- Alternatively, Gerald succeeded in his Colony Drop while still alive due to GUN unable to locate him. The reason Earth even exists is because, without the Chaos Emeralds, the ARK "merely" caused an extinction event similar to the event that wiped out the dinosaurs, or worse, the Great Dying. The survivors used the Chaos Emeralds to escape. This Eggman's desire to destroy the Land of the Sky comes from not just a desire to father a new mankind, but Gerald/an instructed Biolizard surviving the Colony Drop and inspiring decades of omnicidal mania to Eggman's upbringing.
1. The Land of Darkness resembles New York City, and is referred to as "The Ancient Relics".
2. Survivors of the cataclysm, utilizing some type of magic, managed to raise continents into the sky (This also explains why the continents can be destroyed so easily: they were never meant to be there).
3. An unintended side-effect of raising the continents was the creation of the warp zones.
4. Once the continents were raised, the survivors sealed off the surface world with a massive layer of clouds. The entrance was created by Dr. Robotnik blasting his way through.
5. The cataclysm was caused by a powerful demon and/or a demonic army. Since this was presumably thousands of years ago, everybody's pretty much forgotten. Robotnik, after living in The Land of Darkness for awhile, discovered this and used it as inspiration for his Metal Robotnik facade.
Both have inhabited Floating Continents and a desolate, uninhabited surface. The two areas are separated by a thick cloud layer, which can only be crossed through a vortex. Said vortex has a very chaotic environment and will destroy most ships.