Thursday 30 May 2024

The Neolithic Landscape of Avebury and the Kennet Valley

New research "suggests that there is little evidence of widespread woodland removal associated with Neolithic farming and monument building, despite the evidently large timber requirements for Neolithic sites like the West Kennet palisade enclosures. Consequently, there was relatively light human disturbance of the hinterland and valley slopes over the longue durée until the later Bronze Age/Early Iron Age, with a predominance of pasture over arable land. Rather than large Neolithic monument complexes being constructed within woodland clearings, representing ancestral and sacred spaces, the substantially much more open landscape provided a suitable landscape with areas of sarsen spreads potentially easily visible."

FRENCH C, CAREY C, ALLEN MJ, et al. The Alluvial Geoarchaeology of the Upper River Kennet in the Avebury Landscape: a Monumental Transformation of a Stable Landscape. Proceedings of the Prehistoric Society. Published online 2024:1-35. doi:10.1017/ppr.2024.6

Sunday 26 May 2024

Did the Altar Stone come from Ireland?

"First recorded in 1136 by Anglo-Norman historian Geoffrey de Monmouth, the centuries-old legend of Stonehenge’s Irish provenance describes the search by King Aurelius of Britain for a fitting monument to honour those slain by the invading Saxons on Salisbury Plain.

Having first proposed the ‘Giants’ Dance’ on Ireland’s Mount Killara as best-suited, court-magician Merlin is promptly sent forth, along with Uther Pendragon (father of King Arthur) and 15,000 men, to defeat the local king and transport the stones back to Amesbury for re-assembly... Over time, however, the location of the original Irish site of the ‘Giants’ Dance’ at Mount Killara/Killara(us) was lost..... Thomas Johnson Westropp of Attyflin Park, Patrickswell (1860-1922) (provides) a reference to a local mountain named by John Stow and Geoffrey Keating as the source of the Stonehenge pillars! Geoffrey Keating’s AD1634 ‘Foras Feasa ar Éirinn’ delightfully provided the name of the mountain in the original Irish language, - ‘Sliabh gCláire’."

Larry Joy continues in "I was in the happy position of being able to instantly identify Keating’s reference since this peak and the magnificent Dunglara (Dún gCláire) hill fort ( 52.38795°N, 8.39785W) on its northern slope tied in neatly with my research. The mountain was originally named for its location overlooking Clár Múmhan, the Plain of Munster, (slíabh - mountain, gCláire - of the plain) and is known as Sliabh gCláire throughout medieval Irish literature.

Somewhere along the line the original name of the mountain changed, but I can now happily reveal that the legendary Irish mountain forever linked to the iconic Stonehenge monument is Slievereagh, above the sequestered hillside village of Glenbrohane in south-east Limerick.

With an outer diameter of over three hundred feet and a circumference of nine hundred, Dún gCláire proves an uncanny match for Stonehenge’s outer henge, while the positioning of their entrances, their alignment to the solstice sunrise and their prominent locations within pre-historic tribal strongholds provide further eerie parallels."

There is obviously no match between the geology of the area and the Sarsens and Bluestones of Stonehenge but what about the Altar Stone? Dún gCláire is situated on the  Kiltorcan Formation of Old Red Sandstone. a Devonian sandstone.

The latest geological information about the Altar Stone is Bevins et al. or

which describes the stone as: "a sandstone of continental origin.. unusually high Ba content (all except one of 106 analyses have Ba > 1025 ppm), reflecting high modal baryte. Of the 58 ORS samples analysed to date from the Anglo-Welsh Basin, only four show analyses where Ba exceeds 1000 ppm, similar to the lower range of the Altar Stone composition. ...It now seems ever more likely that the Altar Stone was not derived from the ORS of the Anglo-Welsh Basin, and therefore it is time to broaden our horizons, both geographically and stratigraphically into northern Britain and also to consider continental sandstones of a younger age."

Their map of Ba concentrations is slightly misleading in that whilst in includes the whole of Ireland, it is only in Northern Ireland that the Ba concentrations have been mapped. 

The Soil Geochemical Atlas of Ireland provides Ba analysis of the rest:

This is not quite comparable especially as the composition of sandstones depend on the palaeodrainage pattern, as shown by a study on the Dingle peninsular, and there appears to be high Barium concentrations to the the north from where the sand granules that formed the sandstone may have come.  

Maybe the hunt for the Altar Stone source should include Ireland as well as northern Britain.

(Click any picture to embiggen)