Friday, 4 January 2013
Rhosyfelin Dig Site
As a service to mankind in general, and Kostas in particular, I have marked the approximate dig site at Rhosyfelin with a greenish blob on this satellite image. The river flows along the shady area in the wood from the south (bottom of photo) towards the north, curving gently along the bend in the valley.
The topography of the valley is actually quite complicated here, with many relict features which I attribute to meltwater erosion on a substantial scale, maybe partly during the Devensian glacial episode but probably mostly in earlier glaciations including the Anglian. The meltwater erosion might have been subglacial. The zig-zag in the road has messed things up a great deal, but if we eliminate the activities of the road-builders we can see that there is a strange double channel cut on the north side of the infamous Rhosyfelin rocky ridge -- water must have been carried north-eastwards into the main channel.
As far as the slope deposits are concerned, as exposed in the dig, they have come from several different directions, moving NE (up against the rock face in the southernmost part of the dig site) -- then E, and then SE along much of the edge of the dig as shown in the photos.
In this photo the direction of debris movement has been more or less from behind my highly reputable friends towards the bottom of the photo (NW towards SE).