Thanks for the link. It's a problem everywhere isn't it? Folk like to build stuff.
I just can't see a way to stop it, though hopefully this will help (from little acorns...). Most people just don't really want to think about their actions. That's life and humans unfortunately. I hate coming across orange peel, banana skins etc on hills, just gets my blood boiling. If folk can't be bothered to take their own rubbish home with them what hope is there for just a pile of old stones on top of a hill to be left alone?