Diagram showing a spit

A spit is a deposition landform found off coasts. Deposition is the geological process by which material is added to a Landform or land mass The coast is defined as the part of the land adjoining or near the Ocean. At one end, spits connect to land, while at the far end they exist in open water. ^[1] 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. A shoal or sandbar (also called sandbank) is a somewhat Linear Landform within or extending into a body of Water, Headlands and bays are two related features of the coastal environment Longshore drift (sometimes known as shore drift, LSD or littoral drift) is a geological process by which Sediments such as sand 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. ^[2]

However, where the direction of the shore inland reenters, or changes direction, such as at a headland, the longshore current spreads out or dissipates. No longer able to carry the full load, much of the sediment is dropped. This is also known as deposition. This submerged bar of sediment allows littoral drift to continue to transport in the direction the waves are breaking, forming an above-water spit. Without the complementary process of littoral drift, the bar would not build above the surface of the waves becoming a spit and would instead be leveled off underwater. ^[1]

Spits occur when longshore drift reaches a section of headland where the turn is greater than 30 degrees. Longshore drift (sometimes known as shore drift, LSD or littoral drift) is a geological process by which Sediments such as sand A headland is an area of land adjacent to water on three sides They will continue out into the sea until water pressure (such as from a river) becomes too much to allow the sand to deposit. The spit may then be grown upon and become stable and often fertile. A spit may be considered a specialized form of a shoal. A shoal or sandbar (also called sandbank) is a somewhat Linear Landform within or extending into a body of Water, As spits grow, the water behind them is sheltered from wind and waves, and a salt marsh is likely to develop. A salt marsh is a type of Marsh that is a transitional intertidal between land and salty or Brackish water (e

Wave refraction can occur at the end of a spit, carrying sediment around the end to form a hook or recurved spit. ^[1] Wave refraction in multiple directions will cause a complex spit to form. Incoming waves that come in a direction other than obliquely along the spit will halt the growth of the spit, shorten it or eventually destroy it entirely. ^[1]

The sediments that make up spits come from a variety of sources including rivers and eroding bluffs, and changes there can have a large impact on spits and other coastal landforms. Activities such as logging and farming upstream can increase the sediment load of rivers, which may hurt the intertidal environments around spits by smothering delicate habitat. Roads or bulkheads built along bluffs can drastically reduce the volume of sediment eroded, so that not enough material is being pushed along to maintain a given spit.

If the supply of sediment is interrupted the sand at the neck (landward side) of the spit may be moved towards the head, eventually creating an island. An island (ˈaɪlənd or isle (/ˈaɪl/ is any piece of land that is completely surrounded by water in two dimensions above high tide and isolated from other significant If the supply isn't interrupted, and the spit isn't breached by the sea (or, if across an estuary, the river) the spit may become a bar, with both ends joined to land, and form a lagoon behind the bar. A shoal or sandbar (also called sandbank) is a somewhat Linear Landform within or extending into a body of Water, A lagoon is a body of comparatively shallow salt or Brackish water separated from the deeper Sea by a shallow or exposed sandbank, coral If an island lies offshore near where the coast changes direction, and the spit continues to grow until it connects the island to the mainland, it is then called a tombolo or a bar. A tombolo is a deposition Landform such as a spit or bar which is attached to the mainland by a narrow piece of land

When talking about spits, the end of the spit attached to the mainland is called the proximal end and the end jutting out into the stretch of water, is called the distal end.

Spits in the UK are caused by prevailing South-Westerly winds, which give the spits their direction. However, when the direction of the wind changes for a short while the spit may change in direction for a short while forming a hook. Many spits have hooked or curved ends.

See also

• List of spits (landforms)
• Shoal

References