I don't think that you're going to find large patterns of ruins. The best you might be able to find are patterns of pebbles and cracks and rocks and blricks and such. For elevations, well, darker colors are lower and lighter colors are higher so maybe airbrush in some colors and set the layer to overlay or soft light or something.

It would be most helpful if you could tell us what software you are using and also an example image of what you're aiming for so that we can understand better.