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The Altar Stone's origin in听Northeast Scotland is at least 750 kilometres away from its current site in Wessex, perhaps more than 1000 kilometres if it travelled by sea. Plate tectonics and precise radiometric age dating are keys to this discovery.

Almost exactly 60 years ago a series of papers convinced the geological world that the disputed idea of continental drift was correct, with the concept of plate tectonics (a continual process of the earth鈥檚 crust being created and destroyed) being the mechanism for this movement. Since the Proterozoic (2.5 billion years ago) the movements of landmasses over thousands of millions of years have been reconstructed to show cycles of coalescence, break-up and recombining of super-continents.

Zircon, rutile and apatite are small rare minerals found in igneous rocks, more so in acidic/granitic rocks than basic/basaltic ones. As they are chemically inert and quite resistant to weathering:

• a) they are ideal for obtaining radiometric ages to date their creation within their parent igneous body;
• b) they can be a significant detrital component in clastic sediments such as sandstone (recognising that their radiometric age is usually earlier than that of the enclosing sediment formed from the eroded parent igneous body).

This new study, published in Nature, analyses the chemical and isotopic composition of detrital zircon rutile and apatite grains within the Altar Stone, a Palaeozoic Old Red Sandstone, to determine their isotopic ages and so help to pinpoint the origin of the sediment. An earlier study in 2023 by a team of eight researchers led by Richard Bevins and published in the Journal of Archaeological Science: Reports demonstrated that the Altar Stone was not Welsh but probably from northern England and perhaps Scotland. 听

In 2020 Bevins鈥� team had noted the presence of a few extremely old and so intriguing zircons in the Altar Stone, and asked colleagues in Australia to confirm their presence and to provide additional dating. This they have done with breath-taking results based on uranium-lead and lutetium-hafnium radiometric dating from these grains of zircon, apatite, and rutile.

It is ironic that every time researchers are asked to investigate the Altar Stone鈥檚 origins, from the original duo (Rob Ixer and Peter Turner) in 2006 to over 12 contributors by 2024, its source moves further and further away from its original proposed source location on the banks of Milford Haven in Wales.

The Australian-led team was able to determine that grains within the Altar Stone have a range of ages revealing their formation during different igneous events. Some gave Ordovician ages of 470鈥�444 million years ago, slightly older than the formation age of the sandstone. But mixed in with these are grains that are far older, more than a billion years old, which must have derived from more ancient Archaean rocks. Their various ages reveal that these eroded grains come from the ancient landmass/terrane of Laurentia now forming most of North America and Greenland.

Laurentian igneous events are much earlier than those of the Gondwanaland terranes of Ganderia, Meguma and East Avalonia which form the underlying basement of most of England and Wales as well as the eastern coastal strip of North America. Consequently, no Old Red Sandstone sandstones in England and Wales carry an abundance of these very old Laurentian mineral grains.

Tectonic processes over almost 100 million years slowly brought the landmass of Laurentia together with Ganderia, Meguma and East Avalonia. Their join, which runs roughly along the border between England and Scotland, is known as the Iapetus Suture. It is associated with the mountain-building event known as the Caledonian Orogeny, causing the abutting of Scotland against England. Crucially, only British Palaeozoic rocks north of the Iapetus Suture can have Laurentian characteristics. Hence the Altar Stone must be Scottish.

Although more sampling is needed to pin down the Altar Stone鈥檚 source even more precisely, these extraordinary results reveal that it most closely matches Old Red Sandstones from the Orcadian Basin which听 includes the islands of Orkney and Shetland as well as much of northeast Scotland. These rocks are quite unlike the Old Red Sandstone of the Anglo-Welsh Basin and comprise a 2 kilometre-thick sequence of sandstones, limestones and shales deposited in what was once a large lake system. The basin is flanked on all sides by Laurentian basement from which the sediment derived its zircons and other minerals (see image above).

As (Freelance archaeologist, journalist and Editor of British Archaeology)听has said:

鈥�The idea that Neolithic people brought megaliths to Stonehenge from hundreds of kilometres is not new. Confirmed distant sources, however, were all in Southwest Wales. Northeast Scotland is both in a new direction and significantly further away. In addition, for people to deliver this stone intact to Stonehenge must have required a considerable amount of effort and care."

Putting aside Merlin鈥檚 magic or space aliens鈥� tractor beams, there are two alternatives: glacial dumping on Salisbury Plain or physical manhandling by Neolithic people, either overland or by boat. There is no evidence for any glacial erratics on Salisbury Plain; the nearest erratics to the west of Stonehenge abut the Somerset coastline and to the north of Stonehenge they are more than 100km distant.

This astonishing result now raises many archaeological questions, notably how the Altar Stone was transported and why.

According to Mike Parker Pearson (Professor of British Later Prehistory, 最准的六合彩论坛 Institute of Archaeology):

鈥�This reveals that Stonehenge was an even more remarkable collective achievement than we鈥檇 thought. Although not the largest of Britain鈥檚 stone circles, it easily had the longest reach, drawing in people from far and wide. No other circle was made entirely of distantly-sourced stones. Even Stonehenge鈥檚 huge sarsens had to be brought from 15 miles (24km) away. This has to be one of the biggest clues about its purpose 鈥� a monument to unite people on a grand scale.鈥澨�

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Citation:听Clarke, A.J.I., Kirkland, C.L., Bevins, R.E.听et al.听A Scottish provenance for the Altar Stone of Stonehenge.听Nature听632, 570鈥�575 (2024).

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