12/4/2023 0 Comments Sea stack landform![]() ![]() Dunes may form anywhere that eolian processes (wind transportation) occur. Secondary dune fields may lie further inland. The primary dune ridge (foredunes) lies adjacent to the shoreline. Dunesĭunes are critical to the health and sustainability of sandy beaches. Beaches are very dynamic environments, with coastlines that can change daily, making them challenging places to manage. The beach is often bounded on the upland side by a cliff, dune, or vegetation. A beach is defined as the location along a shoreline where the sediment is in motion, being moved by waves, tides, and currents. BeachesĪlthough varying in length, width, sand composition, and permanence, beaches are the most well-known coastal feature. Cape Cod (Massachusetts) is a famous cape that terminates at Provincetown spit. The spit is then called a bay barrier or a bay-mouth bar. If a spit grows long enough, it can completely cut off a bay from the ocean, forming a lagoon. Barrier spits may partially block the mouths of bays. A barrier spit is the landform resulting from the deposition of sediments in long ridges extending out from coasts. Barrier Spitsīarrier spits are made up of sediments that have been suspended by waves and transported by currents. Human activities may interfere with this balance, causing costly damage, both economically and environmentally. Without intervention, barrier islands maintain a state of dynamic equilibrium between sediment exchange, wave energy, and sea level rise. Features such as sand dunes, maritime forests, inlets, lagoons, back-barrier marshes, and vegetation constitute these fragile coastal systems. These important environments protect the mainland from storm events and wave action, while providing a vital ecosystem for many species. Barrier Islandsīarrier islands are one of the most common and distinguishable features of the Atlantic coast. Features such as spits, barrier islands, tombolos, and dunes are classic forms in sandy beach environments. Geologic Features of Sandy Coastsĭepositional processes along coastlines, such as sediment transport, form sandy beaches and create highly complex landforms that experience constant change and movement. These narrow strips of sand serve as obstacles to wave activity, protecting fragile environments that lay further inland, for example, marshes, tidal flats, and lagoons. Coastal barriers are highly complex and dynamic landforms that experience constant change and movement. Sandy beaches may be found in other tectonic settings or depositional environments, such as pocket beaches at Channel Islands National Park and beaches near the mouth of San Francisco Bay at Golden Gate National Recreation Area in California.ĭepositional settings along sandy coasts produce barrier structures such as bay barriers, barrier spits, and barrier islands. Many of our favorite beaches are found on sandy coasts: Cape Cod National Seashore in Massachusetts, Cumberland Island National Seashore in Georgia, Assateague Island National Seashore in Maryland and Virginia, Padre Island National Seashore in Texas, and Gulf Islands National Seashore in Florida and Mississippi. Typically located on passive margins, in areas characterized by low-wave energy, a wide continental shelf, and high offshore sediment influence, sandy beaches are found in wave-dominated, depositional settings such as the Atlantic Ocean and Gulf of Mexico coasts. Sandy beaches are highly dynamic environments subject to rapid, extreme changes. Windswept beach, Fire Island National Seashore, New York (2015). ![]()
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