Kathy Monti, age 13, of New Brunswick, N.J., for her question:

HOW DID ALL THE SAND GET ON THE BEACHES?

Most of it is toted there by the rushing rivers  and the sand making process started long ages ago. Grains of golden sand are gritty crystals, made of silicas and other extra hard minerals. Usually they form in volcanic lavas, as these mixtures of assorted minerals cool in the air. The sand making ingredients form gritty little crystals embedded in softer, less durable rocks.

The winds, the rains and especially the rushing rivers are forever eroding the rocks of the earth's surface. Naturally the softer minerals are washed away first. When this happens, for example, to great slabs of granite, piles of gritty sand are set free and left behind. Rivers tend to wash the golden grains down to the beaches by the sea. More sand is added as pounding waves release gritty grains embedded in underground rocks.