I feel bad for themodman, the last half a page of shite(correct spelling) is entirely unneeded here and we've forgotten what the thread was about in the first place.
I'd pop a power fractal after the compute terrain node and set its displacement direction to one of the laterals or, use a redirect shader anywhere in the network to push areas outwards along the X/Z axes, that'll give you shelves, just watch out for small scales, else you'll end up with spikes. You can specify blending shaders for the redirecting fractals or, as the blend shader to a regular fractal, if you use that method.
* Mhaze; Capital letters and full stops after a sentence, please! However many words contained therein!
