A beach is a landform that is composed of the materials deposited by waves along the edge of an ocean, sea or lake. This material includes sand, gravel, crushed shells and organic matter carried by wind and water. Beaches are found around the world and, in fact, form in three different types: a narrow strip of sediment bordering a rocky or cliffy coast (rock beaches), the outer margin of a plain of marine or fluvial accumulation (free beaches) and long, straight shore bars that separate lagoons from open seas (ocean banks). Beaches are never stationary for very long; they are always moving.
Beaches are built and destroyed constantly, from hour to hour and season to season, by the nature of sediment drift and the size and strength of wave action. The sand on the beach is normally of a fairly similar, or homogenous, grain size distribution; however, this depends largely on the energy of waves. High-energy waves produce more uniform sand surfaces than lower-energy ones.
When a large amount of sand is displaced at one time, it may be gathered by the force of the wave to create a ridge or hill that extends from the beach berm. If the sand has a high water content, a lagoon may be formed. Over a longer period of time, sand transported by waves may collect enough to create an island or barrier that cuts off the beach from the open water.
The beach berm is the sandy slope that forms the part of the beach that is exposed at low tide. The berm is usually lined with flora that helps to stabilize the sand and slow erosion. The loss or destruction of this flora, through the use of herbicides, excessive pedestrian or vehicle traffic, or disruption of freshwater flow, may accelerate the erosion of the berm and dunes.
Beach sand also is important for wildlife. Many species of birds nest on beaches and in the adjacent tidal zones. In addition, seals, sea lions, a variety of crabs, clams, scallops and sand dollars, fish and marine invertebrates all depend on beaches or the tidal zones just offshore. Beaches and the tidal zones that surround them are protected by many of the nation’s 180 coastal or island national wildlife refuges.
When visiting a beach, please keep it beautiful and clean by packing out all trash including monofilament fishing line, hooks and loose packaging, which can harm wildlife that tangles in the lines or is jabbed by the hooks and swallows the packaging. In addition, respect the fragile dune ecosystem by staying on trails and off closed beaches; do not walk in the dunes and do not disturb wildlife, their nests or their young. By following these simple do’s and don’ts, we can enjoy the wonders of our natural beaches for generations to come.