When wave energy passes through water into a shallow area, the waves break. The lower part of the circular motion slows down as it scrapes the shallow bottom, and the upper part of the wave continues moving forward until it falls into air, or breaks. When the wave breaks, air bubbles are mixed into the water, turning the waves bright white in the surf zone.
Wave energy that passes through water is transferred to the shoreline in the
surf zone. The surf can erode rocks and cliffs,
move sediments, and grind down shells and pebbles
into fine grains of sand.