Casten Dyke South

Has been described as a Possible Linear Defence or Dyke

There are earthwork remains

NameCasten Dyke South
Alternative Names
Historic CountryYorkshire
Modern AuthorityNorth Yorkshire
1974 AuthorityNorth Yorkshire
Civil ParishKilburn High and Low

A linear boundary earthwork, which has widely been accepted as being a prehistoric dyke, associated with Casten Dyke North (UID 57368), the Cleave Dyke (UID 1032865), and the early Iron Age promontory fort at Roulston Scar (UID 57324), has been reinterpretated as being of medieval date. The boundary runs in a straight line from W to E. Over a distance of 260m at its W end, it survives in reasonable condition as an earthwork (Scheduled). The W terminus is the side of a steep-sided valley, Boar's Gill; a post medieval limestone quarry (UID 1526097) located here has potentially destroyed elements of the monument. The E end of the monument, which has been ploughed away but is clearly visible on early aerial photographs, extended for a further c200m to the head of another ravine, Hell Hole. The last few metres of the ditch may survive, although is is difficult to distinguish the artificial earthwork from erosion. The boundary would thus have cut off a block of landscape to the S, the southern edge of which is defined by the S escarpment of the Hambleton Hills. However, it seems likely on the evidence of both the form and plan relationship of Casten Dyke South that it is a later addition, probably of medieval date. The linear earthwork was reused as a field boundary into the 20th century. This feature ws mapped as part of the North York Moors National Park NMP, visible as earthworks on air photographs. The monument appears to be largely extant on the latest 2009 vertical photography. (PastScape)

There can be little doubt that the form of Casten Dyke South shows that its purpose was to enclose the land to the south, a promontory of c.23 hectares, by running between two steep- sided natural valleys, Boar's Gill and Hell Hole. This may have been done for agricultural purposes in either the late medieval or early post-medieval periods

Nevertheless, it remains a distinct possibility that the dyke was either created specifically for the Battle of Byland, or that it was an earlier, prehistoric, boundary which was re-used during the battle. By sealing off the south side of the plateau, and with very steep slopes on all other sides, any English force encamped within would have felt they held a reasonably secure position, particularly if they were augmented by another force close by to the west which had modified the northern rampart of Rouslton Scar. The plateau also overlooks Boar's Gill and Hell Hole, both of which would have provided routes up the natural escarpment for the Scottish army seeking to outflank the English. It is less easy to make a case for Casten Dyke North having been created specifically for the battle, although the anomalies apparent at the north-east end close to Flassen Gill are interesting. If either of the dykes were created or partly used during the battle, then this would force a re-assessment of the battle itself; the traditional narrative suggests that the battle was a hastily organised action, but the creation and use of defensive earthworks would indicate that it involved a certain amount of preparation on both sides. (Richardson and Dennison 2016)

Gatehouse Comments

The Battle of Byland was a relatively small battle of 1322, between a few thousand Scots and several hundred English. Fundamentally it was a delaying action by the English to allow Edward II to escape from an unexpected Scottish force. The use of earthwork defences for the English force is entirely sensible. The question is how much time the English Force had to dig defences or if they were just reusing a pre-existing earthwork.

- Philip Davis

This site is a scheduled monument protected by law

Not Listed

Historic England (PastScape) Defra or Monument number(s)
County Historic Environment Record
OS Map Grid ReferenceSE518816
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  • Spratt, D., 1982, ‘The Cleave Dyke System’ The Yorkshire Archaeological Journal Vol. 54 p. 33-52


  • Shaun Richardson & Ed Dennison, 2016, CastenDyke North and Casten Dyke South, Kilburn Moor and Scawton Moor Plantations, Hambleton, North Yorkshire: Archaeolgical Surveys (Ed Dennison Archaeological Services Ltd 2016/516.R01)
  • Boucher, A., 1996, Casten Dyke, North York Moors: Earthwork Survey (Archaeological Services WYAS archive report for NYMNP)