12- Water resources:
For centuries, it was not known that rivers originate mainly from clouds colliding with the cold peaks of lofty mountains. They condense into rain water, or freeze as ice that melts away later. In either case, water flows down the river stream. This coupling between lofty mountains and rivers formation is stated in the verse:
§ And have placed therein firm and tall (lofty) mountains, and have given you to drink sweet water? [77/27].
On the other hand, the original source of springs and underground wells is also rainwater; that infiltrates the ground to finally collect in huge underground aquifers. This is a discovery of modern science (Plessey 1570 A.C.), that was stated explicitly in the verse:
§ See you not that Allâh sends down water (rain) from the sky, and causes it to penetrate the earth, (and then makes it to spring up) as water – springs. [39/21.
For centuries, the saline seas and oceans were the main sources of pearls and other precious stones. Relatively recently, however, it was discovered that some freshwater rivers, as well, contain a variety of precious stones. These include pearls in some rivers in the British Isles, Czechoslovakia and Japan, as well as several other stones like diamonds, sapphire and zircon in different rivers and river sediments. This confirms the information given by the verses:
§ And the two seas (kinds of water) are not alike, this is fresh and pleasant to drink, and that is salt and bitter. And from them both you eat fresh tender meat (fish) and derive the ornaments that you wear. [35/12]
§ He has let loose the two seas ( the salt and fresh water ) meeting together. Between them is a barrier none of them can transgress. Then which of the Blessings of your Lord will you deny? Out of them both come out pearl and coral. [55/19-22]