I just searched and found this on the net. I did not check it.
[AL-QUR'AN 55:19:20]
In the Arabic text the word 'barzakh' means a barrier or a partition. The Arabic word 'maraja' literally means 'they both meet and mix with each other.' Early commentators of the QUR'AN were unable to explain the two opposite meanings for the two bodies of water, i.e. they meet and mix, and at the same time, there is a barrier between them. Modern Science has discovered that in places where two different seas meet, there is a barrier between them. This barrier divides the two seas so that each sea has ita own temperature, salinity and density. {Principles of Oceanography, Davis, pp. 92-93.} Oceanologists are now in a better position to explain this verse. There is a slanted unseen water barrier between the seas through which water from one sea passes to the other. But when the water from one sea enters the other sea, it loses its distinctive characteristic and becomes homogenized with the other water. In a way this barrier serves as a transitional homogenizing area for the two waters. This scientific phenonmenon mentioned in the QUR'AN was also confirmed by Dr. William Hay who is a well-known marine scientist and Professor og Geological Sciences at the University of Colorado, U.S.A.