Branwen wrote:
I suppose I would have expected the boulders to be half buried and half sticking out of the peat, but now I think of it more, there are a lot of places where the ice scraped down to the bedrock. And there a stone lies, no peat laid down around it cos nothing grew there. That would explain why the boulders are on top, not buried, I guess.
It depends on the amount of peat . Under the peat is often gravel or the earth that supported the trees prior to the peat deposition .I'm no geologist but from observation erratics can create their own micro topography rain falling from the edges providing small amount of nutrients to otherwise acid soil , animals use them for shelter which lowers the height of surrounding peat etc . There is bound to be a huge amount of archaeology under peat .