After much delay in trying to figure out how to make mountains more than boring up-and-down rises, I tried plugging a power fractal + warp shader into the base terrain. It's far from perfect but getting nearer to what I want to achieve. Still more work to do.
Please ignore the foliage. I did little more than slap it down just to hide some of the strange formations. For me it's the terrain that matters most.
It's quite a striking formation, although a bit spiky. Where are you taking it next?
domdib - with Terragen 2, it has never been so much as where I take it, but where it takes me...