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.