There is a method of using some form of tile or wall covering to approximate sedimentary rock like sandstone and limestone. It's broken, glued together and fit in place. What is it one breaks? I can't remember.
Gene
http://www.pacificcoastairlinerr.com/more_rocks/ (http://www.pacificcoastairlinerr.com/more_rocks/)
(http://www.pacificcoastairlinerr.com/more_rocks/image/close_up.JPG)
(http://www.pacificcoastairlinerr.com/photos/bush_background.jpg)
Thank you if you visit
Harold
I think what you're after are plain old ceiling tiles Gene.
Sid
The material is known as "Celotex" and was installed in 1X2 foot pieces on a grid of furring strips, and is a royal pain to install recessed lighting in, old work style. It does make great looking sedimentary rock. Why don't you go out and find some good specimens of what you are looking for and make moulds of [them]; this way, you have the ability and resource to make more. THese castings can be placed in any position you like. I had placed four exact castings on my layout in the same area once, and it fooled everyone-not mother nature, though.
The Old Reprobate
Thanks, guys. That's what I thought they were.
Gene
Wow, Harold....
Again, those look fantastic.