Karen Kent, age 12, of Eaton Rapids, Michigan, for her question:

How can water get into underground streams?

A large percentage of water from every shower sinks down into the soil where it may repose as buried ground water. Every rainfall adds to these stores of under¬ground water and so do the melting snows of spring. There is an immense amount of underground water in the land. Its storage is governed by the nature and the formations of rocky layers far below the surface. Reservoirs of deep ground water rest on solid slabs of shales and granites because it cannot seep through these dense rocks. Some gets trapped in the spongy holes of sandstone and other porous rocks. And water tends to dissolve limestone and other soft calcium rocks.

The pattern of buried ground water is forever changing. Its upper level rises with extra rainfall and falls during droughts. It flows down dense underground slope sand nibbles holes in soft limestones. Sometimes it chisels out tunnels and flows through chalky or limestone hills in underground streams.