Paul Whiskeyman, age 10, of Lititz, Pennsylvania, for his question:

How did all that sand get on the beaches?

You can thank the earth, the rains and the rushing rivers and also the turning tides of the oceans. When you hold a handful of golden beach sand you can feel its gritty little grains run through your fingers. These golden grains are made mostly of quartz. The earth formed this quartz and all the other rocky minerals long ages ago. But quartz happens to be the hardest of the common minerals. The earth formed pebbles and large slabs of quartz. Small gritty crystals of quartz were peppered into mineral mixtures to make many granite type rocks.

Most of this quartz was formed far, far from the sea. The falling rain worked slowly, dissolving the softest minerals in the rocks and letting the rivers wash them away. But the stubborn quartz was hard to dissolve. However, many of its tough slabs and pebbles were battered and bashed into tiny grains. Meantime, tough little grains were freed from dissolved granites. Tons of this gritty sand were captured and swept away by the rivers and dumped into the sea. There the turning tides swept the sand back and spread it in smooth layers along the beaches.