Skyreholme 1
Image by BrigantesNation

http://www.themodernantiquarian.com/post/27651

All of these look extremely natural to me. I trip over bits of stone like this every time I go out (well, it seems that way).

Apart from that, which of those names apply to which of the many sites up there?

You could add them as alternative names (if you haven't done so already - I only looked at the images)

I retract the 'all' and say a lot of them look natural to me ...