Floor
The floor of Gaea is 250 km wide and 30 km thick, with an outer radius of 650 km. The books site great subterranean (or subgaean, rather) "bone plates" that are held in place by the cables. I can't even guess at the nature, size, or geometry of these, so for now I wont try. These pictures are here mostly to illustrate the 30 km thickness of the floor
The inner surface of the floor makes up the landscape that is lived and traveled upon. Great systems of caverns are known to link the Gaean regional brains 5 km below the surface. Also contained at some unknown distance below the land surface is a particle accelerator that runs completely around Gaea's circumfrence, officially granting Gaea more accessories than Barbie.
A notable feature of the floor's terrain are the north and south highlands. The land near the walls rises 3 km on near-vertical cliffs, plateau's and then rises gently to meet the walls. I have not been able to include this feature with the model yet. There is a painstaking way of doing it, but I'll save that for when I can figure out how to do the rest of the terrain modeling.
In the above pic you can see pretty clearly how the surface texture has been faked, mirroring the eastern Oceanus and western Rhea textures. I made these textures in twenty degree increments for quick and dirty render testing. More accurate terrain textures on the way, promise