Archaeologists carrying out an excavation at Stonehenge say they have broken through to a layer that may finally explain why the site was built. The team has reached sockets that once held bluestones - smaller stones, most now missing or uprooted, which formed the site's original structure, built more than 4,500 years ago and then altered over centuries. The researchers believe that the bluestones could reveal that Stonehenge was once a place of healing. The team now needs to extract organic material from these holes to date when the stones first arrived.
     Professor Tim Darvill, of Bournemouth University, who is leading the work with Professor Geoff Wainwright, president of the Society of Antiquaries, said: "The first week has gone really well. We have broken through to these key features. It is a slow process but at the moment everything is going exactly to plan." The two-week excavation is being funded by the BBC and filmed for a special Timewatch programme to be broadcast in the autumn. Special permission had to be obtained from English Heritage, guardian of the stones, and the government for the first excavation since 1964. The digging, extending a trench first opened in the 1920s, will last a fortnight, though post-excavation work will take months if not years.
     Professors Darvill and Wainwright say that finding out more about the history of the bluestones could be key to solving the mystery of why the 4,500-year-old landmark was erected.
They believe that the bluestones, which were transported 250km (150 miles) from the Preseli Hills in Wales to the Salisbury Plain in Wiltshire, were brought to the site because the ancient people believed they had healing properties. Professor Geoffrey Wainwright said the site could have been a 'Neolithic Lourdes'. They believe that many bodies excavated from hundreds of later burial mounds in the surrounding landscape, including the 'Amesbury Archer' found six years ago, show serious health problems such as contorted limbs or spines, supporting their theory. In Wales, Wainwright said, people were still seeking cures at the springs near the bluestone quarry late into the last century. Stonehenge attracted sufferers who chipped fragments of the bluestones as healing charms right into the 19th century.
     Wainwright and Darvill believe the bluestones were dragged across land and carried by boat, and reject the rival theory that glaciers left them scattered across Salisbury plain. "It is the bluestones which are the key," Wainwright said. "They were retained at every stage of the structural life of the monument, around 1,500 years. The sarsens are fantastic things in their own right," Darvill said, "but essentially they're just scenery, a backdrop for the bluestones." The giant sarsen trilithons, which came from about 20km (12 miles) away, were thought to have arrived much later. The original setting for the Double Bluestone Circle, the first stone circle that was erected at Stonehenge, is no longer visible. The bluestones seen by visitors today are later re-erections.
     Archaeologists tried to date the first bluestones circle in the 1990s and estimated that it was put up at around 2,550BC; but a more precise dating has not been possible. Principally, this is because materials removed in earlier excavations were poorly recorded and cannot be attributed with any certainty to specific features and deposits. The 3.5m by 2.5m trench that is being excavated in the new effort will aim to retrieve fragments of the original bluestone pillars that can be properly dated.
     As well as reaching the bluestone sockets, the archaeologists have also unearthed a whole host of other finds as they have peeled back the layers of the 2.5m-by-3.5m (8.2ft-by-11.5ft) trench. These include a beaker pottery fragment, Roman ceramics and ancient stone hammers. If the excavation bears out Wainwright and Darvill's ideas, it would blow out of the water the rival theory of their colleague, the equally distinguished archaeologist Mike Parker Pearson, who after excavating at nearby Woodhenge is convinced his site was a henge for the living, and Stonehenge the abandoned realm of the dead. "A very elegant theory," Wainwright sniffed, "lacking only the quality of a shred of supporting evidence."
     Dr Simon Thurley, chief executive of English Heritage, commented: "Very occasionally, we have the opportunity to find out something new archeologically - we are at that moment now. "We believe that this dig has a chance of genuinely unlocking part of the mystery of Stonehenge."

Sources: BBC News (31 March 2008), The Guardian (1 April 2008), BBC News (9 April 2008)