A dry stone wall is built from stone alone, with no mortar of any kind. It stands because of the weight of the stone, the friction between the pieces, and the way each one is placed. There are around 125,000 miles of them in Britain.
How they are built
The structure is more sophisticated than it looks. A proper wall is two walls leaning slightly into each other, with the gap between filled with small stone:
- Foundation stones — the largest, set into a shallow trench.
- Two faces, built up in courses, each stone laid with its length running into the wall rather than along it, so its weight ties the structure together.
- Hearting — small stone packed into the middle. Not rubble thrown in; carefully placed, and the part most often done badly.
- Through stones — long stones spanning the full width at intervals, tying the two faces together. Often visible sticking out.
- Copestones — the top course, set vertically, locking everything below and shedding rain.
The wall is built with a batter — narrower at the top than the base — so that settlement tightens it rather than loosening it. A well-built wall can stand for a century or more and will flex with frost and ground movement in a way a mortared wall cannot.
Why there are so many
Two reasons, and they combine.
First, clearing the fields. Upland soil is full of stone, and it had to go somewhere. Building it into a boundary solved two problems at once.
Second, and decisively, the enclosure of common land through the eighteenth and nineteenth centuries. Parliamentary enclosure acts divided open fields and commons into private holdings, and each new holding needed a boundary. Enormous mileages of wall were built in a few decades by gangs of professional wallers working to specification — which is why the Pennine and Dales walls run so straight and so implausibly far up the hillsides.
The regional styles
The stone dictates the look, and a practised eye can place a wall from a photograph:
- Yorkshire Dales — grey limestone, neat courses, and the densest network in Britain.
- Lake District — slate and volcanic stone, often with distinctive vertical coping.
- Cotswolds — honey-coloured limestone, low and often thin.
- Cornwall — the “Cornish hedge”, stone faces with an earth core, planted on top and flowering in spring.
- Scotland and Wales — granite and slate, rougher and more irregular.
The craft now
Dry stone walling is a living trade with a formal structure. The Dry Stone Walling Association runs a certification scheme from Initial through to Master Craftsman, and there are competitive walling matches at agricultural shows judged on speed and quality.
The economics are hard. Rebuilding a collapsed wall costs far more than putting up a fence, and much of what survives does so through conservation grants, national park schemes and volunteer working parties. A great deal of British wall is now in poor repair for exactly that reason.
Wildlife
The gaps matter. Dry stone walls are full of cavities, and they shelter wrens, wheatears, stoats, weasels, lizards, hibernating amphibians and enormous quantities of invertebrates, along with mosses, lichens and ferns. A mortared wall is a dead structure; a dry one is a habitat, and its ecological value is a substantial part of the case for maintaining it.