Dunes form as wind blows sand across the beach and plants such as dune grass and sea rocket take root, trapping sand to form a foredune. As more sand blows across the beach, plants are covered and grow up through the sand, and the taller plants trap more sand so the dunes grow higher into primary dunes. Because beaches are exposed to high tides and storms, only short, salt tolerant, flexible plants grow there. Behind the primary dunes, older secondary dunes are more protected from salt and wind and support shrubs and trees including red cedar, northern bayberry, and black cherry. On many barrier islands, dunes were once bulldozed to build homes, but Avalon preserved most of its oceanfront dunes and continues to preserve and enhance them by planting dune grass. The beach builds up during the summer and erodes during the winter, mainly at Avalon’s north end, because of tides, waves, and storms, and new dunes always form on the ocean side with the help of pioneer plants.