Stonehenge Riverside Project: 2007 Excavation VI
New light on the bluestones
In 1947 J.F.S. Stone found a group of bluestone chippings just to the south of his trench into the Greater Cursus´ south ditch. Petrological re-examination by Dr Rob Ixer has revealed that these are indeed South Welsh bluestones of rhyolite, calcareous ash and tuff and that the stone from the cursus ditch can be matched with one of the bluestone sandstones from Stonehenge. No Preseli dolerites were present in this surface scatter. One of the rhyolite chippings probably derives from Stone 48 at Stonehenge, though whether it was detached before or after its erection at Stonehenge has not been established.
Re-examination of petrological slides of the sandstone from the cursus ditch and the sandstone Altar Stone from within Stonehenge by Dr Rob Ixer and Dr Peter Turner has revealed that these come not from the Milford Haven area of South Wales, as previously thought, but probably from further east and inland in the Brecon Beacons. This may have a significant impact on the hypothesis that the bluestones were brought south from Preseli to Milford Haven, where other non-dolerite bluestones were picked up, and then were rafted along the coast to the Severn Estuary. Instead, it may be more likely that all the stones were dragged overland eastwards past the Brecon Beacons to a crossing point over the Severn and then taken southwards to Wessex.
The main aim of geophysical survey in 2007 was to complete the large-scale coverage of Durrington Walls and its environs, and to prospect over new areas planned for excavation in 2008.
Resistivity survey was finally completed at Durrington Walls, thereby providing a comprehensive coverage by magnetometry and resistivity across the entirety of this large monument and its surrounds. Although resistivity survey outside the west entrance failed to identify the henge bank with any clarity, when taken together with the topographic survey of the surviving earthwork, it could be seen that the henge bank did not extend as far to the west as has previously been thought. Unfortunately the quantities of ironwork in the soil in this area (used as a WW1 army camp) prevented magnetometry being of any use.
Magnetometry and resistivity were carried out in 2007 prior to excavations around the Cuckoo Stone and south of Woodhenge, as well as at the west end of the Greater Cursus. Although the results provided little further information prior to excavation than was known from parchmark and topographic survey, they confirmed the accuracy of the parchmark survey at the Cuckoo Stone and south of Woodhenge.
In preparation for excavations in 2008, magnetometry and resistivity surveys were carried out at the east end of the Greater Cursus, the southwest end of the Stonehenge palisade, the area immediately in front of Stonehenge and at the `elbow´ of the Stonehenge avenue. The surveys at the southwest end of the Stonehenge palisade were complemented by trials of Chris Gaffney´s prototype magnetometer cart. These were very successful and revealed, among other features, a complex of pit-like anomalies to the north of the palisade.