The geology of Stanton Drew

I have been looking at the big report from 2010 on the stones of Stanton Drew, in the hope that this will give us some guidance on the role of the Avon Ice Lobe on moving stones about in that general area.   Stanton Drew lies south of Bristol and west of Bath, to the north of the Mendips.  There are three circles, all somewhat ruinous.  This is the reference:

Stanton Drew 2010
Geophysical survey and other archaeological investigations
Report compiled by Jude Harris
Bath and North-East Somerset (BANES)
www.bathnes.gov.uk
Bath and Camerton Archaeological Society
www.bacas.org.uk
Contributors:  John Oswin and John Richards, Richard Sermon, Vince Simmonds

http://www.bathnes.gov.uk/sites/default/files/sd_2010_report_low_res.pdf

The main rock types represented in the stone circles are as follows:

Descriptions:

Oolitic Limestone Jurassic age
At the Stanton Drew site at least four principal rock types have been identified and are briefly described below as an Oolitic Limestone of Jurassic Age circa 205–142 Ma (figure 6.2). These rocks are a pale grey-yellow colour.

Silicified Dolomitic Conglomerate of Triassic Age, circa 248–205 Ma
These rocks have a wide range of colours from pale pink to orange-pink with some bright, sometimes ochreous orange, through to dark rust, and purple-red blotches, the red and orange colour is indicative of the mineral iron content of these Triassic rock types (figure 6.3). The rocks have a glassy, metallic appearance and feel and the surface has been described as pitted, pock-marked, frothy, knobbly and gnarly.

Dolomitic Conglomerate also of Triassic Age
This is a weathered pale grey-pink and has a lesser degree of silicification (figure 6.4). The varying clasts range from rounded to sub-angular fine to coarse gravel, pebbles and cobbles of limestone and sandstone. There are also some silicified fossil fragments from the remains of limestone clasts within the conglomerate and the stones again have a substantial cover of lichen.

Pennant Sandstone of Carboniferous Age  circa 354–290 Ma
These rocks are of a pink to fawn colour and distinct bedding layers are clearly visible, in particular cross-stratification which is typical of material that has been laid down in deltas (figure 6.5). There is a layer of sub-rounded to rounded fine to medium gravel of quartz.

Summary:

Within the Great Circle the vast majority of visible stones comprise a silicified Dolomitic Conglomerate, with the remaining other rock types comprising Oolitic Limestone, Pennant and a Dolomitic Conglomerate that has a lesser degree of silicification. The stones that form the Northeast Circle and the Avenues comprise mostly silicified Dolomitic Conglomerate and a small number of Oolitic Limestone. The orange to rust-red colours of the silicified Dolomitic Conglomerate do not look out of place at Stanton Drew, matching well with the local red sandy soils and the Triassic Mercia Mudstone that underlies the monument site. The majority of the stones in the SSW Circle comprise silicified Dolomitic Conglomerate, although at least one stone is of the local sandstone, possibly from the sandstone bands that are found within the Mercia Mudstones of this area and are visible in the local environment. The stones used in the construction of ‘The Cove’ comprise a Dolomitic Conglomerate that has been silicified but to a lesser degree. Within some of the limestone clasts are the silicified fossil remains of Siphonodendron, a rugose coral of Lower to Upper Carboniferous age (Black 1970). In the light some of the silicified clasts within the Dolomitic Conglomerate can be seen to sparkle due to the quartz crystallisation. The stones of the cove lack the vivid oranges and rusty-reds of the more silicified rocks found within the Circles and Avenues and they are greyer in colour.

So far so good.  But then note this:

"As the perception and cognition of landscape is altered by the construction of a monument, then the actual physical landscape is also altered. The monument becomes part of the landscape while the landscape then becomes materialized in the monument. The materials that are used to construct the monument might have been selected and gathered from specific sources within the landscape and are incorporated into a new form as part of the monument. The social and ritual performance of monument construction can alter entire landscapes (Goldhahn 2008: 59). When considering the monuments at Stanton Drew, their place within the landscape, of which they have become a part, is a significant factor. This also applies to the individual stones that remain a part of that landscape. When describing the geology and landscape of the stones and surrounding areas it is with these considerations in mind."

This is profoundly disappointing.  There is a lot of good work in this Report, and a huge amount of technical detail, but the authors seem to be so preoccupied with the archaeological fantasies of the moment that nobody -- even the geologist involved -- appears to have asked the fundamental questions:  Where did the Stanton Drew rocks come from?  Did they all come from the west?  Could they all be glacial erratics?  Were they in the area well before the stone circles were built, and could their presence here have been the key determinant in the siting decisions of the builders? 

Until those questions are answered, what on earth is the point of wild speculations concerning social priorities and rituals?