Granted some of the books are pretty loosely related to geology, but I thought it was still fun.
The Big Rock Candy Mountain (This is actually a book?)
The bible of the evolutionary biologist The Origin of Species.
Under the Volcano (I bet it's hot)
Here is a view of the entire sculpture. Sorry it is a little washed out, it was pretty bright that day and my ipod apparently couldn't handle it.
UPDATE: Here is a better photo that isn't as washed out.