This is looking down half way across. The rocks are still quite angular which shows that they haven't been transported very far. Pebbles on the beach are much more rounded. I'd say that the pebbles in the amazing conglomerate rock at Dunnotar Castle that I blogged about in August were much more like beach pebbles.
The fields often have massively thick walls. The stones were all over the fields and had to be put somewhere when the fields were cleared. I'm guessing that this was glacial deposition rather than fluvial but I might be wrong.