Stonehenge study upends a 100-year-old theory and suggests further discoveries to come

Stonehenge stone 80, popularly referred to as the "Altar Stone," has a secret that a team led by academics at Aberystwyth University in the UK has uncovered. This secret suggests that Stonehenge stone 80 did not originate from the same source as other stones used in the building. The Altar Stone is distinctive, because it could come from a quarry considerably farther away from Stonehenge than many of the smaller stones, which are thought to have come from a location 140 miles distant.

The research team describes in a paper published in the Journal of Archaeological Science, "The Stonehenge Altar Stone was probably not sourced from the Old Red Sandstone of the Anglo-Welsh Basin: Time to broaden our geographic and stratigraphic horizons?," how recently discovered data is refuting a theory that dates back a century.

Given that it is composed primarily of sandstone as opposed to the volcanic bluestones that make up the inner circle of Stonehenge, the Altar Stone at Stonehenge is unlike any other stone among the bluestones of Stonehenge. The term "bluestone" describes the smaller stones of Stonehenge that become blue when wet.

According to earlier hypotheses, the Altar Stone, like other bluestones mostly from the Mynydd Preseli region of west Wales, originated from the Old Red Sandstone formation.

When what is now Europe and North America collided about 400 million years ago, the Old Red Sandstone formation was formed. The formation extends as far north as Greenland and Norway and on both sides of the Atlantic.

Using samples from the Old Red Sandstone formation in the Anglo-Welsh Basin, the researchers used optical petrography, portable XRF analysis, automated SEM-EDS analysis, and Raman Spectroscopy to look into the origin of the Altar Stone. The Altar Stone stands out from the majority of other basin and bluestone samples due to its high barium concentration.

The results show that the barium concentration of the Altar Stone is remarkable. Although certain samples from basin formations have compositions similar to the Altar Stone, their differences in mineralogies rule them out as being from the same source. This casts doubt on the Anglo-Welsh Basin as the Altar Stone's original location, indicating the need to expand the search both geographically and stratigraphically towards northern Britain and to look for newer sandstones.

Early Stonehenge excavators referred to the bluestones, which are mostly igneous in nature, as "Foreign Stones" since they were not the same as the larger, locally derived sarsen stones. Large stones used in building are believed to have originated from a source 15 miles distant, which is still a very amazing feat considering the weight of each stone (up to 55 metric tons) and implies that the place where they were brought had great significance.

One of the world's longest transit routes from source to monument building site, the majority of the bluestones have been sourced from the Mynydd Preseli region in west Wales, 140 miles west of Stonehenge.

The researchers suggest that the Altar Stone be "de-classified" as a bluestone in light of their findings, severing the connection to the Stonehenge bluestones that are descended from Mynydd Preseli. If this is accurate, the hunt for the history of the Altar Stone is far from over.

What significance does Stonehenge have?

Archaeology has proved that the structure has been given several accepted meanings over a period of 5,000 years, despite the fact that numerous astronomical ideas have been put out and afterwards proven false. It would only make sense to include the monument in gatherings if there is a local custom, whether druidic or not, as well as a location to bury the dead, seek holy healing, and meditate.

Among the stones, there have undoubtedly been many different kinds of rituals performed, not the least of which is the contemporary tourist custom of snapping selfies. Irrespective of its initial purpose, Stonehenge's legacy lies in the countless moments of amazement, enigma, creativity, and nostalgia it evokes.