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A spit is a rather special type of sand of shingle beach. Instead of hugging the coast, a spit projects out into the sea and is joined to the mainland at only one end.
Spits form where there is an abrupt change in the shape of the coastline, such as the entrance to an estuary or the coast turns abruptly inland. Longshore drift, which would usually move sediment along the coastline, tries to continue in the same direction despite the coastline having veered inland. Instead of depositing sediment on the shore it carries it out to sea along a path parallel to the earlier stretch of coastline. The strength of longshore drift decreases when it is further away from the shore, so it begins to drop its load, depositing sediment in a long line on the sea bed. Over time this accumulates and rises above the sea surface, forming a Spit, a band of land that then protects the area behind it. The protected area is sheltered from wave action and becomes a zone where deposition prevails. As sediment accumulates in the area behind the spit a salt marsh is created, linking the spit to the mainland.
Three good examples of spits in the UK are Orford Ness in Suffolk, Spurn Head at the mouth of the Humber, and Hurst Spit in Hampshire.
Hooked spits are also known as recurved spits, and they look like spits with a curved seaward end. The curve, or hook, is caused by a change in current direction or by wave defraction.
If the wave direction at the end of the spit is altered, or defracted, it then strikes the spit at a different angle, causing the end of the spit to curve in line with the new wave direction.
Spurn Point, near Hull,is a 5.5 kilometers long curved spit projecting into the Humber Estuary where the river enters the North Sea. It consists of sand and shingle transported down the Holderness coast by longshore drift.
Although 5.5km long it is only 50 m wide and vulnerable to storm damage. During a violent storm in 2013 the spit was breached and cut in half, the road along it being ripped apart in the process..