Did ice carry the whole "bluestone quarry" to Stonehenge?

Before and After?  Just think about it.....
Above:  the Big Rocks erratic cluster at Okotoks in Alberta.  Below:  Stonehenge from the air.


In my last post I suggested that glacier ice might have entrained extremely large masses of bedrock (maybe weighing thousands of tonnes) during its passage across North Pembrokeshire during the Ice Age.  If that happened -- and such a thing is quite possible -- we do not have to worry about where the "bluestone quarry / quarries" might have been, since it or they might have have been dumped at or near to Stonehenge itself.  In other words, if we are looking for traces of bluestone quarrying, we need look no further than Stonehenge itself.

I don't think I have descended into madness here -- and indeed the specialist literature is full of examples of truly enormous slabs of bedrock that are dragged along on glacier beds or even entrained into glaciers along shear planes.  FOR EXAMPLE:

1.  A slab of Cretaceous rock in Caithness, measuring 200m x 137m x 8m
2.  A raft of limestone in Northumberland 800m long
3.  At Great Potton, a raft of limestone over 300m long
4.  At Melton Mowbray, a raft of Lincolnshire Oolite 275 x 90m in extent
5.  On Anglesey more than one limestone block over 90m long
6.  Near Abergavenny a gritstone erratic 180m long
7.  The "schollen" of Germany -- made of Tertiary and Cretaceous clays and sands -- up to 4 km x 3 km x 120m
8.  SW Alberta -- one erratic measures 24m x 12m x9m, weighing more than 18,000 tonnes
9.  Malmo, Sweden, an erratic mass of chalk resting on till is 5 km x 300m x 50m.  Extensively fractured, but still coherent.
10.  Ohio -- a tabular erratic resting on till has an area of 1850m2 and a weight of c 13,700 tonnes, but a thickness of only 1.5m.

Some of these dimensions are amazing, and the entrainment of erratics on this scale can only be accounted for by "freezing on" conditions at the rock-ice interface creating a bond that is stronger than the bond contained within the unfrozen bedrock deeper down.  So the frictional drag in the coherent rock is overcome, and massive slabs are dragged away.  So this happens -- the fact of the matter is supported by observations in the field, and by glaciological theory.

What happens after the entrainment has occurred?  Well, it has to be said that except in rare cases (see above) these great entrained slabs are quickly broken up during glacier transport.  Some great slabs survive for 20 km from their places of origin, but seldom for much further.  So the more common scenario would be for slabs to move up into a glacier along shear-planes and to be subjected to sufficient stresses to break them up into smaller bits and pieces, while still being carried along together, in a cluster.  That, in my view, is a distinct possibility with respect to the Stonehenge bluestones.  Because of the preexisting tendency of spotted dolerite (for example) to break up into pillars because of the joint / fracture pattern in the native rock, elongated pillars and slabs would have been the natural features to have resulted from this process.  If some larger masses of bedrock did survive until they were dumped somewhere on Salisbury Plain, then relatively simple wedging and levering might well have allowed these masses to be "quarried" by the builders of Stonehenge to give a supply of further useable orthostats.  The builders used up whatever resources were available to them -- and when they were gone, they were gone -- the building work shuddered to a halt, and there never were enough bluestones to finish the job. 

My preferred scenario here would be for some pillars and slabs to have been entrained individually by overriding ice from a number of locations where "entrainment conditions" were met at the base of the glacier -- with further supplies of stones coming from great entrained masses which were then, to a greater or lesser degree, broken up during transport.

Yes, this is an "extreme" theory -- and everybody will say that there is no independent evidence in support of it.  But we are very arrogant indeed if we think we already know everything there is to know about the sediments present on Salisbury Plain, and I for one am not yet prepared to rule out a number of glacial possibilities, of which this is just one.......