Newall's ignimbrite boulder (update)

 

I have come across a number of references to a strange boulder of Ordovician ignimbrite which was found during Col Hawley's excavations at Stonehenge in the 1920's, together with "other striated erratics." These were assumed to be metamorphic rocks of Welsh origin. Apparently some of the archaeologists at the time of excavation thought the stones were glacially derived, although Hawley would have none of it. According to legend, the stones were shaped by ice, faceted, and some had striations on them. James Scourse discusses this on pp 285 and 287 of his chapter in the "Science and Stonehenge" book, and tends to dismiss the evidence as unreliable. But I'm not so sure, and tend to be more trusting of the word of Newall and Kellaway....... not to mention the apparent agreement of Dale and Engleheart with reference to a glacial origin for this material.

Newall kept the "boulder" and other material for almost half a century, and then passed it on to Geoffrey Kellaway around 1969-71. Kellaway took photos of the boulder and published them here in 1991: "The older Plio-Pleistocene glaciations of the region around Bath." In Kellaway, GA (ed) Hot Springs of Bath, pp 243-41. I have not seen this article or the photos, but Scourse describes the boulder in question as a "sub-angular to sub-rounded, faceted and bleached clast". Scourse also says that the signs of striae are not clear enough to be convincing.

Thorpe et al tried to trace this boulder, but could not find it. So what happened to this little Newall collection? Geoffrey Kellaway sadly died in 2013 -- is the boulder still in the possession of his family, or has it ended up somewhere else?

Anyway, thanks to Philip for scanning the two images from Kellaway's paper.  They are BGS photos, which means that he took them during the course of his official work.  I have no reason to doubt Kellaway's word on the "erratics" found by Hawley, or the existence of the "Newall boulder", or the authenticity of the photos.  The boulder recorded here wasn't very big, maybe c 25 cm x 12 cms and weighing in at c 10 kg.  

If Kellway says the boulder was an "ignimbritic tuff-lava" probably of Ordovician age and possibly originating in North Wales, I am prepared to accept that until somebody comes up with a more accurate piece of provenancing.  His comments about weathering are also quite sensible, as are those on the striations -- he says they "may be" of glacial origin.  The images are not clear enough to pick up detailed surface markings.

It would be disrespectful of a good scientist to simply dismiss this evidence out of hand, and unless anybody has a better explanation for its presence at Stonehenge, embedded in chalky rubble,  I think we are duty bound to accept it as evidence of glaciation at Stonehenge.

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Click to expand.  RSN-18 is presumably Newall's sample number.

PS.  Thanks to Philip, here is the text relating to the boulder.  In spite of a somewhat convoluted discussion of its origins, it seems to be carefully thought out.  We can forget about the "Pliocene glaciation" which was one of Kellaway's pet theories and concentrate on the provenancing discussion and on the "context" of the erratic.  The fact that the stone was not found in "a secure archaeological context" will no doubt be used in some quarters as an argument for simply forgetting about it, or pretending that it is simply "adventitious."  I do not accept that for a moment.  It was certainly not carted to Stonehenge as a piece of roadstone.   All that we know from the context is that somebody foolishly thought the stone was of no interest, and threw it out.  That was a silly thing to do, since its presence at Stonehenge might actually be rather important.