That looks like it's using a procedural shader called Strata and Outcrops Shader so that's your first hint if Vue can procedurally produce those you've got a start spot. Next there's a lot of small scale noise bumpiness, likely a Power Fractal Shader, they do displacement and colour and are a basic texture start point...I'm sure there's a Vue procedural similar to that. There is evidence of the Fake Stone Shader on the lower levels and and the rock object [a procedural] may have been used . The fake stones could be done with a masked rock ecosystem...can you vary the size with in an ecosystem...I don't use them in my PLE version Vue so I dunno bout that. Texturing you'll have to get help from the Vue Wizards...there's  a bunch of really knowledgable folks here so you should be able to crack this nut....Good luck and I do hope what I've written helps.. ...

 

Once in a while I look around,
I see a sound
and try to write it down
Sometimes they come out very soft
Tinkling light sound
The Sun comes up again