Built to align with the sunrise on the summer solstice and the sunset on the winter solstice, the construction of Stonehenge is thought to have been completed in several phases from 3100 BC to 1600 BC. The easily recognisable outer circle of large stones was placed between 2600 BC and 2400 BC, while the smaller inner circle was placed in the years between 2400 BC and 2200 BC.
These outer stones are formed of sarsen sandstone, transported to the south of England by glaciers during the Ice Age. The inner stones are bluestones (the most common being Preseli Spotted Dolerite) and thought to be brought from Pembrokeshire.
Until recently, the belief was that the altar had similar origins. Thought to have been laid around 2600 BC, the original prediction was that the stone was from the Senni Beds formation of Old Red Sandstone in Wales.
However, a new study shows that this is not the case – the stone has travelled much further than that. By geochemically analysing the crystals within the slab, scientists are now aware that this stone was transported by the Neolithic people 800 kilometres from the Orcadian Basin in the north-east of Scotland to Salisbury Plain, to serve as the centre piece for this immense monument.
This discovery has been met with much excitement, as it has revealed more to us about the Neolithic architect’s knowledge and understanding of stone, as well as raising questions about their transportation technologies.
