Nice image and textures but I like it better when I crop out the horizon. I feel that it strengthens the image. You might try printing it that way or trim it off.
Composition and blending of tones combine to evoke a feeling of peace and calm. Very well done. Reminds me of some of David Fokos' work. (http://www.robertkleingallery.com/gallery/fokos)
It adds the dimension of "deep space"...it is vitally important to this image. Without the horizon it becomes just another image about a bunch of rocks.