Plate Tectonics

Wouldn't, in theory, the plates just "fall off" on a FE?

I don't see any plates moving south on that map.

Also a point that should be made about the ice wall is that there is an upper limit as to how high a mountain can get before it's huge mass will cause it to start sinking. I poked around on the Internet and apparently it's been estimated to be about 30km under Earth's gravity, so you'll need something else to hold in the atmosphere above that.

Also a point that should be made about the ice wall is that there is an upper limit as to how high a mountain can get before it's huge mass will cause it to start sinking. I poked around on the Internet and apparently it's been estimated to be about 30km under Earth's gravity, so you'll need something else to hold in the atmosphere above that.

Assuming that to be true, mountains are formed very differently than what I am proposing. Any tower/mountain/building et cetera has different structural integrity.
Structure and size is bound to vary by a mountainous rim, created by the UA, rather than subduction zones.