Along the Texas coast, many beaches have hills of sand behind them. These hills are called dunes. They may look like piles of sand that the wind blew together, and that is partly true. But dunes also protect the land behind them.

Dunes form when the wind blows dry sand away from the water’s edge. The sand piles up against things such as plants, seaweed, or pieces of driftwood. Little by little, the piles grow taller.

Plants are what hold a dune together. Sea oats and other grasses grow on the dunes. Their long roots spread through the sand like a net and keep it from blowing or washing away.

During a big storm, high waves crash onto the beach. A healthy dune can help block the waves and slow down the water before it reaches roads and houses.

Because dunes are so important, people are asked to stay off them. Walking on a dune crushes the plants, and without plants, the sand can blow away. Many beaches have wooden walkways that let visitors cross over the dunes without stepping on them.