Nutrient- and sediment-laden fresh water from the Fraser River in British Columbia rides up and over salty ocean waters, which are beginning to march upriver during flood tide. The interaction of the two water masses of different salinities and densities in the estuary creates underwater turbulence and mixing that naturally flushes and energizes the coastal system.

The Holy Quran has mentioned this fact, Allah SWT says: (And He it is Who hath given independence to the two seas (though they meet); one palatable, sweet, and the other saltish, bitter; and hath set a bar and a forbidding ban between them) [25/53].

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By: Abduldaem Al-Kaheel

Source: WHOI