Salon is increasingly unfashionable

Here is the latest from Salon -- based on those press releases of a few weeks ago relating to the zircon research and the identification of the bluestone source at Pont Saeson.

Quote:  "The finding has implications for the route by which the stones were transported to Stonehenge. Previous theories have suggested an arduous overland haul south from the peaks of Mynydd Preseli to Milford Haven, and then by sea and river to Salisbury Plain. These new outcrops are only a short distance (c 5km) from the harbour at Newport: the overland journey would have been much shorter, but the voyage via the Irish Sea is considerably longer and potentially more hazardous."

In deference to "our Fellows Geoff Wainwright and Tim Darvill", whoever wrote this appears to be incapable of accepting that the bluestone assemblage at Stonehenge (and vicinity) is so varied that the increasingly convoluted idea of human transport over land and sea has to be dumped.  Are they going to "explain away" every new stone source, as it is discovered, by invoking some new and ever more wacky transport route?  Isn't it time that somebody at the Society took our two illustrious professors to one side and reminded them -- ever so gently -- that there are such things as glaciers?
 
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SALON - the Society of Antiquaries of London Online Newsletter
Salon 252: 28 March 2011

Zircon provides key to Stonehenge ‘bluestone’ sources


Our Fellow Dr Rob Ixer, of the University of Leicester, along with co-researchers Dr Richard Bevins, Keeper of Geology at Amgueddfa Cymru — National Museum Wales, and Dr Nick Pearce, Reader in Geochemistry at Aberystwyth University, have used the mineral zircon to pin down the provenance of some of the ‘bluestones’ that were used to form the first stone circle at Stonehenge.
‘Bluestone’ is the common name for spotted dolerite, which is blue-grey in colour when wet or freshly quarried. Also known as ‘preselite bluestone’, the source of these relatively rare igneous rocks was traced by the petrologist Herbert Thomas in 1923 to Carn Menyn, an outcrop in the Mynydd Preseli (Preseli Hills) of Pembrokeshire, where our Fellows Geoff Wainwright and Tim Darvill have been carrying out fieldwork for the last ten years.
However, not all of the orthostats that survive today from that first Stonehenge circle are made of preselite, and precise sources for some of the other ‘bluestones’ have proved harder to pin down because they consist of the much more abundant fine-grained rhyolites, tuffs and sandstones that are hard to tell apart under a microscope.
To crack this problem, Dr Ixer and his colleagues have built on recent research showing that igneous rocks from different magma flows contain differing amounts of the mineral zircon and have their own distinctive compositions. In a paper published in the March 2011 edition of the Journal of Archaeological Science, they show how the unique zircon signatures of the Stonehenge rhyolites enables the stones to be matched to outcrops within the Fishguard Volcanic Group. These exposures are found in an irregular band that crosses north Pembrokeshire some 8km to the north of the Mynydd Preseli, stretching from Crymych in the east to Strumble Head in the west. One particular rhyolite has been pinned down to an outcrop in a steep-sided valley near Pont Saeson.
The finding has implications for the route by which the stones were transported to Stonehenge. Previous theories have suggested an arduous overland haul south from the peaks of Mynydd Preseli to Milford Haven, and then by sea and river to Salisbury Plain. These new outcrops are only a short distance (c 5km) from the harbour at Newport: the overland journey would have been much shorter, but the voyage via the Irish Sea is considerably longer and potentially more hazardous.
Location map of north Pembrokeshire showing key localities as well as the outcrop of the Fishguard Volcanic Group in relation to the Mynydd Preseli. Possible source locations for the Stonehenge spotted dolerite bluestones are shown (see key for symbols).

Credit: Dr Richard Bevins, Keeper of Geology at Amgueddfa Cymru — National Museum Wales