Originally Posted by WoodlandBrew
The best example I can think of showing stratification of solutions is a trying to pour a back and tan... without a spoon. Even with a spoon it is difficult achive something other than just brown.
Not really the best example, but you are somewhat correct. Some mixing will occur.
However; water and the finished wort, aren't anywhere near the same specific gravity. The best example that you can see if simple.
Take a glass, fill it with water 3/4 of the way full. Top it off with maple syrup. Both are thin.
Pour the syrup in as rough as you'd like. Watch the bottom of the glass.
It'll collect most of the heavy gravity syrup. The water will taste sweet, but mix it up, and taste it again... it'll be sweeter.