Notice the smooth beach between the ocean and the dunes. This smooth beach is the intertidal zone. The intertidal zone is where you might find a conch shell washed up on the shore. Cape Lookout National Seashore is covered with seashells. The dunes start above the high water mark from the high tide.
Sand is moved back and forth by the wind and the waves.
The dunes are high enough to escape the action of waves. Here, grasses can take root. These grasses keep the sand from being blown away by the wind. Grasslands are important for preserving the islands, keeping the sand from being blown into the sea. These grasslands also are an important food resource for insects and birds.