Earlier this year I was able to cross one of those important 'must do' items off my list when I attended my first Summer Solstice celebration at Stonehenge. It was my fourth visit to the prehistoric monument, but the first time I was able to go past the protective crowd barrier and actually touch the great stones (a privilege afforded to visitors only twice a year on the two solstices, as well as to the odd American president on request).
Yours truly touching Stonehenge.
Little did I know that a handful of weeks later I would get another chance to come into contact with Stonehenge, this time, within the Museum's walls.
Because, as I recently learned, up above my office in a mineralogy storage room, there sits a miniature model of Stonehenge made from the same stones as the original. Not from the actual Stonehenge stones, I should clarify (although before it became a protected site, tourists were able to, and did, chip off bits of the stone to take home as souvenirs), but stones taken from the sites the Stonehenge stones originate from, at least according to the thinking at the time it was made.
Our miniature Stonehenge was commissioned by Herbert Thomas, from the Geological Survey, in the 1920s or 30s. The lapidary (the stone cutting and polishing) was carried out by a D W Hepple.
Our model, showing the complete double concentric arrangement of sarsen stones (outer circle and inner horseshoe), and matching formation of bluestones inside.
Our mini Stonehenge (its scale is 1:60) was once display on one of the mezzanine levels of the current Earth Galleries building (aka the Red Zone), but was removed sometime in the mid-to-late-1990s and put into storage. It only came to light again very recently when is was discovered in a Museum outstation, from where Earth Sciences curator David Smith urged its return.
Of the model, and Stonehenge, David explains:
In 1923 Herbert Thomas published a paper which went some way to identifying the source, the provenance, of Stonehenge. He was the first person that proposed that the bluestones came from the Preseli Mountains in Pembrokeshire. The model was made sometime after this, and before his death in 1935.
Stonehenge is constructed from three broad rock types. The huge lintelled megaliths from a strongly-cemented sandstone, the smaller stones from a variety of volcanic rocks, nicknamed ‘bluestones’, and a micaceous sandstone forming the altar stone. Thomas's theory was that the bluestones – which form the inner circles – were excavated, and somehow transported over land to Amesbury.
Whilst it has been determined that the much larger sarsen stones were transported separately from 20 miles away, north on the Marlborough plain, the mode of transportation of the bluestones remains a mystery. Recent theories have proposed transportation by glaciers of the last ice age, or humans taking the stones to Milford Haven and shipping them through the Bristol channel. The altar stone would have been picked up on route in Milford Haven.
Mini Stonehenge, including the heel stone, which in real life stands 90 yards from the altar stone.
Our Stonehenge sarsens with lintels measure 3.5 inches high. The real Stonehenge is up to 24 feet, or 288 inches.
Almost a century later, part of Thomas' theory does stand up. He predicted that one variety of the bluestones, a type of spotted dolerite, was from a tor on Preseli hill called Carn Meini. Late last year the exact quarry from which they were taken was discovered to be just one mile away from where Thomas predicted, on a hill called Carn Goedog.
Work is ongoing between the University of Oxford, the Open University and University College, London to determine the exact source of the other volcanic rock types that make up the bluestones. Scientists have gone right back to the original rock chips and thin sections described by Thomas, some of which have been preserved here at the Museum, and compared them with modern samples. David says:
In 1991 English Heritage extracted sub-samples from some of the key monoliths of Stonehenge for research. These rare samples and analytical products are now archived at the Museum. The research group have analysed them using modern techniques, that Thomas wouldn’t have even imagined possible, to compare and hopefully match the geochemistry with samples collected from various outcrops in the eastern Presili mountains.
Once published, David hopes to spread the word of the latest findings, and the role played by the Museum’s collection in the puzzle, along with the mini Stonehenge model.
The model needs some conservation work, but I'd like to get it out on display in the Earth Sciences lobby, or in a public space if possible, and use it to help tell the story of where our current Stonehenge knowledge is.
In the mean time, visitors can see a sample of Stonehenge sandstone in the Earth's Treasury gallery.