Megalith quarries for Stonehenge’s bluestones - Mike Parker Pearson, Josh Pollard, Colin Richards, Kate Welham, Chris Casswell, Duncan Schlee, Dave Shaw, Ellen Simmons, Adam Stanford, Richard Bevins & Rob Ixer
Geologists have long known that Stonehenge is formed of two main types of stone: a silcrete, known as ‘sarsen’, was used for the large trilithons, sarsen circle and other monoliths, and a variety of ‘bluestones’ was used for the smaller standing stones, which were erected in an inner ‘horseshoe’ and an outer circle. Of these 43 bluestone pillars, some 27 are of spotted dolerite known as ‘preselite’ – an igneous blue-green rock characteristically speckled with ovate patches of pale-coloured secondary minerals –
which can be provenanced in Britain only to the Preseli hills (Mynydd
Preseli) in north Pembrokeshire, west Wales, about 230km away from Salisbury Plain
More at
https://eprints.soton.ac.uk/421631/1/Megalith_quarries_Antiquity_REVISED.pdf
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