Andre Pattenden/English Heritage
Stonehenge, an icon of European prehistory that draws greater than one million guests a yr, isn’t out of the information. But, surprisingly, there’s a lot we don’t find out about it. Discovering the sources of the stones used to construct the monument is a elementary query that has vexed antiquaries and archaeologists for over 4 centuries.
Our interdisciplinary group, together with researchers from 4 UK universities (Brighton, Bournemouth, Studying and UCL) and English Heritage, has used a novel geochemical strategy to look at the big “sarsen” stones at Stonehenge. Our outcomes affirm that the close by Marlborough Downs have been the supply area for the sarsens, but in addition pinpoint a particular space because the most probably place from the place the stones have been obtained.
Two essential sorts of stone are current at Stonehenge: sarsen sandstone for the large framework of upright stones capped by horizontal lintels; and a mixture of igneous rocks and sandstones collectively referred to as “bluestones” for the smaller components throughout the central space.
James Davies/English Heritage
Analysis within the final decade has confirmed that the igneous bluestones have been dropped at Stonehenge from the Preseli Hills in Pembrokeshire, over 200km to the west. The sandstones have been tracked to jap Wales though the precise outcrops have but to be discovered. Nonetheless, the origins of the sarsen stones has, till now, remained a thriller.
Stonehenge is a sophisticated and long-lived monument constructed in 5 essential phases. The earliest, dated to about 3000BC, comprised a roughly 100m-diameter round enclosure bounded by a financial institution and exterior ditch. Inside have been varied stone and timber constructions, and quite a few cremation burials.
The sarsen constructions seen right this moment have been erected round 2500BC and comprised 5 trilithons (the doorway-like constructions shaped from two uprights joined by a lintel) surrounded by a circle of an additional 30 uprights linked by lintels. The trilithons have been organized in a horseshoe formation with its principal axis aligned to the rising midsummer solar within the northeast and the setting midwinter solar to the southwest.
Finding the sarsen supply
Typical knowledge holds that the sarsens have been dropped at Stonehenge from the Marlborough Downs, some 30km to the north, the closest space with substantial scatters of enormous sarsen boulders. Nonetheless, the Marlborough Downs are in depth and larger precision is required to grasp how prehistoric peoples used the panorama and its sources.
Our analysis has recognized what could be termed the “geochemical fingerprint” of the Stonehenge sarsens. We began by analysing the geochemistry of all 52 remaining sarsens at Stonehenge (28 of these initially current are actually lacking, having been eliminated way back).
This part of the work concerned utilizing a non-destructive know-how known as transportable x-ray fluorescence spectrometry (PXRF). Finishing up the PXRF analyses required entry to the monument when it was closed to guests and included a number of night time shifts and one early morning analysing the lintel stones from a cellular scaffold tower. Knowledge assortment is rarely straightforward!
David Nash, College of Brighton, Creator supplied
Evaluation of the PXRF information confirmed that the geochemistry of a lot of the stones at Stonehenge was extremely constant, and solely two sarsens (stones 26 and 160) had a statistically completely different chemical signature. This was an attention-grabbing outcome because it urged we have been in search of a single essential supply.
Then got here a significant stroke of luck. We have been in a position to analyse three small samples that had been taken from one of many stones in 1958, Stone 58, a part of the group of sarsens with a constant chemistry. Utilizing a way referred to as inductively coupled plasma mass spectrometry (ICP-MS) gave a high-resolution geochemical fingerprint for the Stonehenge sarsen. Like all good detectives, we might now evaluate our fingerprint with these of the potential sources.
Sam Frost/English Heritage
Sarsen blocks are discovered broadly scattered throughout southern Britain, broadly south of a line from Devon to Norfolk. We sampled stones from 20 areas, together with six within the Marlborough Downs, and analysed them utilizing ICP-MS.
Evaluating the geochemical signature from Stone 58 in opposition to our ensuing information revealed just one direct chemical match: the realm referred to as West Woods to the south-west of Marlborough. We might due to this fact conclude that a lot of the Stonehenge sarsens have been from West Woods.
Our outcomes not solely determine a particular supply for a lot of the sarsens used to construct Stonehenge, but in addition open up debate about many linked points. Researchers have beforehand urged a number of routes by which the sarsens could have been transported to Stonehenge, with out really figuring out the place they got here from.
Andre Pattenden/English Heritage
Now these will be revisited as we higher admire the trouble of shifting boulders so long as 9m and weighing over 30 tonnes some 25km throughout the undulating panorama of Salisbury Plain. We will really feel the ache of the Neolithic individuals who took half on this collective effort and take into consideration how they managed such a Herculean process.
We will additionally ask what was particular concerning the West Woods plateaux and its sarsens. Was it merely their form and dimension that attracted consideration? Or was there some extra deep-seated motive rooted within the beliefs and identities of the people who constructed Stonehenge?
Revealing that every one the stones got here from a single essential supply can be necessary and accords with the proof that the sarsens have been all erected at a lot the identical time. However what concerning the two sarsens whose fingerprints differ from the principle supply? The place did they arrive from? The search continues, and the questions simply preserve coming.
David Nash acquired funding for the analysis described on this article from the British Academy and The Leverhulme Belief.
Timothy Darvill acquired funding for the analysis described on this article from the British Academy and The Leverhulme Belief.