Kent TelTer, Age 10, Of Albomarle, N.C.., for his question:
what causes ocean water to be salty?
A pinch of salt will dissolve and disappear in a glass of water. The salty chemicals of the ocean are also dissolved in water. If we could separate them from the sea, we would have enough powdery chemicals t0 cover all the earth's dry land with a layer 400 feet deep. And every year the salty sea is becoming saltier.
A cubic yard of sea water contains about 60 pounds of disso1ved chemicals. This is enough water to fi11 a tank one yard wide, one yard deep and one yard high. A cubic mile of sea water contains 166 million tons of salty chemicals, and it is estimated that the dissolved chemicals in the entire ocean weigh about 50 quadrillion tons.
Yet, in the distant past, the oceans of the earth were filled with fresh water, or, at any rate, with water as fresh as that in our rivers. Year by year, the sea has stolen its store of dissolved chemicals from the dry land, and it is estimated that this robbery story has been going on for at least 400 million years.
The sea, you would think, must need a gang of acomplices to carry out such a gigantic robbery. And so it has. Its partners in crime are the sweeping rivers, the swift streams that dig through the rocks and cut their pathways into the soil, the little rills and rivulets that gush along giggling over the pebbles and gravel.
This busy crew of merry criminals works day and night to gather loads of chemical loot from the land and dump it into the sea. And there is nothing we can do to stop them. The constant dripping of water, you have heard, will wear away the hardest stone. It does so by dissolving some of the chemicals in the stone ark. Carrying them away the stone becomes weakened and soon the dripping water is washing away chips and fragments.
The running water of our river systems laps at the soil and the rocks. The salty chemicals dissolve more readily than others, and they are soon licked up by countless tongues of running water. The streams bearing their salty loot join to form rivers and the rivers carry the growing load of plunder down to the sea.
The sun evaporates water vapor from the surface of the sea, but the dissolved chemicals stay behind. The vapor forms clouds which drop rain on the land, and solve of the rainfall runs into the rivers. Every year, billions of tons of chemicals are stolen from the land and added to the sea.
A touch of sea water on the tongue has a salty flavor, and most of its dissolved chemicals are various salts. Almost 80,% is ordinary table salt. Also, there are sizable quantities of magnesium chloride and sulphates of magnesium, sulphur and potassium. Salts are most abundant, but more than 50 elements have been found dissolved in the ocean. In a cubic mile of sea water, there is enough gold to make you the richest boy in the world.