(View exact match)bluestoneCATEGORY: geology
DEFINITION: A type of bluish-gray combination of dolerite, rhyolite, and volcanic stone used in the second phase of building Stonehenge. The source seems to be the Preseli Hills of South Wales, 215 km away.
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DEFINITION: Ancient monument on Salisbury Plain, Wiltshire, England, the remains of four massive trilithons surrounded by concentric circles of megaliths, probably constructed since c 3200 BC. It was a major Neolithic and Early Bronze Age ritual monument, architecturally unique, surrounded by a whole complex of barrow cemeteries and ritual sites. It had many phases of reconstruction. Apart from a cursus, the oldest structure was a circular earthwork about 100 meters in diameter, consisting of a ditch with an inner bank broken by a single entrance. Just inside the bank was a ring of 56 Aubrey holes (pits), some of which contained cremations. There were further cremations in the ditch and on the inner plateau. The presence of grooved ware pottery, together with radiocarbon dates from a cremation suggest that Stonehenge I belongs to the end of the Neolithic. Phase II occurred in c 2200-2000 when two concentric rings of sockets were dug at the center of the site for the erection of 80 bluestones imported from the Preseli Hills of southwest Wales. To this period belongs the Avenue, two parallel banks and ditches which run from the entrance to the river Avon 3 km away. In Stonehenge's third phase, the bluestones were removed, and Sarsen stones, some weighing over 50 tons, were brought from the Downs 38 km away to the north. These blocks, unlike those of any other henge or megalithic tomb, were dressed to shape before erection, and were then set up as a circle of uprights with a continuous curving lintel, enclosing a U-shaped arrangement of five trilithons. This phase has been dated 2120 +/- 150 BC and its work was carried out by the bearers of the Wessex culture. At a later stage (phase IIIc) the bluestones were re-erected in their present positions, duplicating the sarsen structure. There is a radiocarbon date of 1540 +/- 105 BC for the early part of this final stage, and the whole of Stonehenge III probably falls within the Early Bronze Age. The final stage came in the Middle or Late Bronze Age when the Avenue was extended 2000 meters east. The function of the monument is usually held to be religious, though it had no connection with the Druids. Theories are that the northeast-southwest axis may suggest some form of sun cult, the stone settings may have been used for astronomical observations in connection with the calendar, and the Aubrey holes for calculating the occurrence of eclipses. It has also been interpreted as the temple of a sun or sky cult. Archaeologists have long been fascinated by this monument, with its evidence of massive manpower input (one calculation suggests 30 million man-hours would have been required for the phase IIIA structure), its architectural sophistication, and astronomical alignments.