ditch and southern bank survive as earthworks on the west side of the modern field boundary wall at the western end. The fifth linear boundary runs north east from the junction of the two WNW to ESE boundaries as far as the head of a stream gully at the top of Silpho Brow. In the centre there is a slight change in direction. This boundary also has a steep-sided `V' shaped ditch between two parallel earth and stone banks with an overall maximum width of 15m. On the north west side of the north western bank and parallel to it, there is an additional shallower ditch and bank which have an overall width of 5m. Originally the larger ditch would have been continuous with the larger ditches of both the WNW to ESE boundaries, with the large north western bank turning to join the large northern bank of the western WNW to ESE boundary and the south eastern bank turning to join the northern bank of the eastern WNW to ESE boundary. However, this junction is no longer visible, since the earthworks have been levelled and infilled by the construction of a field entrance. A road divides this boundary into two parts; to the south west of the road the banks have been ploughed level and the ditch infilled so that they are no longer visible as earthworks, although the eastern edge of the south eastern bank is followed by a modern field boundary wall. To the north east of the road the boundary has a modern break where a footpath passes through. On the south side of the western WNW to ESE boundary and immediately adjacent to it there is a round barrow. It is situated at the point where the boundary changes direction; the change of course would have been deliberate in order to respect the round barrow. The barrow originally had an earth and stone mound 13m in diamteter, which has now been levelled by ploughing and is only visible as a crop mark on aerial photographs. In the angle between the western WNW to ESE boundary and the NNE to SSW boundary adjacent to it, is the area of intersecting hollow ways. These have open `U' shaped profiles, and measure up to 3m across and up to 0.6m deep. They criss-cross the area running either north east to south west or north west to south east, from the direction of the head of the stream gully flowing into Breaday Gill. The hollow ways represent routes which were established from the medieval period onwards, and perhaps earlier. The square barrow lies within the area of hollow ways. The barrow has a flat-topped earth and stone mound which stands up to 0.5m high. It is sub-rectangular in plan and measures 6m NNE to SSW, by 5m. In the centre of the mound there is a hollow caused by partial excavation in the past. The mound was originally surrounded by a ditch up to 2m wide but this has become infilled over the years by soil slipping from the mound so that it is no longer visible as an earthwork. The buried ditch on the west side of the mound has been truncated by one of the hollow ways. The linear boundaries form a system enclosing an area which would have been a land unit in the prehistoric period. They were constructed in an area where there were already many prehistoric burial monuments. Elements of the boundary system were later reused in the Anglo-Saxon and medieval periods as estate boundaries for lands belonging to Whitby Abbey. Field boundary fences and walls run along the western WNW to ESE linear boundary and the southern part of the southern north east to south west boundary. They also run across the two WNW to ESE boundaries, on the southern side of the road crossing the western one and at the extreme west end of the eastern one. All fence posts and walls are excluded from the scheduling, although the ground beneath them is included.

MAP EXTRACT The site of the monument is shown on the attached map extract.


The contents of this record have been generated from a legacy data system.

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Books and journals
Spratt, D A, Linear Earthworks of the Tabular Hills: North East Yorkshire, (1989), 65
ANY 127/27, (1984)
NYMNP Meridian 1:10000 AF/95C/381 run 18 frame 7666,
Title: 1st Edition Ordnance Survey 6" sheet 77 Source Date: 1854 Author: Publisher: Surveyor:
Title: 2nd Edition Ordnance Survey 25" sheet 77/2 Source Date: 1928 Author: Publisher: Surveyor:
Title: Forestry Commission Areas North York Moors Archaeological Survey Source Date: 1992 Author: Publisher: Surveyor: Site no. 3.21
Title: Forestry Commission Areas North York Moors Archaeological Survey Source Date: 1992 Author: Publisher: Surveyor: Site no. 3.45
Title: Forestry Commission Areas North York Moors Archaeological Survey Source Date: 1992 Author: Publisher: Surveyor: Site no. 3.48


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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