Oh dear, this faulty argumentation again. Sigh. For the hundredth time, if not thousandth time, science at the time may have been different from now, but sailors and 'scientists' at the time were very well aware of this "barrier". Estuaries were everywhere, and no one spending a few years around them would fail to notice the apparent failure of salt and fresh water to mix.According t the quran (again more than 1400 years ago) the river water does not mix with the sea water, further more there is a barrier between them! Yet in recent days according to researches. when river water meets the salty sea water they do not mix they go back to their own waters and at the point where they meet there is a barries of water that is less salty than the sea water and not fresh as the river water, which does not allow these waters to mix!
Man, you wanna tell me that a Man living in the desert 1400 years ago, made this claim when at these days science was very poor!
Note the word "apparent". You see, the two can definitely mix (and thus contradict there is a forbidden barrier!), but need stirring to speed that mixing up.
And if you call Mohammed an illiterate (which is questionable interpretation of the koran - a much more likely interpretation just indicates he wasn't jew or christian), do remember that he worked closely with various merchants, many of which will have travelled the rivers and oceans and thus would have known.
Sorry, but you just made a fool of yourself by claiming people didn't know of the apparent poor mixing of fresh and salt water (extremely unlikely), and you actually showed the koran is wrong by claiming there is a forbidden partition. The koran claims it isn't wrong on anything, so you now either must admit you muslims don't understand the koran, or the koran *is* wrong.