Deep in the dark heart of a passage grave on Anglesey (Wales), archaeologists have discovered a decorated slab carved 4,500 years ago for the dead and their guardians, missed when the tomb was originally excavated over half a century ago. The newly revealed carving at Barclodiad y Gawres, a chevron design pecked into the rock with a stone chisel, brings to six the number of decorated slabs with lozenges, cupmarks, concentric circles and spirals in a tomb already regarded as one of the most spectacularly decorated prehistoric burial monuments in Britain. In February 2006 a team from the University of Bristol organised by Archaeology Safaris, recorded the stone using a variety of techniques including digital photography and tracing on acetate. The results from this fieldwork acknowledged the initial discovery in 2001 by amateur archaeologists Maggie and Keith Davidson. The carving is much fainter than on the other slabs, and was missed when the tomb was first excavated in the early 1950s.
     The pecked lines on the newly discovered decorated stone are not as clearly defined as those on other stones, and are arranged to form a series of geometric patterns. The fine pecking technique has helped to conceal them until very recently. Following a detailed study of the monument it was revealed that the original excavation team had missed this and several other stones that contained rock art. Other stones highlighted by the Bristol University survey team included stones within the western chamber each possessing several cupmarks (Stones 20 and 21). A single cupmark was also recorded on the north-eastern corner of the capstone that covers the southern chamber. Dr George Nash, from Bristol University, who led the team, described the discovery as "highly significant": the chevron design is unique in the region, and only two similarly decorated tombs have been recorded, one nearby on Anglesey, and one in Liverpool which has now been destroyed.
     Apart from its significance as a gallery of prehistoric art, Barclodiad y Gawres has a unique place in British archaeology, as the setting for one of the more revolting stews ever recorded from the ancient world. Originally the whole structure was covered with a turf mound, now replaced by concrete. The seven metre-long passage led to a cruciform burial place, where three small stone cells opened off a central chamber. Remains of cremated human bone were found in the cells, but the central chamber seems to have been used to prepare a stew with some, mercifully lost, ritual significance: analysis suggests the ingredients included fish, eel, newt, frog, toad, mice, shrew and snake.
     The passage grave type is more common in Ireland, where the most spectacular examples, such as Newgrange, have richly decorated slabs with almost the entire original surface of a rock the size of a small car pecked away, to leave a pattern in relief. The Irish tomb builders may have directly influenced the monuments on Anglesey and the west coast of Britain.
     There is general consensus that the carvings deep within the passage graves must have been part of a complex ritual of the dead. In many tombs, such as Barclodiad y Gawres, the carvings are only visible from within the tomb, and often mark thresholds, lintels or entrances to the chambers. Archaeologists believe that the majority of the people whose most important dead were buried in such structures would never have been admitted to the secret rituals inside, but kept outside peering into the ominous darkness of the world of the dead.

Sources: The Guardian, The Megalithic Portal (24 April 2006)