Erratic speculations

Three pictures from at area that might be expected to supply erratic material into the Irish Sea Glacier as it flowed across this area on its way towards Salisbury Plain.  Top:  one of the tors on the ridge crest.
Middle: a perched block (locally derived) on the same tor.  Below:  rocky outcrop (one of many) in among the gnarled oak trees of Tycanol Wood.  In the lower part of the wood, the rocks are partly rhyolites.  The tors are made of dolerite.