A spit or sandspit is a deposition landform found off coasts. At one end, spits connect to land, while at the far end they exist in open water. A spit is a type of bar or beach that develops where a re-entrant occurs, such as at cove's headlands, by the process of longshore drift. Longshore drift (also called littoral drift) occurs due to waves meeting the beach at an oblique angle, and backwashing perpendicular to the shore, moving sediment down the beach in a zigzag pattern. Longshore drifting is complemented by longshore currents, which transport sediment through the water alongside the beach. These currents are set in motion by the same oblique angle of entering waves that causes littoral drift and transport sediment in a similar process.
Tombolo
A tombolo or sometimes ayre is a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached the island is then known as a tied island. They usually form because the island causes wave refraction, depositing sand and shingle moved by longshore drift in each direction around the island where the waves meet. Eustatic sea level rise may also contribute to accretion as material is pushed up with rising sea levels.
Salt Marsh
A salt marsh (also known as saltings) is a type of marsh that is a transitional intertidal between land and salty or brackish water (e.g.: sloughs, bays, estuaries). It is dominated by halophytic (salt tolerant) herbaceous plants. Historically, salt marshes have sometimes been treated as "wastelands", along with other wetlands. Salt marshes are one of the most biologically productive habitats on the planet, rivaling tropical rainforests. The daily tidal surges bring in nutrients, which tends to settle in roots of the plants within the salt marsh. The natural chemical activity of salty (or brackish) water and the tendency of algae to bloom in the shallow unshaded water also allow for great biodiversity.
Salt marshes provide a benefit by protecting against severe weather. In the past, substantial areas of saltmarsh have been reclaimed as agricultural land and for urban development, but in the United States and Europe they are now accorded a high level of protection by the Clean Water Act and the Habitats Directive respectively. There is growing interest in restoring salt marshes, through managed retreat or through the reclamation of lands used for other purposes by salt marsh vegetation.
Spits, Tombolos and Salt Marshes
Spits
Tombolo
A tombolo or sometimes ayre is a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached the island is then known as a tied island. They usually form because the island causes wave refraction, depositing sand and shingle moved by longshore drift in each direction around the island where the waves meet. Eustatic sea level rise may also contribute to accretion as material is pushed up with rising sea levels.
Salt Marsh
A salt marsh (also known as saltings) is a type of marsh that is a transitional intertidal between land and salty or brackish water (e.g.: sloughs, bays, estuaries). It is dominated by halophytic (salt tolerant) herbaceous plants. Historically, salt marshes have sometimes been treated as "wastelands", along with other wetlands. Salt marshes are one of the most biologically productive habitats on the planet, rivaling tropical rainforests. The daily tidal surges bring in nutrients, which tends to settle in roots of the plants within the salt marsh. The natural chemical activity of salty (or brackish) water and the tendency of algae to bloom in the shallow unshaded water also allow for great biodiversity.
Salt marshes provide a benefit by protecting against severe weather. In the past, substantial areas of saltmarsh have been reclaimed as agricultural land and for urban development, but in the United States and Europe they are now accorded a high level of protection by the Clean Water Act and the Habitats Directive respectively. There is growing interest in restoring salt marshes, through managed retreat or through the reclamation of lands used for other purposes by salt marsh vegetation.
Sources
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