Image Reaper: Check up on that technique again. There are some excellent pictures in a High Times from...oh I want to say sometime in 2002? Anywho, it's not the top half of the previous soil that is left above the new soil but rather a very small amount. To put it more plainly, it's more like small steps as opposed to one of those Mayan pyramids. And it does work nicely. I would only recommend using this technique with soil though and not something like a peat-based medium, which isn't quite as steadfast.