First time here so be gentle..
Anyways, most of you guys have touched on this and I might have missed the discussion about it, but to me this looks like a classic super continent that is breaking up. So my thought, since we don't have to work on geological time scales due to "magic" in the form of high storms driving the continental divides, we could reasonably assume that the this pangea type world could have been much more compact in the 1st few desolations.
To my eye, the epicenter of the original continent between the purelake and tarat sea with much more forced expansion north of purelake almost as if there was a force driving the land apart. Here's what I thought it could look like: http://i.imgur.com/X1aIRGf.png The picture isn't great but you can imagine looking from the original to this where pieces might fit together.
One interesting side, is that Kurth gets placed right at the top, middle of the purelake. The only reference I've read is Kal talking about seeing the world and mentions Kurth as the "city of lightning." Depending on timescale, how fast the expansion is happening, Kurth could be the obsidian city Dalinar saw in his vision (most likely a longshot). Ru Parat also looks like it could have merged with the purelake as well but there really isn't any mention of the city and it could have been founded much after.
Just a different way of looking at the map.
