Prehistoric cairns in the Welsh mountains

I first became interested in prehistoric cairns during the expedition phase of my Mountain Leader (Summer) training at Plas y Brenin which was spent on the Carneddau (appropriately enough) in Snowdonia. Prehistoric cairns are stone-built burial mounds which can vary considerably in size and generally date from the Bronze Age.  On Ordnance Survey maps, they are denoted by the legend Cairn.  On the Carneddau, I was impressed at both the size of the cairns, particularly Carnedd Fach, and their locations.  It probably helped that, although chilly (after all, it was only the end of June), the pellucid quality of light on the evening of one of the longest days of the year was breathtaking and we could clearly see Snaefell on the Isle of Man from the summit of Carnedd Lleywelyn. Sadly, I had no camera with me. As we made our way across the Carneddau summits so very late at night that it was almost dawn, I could see why the builders of these massive monuments had built them where they did.  What struck me, however, as someone used to the round barrows of southern England, was how unusual the positioning of these cairns was.

The interpretation of barrows in the landscape is dominated by Dave Field’s (1998) excellent analysis of the siting of round barrows in South East and Central Southern England.  He noted that barrows tended to be clustered together, often on ridges overlooking river valleys and that individual barrows were false crested, in other words, situated close to, but not on, the highest point of a ridge.

Early Bronze Age round barrows near the Sanctuary, Avebury, Wilts.

Early Bronze Age round barrows near the Sanctuary, Avebury, Wilts.

He also claims that round barrows are located on marginal land.  I would dispute the reasons Field posits for this distribution: there is no evidence of a concept of territoriality in the Early Bronze Age and I’m not at all certain sufficient land was cultivated to facilitate the formation of ideas of marginality (ibid, 316-7).  However, the kernel of the paper remains a very useful tool for understanding the distribution of round barrows in southern Britain.

My observations of the Carneddau examples and other cairns in Snowdonia suggested that their location was very different to their southern earthern counterparts. In North Wales, a significant number of cairns were sited on summits  and cairns tended to be solitary structures set well apart from each other.  Further observation and map work in the Brecon Beacons in South Wales confirmed my initial impression, the location of some cairns was markedly different, in many cases, to that of earthern round barrows.  In order to understand the landscape setting of cairns, I needed to do some fieldwork.

A sunny day in September

The first field investigation took place in September 2012 in the company of Mike McQueen.  The location was the eastern end of the Mynydd Du, the massive limestone scarp situated at the western end of the Brecon Beacons.  The day was beautifully sunny, but on top the wind was cutting and we both walked with belay jackets on, such was the wind chill for that time of year.  We investigated five cairns located on Fan Brycheiniog, Fan Foel, Picws Du  on a circuit  walk from Glyntawe, north along the Beacons Way to Llyn y fan and then up and over the scarp to Bannau Sir Gaer and on to  before turning south and making our way over Cefn Mawr back to Glyntawe, a circuit of some 22 kilometres and 1500 metres climbed.

Fan Brycheiniog

The first cairn at Fan Brycheiniog, is located just below the 800mOD contour on a spur jutting out north and eastwards from the main scarp ridge.  According to the map, it lies in a false-crested position with the summit of the hill (802mOD)lying a few metres to the south-west.

Note the raised platform at the base of the cairn


On the ground, the cairn has every appearance on being the highest point on the ridge.  It has extensive views in all directions but the viewshed to the west, north and east are particularly good.

As can be seen from the photos, the modern cairn sits on a raised platform which is eroding on its south-western side and seems to be composed of large stones.  Without excavation, it is difficult to be definitive, but the platform would appear to be a circular stone feature constructed to emphasis the size and position of the cairn.

The cairn visually dominates its surroundings, especially the low-lying moor north of the scarp slope and the platform reinforces the impression of size and solidity.

Fan Foel

Located at the approximate centre of a broad, flat summitted spur some 150m wide, this cairn is situated just below the 780mOD contour. Like FanBrycheiniog, the map suggests that the Fan Foel cairn is false-crested with the summit of the spur lying to the south-west of the monument but it is not evident on the ground.

Again, the cairn appears to incorporate a platform raising it above the surrounding ground level. This cairn was excavated on behalf of Cadw and the Brecon Beacons National Park by Cambria Archaeology in June 2004 (link) because of erosion.  Evidence of a stone kerb and a cremation burial in a central stone cist were uncovered, along with a number of artefacts dating from the Early Bronze Age.

Note the torn fabric “protecting” the excavated cairn


I’m not sure that the cairn was done any favours by the excavation as the site is currently open to the elements and the protective material laid down over the archaeological features is exposed and weathering.    Despite being located on a very prominent spur whose steep sides project into the surrounding moorland, the cairn has a relatively restricted viewshed to the lower ground to the west, north and east and down the valley of the Afon Twrch running across the Mynydd Du in a south-westerly course because it is placed towards the centre of a broad, flat spur.


Picws Du

This cairn, located at the top of a long, steep climb from the valley of Nentydd Blaen-Twrch, proves a popular stopping point for hikers and when we arrived there a large group from London were enjoying a break, sitting on the cairn.

Situated at the very end of this slight spur, Picws Du cairn has an elevation of 749mOD and dominates its immediate surroundings on the southern dip slope.  Again, the cairn has a broad, raised platform but is not false crested.  It occupies the highest point of the hill, perched on the very edge of the scarp slope with extensive views to both north and south but little visibility to east or west.  The steepness of the dip slope dropping away to the south of the cairn would make this monument a very obvious landmark when viewed from the southern Mynydd Du.

Carnau’r Garreg Las

We then set off eastwards across the summit of Bannau Sir Gaer, and loped downslope through deep heather to the watershed between Afon Mihartech and Twrch Fechan before climbing the northern end of Garreg Las to investigate the pair of cairns on the boulder-strewn summit.

Garreg las south small

Both cairns are massive, composed of boulders from the rocky summit of the ridge and very different from the cairns we had looked at before.  The stone is very pale, almost white and it glitters in the sunlight with the amount of quartz in it; the cairns are certainly eye-catching.  Both are located on the on the summit plateau and the northernmost cairn is the highest point on Garreg Las.

The cairns have been hollowed out to an extent from the top, in order to create walker’s shelters.  They both enjoy extensive viewsheds to the north and west  but views are very limited to the south and east.

The southernmost cairn may have structures associated with it but it was very difficult to tell what was natural and man-made.

After taking some photos, we turned east and made our way down to the Twrch Fechan, past Pwll Cynrig (Pool of the King?) and across to the ford below Brest Twrch and the path back towards Glyntawe and well earned fish and chips in Brecon.