This is my first tutorial on here so please bear with me. I thought I'd give something that would show just how easy creating a surface render can really be.
This tutorial will show you a technique that allows you to experiment with the settings, in order to achieve what your after, rather than go hunting over the web for someone elses work, leaving all the credit to yourselves ;o)
I use AdobePhotoshop but Gimp is free and does a good job as well. The same technique applies.
Here is my finished result from the tutorial.
1. create your document to the size you want to work with (I'm running with 512,512 for this tutorial), then fill your image with black.
2. Set the Background colour to Black and the Foreground colour to White.
Then apply a cloud render -- Filter~Render~Clouds.
3. View the channels window -- Window~Channels.
4. create a new Alpha channel.
5. On this alpha channel we apply a Difference Clouds Render -- Filter~Render~Difference Clouds.
You can keep re-applying difference clouds as many times as you wish for varying results, but for this tutorial, once was enough for me.
6. Now we select the original RGB channel and go back to our Layers window.
7. Make sure the layer is selected, then apply lighting effects to the layer -- Filter~Render~Lighting Effects.
8. Ensure you are using the Alpha Channel you created in the texture Channel selection box and the height setting is 100% mountainous, then let your experimenting begin. This image is showing the settings I used for this tutorial. Don't be afraid to play, it's how we learn.
9. Time to add colour to our texture. Add a new adjustment layer for the Hue and Saturation -- layer~newAdjustmentLayer~Hue/Saturation.
10. just go ahead and click the OK button here.
11. Put a little tick in the Colorize box, as shown here, then it's back to experimenting again with the slider settings to achieve a lovely, appealing colour.
12. Flatten your Image, save it out to your desired format and your done, Unless of course there is an experimentalist in you, then see how far you can push it.
I hope this has been informative and encourages you to create your own Rocky surfaces.