Thank you for the tips, I like your edit on the back mountains agent00x, will try to do something like that 
Yes, as a supporter of entirely all-sufficient [googled the word] pieces of art I estimate anything given without a context as a standalone subject which, according to my beliefs, should represent something (a whole story, ideally), so may be my critics are excess here; in addition, your background, Pukahuna, conveys the mood (see my first comment) amazingly well. The picture is still near-perfect anyway even without context, which means a lot, I should say.
I can see all the crits mentioned below but I don't think it applies to this BG unless you mean as a standalone piece.
In gameplay when these two layers are scrolling (parallax) and you add the playable layer, sprites and GUI and its all in movement this BG will look terrific.
http://i.imgur.com/g931sXy.png
I used mostly copy-paste to your elements, and the eraser. I just want to say you can do more of what you already have by some simple operations, and it won`t be repetitive. =)
I think what feels a bit odd, is that all the rocks are all on the exact same slant.
While it looks great, the repetitiveness (copy/paste foreground/background) does hurt it a bit. Very nice none the less.
That`s nice. The colours are chilling; at the same time, the landscape is not full of serenity but gives a small tense. May be because this place seems [to me] like dead-silent with no life at all.
I found it a bit repetitive, actually. A touch of difference here and there, and it will be perfect.
Wow! Cool!