The Abyss is mostly always distinct in its hierarchical structure, resembling stacked pancakes with a layer-upon-layer formation. This is clearly not a product of natural formation... Normal geographical structures have no need to be built like the strange layers of a building.
"In fact, this is the essence of the Abyss, the result of constant plundering; each layer is a world that has been plundered. Once a world completely slips into the Abyss, it becomes a new floor of the Abyss..."
Therefore, most such layered terrains are found in the Abyss, transformed from other Secret Realms.
Such terrains naturally trouble orderly societies, with transportation difficulties and vastly different environments. The continuous collisions and changes between the floors make stable passageways unrealistic, let alone establishing a relatively stable realm.
