The Stonehenge Moraine?

Looking afresh at the Judd article from 1903, and recalling the ideas of Geoffrey Kellaway, maybe the time is right to resurrect the question of whether there might have been a moraine at or near Stonehenge, laid down a very long time ago (during the Anglian Glaciation) at the easternmost extremity of Irish Sea Glacier advance.

I know that certain geomorphologists, including Prof James Scourse, Prof David Bowen and Dr Chris Green, have rubbished this idea with great enthusiasm, claiming that it is glaciologically implausible and unsupported by any field evidence.  As I recall, all three of them have used the word "impossible" -- causing me to recoil in horror and the archaeological establishment to rub its hands in glee.

But Wesley John Judd (he must have been a good Methodist, with a name like that, so maybe he enjoyed divine inspiration) was no fool.  Look carefully again at his paper.  He clearly was not too sure where the ice had come from (north or west, or maybe north-west) but he clearly had suspicions that the assemblage of debris at Stonehenge had come from North Pembs or North Wales.  He also observed that in areas affected by very ancient glaciations, most of the till would have been eroded away by river action and solifluction after hundreds of thousands of years, leaving only a thin scatter of erratics here and there.  Further, he observed that scattered hard stones (including bluestones) left behind on Salisbury Plain would have been targetted down through the centuries for building purposes, millstones etc -- and this was a point also made quite forcefully by Olwen Williams-Thorpe and her colleagues during the Open University studies around 1990.

Things get even more interesting when we look at his identifications of stones.  He seems to have concentrated not on the bluestone monoliths or orthostats themselves, but on the debitage or debris in the Stonehenge soil layer.  And what did he identify?  An extraordinary assortment of "rubbish stones" including fissile sandstones, micaceous sandstones, greywackes (argillaceous and easily broken down), flagstones, slates and "clay-slates", and fine-grained glauconitic sandstones.  He made the point specifically that all this material did not seem to be very closely related to the remaining standing bluestones -- so he concluded that only the hardest stones had survived to the present day, with all the rubbish material breaking down and becoming incorporated into the soil layer over many thousands of years.

What if all that debris was in the soil layer long before Stonehenge was built?  It's perfectly feasible. Might we therefore be looking at the remains of an ancient till deposit, or even a moraine?  Judd himself seemed to think -- right at the end of his note -- that the presence of this feature -- with an abundance of foreign stones readily available to the builders of Stonehenge -- might have actually determined the precise position of the monument.  Nothing to do with ley lines or astronomy or anything else of an esoteric nature -- straightforward opportunism on the part of the tribes who lived on Salisbury Plain.

Now I'm not familiar with all of the details of the current geology, and I need advice on all of this, but it seems that there are clues in the recent work published by Rob Ixer and Richard Bevins that suggest that Judd was pretty much on the ball.  They have already said in print that much of the debitage is unrelated to the nature of the bluestone monoliths.............

One further intriguing thought comes into my head.  It's difficult to know from Judd's descriptions precisely which sedimentary and metamorphic rock types he is talking about -- names have changed over the years.  But when he talks of fissile sandstones, greywackes, slates, flagstones, clay-slates and so forth he could well be describing the non-volcanic rock types that occur in association with the Fishguard Volcanics in the eastern Preseli Hills and Dinas-Newport area of North Pembrokeshire.  If you walk around the area today the intervening areas between the volcanic and intrusive rock outcrops (the rhyolites and dolerites) are underlain by shales, mudstones, sandstones and ash beds, sometimes in an unaltered sedimentary state, sometimes partly metamorphosed, and sometimes transformed into slate.

So could this non-igneous debitage also have come from this same narrow zone (about 3 km wide) which I have already speculated on as a possible zone of entrainment between Welsh Ice and Irish Sea ice at the time of the Anglian glacial episode?

More and more intriguing --- watch this space.