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Friday, 4 September 2015

The Rhosyfelin "Revetment"






Ever since publishing Davey's report of last year's MPP talk at Castell Henllys, I have been wondering about what that "revetment" remark was all about:

http://brian-mountainman.blogspot.co.uk/2014/09/rhosyfelin-report-on-mpps-17th.html

Over the past winter, much of the site has been buried beneath that large black plastic sheet, but on going through my photos of last year's dig, I found some that I had overlooked.  Now it all makes sense -- well, sort of......

To quote Davey:

He was excited by what had turned up in the last few days of digging, firstly there was the forecourt at Rhosyfelin, there were slides indicating a shallow bowl containing rock clutter and in and around this he said that there were at least three standing stones, all packed at their respective bases by other smaller stones. The purpose of these standing stone was to act as fulcrum to stones being prised off the cliff face. The evidence being crush marks on the top of these stones.

He said that they had made a very important discovery, underneath that large slab in the foreground, they had found that it was resting on a man made terrace and in this terrace was upturned basket shaped lumps of earth and stone. He was particularly excited by these and the way he talked suggested that they were created in a similar fashion to making sandcastles on the beach.
 

He said that they had found the course of the river in the area of your picture and he said that there is a semi circular line of stones which was obviously man made, he described it as a revetment and went on say that it could once have been a jetty, not for putting these 2 ton stones on rafts to float down the river, it was obviously far too shallow, but to load on to sledges to carried further north.

Let's forget about forecourts, fulcrums and crush marks and put those down as products of a fertile imagination, but what about the "man-made terrace",  the "upturned basket-shaped lumps of earth and stone",  and the "revetment" or "sledge-loading jetty"?


Well the photo reproduced above, with and without my red markings, seems to explain at least some of the Prof's thinking.  The dashed lines show the position of the so-called semi-circular revetment presumed to have been used for the loading of 2 tonne stones (what about 8-tonne stones?) onto rafts or sledges.  I suppose this is what MPP means when he says he has found the old course of the river.  The solid red line shows a "route" marked out with string last year, presumably indicating the route that would have been used for dragging stones from the "quarry" to the loading facility.


Again, this is a quite wonderful archaeological artifice, created by the removal of all the fines and "inconvenient" stones from the "outside" of this magical quayside.  Before excavation, the grey and foxy-red fluvioglacial and alluvial sediments covered these big stones.


So now we have this glorious image of the loading crew sitting by the quayside, listening to the gentle murmuring of the waves, with their raft bobbing about gently in the shallows, as they wait for the next bluestone to be delivered by the quarrymen.........


I suppose this is why the 2015 dig might well concentrate on the valley floor, with a view to showing the world what the quayside and the old river bed might have looked like in the good old days.



6 comments:

chris johnson said...

A couple of years back Mike said he was expecting to find such a feature as you now describe. How prescient of him to now actually find it.

I wish I could be sure to be in Pembrokeshire the next couple of weeks to pick up more rare pearls of wisdom.

TonyH said...

"Let's forget about forecourts, fulcrums and crush marks, and put those down to products of a FERTILE imagination...."

Fertility in a soil context relies, if man introduces farming year upon year, on manure to maintain that fertility...... do you follow my drift?

MPP's self - confessed Hero is Indiana Jones......it's on his Amazon site.

Presumably Harrison Ford is already being booked to play MPP in a future epic.

TonyH said...

"There are none so deaf as those who will not hear" (old saying, date unknown, certainly prevalent Up t'North.

Just how open a mind does Mr Michael "Ruling Hypothesis" Parker Pearson [and Friends] possess? To what extent could Geomorphology and Glaciology be part of His/ Their World View?

Please discuss.

I.R.A. Doubter said...

Nevertheless, those who play with ice can also slip, fall, and and end up looking silly.

BRIAN JOHN said...

Very true, Mr Doubter. History is full of hypothesis that bite the dust, in glaciology as in every other field. I have had a few myself which have had to be ditched / modified. I am not complacent. I simply try to describe what I see, interpret what others claim to see, in the light of my own experience, and expect the truth to prevail eventually...... weight of evidence is what matters in the end.

Ms Doubter said...

Agreed