The content below was copied with the generous permission of the author Sean Adcock.
This Master Class article originally appeared in the Autumn 2009 issue of Stonechat, produced by the North Wales Branch of the Dry Stone Walling Association of Great Brittan. This entire issue of Stonechat, and many more, are available at http://www.dswales.org.uk/Stonechat.html
Thank you to Sean for allowing us to provide this content, and please donate to The North Wales Branch.
The end is nigh, but first…
Plumbing the depths
I’ve had a query about “plumb” vis-à-vis “running” joints – someone must actually read these articles. For many the terms plumb and running are interchangeable. However to my mind there is a distinction which I have applied within these articles. Given that a running joint is any set of aligned joints vertically, diagonally or staggered then there is merit in referring to that set which are aligned vertically as a “plumb” joint. I however would take the distinction further. Two or three stone joints are far more common than long ‘running’ joints, a two stone joint can hardly be referred to as ‘running’ and three stones are hardly breaking into a jog. A whole world of possibilities has just sprung to mind; maybe a two stone joint should be a sprint; a joint stretching from footing to cope – a marathon; might a diagonal joint be a relay. Sorry I digress, it must be the after effects of the shock, or even euphoria, from getting a query. Not only are two stone joints more common as I mentioned last time in some patterns they are an integral component, but ‘(vertical) two stone joint’ is an unwieldy phrase ‘plumb joint’ says it all and rolls off the tongue (and onto the page) better. I rest my case.
Meanwhile there is also an addendum to the rebating of stones to fit around others. This might all be very well where the rebates are relatively small compared to the stone the rebate is in. If you rebate thinner stones then there is a danger that any movement will create pressure points, and all you are doing is replicating the problems that you would have with using a “shim” as discussed last time…
There is an order to all things
In part 1 I introduced a number of patterns of random wall, in part 2 I outlined a technique used for random wall which with subtle variations leads to these patterns. Just to remind you…
Broken down to its absolute basics, random walling is just about employing snecks and jumpers with a bit of coursing; although it may well be that the coursing is in effect just levelling two adjacent stones, and no more.
How you put these together creates the pattern – from very random or random rubble through to much more formalised coursed random as we saw in Stonechat 17. Stone shape/type obviously plays a part but in this respect it is primarily because this determines how you implement the putting together bit.
Now I will introduce a couple more random patterns and look at how all these basic patterns can themselves be subtly varied in association with different stone type/shape, to produce a cornucopia of styles. Hopefully following on from parts 1 and 2 it will now be clear how to simply describe a wall as simply being random is perhaps to do it an injustice. More likely I shall just muddy the waters further.
Simple Random and revisiting Random Rubble
Having suggested in part 1 that the default for random walls is random rubble, which in dry stone walling terms is generally particularly irregular stone. However regular stone can be used to form a very irregular random pattern as in this example, from Low Bradley, near Skipton, North Yorkshire At around 5 feet high including covers and copes, most of the building stones are under 2″ thick. Normally thin flat stone would be associated with coursed walling
The wall shown at the top of the next page could be classified as ‘random rubble’ since strictly speaking rubble really only means not dressed. However wallers tend to apply ‘rubble’ to more angular stone and hence a distinction can be made between ‘random rubble’ and ‘simple’ random or just ‘random’ if no other pattern can be readily distinguished. At a basic level simple random and random rubble are essentially the same.
Joints are frequent in this style of wall although they can be avoided with care. Where this is achieved it tends towards a slightly less random face, mistaken by many for coursed walling. However the walls are not coursed as many of the adjacent stones are of differing heights, this is more obvious where larger and less regular stone is used. A wall where many of the stones are around 6″ (15 cm) high with adjacent stones around an inch (25 mm) lower looks obviously random, where the stones are only around 1 ½” (38 mm) thick a difference in height between stones of only (6 mm) is proportionately the same, although nowhere near as obvious. Hence the wall is only well structured, rather than coursed. The more regular the stone, the finer becomes the distinction.
In dry stone walling it tends to be found where the stonework is levelled along the length of the wall prior to the installation of through-stones although many wallers shy away from it as a method unless the levelling stones are quite thick as it can lead to bands of thin stone within the face of the wall. It can also be found in some areas with ‘slabby’ flat sandstones. Here every time you need to get a longer stone or slab on you have to level off, hence it can be expedient to level off a section to facilitate the placing of several of these stones. The whole problem of tracing a number of long stones next to each other is of course another kettle of fish which has been dealt with elsewhere. (Stonechat 11)
Most well structured random walls are to some extent “random brought to courses”. True random brought to courses walls are brought to a level on two, three, or more occasions (depending on their height and stone size) as they are built up.
P.McAfee (“Irish Stone Walls”. The O’Brien Press, Dublin 1977.) provides a useful stylised diagram.
In practice dry stone duplication of this pattern is rare, it is more common in masonry walls, a noted example being the 7 mile Penrhyn Castle Park Wall (shown below).
More normal practice is a rough levelling of the wall without using small stone in the smaller dips, instead placing a larger stone on them in effect breaking the coursing.
The end result can produce a well structured random face, which under close examination reveals some lines of levelling off. This is similar to breaking coursing on slopes as mentioned in part 2, and hence one reason why that specific practice is a good illustration of this principle.
Other patterns
There are several masonry terms I have not yet introduced, partly because they tend to be used by some rather than most writers. For example JM Nickey (“The Stoneworkers Bible” TAB Books, Pennsylvania, 1979) refers to snecked rubble, which in dry stone walling terms could be seen to make some degree of sense although following my analysis in part 2 its likely to apply to most ‘random’ walls. Another pattern Nickey uses is snecked coursing – at first this appears slightly oxymoronic although think about it and it does make some sense within coursed random work,
Another masonry term “squared random rubble uncoursed”, is a bit of a mouthful. We are in danger of stringing all sorts of terms together to come up with descriptions, However within masonry it of course makes perfect sense – squared in masonry means slightly worked with a hammer, random rubble is rough stone, un-coursed is random so applied to dry stone work it just means a random wall built of fairly regular stone. However within masonry the pattern itself has lots of snecks and soldiers, jumpers and even upright jumpers, which if duplicated in dry walling would be frowned upon as inappropriate. An issue we shall briefly return to.
Using and combining these masonry terms allows us to better describe random walls, and maybe we could go even further and come up with our own new definitions. Could Derbyshire Limestone walls be dubbed “extravagantly random snecked”?
Stonechat 15 dealt with polygonal walls in some detail. It is of course a random pattern in its own right, but I daresay if we lived in an area where polygonal walls predominated we’d be identifying more patterns as in the very least stone type would influence the exact pattern. Food for thought, and some questions for Miguel Ramis. Watch this space.
Anyway just as a reminder of polygonal, here are a couple of photos from Mallorca (right and top of next page).
As noted in Stonechat15 polygonal is not a type of wall readily/frequently identified in this country. However many ‘very’ random walls of irregular shaped stone verge on it. The key is to whether or not the stones are generally set with the long axis of their set to the horizontal.
The stonework at Winskill farm near Settle, North Yorkshire verges on the polygonal (see below). Frequently such stonework would just be put down to poor workmanship however it is thought to be over 200 years old and whilst its longevity is at least partly due to ground conditions (very hard/thin soil), it cannot be dismissed out of hand. To simply refer to it and the Low Bradley wall as “random” hardly tells the story, does it really differ significantly from the wall at Sa Colabra?
To finish off I’d like to look at a number of Lake district walls which whilst different patterns, are subtly similar in many ways. Hopefully they will serve to illustrate how just a few changes (whilst still using same basic constructional approach) lead to a variety of similar patterns with the first markedly different to the last.
If we start this sequence at Grange in Borrowdale, Cumbria, with a formal cobble and slate garden wall, verging on the coursed.
Moving out of the village towards Rosthwaite the walls become slightly less formal.
Beyond Rossthwaite and more into the countryside less slates and somehow more random, into Buttermere more or less the same mix of stone but more random.
The wall at the top of the next page from further south in Eskdale and much further north in Munngrisdale. Neither has slates, the eskdale wall is is somewhat more regular, than Buttermere but still a random structure. Mungrisdale has a very different stone type, and far more regular build. Yet quite similar to both Eskdale and especially the first Rosthwaite wall when you analyse its structure.
Getting closer to home we can see how different stone can produce in some way similar results to a couple of the Lakeland examples.
The wall on the left is from the Ffestiniog railway, near Rhiw Goch. Many of the walls to the east of Penrhyndeudraeth, in and around Coed Cae Fali replicate this pattern, which in its own way isn’t a million miles away in terms of pattern to those around Grange. Then there’s this wall from near Llanwrtyd in Powys whilst it differs from the slate cobble walls it should be possible to see that it is only a step or two away given style and structure from those around Grange, and how any one of the walls is in reality only a small step away from any other, even though at first sight they might look quite dissimilar.
–Sean Adcock