Nice values in this one; there's a definite separation between foreground, middle ground and background. The light and dark extremities add a nice sense of depth, though it feels a little monochromatic with the color, which some subtle blues in the background might have been able to help.
Very very cool cave sketch. Very well done, but it's a cave and caves gather moisture, so there should be some water dripping from the ceiling... Hence the stream/river in your cave. It's really good, looks pretty damn real; I wouldn't mind going there to do some observational sketches.