Also, as several have mentioned, don't forget that any material can be colored to produce even more variations.
As Pete said, what you want is a variation of texture.
I used the local sandy soil in my freight yard - no baking. I figured if something could live "frozen" in solid white glue, it deserved to survive!
But, the longer I looked at it, I began to wish I had used a darker ground cover such as cinders. It was depressing to calculate how many pounds of new, darker ground cover (and how many hours!) I would need to do the changeover. The yard is 35' long!
Then, one day I found a can of almost black flat latex house paint in the "oops" department at Lowe's. As an experiment, I took a 2" brush and started slapping on the paint, covering everything - ties, rails and dirt - with a thick layer of paint.
A half-hour later, it was done, with a lot less grief than I had imagined! Just enough brown showed through to give it a little variety in color in places.
The paint was removed from the rail tops with a block of pine and, later, an LGB track cleaning block.
Jim
