The Altar Stone in close up

My photo - click to embiggen 

Full size photo - https://photos.app.goo.gl/fgJgkqLgdkMhzvyj9

Thought experiment: What if the Altar Stone is a later, say, Roman addition to the monument? Is there anything that proves it isn't? If it was what would we expect it to be like? How could we tell? Where might they have brought it from?

The answer is probably where would we expect to find debitage from it and it seems it was found deeper than we we would expect from such a late introduction to the site.

Ireland Ba Map - sadly incomplete.

 From GSI.ie

The Altar Stone - Not welsh, so where is it from?

An important paper on the Stonehenge Altar Stone has just been released:

It probably didn't come from South Wales and surrounding areas.

Its petrographic fingerprint which includes a diagnostic high Barium (Ba) content mostly doesn't match the Old Red Sandstones (ORS) of the area, and the ORS rocks there that also have a high Ba don't match other characteristics. 

The hunt for the source is on.  Suitable areas that also have neolithic sites are the top suspects.

AlexD, CC BY-SA 3.0, via Wikimedia Commons - Old Red Sandstone is coloured Brown 

The paper: - Open Access.

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?, 

Abstract

Stone 80, the recumbent Altar Stone, is the largest of the Stonehenge foreign “bluestones”, mainly igneous rocks forming the inner Stonehenge circle. The Altar Stone’s anomalous lithology, a sandstone of continental origin, led to the previous suggestion of a provenance from the Old Red Sandstone (ORS) of west Wales, close to where the majority of the bluestones have been sourced (viz. the Mynydd Preseli area in west Wales) some 225 km west of Stonehenge. Building upon earlier investigations we have examined new samples from the Old Red Sandstone (ORS) within the Anglo-Welsh Basin (covering south Wales, the Welsh Borderland, the West Midlands and Somerset) using traditional optical petrography but additionally portable XRF, automated SEM-EDS and Raman Spectroscopic techniques. One of the key characteristics of the Altar Stone is its 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. However, because of their contrasting mineralogies, combined with data collected from new automated SEM-EDS and Raman Spectroscopic analyses these four samples must be discounted as being from the source of the Altar Stone. 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. There is no doubt that considering the Altar Stone as a ‘bluestone’ has influenced thinking regarding the long-held view to a source in Wales. We therefore propose that the Altar Stone should be ‘de-classified’ as a bluestone, breaking a link to the essentially Mynydd Preseli-derived bluestones.

Richard E. Bevins, Nick J.G. Pearce, Rob A. Ixer, Duncan Pirrie, Sergio Andò, Stephen Hillier, Peter Turner, Matthew Power,

Journal of Archaeological Science: Reports, Volume 51, 2023, 104215,ISSN 2352-409X,

https://doi.org/10.1016/j.jasrep.2023.104215

(https://www.sciencedirect.com/science/article/pii/S2352409X23003905)

Ground Penetrating Bayonet

Before modern gizmos were invented the usual way to locate buried stones was to prod the ground with a bayonet, Alexander Thom amongst others was a keen proponent of the method into the 1960s.

So it is fascinating to spot a bayonet in among the tools of Atkinson's 1958 excavations at Stonehenge.

 It appears to be an Enfield Socket Bayonet fitted with a handle - or something similar.

I note English Heritage sell replica bayonets - https://www.english-heritageshop.org.uk/british-enfield-rifle-bayonet - "This type of bayonet was manufactured in England from 1853 to around 1870 and saw service until about 1875. It was designed to fit the Enfield 1853 Pattern Musket (also known as the P53 Enfield). It saw service in the Crimean War, American Civil War, New Zealand Land Wars and the Indian Mutiny. It is a typically British design in that it has a blade “shoulder” and is shallow fullered."

Though I doubt they would approve of their use at Stonehenge now.

 

From: https://historicengland.org.uk/images-books/photos/item/P50851 

Excavations between fallen Trilithon upright stone 55 which broke into two pieces. 1958. 

The underside of stone 55B - 1958

The underside of stone 55B as it is lifted from its fallen position. An unreported stone lift.

1958 Excavation Of Altar Stone, Stone 80

https://historicengland.org.uk/images-books/photos/item/P51908 Photographer: Atkinson, R J

Craig Rhos-y-felin Bullet Stones

The rhyolite boulder collected by R. S. Newall in 1924 from an excavation at Stonehenge which has been discussed before at length - https://www.sarsen.org/2023/07/the-erratic-that-came-in-from-cold.html - has an appealing "bullet" shape.

The pillars at Craig Rhos-y-felin, where the boulder has been petrographically matched to, tend to have these rounded tips and the excavations there revealed many such bullet shaped tips that have broken off. These boulders still at the quarry obviously haven't been transported anywhere and so the bullet shape of the boulder "is a tale... signifying nothing.” 

Photo by Adam Stanford - annotated by me

Photo by Mike Parker-Pearson with "Newall's Boulder" floated in by me. 

Photos of quarry from, and more information available at :

Craig Rhos-y-felin: a Welsh bluestone megalith quarry for Stonehenge 

Published online by Cambridge University Press: 07 December 2015 

Mike Parker Pearson , Richard Bevins , Rob Ixer , Joshua Pollard , Colin Richards , Kate Welham , Ben Chan , Kevan Edinborough , Derek Hamilton , Richard Macphail , Duncan Schlee , Jean-Luc Schwenninger , Ellen Simmons and Martin Smith

Craig Rhos-y-felin 2014 - 2023

Click  any photo to embiggen A few photos from my periodic visits - the vegetation recovery from 2014, the excavation years to 2023 is great to see.  The bottom photo looking down on it is from 2016 - Please feel free to copy and use the photos if they are useful

Strange lines in the landscape

Two parallel soil marks behind what was the car park, not seen them before.  

I can't see any evidence on the 1943 photo;

UPDATE - a slightly different shot to the first one shows dust (I think)billowing up from the end of the further line. I think they may be marks left by a cultivator. But no sign of a tractor.