Skyworld: Canyons

You did well creating a sense of depth by changing the hues and vibrancy of the rocks as they recede into the cloudy background. It's immediately apparent what parts of the landscape are in the foreground and what parts are in the background by the way you used light and color---it's easy to understand and it's harmonious. You avoided the chaotic, blended-in look that a landscape made entirely of one material could have had. What could add more depth and pop is more layers; essentially more paint on the canvas. The beauty of most paints is that they're not entirely opaque, and the paint below the top layers shows through enough to create that glowing effect light creates when it strikes an object. The general rule of thumb I use is that if I can still see the grain of the canvas, I don't have enough layers. I think you understand light and hues very well; more layers and more detail in the foreground could turn a well-done piece into a breathtaking one.
As well as a clear sense of depth, there's a clear sense of relational size. It's been established that dragons are usually pretty big, and the size of the opening this dragon is flying through shows me the vastness of the formation, giving it potential to be an awe-inspiring place. However, the dragon itself doesn't give much of an impression. I think that as it is, the dragon could be changed to any other large flying creature and the overall piece wouldn't change a bit. Despite the dragon giving me a sense of the formation's size, the overwhelming question is, "Why is it there, really?" For being a mythical beast, it's an underwhelming component. Having it placed in the dead-center of the piece surrounded by this vast, empty landscape gives me a feeling of eerie loneliness that slightly detracts from the cool, lofty vibe you created with the clouds and the atmosphere. I think putting more dragons flying behind that dragon in the background, putting a more detailed one closer in the foreground, or even just placing the one dragon somewhere besides the exact center would improve the mood of the piece. (The "rule of thirds" is popular with photographers but I think it can be applied to any visual art medium---the eye will be drawn along the lines where you could evenly cut the work into three pieces. Putting objects of interest along those lines is aesthetically pleasing).
The longer I look at it, the more I'm impressed with the use of color. The pale tans where the light washes out the color of the rock, the burnt orange in the shadows, the purple where the mist stands in front of it. It's what makes the piece.