The first I call the pillars. It is the result of playing with the crater shader while trying to learn more about displacement.
The second is just an unfinished image I was working on that I did some post work too. I thought it looked interesting.
Really love the pillars ;).
Nice work! The first one reminds me of this image: http://www.planetside.co.uk/gallery/v/tg2gallery/file_1365442.jpg.html
Love everything about the first. Your textures are always amazing. Maybe you could share a little of your texturing knowledge. We have some people (like me) who are still trying to get this right. Love the sky on the second one and it's a great WIP.