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The Thieves' Dikes: prehistoric linear boundaries and associated features

A Scheduled Monument in Silpho, North Yorkshire

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Latitude: 54.3227 / 54°19'21"N

Longitude: -0.5065 / 0°30'23"W

OS Eastings: 497239.0342

OS Northings: 492925.635

OS Grid: SE972929

Mapcode National: GBR SLXG.46

Mapcode Global: WHGBS.6M21

Entry Name: The Thieves' Dikes: prehistoric linear boundaries and associated features

Scheduled Date: 9 November 1962

Last Amended: 25 January 2001

Source: Historic England

Source ID: 1019627

English Heritage Legacy ID: 34558

County: North Yorkshire

Civil Parish: Silpho

Traditional County: Yorkshire

Lieutenancy Area (Ceremonial County): North Yorkshire

Church of England Parish: Hackness with Harwood Dale

Church of England Diocese: York


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
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
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.

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

Source: Historic England

Reasons for Scheduling

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
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
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

Source: Historic England


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

Title: 2nd Edition Ordnance Survey 25" sheet 77/2
Source Date: 1928

Title: Forestry Commission Areas North York Moors Archaeological Survey
Source Date: 1992
Site no. 3.21
Title: Forestry Commission Areas North York Moors Archaeological Survey
Source Date: 1992
Site no. 3.45
Title: Forestry Commission Areas North York Moors Archaeological Survey
Source Date: 1992
Site no. 3.48

Source: Historic England

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