The animated project I am working on has a scene that takes place inside caves. I have been tackling more seriously my background design lately (alongside with refining the character design) and even if it is not yet the beautiful polished background images, I thought I would post the thumbnails I am working on at the moment. 

As I started working towards the realization of the background I have been reading much more about painting, and how it is all about value and composition (versus drawing that can be a lot about the line)
I took upon doing the background in soft pastel, after seeing Ralph Eggleston's work on Nemo. The logic of pastel is rather different than drawing it is actual painting; applying full flat pigment to the page.
Therefore I am doing so thumbnail before hand, and it feels like good practice anyhow.