bluestones: preseli – stonehenge


a team of scientists and researcher from ucl, university of manchester, bournemouth university, university of southampton, university of leicester, amgueddfa cymru – national museum wales, and dyfed archaeological trust. have excavatied two quarries in wales by a thought to be the sources of stonehenge’s ‘bluestones’. – and this may eventually shed light on how they were quarried and transported to the original henge before the large sarsens were incorporated and the bluestones move for the second time to there present position,
geologists have known since the 1920s that the bluestones were brought to stonehenge from somewhere in the preseli hills, but these excavations have now located the actual quarries and outcrops from which they came.
the stonehenge bluestones are of volcanic and igneous rocks, the most common of which are called dolerite and rhyolite. the outcrops have been identified with carn goedog as the main source of stonehenge’s ‘spotted dolerite’ bluestones and the outcrop of craig rhos-y-felin now identified as a source for one of the ‘rhyolite’ bluestones.
the special formation of the rock, which forms natural pillars at these outcrops, allowed the prehistoric quarry-workers to detach each megalith using wooded wedges, with a minimum of effort. the wooden wedges would be placed into the cracks between the pillars and the rain would swell the wood and thereby ease each pillar from the rock face  they would then be lowered onto platforms of earth and stone, from where the 2 tonne stones could be moved away along trackways. it could well be the outcrops had special significance for prehistoric people.
radiocarbon-dating of burnt hazelnuts and charcoal from the quarry-workers’ camp fires reveals that there were several occurrences of megalith-quarrying at these outcrops. both of the quarries in preseli were exploited in the neolithic, between 4,000 to 5,000 years ago, and craig rhos-y-felin was again quarried in the bronze age, around 4,000 years ago. dates of around 3400 bc for craig rhos-y-felin and 3200 bc for carn goedog, although they were not to arrive at stonehenge. it is now conjectured that the stones were first used in a local monument, somewhere near the quarries, and then dismantled and moved off to wiltshire. if this is true, the ruins of any dismantled monument are most likely to lie somewhere between the two megalith quarries.  geophysical surveys and trial excavations have been conducted to test this theory.  aerial photographic analysis has also been made throughout the area and the most likely sites identified.
the megalith quarries are on the north side of the preseli hills, and this location undermines previous theories which suggest the stones were taken southwards from the hills to milford haven to be floated on boats or rafts. but the  more likely route would have been northward, then either by sea around st david’s head or eastwards overland through the valleys along what is now the a40, using  teams of people or oxen. elsewhere in asia and india single stones of this size, have been carried on wooden lattices by groups of around 60 people.
as to what monument(s) that might have been dismantled to provide the megaliths for stonehenge, quoting the end of the ‘antiquity ’article: ‘such an act could have served to merge two sacred centres into one, to unify two politically separate regions, or to legitimise the ancestral identity of migrants moving from one region to another. future research into neolithic monuments within north pembrokeshire may shed light on these possibilities.’ given this is now a monument and not a stone circle as first suggested, one on the prime candidates might be bedd yr afanc, not far from brynberiana. it is most unusual burial chamber organised as a long, low gallery chamber and having similarities with neolithic burial chambers in ireland dating from about 2500 bc. there is no other burial chamber like it anywhere else in wales. it is shaped like a wedge, but along the centre is a double row of standing stones about 35 feet long, and sits midway between the two quarries.
further excavations are planned for 2016.
sources: university college london/ antiquity