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Saturday, 21 March 2015

Pentre Ifan - Place of Stones

Above is a gallery of images from Pentre Ifan -- all photos taken within 100m of the cromlech itself.  The volcanic ash / agglomerate outcrops hereabouts are extensive, and because most of the fracture planes in the rock are parallel with the rough bedding in the ashes, the rock breaks up into slabs rather than pillars.  In many cases where we see "recumbent slabs" lying in the turf we may actually be looking at bedrock outcrops.  And almost always these exposed upper surfaces are heavily abraded, as a result of glacial action -- probably during the Devensian glaciation.

I'm not sure whether I should refer to many of these slabs and boulders as erratics, because they do not seem to have been moved far from their places of origin.  

There are embankments and terrace-like features on the slope below the cromlech, but it's hard to say whether these features are prehistoric or a result of modern field clearance.

Note that some of the rocks are "on edge" and it is possible that they have been hauled up into "standing stone" positions -- but it is also possible that the slabs have been tipped up by overriding ice.  Some of the slabs lying about in the fields and adjacent to the footpath leading to the cromlech are larger than the capstone itself -- generally assumed to weigh about 16 tonnes.

My conclusion from having a really good look around this site is that the chambered tomb was simply built here because of the sheer abundance of available slab-like stones.  I doubt that any of the stones which we now see in the cromlech has been moved more than 50m from the place in which the tomb builders found it. 


Geo Cur said...

I can't think of any archaeologist who has ever suggested the transport of any stone in amy portal tomb of more than 500 m .
What has changed in the past 15 years and mentioned here a couple of times , is the suggestion that some capstones were not moved but simply had a pit dug around them then lifed in situ . Grimes , excavator at Pentre Ifan may even have been the first to mention this

BRIAN JOHN said...

Yes, in the case of "earthfast" capstones used in Neolithic tombs that's a no-brainer, but I recall in the recent work at Garn Turne there was a serious suggestion by the diggers that the massive capstone had been dragged from an uphill outcrop -- until they realised that they had to abandon that idea. Good for Grimes et al -- perfectly sensible.

The trouble with some modern archaeology is that such is the preoccupation with "location explanations" (see my recent post on Pembrokeshire's Neolithic Tombs) that geology is often completely ignored, and that the most obvious explanation for the siting of a megalithic monument (ie that it was built where the stones were) is quite forgotten about.

Geo Cur said...

But , as also has been explained ,location choice is not as simple as local availability of material e.g. excavated , non portal tomb monuments like Stonehenge.

I should have clarified that I was only talking about UK and Irish portal tombs when mentioning "any portal tomb" .

BRIAN JOHN said...

No problem with that, Goe. As we have discussed many times, in some cases a pre-existing site has been chosen as a place for a megalithic structure. In other cases, pre-existing earth bank and ditch structures have not been used for later stone structures -- quite possibly because no stones were handy in the neighbourhood.