What's the difference if we know or not? We don't know for sure how the round Earth came about either. Yes, there's speculation, but so what?
My speculations on the formation of the flat Earth are that dust and dirt was tumulted and carried by the Universal Accelerator until it got so heavy that the compression created heat and eventually atmosphere as well as water. As for the ice wall, the water was probably frozen in its original state and obviously the water would be on top of the Earth cyllinder. After the sun came into orbit, it heated up the insides, leaving the North pole, which is farthest away from the sun, and the South Pole, which is very far from the sun's rays and is cooled by outer-space, frozen, leaving a large ice wall where the water was frozen quickly as it began to slosh outwards because of the extreme coldness in space.
~D-Draw