Every now and then we come across a fact about our Earth which mystifies us and for which no answer has yet been found. Such a fact is the existence of salt in the oceans. The answer is we simply don’t know how salt got into the oceans. We do know that salt is water-soluble and so passes into the oceans with rain water. The salt of the Earth’s surface is constantly being dissolved and is passing into the ocean.
If all the oceans were to dry up, enough salt would be left to build a wall 180 miles high and a mile thick. Such a wall would reach once around the world at the equator. The common salt which we all use is produced from sea water or the water of salt lakes, from salt springs, and fro deposits of rock salt. The concentration of salt in sea water ranges from about three per cent to three-and-one-half per cent. The Dead Sea which covers an area of about 340 square miles contains about 11, 600, 000, 000 tons of salt.