This rather splendid oblique aerial photo has just been published in Pembrokeshire Life magazine -- it was taken in 2009 by Toby Driver of the Royal Commission. It shows Carn Alw in the foreground and Carn Goedog in the distance. Because of the light snow cover there is tremendous detail in the image -- I have added a few pointers for those who do not know the area. Click to enlarge the image.
The photo shows just how extensive the outcrops of the Carn Goedog sill actually are. As I have explained in previous posts, the assumption that there is a Neolithic bluestone quarry at Carn Goedog is very dodgy indeed, and is based in turn on the assumption that the spotted dolerites ar Stonehenge have been precisely provenanced to the Carn Goedog tor. But these spotted dolerites outcrop all the way along the sill to the vicinity of Carn Alw, and I have seen nothing in the geological papers that demonstrates that any of the spotted dolerite monoliths actually come from the tor rather than from outcrops further to the east or indeed towards the west. The sampling point density is just not great enough for any definitive conclusions to be drawn. The geologists (Richard Bevins and Rob Ixer) sampled the tor because it is a prominent feature and therefore "attracts" the sampling process.
Confirmation bias yet again? I'm not sure I would put it as strongly as that, since I suppose many of the geological samples were taken years ago, long before Neolithic quarries were being thought of in this area. But you must always be careful in this work not to attach "artificial significance" to places simply because they happen to be the places you have sampled........