I'm making a raised border around my gravel garden. Under the gravel the "soil" is just rocks and more rocks. So the border will need to be raised and we've order a few tonnes of topsoil. I've also bought log edging rolls. But how do I install them if I can't hammer them into the hard ground? I can't fill the borders without edging so I feel like it's a chicken egg situation. Any advice on building a border over rocky soil would be hugely appreciated. Tia