Cairns come in a variety of shapes and sizes, from simple piles of stones through to formal pillars and spheres. Cairns have been used for centuries to mark hilltops, mountain passes and routes across rocky terrain. They are also used to mark significant sites such as burials, battle grounds and memorials.
This cairn, near Askrigg in the Yorkshire Dales, is typical of those marking paths across mountain and moorland. Whilst roughly built, it is more than just a heap of stone, and some care has been taken to produce a symmetrical structure. The top 14″ (360mm) or so is made of stones roughly piled on a layer of flat slabs, indicating that the original cairn has possibly been added to by passers-by. The cairning of paths across open country is controversial. Some walkers view them as helpful path finders, especially in misty conditions, whilst others see them as marring a wild and unspoilt landscape. Cairns can also become a focus for erosion.
Cairns used to mount viewpoint indicators, plaques or memorials need to be more carefully constructed, as in the example right. This is probably the easiest formal shape to construct.
Construction
Dimensions
A scale drawing or plan is essential for most cairns. While dimensions of less formal cairns don’t need to be exact, the general dimensions of base and height still need consideration. If the base is too small, you will end up with a needle rather than a cairn. If the base is too wide for the height, to quote one waller, ‘it will look like a giant cow-pat’.
Materials
The style of cairn and the neatness of the stonework depends on the type of stone available, as well as on the skill of the builder. More formal and technically complex cairns tend to be built out of level-bedded stone such as some sandstones or slates. Rougher stone is more suited to larger diameter and less complex cairns. The larger the cairn, the greater the scope for disposing of poorer stone, as the hearting space can be enormous.
Estimating the materials required can be complicated, and it’s always best to over estimate so that you have plenty of choice. For tapering pillars, bell-shaped and conical cairns, get at least enough stone to build a solid cylinder of the same height and base size. For shapes such as pine cones, estimate by using the diameter at the widest point, rather than the base, and expect to have quite a bit left over.
Batter
While most cairns are circular in cross section, their profiles can vary from conical to bell-shaped and other shapes.
If the batter is constant, as in the lower section of the cairn below, line-bars can be erected in a tepee-like structure. However, apart from the difficulty of setting the bars precisely to the right angle, the number of bars required means they get in the way of building, particularly as you gain height. Sooner rather than later you will find you have to remove the bars, and work by eye.
For shapes without a constant batter, you can either work entirely by eye, or rig up a central post with a washer and string. For each layer, fix a peg or some moveable marker on the string, to mark the appropriate radius for the height.
When building by eye you must keep standing back and checking the shape at frequent intervals, and from various angles. Even then smaller bulges and ‘flat spots’ tend to become obvious only after they have developed for two or three layers. Frequent dismantling and reconstruction of parts of the face may be necessary. Whilst perfect symmetry is difficult to achieve, and not appropriate for an informal cairn, it should be borne in mind that structural integrity is closely related to symmetry.
Topping
The problems associated with topping cairns are similar to those of pillars.
The smaller the top diameter of the cairn, the less stable the top layers and top stone are likely to be. The simplest method of topping is to use a suitably shaped flat stone, which ties all the face stones together. This can either be left to give a flat top, or topped with a few more stones to improve appearance, as in the Brora example above.
If the cairn tapers to a point, building becomes increasingly difficult and stone size necessarily decreases. A suitable conical capstone to finish may need to be specially cut. One option is to create the point with a series of flat circular stones, gradually decreasing in size, as in the pine cone cairn below. If you are skilled, patient and have an ample supply of stone, you may be able to dress them yourself.
Cairns under about 8′ (2.4m) total height, where the top can easily be displaced, may need to have the upper layers and topstone mortared or glued to secure.
Plaques
Commemorative cairns frequently have plaques built in or attached. For the former, build alongside and over the plaque as if it were bedrock. Ensure there is good stone length into the wall around the plaque, especially on top, so that it is tied in well. The stones behind the plaque should be properly placed building stone, and not just hearting, so that the plaque itself is not an essential part of the structure.
Plaques can be attached by drilling into suitable face stones, and setting the fixings into epoxy glue.
Conical cairns
Conical cairns are those with a constant batter, either ending in a point, or ‘cut off’ and topped with a slab.
Normally line bars are used to give accurate dimensions. In the example below, another method was used, taking advantage of the trig. point which the cairn was being built to disguise. A pipe flange was attached to the trig point, with a rotating arm of angle iron set level with an adjusting screw, which also served to counteract the weight of the line bar. Care was taken to set the first layers at a true circle, and then the bar was rested against the stone, and rotated as necessary around the cairn. To avoid spiralling, the level of each course was chalked onto the line bar.
The face stones were secured into a core of mortar, as the cairn is of climbable height. The cairn incorporates an information board.
Pine cone cairns and spheres
This limestone pine cone cairn is one of a series built by the sculptor Andy Goldsworthy in Nice, France. The base requires long, wedge-shaped slabs, with each layer projecting a little further, or ‘corbelled’, to the widest point of the cone. The top is finished by a series of concentric circular slabs.
Spherical cairns are built in a similar way to pine cone cairns, using thin layered stone, corbelled out from the base.
Spheres and pine cone shapes can also be constructed hollow. These, at Portrack House, Dumfries and Galloway, are mortared inside and used for storage.
Domes
The dome cairn below is to be found near the A82, about 4 miles east of the National Trust for Scotland Visitor Centre at Glen Coe.
The dome has a diameter of about 17′ (5.25m), with a maximum height of about 12’6″ (3.8m). It was rebuilt in the early 1990s, to replace an earlier cairn to which various stories are attached. One story is that it was originally a much smaller ‘coffin cairn’, used to rest a coffin on its way to wolf-proof consecrated ground, which could involve a long journey in earlier centuries when wolves were numerous.
There are three similarly shaped but smaller dome cairns on the A623 between Wardlow and Stoney Middleton in Derbyshire, of which the largest is about 8′ (2.4m) tall and 13′ (4m) across.
