How can wind and water move loose sand?

A windy beach can look different after the wind blows. Moving air pushes loose sand grains. Some grains roll along the ground. Others hop or are carried a little farther before they land.

The two pictures show twelve pretend sand grains. At first, they are together. Later, six have moved to the right and six have stayed near the start. There are still twelve grains.

Flowing water can move sand too. When the moving water or wind no longer pushes hard enough to keep a grain traveling, the grain settles.

Real sand does not always move by the same amount. Wet sand may stick together, and a stone can block a grain’s path. Many tiny journeys can build a sand pile in one place while taking sand away from another.