Sometimes it might be complicated to understand what I mean. This at least shows you what I meant with a world of layers in my myWorld project. Here you can see a part of a mountain (view from DynMap, a plugin for that) with it's full chunk caves in some areas. MyWorld consisted of 25 of those layers.

I really like the cheesy rock :D
(Buildings and terrain type by #OpenStreetMap, height by #NASA, generated by me, implemented in Java/Bukkit/Minecraft)

55549386s ago, by Antonio