Ok, the node-screenshot
As you can see I've numbered a few (important) nodes.
So I'll write a mini-tut of it right away this way.
1) = the blend shader (scales 80, 120, 40m) which gives variation to the appearance of the stratas. As you can see the stratas aren't applied all over the terrain but just here and there, to say so.
2) = It's also the mix controller of the stratas. The color information of the blend shader controls the way the 2 stratas are mixed together. The merge shader has default settings. This way the trenches/ditches were created, but honestly I can't reason why they appear. It might have to do that the merge shader mixes displacement and that this shaders interprets the color information from the blend shader as displacement. But I can't tell for sure.
3) = This small scale and low displacement powerfractal gives all the surface layers some bump to give the surfacing some spice and detail.
4) = The fake stones shader setup: the fake stones are approx. 25cm each. They looked very spiky and displaced upwards so I lowered the stone tallness and increased the pancake effect but it wasn't satisfying enough. Adding a default shader is an easy way to control many aspects of the stones' appearance. The 2 powerfractal give the stones small scale color detail (not visible I think). The powerfractal is hooked into the displacement input. This powerfractal has same scale size as the stones, has very low color contrast and roughness, low displacement factor (0,15) and roughness and spike limit to prevent the forming of spikes.
But sometimes the renderer has problems to calculate the geometry correctly and displacing the stones then will create very ugly spiky stones.
I found out that adding a TEX coords from XYZ node solves this problem. I think it calculates the normals for the stones (more) correctly and thus make the powerfractal do the work it's supposed to do.
5) = This surface layer gives the rocks its shiny appearance. Unfortunately I've been a little bit too reserved with this effect. I'm thinking about another re-render to make the effect more prominent. The default shader has the same diffuse color as the surface layer. So, the default shader is a child with 100% cover. Adding very little reflectivity and reflectivity roughness in the specularity tab gives the rock-structure a shiny or wet look.
I hope this has been useful for all of you
Martin