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Sunday, 21 August 2016

The Stonehenge boulders

We have touched on this issue many times before, in making the point that most of the 43 bluestones found at Stonehenge (visible stones or buried stumps) are not beautiful elongated pillars, but common or garden lumps of rock best described as boulders.  This point is conveniently forgotten in almost all of the texts and papers on Stonehenge, which pretend that long columns of rock which would look impressive when planted vertically in their sockets were somehow"preferred" and were preferentially collected.

There are only six of these "ideal" pillars or slabs which might fit the bill as standing stones, monoliths or orthostats.   These have all been incorporated into the bluestone horseshoe.   That is a degree of selection that we can probably all agree about......

See the following:

Here again is the full list of the 19 bluestones in the bluestone circle and some buried stumps, from the excellent "Stones of Stonehenge" web site.  The list also refers to to stone shapes, surface characteristics and petrology:

31 -- damaged and heavily worn slab.  Standing.  Recent damage close to ground level.  Spotted dolerite with few spots.
32 -- heavily worn slightly elongated boulder.  Fallen -- resting on stone 150.  Spotted dolerite with pinkish spots -- like stones 150, 34, 35A, 35B (one stone), 39 (?), 47, 49, 64, 67, 69, 70
32c -- altered volcanic ash.  Like 33d.  Foliated rhyolite related to Rhosyfelin debitage?
32d -- another foliated rhyolite stump?  Related to Rhosyfelin material?
32e -- Dolerite stump -- characteristics unknown
33 -- well worn short and stumpy pillar.  Standing.  Signs of shaping -- meant as a lintel?  Spotted dolerite with whitish spots.
33e -- altered volcanic ash (stump).  Like 32c
33f -- altered volcanic ash (stump).  Laminated -- like 40c and 41d
34 -- well rounded small boulder, placed on end.  Spotted dolerite with pinkish spots -- like 32?
35 a and 35 b -- irregular and well worn boulder, embedded in the ground and only just visible.  Spotted dolerite with pinkish spots -- like 32?
36 -- an irregular and heavily worn boulder, slightly elongated.  Modern damage on one edge.  Recumbent
37 -- smallish well-rounded boulder, slightly slab-shaped and set on end.  Spotted dolerite with moderate spots.
38 --  smallish irregular boulder, well worn, fallen and under another stone.  Rhyolite, ignimbrite. Dacitic ash-flow tuff.
39 -- another smallish boulder, well worn, slightly slab-shaped, with some later damage.  Leaning, almost recumbent.  Spotted dolerite with pinkish spots -- like 32?
40 -- Rhyolite, ignimbrite. Dacitic ash-flow tuff. Stump beneath ground? Laminated --  like 33f and 41d?
40c -- stump. Laminated calcareous ash
40g -- below ground stump -- irregular shape. Micaceous andstone. Lower Palaeozoic?
41 --  recumbent elongated boulder with heavy wear -- very well rounded edges
41d -- stump.  Altered volcanic ash.  Laminated -- like 33f and 40c
42 -- recumbent wedge-shaped stone with heavy wear on edges.  Densely spotted dolerite?
42c -- stump.  Sandstone (micaceous).  Lower Palaeozoic?
43 -- recumbent slightly flattened boulder with heavy wear on edges.  Densely spotted dolerite?
44 -- heavily worn boulder just visible in the turf -- recumbent.  Spotted dolerite?  Similar to Boles Barrow dolerite?
45 -- recumbent elongated boulder with heavy wear on edges.  Unspotted dolerite? Different from 44.
46 -- slightly slab-shaped boulder set on edge.  Flaky -- considerable recent surface damage.  Rhyolitic ash-flow tuff like stone 48? Or is it a lava?
47 -- slab with heavy wear on edges -- set on end.  Spotted dolerite with pinkish spots -- like 32?
48 -- small recumbent boulder with heavy wear --  just projecting through the turf.  Rhyolitic ash-flow tuff (flinty blue) but not like stone 46?
49 -- small irregular slab with quite sharp edges.  Upright.  Signs of dressing? Intended as a lintel?  Spotted dolerite with pinkish spots -- like 32?

Many of them probably weigh between 1 tonne and 2 tonnes, and the great majority are heavily abraded, with rounded off edges and apparently a considerable weathering crust or patina.    The Boles Barrow bluestone boulder, recently figured on this blog with the help of new photos from Tony, fits into this pattern remarkably well.

If I was to see this assemblage of battered and abraded bluestone erratics in a modern pro-glacial or ice wastage environment, I would not bat an eyelid.  To repeat what I have often said before, this is as perfect an assemblage of glacially transported erratics as you are ever likely to find gathered together into one place -- with one outlier at Boles Barrow!

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