Newall's Boulder - found at Stonehenge
.JPG)
John's key argument that the boulder that was sourced from Craig Rhosyfelin in Wales and found at Stonehenge was glacially transported is this:
In seeking to understand how the Newall Boulder might have
been transported from its original place of origin, a number
of key features need to be explained:
- 1. a crude bullet shape, with a pointed nose and a blunt back end
- 2. at least five major facets and several smaller ones
- 3. abraded surfaces and edges
- 4. fracture scars on the flanks and especially at the lee or blunt end
- 5. apparent streamlining prominent on one facet
- 6. faint crossing scratches on one facet and weathered parallel scratches on another
- 7. minor crescentic gouges and microfeatures (chip marks or chatter marks) attributed to pressure exerted at particular points.
On the basis of its shape the Newall Boulder is classified
on the Powers six-category scale as sub-angular (Powers,
1953). In general, clasts in periglacial slope deposits
and rockfall fragments tend to be sharp-edged or angular,
simply because they have not travelled far. This boulder is
clearly not simply a broken piece of rockfall debris
E&G Quaternary Sci. J., 73, 117–134, 2024
124 B. S. John: Stonehenge bluestone erratic
The evidence, including many photos, shows that the boulder is identical to those still at Craig Rhosyfelin. They are abraded, rounded, scarred, have apparent streamlining etc.
The simple conclusion is that Newall's boulder shows no signs of glacial transport from Wales to Wessex. John fails to provide any evidence that it differs from its siblings still at Craig Rhosyfelin, he failed to compare them, and unless he can then his whole hypothesis collapses.
John's photo of a boulder at Craig Rhosyfelin
The same photo with the Newall Boulder from Stonehenge added as a photographic layer
.JPG)
Two more photos of similar boulders at Craig Rhosyfelin
Newall's boulder compared to the tip of in situ pillar at Craig Rhosyfelin
No comments:
Post a Comment
Comments welcome on fresh posts - you just need a Google account to do so.