Pamela Tucker, aged 6, of Compton, Calif., for her question:

Why aren't rivers salty if they carry salt to the sea?

It is true that the rivers do carry salt to the sea. This great robbery has been going on for millions of years. The streams and rivers never stop stealing salts and chemicals from the land. They dissolve these chemicals and carry them along to the sea.

The sun dries up water from the face of the sea. But it leaves the salts and chemicals behind. The water in the air falls again as fresh, pure rain. The rain steals mare salts and chemicals from the sand. It runs along in streams and rivers to join the sea again.

River water carries only a small load of salt at a time. Fresh river water does not carry enough salt for you to taste it. But there is always a little. The river also carries small amounts of ell the other chemicals found in the sea. The sea holds onto its salt and chemicals. The river water starts out fresh and clean. And it takes along only a small load at a time.