Where Did The (Great Flood) Water Come From And Where Did It Go?

I'm trying to work out the possilbe mechanism for the sea level changes.I assume conventional geology would involve such mechanisms as changes in ice sheets, glaciers, etc. over the course of centuries.The ICR proposal is daunting. Since the changes are so fast, we can't be talking about freezing that much water that fast. The only mechanism I can think of for the ICR concept is for the continents bobbing up & down like a bunch of bath toys.Look at the Tejas Megasequence. Drop the water level (raise continents) 450 m in a couple days, raise water 150 m, drop water 50 m, raise water 200 m, drop 200 m, raise 100 m all in 20 days by very rough scaling of figure.This is panning for gold on a planetary scale. All loose material on the continents below the peak of 200m above present sea level would be washed into the ocean basins to settle out. The continents would be covered by silts & clays at best, bed rock is more likely.