The age of a dry stone wall is taken to be from the date of its original building, disregarding repairs and reconstructions which have not changed the basic design. A wall may therefore be very ancient, even if all its stones have just recently been repositioned.
By understanding a wall’s geological make-up and design it’s possible to make an intelligent guess as to its history, and the part it has played in the agricultural life of the locality. However, putting a date on its construction is not easy, except where documents such as the Enclosure awards give precise details.
A combined approach of documentation plus observation is essential in the historical study of walls. A few Saxon land charters, such as Grundy, are of assistance in wall dating. Other than these, the oldest documents referring to walls are medieval monastic cartularies. These occasionally note boundary disputes which resulted in the erection of some sort of barrier, although the type of fence is seldom specified. According to Rollinson (1972), the Rydale fence of 1277 is one of the earliest documented, but it was probably a ditch and bank rather than a dry stone wall.
Similarly, the Furness Abbey enclosures of the late 13th century in the Esk Valley headland consisted of a bank, probably topped by a wattle fence, since the aim was to restrict the movement of sheep, but not of deer and fawns. The bank in this case can still be traced and it provides a convenient causeway for walkers through this boggy area. Some of the early Pennine enclosures can be located from other monastic records of about the same period. Later documents include a number of important 16th century maps, more recent estate deeds and maps, tithe maps from the 1840s, Parliamentary enclosure surveys and awards and the first Ordnance Survey maps. The 18th and 19th century maps are especially valuable, not only because in many cases they are accurate enough to pinpoint existing walls, but also because they sometimes mark out what were then considered ‘ancient enclosures’ which are probably of Elizabethan date or earlier (Rollinson, 1962).
Walls which can be dated and tracked down from the written evidence may reveal general characteristics of the walls of their period. Such ‘type’ walls can then be used to evaluate others for which no documents exist.
Although written documents are essential to decide exactly when the different phases of enclosure took place in any given area, the relative age of walls within a district can often be assessed purely from the shape and pattern of the walls themselves. There are a few generalisations which can be made, as follows.
In the ‘Celtic fringe’ of western Britain and Ireland the oldest walls are likely to be clearance walls forming small fields around farmsteads. In areas where the Anglo-Danish open-field system predominated, the oldest walls are those which separate the wet meadows from the common fields, and the common fields from the original wasteland. A continuous wall, unbroken except for gates, is older than all the walls which come to a head against it.
The oldest walls usually use unsorted clearance boulders, sometimes including very large ones. There is little distinct coursing and no throughs or topstones. These walls are more pyramidal in section and in general thicker than later walls built of the same type of stone.
The oldest walls are haphazardly aligned and often change direction to take in large boulders or to avoid streams or other obstacles. Sections between obstacles tend to be curved, not straight. Old walls may have rounded or enlarged corners, like swollen joints, indicating accretion from field clearance over many years. Some ‘consumption dykes’ though were built to order during the Enclosure Era.
Walls closer to a village or farmstead, or to habitation sites which are now abandoned, are likely to be older than walls farther away from the habitation. An exception are the few medieval boundary walls built by monasteries to restrict the movement of sheep, and these, unless they have been rebuilt, are likely to stand out from later enclosure walls by their much cruder style.
Walls built to strict specifications, unvarying over long distances and showing a consistency of style and craftsmanship, were probably built after 1750 as a result of a Parliamentary Enclosure Act. Throughstones were not used in walls until the 18th century. Slate throughs were not used in Yorkshire until the 19th century. Dressed stone was used in dry stone walls by the Romans, but then not again until the 17th century.
Occasionally the shape of the field bounded by a wall may reveal its relative age. Medieval ‘reversed S’ field strips are thought invariably to predate the year 1400. Walls dividing such fields were clearly constructed at some later date. Examples from the 16th century can be seen between Grassington and Hebden in upper Wharfedale.
Sometimes the material of which the wall is built may be correlated with datable industrial, quarrying or mining activity. For example, the slate fences of North Wales are associated with 19th century mining. Railway ties used as cripple holes suggest that a wall was built since the coming of the railway to a particular area.
Occasionally, objects found within a wall may indicate a date by which it had been built. The bowls of broken clay pipes are found fairly frequently, and these can usually be dated with some exactitude.
Wall dating is most productive when it combines a detailed field knowledge with documentary research of the local historian. Raistrick (1966) has done this brilliantly for the village of Linton in Wharfedale. Volunteers making detailed notes of finds made during repair work may help provide new information for interpretation by local experts.