If this is new to you, you should also investigate Perlin noise used to generate terrain. There are many examples online. It uses many of the same concepts alth

If this is new to you, you should also investigate Perlin noise used to generate terrain. There are many examples online. It uses many of the same concepts although it's not quite as intuitive. I suspect it is more efficient, though, although that strongly depends on how good the PRNG you're using is.