Consider the following Qur’aanic verses: “He has let free the two bodies Of flowing water, Meeting together: Between them is a Barrier Which they do not transgress.” [Al-Qur’aan 55:19-20]
In the Arabic text the word barzakh means a barrier or a partition. This barrier is not a physical partition. The Arabic word maraja literally means ‘they both meet and mix with each other’. Early commentators of the Qur’aan 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 the places where two different seas
meet, there is a barrier between them. This barrier divides the two seas so that each sea has its own temperature, salinity and density. 7 Oceanologists are now in a better position to explain this verse. There is a slanted unseen water barrier between the two 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 phenomenon mentioned in the Qur’aan was also confirmed by Dr. William Hay who is a well-known marine scientist and Professor of Geological Sciences at the University of Colorado, U.S.A. The Qur’aan
mentions this phenomenon also in the following verse: “And made a separating bar between the two bodies Of flowing water?” [Al-Qur’aan 27:61]
This phenomenon occurs in several places, including the divider between the Mediterranean and the Atlantic Ocean at Gibralter. But when the Qur’aan speaks about the divider between fresh and salt water, it mentions the existence of “a forbidding partition” with the barrier. “It is He Who has Let free the two bodies Of flowing water: One palatable and sweet, And the other salty and bitter; Yet has He Made a barrier between them, And a partition that is forbidden To be passed.” [Al-Qur’aan 25:53]
Modern science has discovered that in estuaries, where fresh (sweet) and saltwater meet, the situation is somewhat different from that found in places where two seas meet. It has been discovered that what distinguishes fresh
water from salt water in estuaries is a “pycnocline zone with a marked density discontinuity separating the two layers.” 8 This partition (zone of separation) has salinity different from both the fresh water and the salt water.
This phenomenon occurs in several places, including Egypt, where the river Nile flows into the Mediterranean Sea.