Quote Originally Posted by noob View Post
Maybe for some reason heavy elements accumulated on one side more than on the other.(the world is a Toroid so the rules of physics are not the same than in real life else the world would not be a Toroid).
As far as the rules of physics go, if the toroid is spinning then there's an acceleration towards the center. This property has been used in real life to sort material mixes by density - by which I mean it's how centrifuges operate. This would put higher density materials towards the outside ring.

From a physics perspective, that doesn't necessarily mean much for solids - a lot of them are going to be pretty well embedded in the structure. It's more relevant for fluids, particularly the atmosphere. This is where it gets weird, with those fluids being a mix of mostly liquid phase water and the atmosphere. Essentially you get an ocean pushed to the bottom of the outer ring, and an atmosphere that's much denser towards the outer ring than the inner ring out past the ocean layer. This then effectively creates altitude effects, and because of the toroid flattening they're even in an intuitive direction.

This then gets really weird when bringing in gravitational effects, and keeping the fluids around at all necessitates a controlled range of spin velocities and gravitational strengths. This could likely be parameterized pretty easily (Reynolds number style) for a wide range of toroid sizes, but that's more math than I'm willing to put into this.