The four surviving stones at Waun Mawn are of unspotted dolerite, and possibly derive fromoutcrops 3km to the south-east at Cerrigmarchogion on the Preseli ridge (Bevinset al.2014).

As some of these samples could alsohave been either residual or intrusive, we propose that the stone circle was erected inc. 3600–3000 cal BC.This date would place Waun Mawn amongst the earliest stone circles in Britain, alongsideLong Meg and her Daughters in Cumbria (109m diameter) and the stone circle beneath thepassage tomb of Bryn Celli Ddu on Anglesey (18m diameter).

Firstly, an entire tribe moving from Wales to the Salisbury Plain took their encyclopaedia with them. This would require the circle to be erected in the same order as in Wales and oriented in the same direction. In effect, these people were taking their database of knowledge with them, the structure in the stones, and the data in their memories. Secondly, a different tribe conquering those in Wales might identify just how effective this memory technique is and steal only the technology. Essentially, they stole the database structure and filled it with their own data. The bluestones are particularly suited to a mnemonic purpose due to the blotches and blobs in their material makeup.