Shingle is a globally restricted coastal sediment type, occurring infrequently outside north-west Europe, Japan and New Zealand.
North-west Europe is one of the main locations where fringing shingle beaches and structures occur in any quantity and even here larger more permanent structures are rare.
The general term shingle is applied to sediments larger in diameter than sand (>2mm) but smaller than boulders (<200mm). Approximately one-third of the coastline of England and Wales is bordered by shingle and about 900km (5000ha approx.) of this is pure shingle.
Coastal shingle can occur in a number of geomorphologic forms. The largest shingle structure in Britain is the cuspate foreland of Dungeness, Kent, but Orford Ness as well as forming a cuspate foreland, also has the finest example of a pure shingle spit in Europe and possibly the world.
It extends for 16km and amounts to about 570ha of exposed shingle in total. The spit is in a dynamic state, with cycles of deposition and erosion. There is a tendency, on balance, for erosion on the northern, seaward shorelines, with a net deposition at the southern distal end.
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Shingle beaches form on wave dominated shorelines where suitably sized material is available and where there is an occurrence of a high wave energy environment. The main source of new material for most shingle structures comes from coastal cliff erosion and reworking of other existing shingle deposits.
The health and ongoing development of shingle features depend on this continuing supply. As beach development in Britain is primarily longshore derived, on the East Coast there is a requirement for erosion to the North to ensure a supply of sediment southward down the coast.
In Suffolk most structures exhibit continuous longshore drift with shingle being transported and sorted by wave action, and ridges lying parallel to the shoreline tending to be rolled over towards the land by wave action at storm events (eg. Kings Marshes on Orford Ness). This movement can have a serious knock-on effect on low-lying habitats behind the shingle (eg. coastal brackish lagoons). In the future movement is likely to be accelerated by climate change, which may result in increased relative sea level rise and increased storminess.
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In recent times sediment supply has been substantially reduced from human interference, mainly by coastal protection works resulting in sediment starvation. Results can be seen in increased erosional activity or in the reduction in the volume of some barriers where the effects can be seen as a lowering of crest height, quickening land migration and an increased likelihood of breaching during storm events. Further erosional activity and accelerated relative sea level rises may free up new sediment but there are likely to be continuing conflicts regarding protection of areas of potential supply.
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Beach replenishment and mechanical re-profiling are options which have and continue to be carried out but they are likely to be unsustainable options and may fail in the long-term as they do not address the base problem of sediment deficit.
Shingle structures support a number of breeding bird species, including gulls, waders and Little tern. It is also of great importance to invertebrates and on coastal shingle structures in Suffolk diverse invertebrate communities are found, with some species restricted to shingle habitats.
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