My father in law has some erosion problems, and sparse grass growth in his yard. He has pretty hard soil with a lot of small shale type stones that's hard to dig into. We were thinking about spreading a couple of inches of topsoil on top of the existing ground and seeding or possibly sodding on top of the topsoil. Is that reasonable? We wanted to seed if possible in the spring. If we don't till the existing hard ground, will the 2 inches of topsoil support new grass?