There is an interesting letter from Rob Ixer about the recumbent Trefael Stone (and other things) in the latest edition of Current Archaeology. I assume that the letter relates to the second stone found near the edge of the field. I agree that this doesn't look like spotted dolerite, and that it might be an unspotted dolerite. I'll take issue with Rob's use of this phrase: "probably a joint block taken from a Preseli dolerite outcrop....." Dodgy assumption. "Derived from" would have been a better phrase for a geologist!
The presence of elongated lumps of dolerite in the tract of country to the north of the Nevern Valley is rather intriguing. There are quite a few of them, and this led OT Jones to speculate that maybe there was at one time a glacier flowing northwards from Preseli -- he assumed that they were erratics. There are two further possibilities:
1. The dolerite orthostats are not from Preseli at all, but are glacial erratics carried from Pen Caer. That would indicate ice movement west to east -- possible but not probable.
2. The orthostats (including the one in the photo) were collected as gateposts within historical time by farmers who lived in the area. Hundreds of gateposts throughout North Pembs are made of elongated "pillars" of dolerite -- and we know from historical records that farmers used to go up into the mountains to collect them. Much more long-lasting than gateposts made of oak.......
More to be revealed, I'm sure.
THE INKA and STONEHENGE
In your recent article about the Trafael stone (CA 276), it was suggested that the (now recumbent) standing stone found close to the monument was 'probably Preseli spotted dolerite like those found at Stonehenge'. However, while careful re-examination of the photograph confirms that the rock is probably a joint block taken from a Preseli dolerite outcrop, unlike the majority of the Stonehenge dolerite orthostats, it is unspotted. Further macroscopical and new microscopical examination is required before any serious Stonehenge connection could be verified, as - despite the recent confirmation of four small spotted dolerite fragments from Silbury Hill - the dearth of authenticated spotted dolerite orthostats, or even 'debitage', within secure archaeological contexts away from Stonehenge is remarkable.
This also appears to be true for its use in pottery, as no Stonehenge dolerite (or any other bluestone) has been recognised as temper from any [Neolithic] Grooved Ware pottery. This includes pottery found at Trafael and, more significantly, at Durrington Walls and elsewhere in Wessex. What a contrast with the Inka, who used 'off-cuts' from their highest-status buildings to use as temper in Capitol Inka/ Inka Fine Ware, their finest pottery.
Dr Rob Ixer.
Current Archeology (no. 286, January 2014)