Information and Advisory Note Number 25                                                Back to menu

Drystane dykes and stone fanks

1. Introduction

1.1 This information and advice note aims to provide farmers with guidance on the construction and maintenance of drystane dykes and their conservation value in the Scottish landscape.

2 Dykes are a characteristic feature of most upland areas and many parts of lowland Scotland. They are first and foremost practical features in the agricultural landscape, forming field boundaries and pens for stock-management and shelter in exposed areas.

3 The way dykes are built and their overall pattern in the wider landscape reflects local geology, quarrying history, crafts and traditions. They are often long-standing or ancient boundaries providing valuable evidence of the history of land-use and settlement. Dykes are also important as a wildlife habitat, often colonised by a variety of plant and animal species.

2. Values of dykes

2.1 For farmers, dykes are important stock barriers or field boundaries which can shelter grazing livestock and wildlife. Compared with other types of field boundary drystane dykes have the advantages of:

• permanence;
• minimal management needs;
• providing shelter.

2.2 In addition to these agricultural values, dykes provide an important wildlife habitat:

• dykes are often colonised by mosses and lichens, particularly in damp situations. In time, conditions may develop to suit ferns and flowering plants;
• small holes in dykes provide dry, sheltered nest sites for birds such as wheatear, wagtails and wrens (especially the Shetland wren and Fair Isle wren, for which there are few alternative nest sites);
• in an open landscape dykes also provide song-posts for stonechat and whinchat;
• lizards bask on dykes which provide shelter and cover;
• small mammals inhabit dykes and, for weasels in search of eggs and nestlings, dykes provide important hunting sites.

2.3 Dykes, fanks, stells and buchts are important upland features, and are characteristic of particular areas both in their construction and the contribution they make to the local character of the landscape and an understanding of its history.

2.4 Inbye land is liable to agricultural improvement by reseeding and fertiliser application. Often a farmer will avoid taking machinery too close to a dyke for fear of catching the foundations. As a consequence a strip of more diverse vegetation often persists at the foot of the dyke.

2.5 Dykes are often very old and are of considerable archaeological interest, providing evidence of settlement, management boundaries and the development of land-use. Dykes may divide fields with differing soil types and therefore different management regimes, for example head (or "hill") dykes form the boundary between inbye land and rough grazings. They may mark the periodic limits to efforts at land improvement, or define drove roads, once important for stock-movement. The information about land-use history contained in the structure of dykes and their pattern in the landscape may not always be apparent and expert advice may be needed, particularly if it is intended to remove a wall and use the stone elsewhere.

2.6 Advice on the importance of dykes and other historic features may be obtained from a Regional Archaeologist with the local authority, or from Historic Scotland. Some information on settlements associated with dykes may be found in the National Monuments Record for Scotland held in Edinburgh (see below) or on local Sites and Monuments Records held by the Regional Archaeologist.

3. The construction of dykes

3.1 A drystane dyke should be free of mortar and should rely on good construction for its strength and durability. The style of a dyke varies throughout the country and depends on the nature of the stone and the purpose for which the dyke is built. In general freestanding dykes (as oppose to retaining dykes) are built of two " skins" of stone with a batter, which tapers the dyke evenly on both sides from ground level to the top. These skins are tied together by stone laid length-ways into the wall. Some types of stone are common to all dykes:

• Foundations - (or footings) are usually the largest stones available, ideally set onto dry mineral soils, the topsoil having first been removed.
• Face-stones - form the bulk of the building stone for the dyke and an effort is made to present the best "face" of the stone as possible.
• Throughs - are long stones laid right through from one side of the dyke to the other, adding strength at regular intervals in both the height and length of the dyke.
• Hearting - (or "pinning and packing") is formed of small pieces of stone, tightly packed in the centre of the dyke to both fill gaps left between the two skins of the face stones, and to underpin face stones maintaining them in a firm and horizontal position.
• Coping stones - (or topstones, toppers, copers cappers or ragstones) are the large
  stones placed vertically along the length of the top of the dyke. They should be carefully placed so that they pack tightly together and put weight on every top face stone. Coping stones should be tightly fitted in order to withstand the attention of cattle which tend to scratch themselves on the top of the dyke. Coping stones also shed rainfall that would otherwise cause weathering within the dyke.

3.2 Additional points to bear in mind when looking for good quality work are:

• Stones should be laid with the longest dimension into the dyke, rather than along the wall, thus giving greatest strength to the dyke. This is also a more secure position for the stone - it is less likely to be displaced than if it had been laid lengthways along the wall.
• Each gap between stones should be securely covered by a stone in the next course so that there are no vertical breaks in the dyke.
• Stones should not slope into the dyke as water falling on the face of the dyke will then run into the middle, contributing to weathering.
• The face should be even so that no stones are protruding from the dyke except the through stones (see below).
• Stones should be laid horizontally along the line of the dyke even when working on a slope.
• Wedges (smaller stones to secure larger stones) should only be placed on the inside and not on the face of the dyke;
• Coping stones should always be tight. If they are easily moved there maybe a case for adding an additional stone.

3.3 Avoid using mortar to secure coping stones or to fill gaps as this may weaken dykes by reducing flexibility as the stone settles. In some circumstances this can result in a band of mortared coping stones suspended above the settled dyke. Where vandalism is a problem, or alongside busy roads, where mortaring may be advisable, allow the dyke to settle before mortaring if possible. Where mortaring is essential, use the mortar sparingly between the coping stones so that it is not visible in the gap between stones.

3.4 Dykes may collapse for a number of reasons, for example:

• during cultivation machinery may catch the foundations;
• loss of coping stones, due to stock climbing up or rubbing against the dyke, or vandalism;
• building without adequate throughs, or failing to cross joints with successive courses;
• building with a narrow base or wide top;
• the weight of snow drifting against the dyke;
• accidental damage (e.g. vehicles, tipped materials, undermining).

3.5 Top-wiring deters stock from jumping a dyke and dislodging coping stones. It is generally done with one or two strands of barbed wire, though in some areas a low net is used to extend the height of the dyke by about 0.5 metres. Top-wiring can be done with posts on alternate sides of the dyke or along one side of the dyke. It is generally more desirable, visually, to have the posts along one side of the dyke only.

4. Rebuilding of dykes

4.1 With time, even the best drystane dykes will move and lose their line, toppling to one side or the other, or spreading out and then collapsing into the centre. Depending on the amount of deterioration, the dyke can either be " gapped up" by repairs on the remaining standing dyke or taken down to the foundations and completely rebuilt.

4.2 Dykes should be repaired or rebuilt using similar stone and, where it is adequately suited to the purpose, the same style, width and height in order to retain the dyke's character.

4.3 When considering the renovation of dykes which are no longer stockproof, priority should be given to those which are both significant landscape features and which serve the most useful agricultural function such as boundary dykes and the hill dyke.

4.4 Retain stone gate posts where practicable and maintain purpose-built holes (such as 'smoots' or lunkeys) designed to allow water and sheep to pass through the dyke. Also, retain and provide adequate stiles or gates on acknowledged access routes to avoid damage from people climbing dykes. Provide signposts to encourage walkers to use proper stiles.

4.5 Complete rebuild of a dyke should include "ridding out", or removal of old footings, rather than simply building over what may be insecure foundations. Take care to avoid damage or removal of dykes which may be of archaeological interest.

4.6 When dyking around a feature from which stock should be excluded (for example woodland) place any protruding throughs on the non-stock side, making it more difficult for sheep to climb.

4.7 Remove unsightly metal sheeting, old wire, planks etc. which may have been used to block gaps. Dispose of these safely and well away from access routes or stock.

5. Maintenance of dykes

5.1 On-going maintenance is important to ensure that sound dykes and fanks do not fall beyond economic repair

5.2 Replace loose or fallen stones (particularly copings) to prevent water and frost damaging the dyke.

5.3 Avoid planting trees too close to dykes since their root plates shift in strong winds and may weaken the foundations.

5.4 When repairing a section of dyke that has been pushed out by a nearby tree, consider adjusting the line of the dyke slightly to avoid the tree, or leave a gap in the dyke and erect a section of post and rail fencing. Where necessary, remove young shrubs and trees which are undermining dyke footings or causing slumping. Leave mature trees, the removal of which could cause even more damage.

5.5 Wherever possible avoid the drift of herbicides or pesticides onto dykes which harbour plants or invertebrates, or onto species-rich field margins adjacent to the dyke.

6. Stone-carting

6.1 In some instances, it will be necessary to consolidate limited stone into the most important dykes. Sometimes the stone is found on the holding, alternatively it might be brought from elsewhere. When looking for sources of stone, avoid:

• old, historic dykes;
• archaeological sites or features;
• digging out foundations of dykes when they are removed, as these preserve an historic record of the old boundaries.

6.2 To protect landscape and archaeological interests, ESA schemes do not allow the removal of any dykes unless authorised in writing by the Secretary of State. Dykes or fanks to be used as a source of stone should be identified in an ESA farm conservation plan.

6.3 When stone is being transported for dyke repairs ensure that the machinery used causes no damage to valuable habitats or historic features along the route.

7. Stone fanks and planticrubs

7.1 Stone fanks (stells or buchts) on the hill, are now rarely put to their original use as gathering pens but can still give much needed shelter, or act as holding pens for sheep in need of special attention. They are a particularly striking feature of the upland landscape and, wherever possible, should be maintained.

7.2 Planticrubs are traditional small circular stone enclosures, used in Shetland and Orkney for sheltering and raising young cabbage plants. Some are still in use.

8. Caithness flag fence and other regional variations

8.1 The style of dyking varies across the country. In Caithness thin, flat rectangular flags are set vertically into the ground edge-to-edge along a boundary. Each may be secured to its neighbour by a large metal 'staple' bridging the gaps between stones.

8.2 Large stone in some areas results in a 'single' dyke being built, where all stones span the width of the dyke. A variation is the half dyke where the lower part of the dyke, at its widest, is built of two skins, while the upper half narrows to a single skin.

9. Drystane dyking - costs and grant aid

9.1 The costs of a drystane dyking project is affected by many variables, examples include:

• height and line of the dyke;
• slope of the ground (both along and across the line of the dyke);
• whether any part of the dyke is a retaining dyke;
• access to the site and to extra stone;
• exposure of the site for the dyker
• conditions underfoot;
• stone-size and regularity of stone shape;
• availability of important stone such as throughs and coping stones;
• the difficulty of "ridding-out";
• features to be incorporated (stiles, smoot or lunkey holes, sheep-creeps or cheek-ends or dyke-heads, i.e. where the dyke ends);
• whether or not the dyke has to be maintained as stock-proof during work.

9.2 In some circumstances the use of conservation volunteers may be appropriate for drystane dyking work. The Scottish Conservation Projects Trust is able to advise on whether projects are suitable and can assist with obtaining volunteer groups for the work.

9.3 The ESA schemes requires existing stockproof dykes to be maintained in a stockproof condition. Payments may also be available for the restoration of existing dykes and for building new dykes.

9.4 Under its Discretionary Payment for works to encourage regeneration of tree cover, the Forestry Authority has, in some situations, contributed 50% of the equivalent fencing cost towards a drystane dyking project.

9.5 Grant aid may also be available under other SOAEFD schemes.

Further reading and references

• Countryside Commission for Scotland "Drystane Dykes". Information Sheets, nos. 4.10-4.10.15.
• Brooks, A, (1986), "Drystone Walling - A Practical Conservation Handbook". BTCV.
• Rebane, M, and Andrews, J, (1994), "Farming and Wildlife - a practical management handbook", (RSPB).

Authors

• Jeremy Roberts, Agricultural and Woodland Environments Branch (AWEB)
• Vyv Wood-Gee
  Countryside Management Consultant
  Scabgill
  Braehead
  Lanark, ML118HA

Contacts for advice and information

Jeremy Roberts

Daniel Gotts
Agriculture and Woodland Environments
Branch
Research & Advisory Services Directorate
Scottish Natural Heritage
2 Anderson Place,
EDINBURGH
EH65NP
Tel: 0131-447 4784

Historic Scotland
Longmore House
Salisbury Place
EDINBURGH
EH91SH
Tel 0131 668 8777

National Monuments Record of Scotland
John Sinclair House
16 Bernard Terrace
EDINBURGH
EH8 9NX
Tel 0131 662 1456

Training

The following organisations offer training in drystane dyking:

ATB Landbase
Tel: 0131-335 3830

Scottish Conservation Projects Trust
Tel: 01786 479697
 

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