Cerrig Marchogion on Mynydd Preseli

The rock outcrops on the Preseli ridge referred to as Cerrig Marchogion (the rocks of the knights) are difficult to photograph, but this free picture has just been posted on the Pembs CC web site as part of the "Year of Legends" campaign. I think it was posted in connection with the legends of King Arthur and the existence of the "Golden Road" trading route -- but these little crags (hardly any of them are more than 3m high) are of more interest to readers of this blog as possible sources for the spotted dolerites at Stonehenge.  Ixer and Bevins say that their preferred source is Carngoedog, but they say that the spotted dolerites here are geochemically and petrographically very similar, and they probably belong to the same sill or volcanic outcrop. Of course, chunks of this rock could have been entrained by over-riding ice from both locations.

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