On the southern slope of Cefnen Wen in North Wales are two scheduled multiple stone rows. There are no other similar rows in the whole of Wales and indeed the nearest comparative examples are a row at Corringdon Ball, South on Dartmoor and several even further away in Caithness and Sutherland in the far north of Scotland. This anamalous situation has previously been commented upon, but now it would appear that there is an explanation. The two rows are Hafod y Garreg and Hafod y Dre. Both have traditionally been accepted as prehistoric multiple stone rows, but a particularly clear aerial photograph available on Bing Maps highlights that everything is not as it seems.
Aerial photograph of Hafod y Garreg (Source: Bing Maps).
Viewed from above, the lines of stones identified as stone rows look like patterned ground formed by periglacial activity. A mixture of stripes (ie. lines of stones) and circles are characteristic of land forms produced under periglacial conditions and the examples visible at Hafod y Garreg are typical. This explanation fits the evidence much better than the idea that this represents a multiple stone row. Excavation would rapidly confirm or refute this interpretation. The identification of a pair of multiple stone rows in this part of Wales has always been seen as an extraordinary anomaly and this aerial photograph provides an alternative and more plausible explanation.