9781422280492

The Many Uses of Salt

Our oceans are the greatest single source of salt.

Bonneville, around 12,500 years ago. Scientists estimate the lake was as large as present-day Lake Michigan and a thousand feet deep at its peak. The greatest natural source of salt, however, is the ocean itself. The ocean covers 70 percent of our planet. In fact, 97 percent of the earth’s water is salty. It has been estimated that if we were to extract all the salt from the ocean and pile it on the earth’s surface, it would create a layer over 500 feet thick—that’s the height of a skyscraper! All this salt gets into the ocean through the action of rain. As rain falls on land, it washes over rocks. Acids in the rain break down, or erode, the rocks. This creates the charged atomic particles known as ions. The ions flow with the rain down into streams and rivers and out into the sea. Sodium and chloride account for 90 percent of the ions in the ocean, and together they form salt. The salt stays in the ocean because when the water evaporates, it leaves the salt behind.

13