LOL! I would of course defer to Midgard!
Well met ! From Redrobes
I'll ask him to comment more if you think it would help. I duck the issue cos I don't know anything about it. I am a me-dem Tolkien fraud !
Mythologically, as I understand it, Middle Earth was at one time understood to be a flat world but, through the magic of magic, it was transformed into a round world following the second age, when the Undying lands were removed from the world (in a stricly physical sense), which is what prevents all but the elves (who apparently can sail on metaphysical seas) from reaching them.
I'm not 100% sure on that, though, but it's something I've read about recently.
Anyways... I think it's been covered here, you can have the edges of your world be due to any number of things. The ocean plunging away into a bottomless abyss is but one of many fun ways to create your world. Go with whatever strikes your fancy!
I think, therefore I am a nerd.
Cogito, ergo sum nerdem.
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