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The coast, also known as the coastline or seashore, is defined as the area where land meets the
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
, or as a line that forms the boundary between the land and the
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
or a
lake A lake is an area filled with water, localized in a basin, surrounded by land Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situated at elevations above sea level (variable ove ...

lake
. The
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
has around of coastline. Coasts are important zones in natural
ecosystems An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

ecosystems
, often home to a wide range of
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
. On land, they harbor important ecosystems such as freshwater or estuarine
wetlands A wetland is a distinct ecosystem that is flooded by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in the soils. ...

wetlands
, which are important for bird populations and other terrestrial animals. In wave-protected areas they harbor
saltmarshes
saltmarshes
,
mangroves A mangrove is a shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Pl ...

mangroves
or
seagrass Seagrasses are the only flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anyt ...
es, all of which can provide
nursery habitat In marine environments, a nursery habitat is a subset of all habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, includin ...
for finfish,
shellfish Shellfish is a colloquial and fisheries Fishery is the enterprise of raising or harvesting fish and other aquatic life. Commercial fisheries include wild fisheries and Fish farming, fish farms, both in fresh water (about 10% of all catch) and t ...

shellfish
, and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals (e.g.
mussels Mussel () is the common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in downtown Boston, Massachusetts. It is some ...

mussels
,
starfish Starfish or sea stars are star-shaped In mathematics, a Set (mathematics), set S in the Euclidean space \R^n is called a star domain (or star-convex set, star-shaped set or radially convex set) if there exists an s_0 \in S such that for ...

starfish
,
barnacles A barnacle is a type of arthropod An arthropod (, (gen. ποδός)) is an invertebrate animal having an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda,Reference sh ...

barnacles
) and various kinds of
seaweeds Seaweed, or macroalgae, refers to thousands of species of macroscopic The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments. It i ...

seaweeds
. Along
tropical The tropics are the region of Earth surrounding the Equator. They are delimited in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S; these latitudes correspond to ...

tropical
coasts with clear, nutrient-poor water,
coral reefs ''Coral Reefs'' is a quarterly peer-reviewed scientific journal dedicated to the study of coral reefs. It was established in 1982 and is published by Springer Science+Business Media on behalf of the International Society for Reef Studies, of which ...

coral reefs
can often be found between depths of 1 – 50 m. According to a
United Nations The United Nations (UN) is an intergovernmental organization aiming to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be a centre for harm ...

United Nations
atlas, 44% of all people live within 150 km (93 mi) of the sea. Because of their importance in society and high concentration of population, the coast is important for major parts of the global food and economic system, and they provide many
ecosystem services Ecosystem services are the many and varied benefits to humans provided by the natural environment and from healthy . Such ecosystems include, for example, s, s, s and s. These ecosystems, functioning in healthy relationship, offer such things ...
to humankind. For example, important human activities happen in . Coastal
fisheries Fishery is the enterprise of raising or harvesting fish and other aquatic life. Commercial fisheries include wild fisheries and Fish farming, fish farms, both in fresh water (about 10% of all catch) and the oceans (about 90%). About 500 million pe ...
(commercial, recreational, and subsistence) and
aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the farming of fish Fish are , , -bearing animals that lack with . Included in this definition are the living , s, and and as well as various extinct rel ...
are major economic activities and create jobs, livelihoods, and
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

protein
for the majority of coastal human populations. Other coastal spaces like
beaches File:YBF 2010 - Bikini Bar perjantaina.jpg, A summer tourism at the Yyteri Beach in Pori, Finland. A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from Ro ...

beaches
and
seaside resorts A seaside resort is a resort town ski resort, Slovakia Image:Nusa dua beach.jpg, Nusa Dua in Bali, Indonesia A resort town, often called a resort city or resort destination, is an urban area where tourism or vacationing is the primary compone ...
generate large revenues through
tourism Tourism is travel Travel is the movement of people between distant geographical location In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of th ...

tourism
.
Coastal ecosystems A marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Marine coastal ecosystems include many different types of marine habitats, such as estuaries and lagoons, salt marshes and mangrove forests, seagrass mea ...
can also provide protection against
sea level rise Tide gauge measurements show that the current global sea level rise began at the start of the 20th century. Between 1900 and 2017, the globally averaged sea level Mean sea level (MSL) (often shortened to sea level) is an average In colloqu ...

sea level rise
and
tsunamis A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquake An earthquake (also known as a quake, tre ...

tsunamis
. In many countries,
mangroves A mangrove is a shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Pl ...

mangroves
are the primary source of wood for fuel (e.g. charcoal) and building material. Coastal ecosystems like mangroves and seagrasses have a much higher capacity for
carbon sequestration Carbon sequestration or carbon dioxide removal (CDR) is the long-term removal, capture or sequestration of atmospheric carbon dioxide, carbon dioxide from the atmosphere to slow or reverse atmospheric CO2 pollution and to Climate change mitigat ...

carbon sequestration
than many terrestrial ecosystems, and as such can play a critical role in the near-future to help mitigate climate change effects by uptake of atmospheric anthropogenic carbon dioxide. However, the economic importance of coasts makes many of these communities vulnerable to climate change which causes increases in
extreme weather Extreme weather or extreme climate events includes unexpected, unusual, severe, or unseasonal weather Weather is the state of the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφα ...

extreme weather
and sea level rise, and related issues such as
coastal erosion Coastal erosion is the loss or displacement of land, or the long-term removal of sediment Sediment is a naturally occurring material that is broken down by processes of weathering Weathering is the deterioration of rocks A roc ...
,
saltwater intrusion Saltwater intrusion is the movement of saline water Saline water (more commonly known as salt water) is water that contains a high concentration of solvation, dissolved salts (mainly sodium chloride). The salt concentration is usually expressed i ...
and
coastal flooding Coastal flooding normally occurs when dry and low-lying land is submerged by seawater. The range of a coastal flooding is a result of the elevation of floodwater that penetrates the inland which is controlled by the topography Topography is ...
. Other coastal issues, such as
marine pollution Marine pollution occurs when substances used or spread by humans, such as industrial Industrial may also refer to: Industry * Industrial archaeology, the study of the history of the industry * Industrial engineering, engineering dealing with ...
,
marine debris Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing a ...

marine debris
, coastal development, and
marine ecosystem Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in Saline water, waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% ...
destruction, further complicate the human uses of the coast and threaten coastal ecosystems. The interactive effects of climate change,
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
,
overfishing Overfishing is the removal of a species of fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, an ...
and
water pollution Water pollution (or aquatic pollution) is the contamination of water bodies ( Lysefjord) in Norway Norway ( nb, ; nn, ; se, Norga; smj, Vuodna; sma, Nöörje), officially the Kingdom of Norway, is a Nordic countries, Nordic c ...

water pollution
(especially
eutrophication Eutrophication (from Greek ''eutrophos'', "well-nourished") is the process by which an entire body of water (Lysefjord) in Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokmå ...

eutrophication
) have led to the demise of coastal ecosystem around the globe. This has resulted in population collapse of fisheries stocks,
loss of biodiversity Biodiversity loss includes the extinction of species worldwide, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, depending on w ...
, increased invasion of alien species, and loss of heathy habitats. International attention to these issues has been captured in
Sustainable Development Goal 14 Sustainable Development Goal 14 (Goal 14 or SDG 14) is about "Life below water" and is one of the 17 Sustainable Development Goals The Sustainable Development Goals (SDGs) or Global Goals are a collection of 17 interlinked global goals designed ...

Sustainable Development Goal 14
"Life Below Water" which sets goals for international policy focused on preserving coastal ecosystems and supporting more for coastal communities.United Nations (2017) Resolution adopted by the General Assembly on 6 July 2017, Work of the Statistical Commission pertaining to the 2030 Agenda for Sustainable Development
A/RES/71/313
Likewise, the United Nations has declared 2021-2030 the
UN Decade on Ecosystem Restoration The United Nations Decade on Ecosystem Restoration runs from 2021–2030. Similar to other nature related international decades, its purpose is to promote the United Nation's enviromental goals. Specifically, to facilitate global cooperation for the ...
, but restoration of coastal ecosystems has received insufficient attention. Because coasts are constantly changing, a coastline's exact
perimeter A perimeter is either a path that encompasses/surrounds/outlines a shape (in two dimensions) or its length ( one-dimensional). The perimeter of a circle A circle is a shape consisting of all point (geometry), points in a plane (mathema ...

perimeter
cannot be determined; this measurement challenge is called the
coastline paradox The coastline paradox is the counterintuitive observation that the coastline of a landmass does not have a well-defined length. This results from the fractal curve-like properties of coastlines, i.e., the fact that a coastline typically has a fra ...
. The term ''coastal zone'' is used to refer to a region where interactions of sea and land processes occur. Both the terms ''coast'' and ''coastal'' are often used to describe a geographic location or region located on a coastline (e.g., New Zealand's
West CoastWest Coast or west coast may refer to: Geography Australia * Western Australia *Regions of South Australia#Weather forecasting, West Coast of South Australia * West Coast, Tasmania **West Coast Range, mountain range in the region Canada * British ...
, or the East,
West 250px, A compass rose with west highlighted in black West or Occident is one of the four cardinal directions or points of the compass The points of the compass are the vectors by which planet-based directions are conventionally defined. A co ...
, and
Gulf Coast The Gulf Coast of the United States is the coastline The coast, also known as the coastline or seashore, is defined as the area where land meets the sea or ocean, or as a line that forms the boundary between the land and the ocean T ...
of the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

United States
.) Coasts with a narrow continental shelf that are close to the open ocean are called ''pelagic'' ''coast'', while other coasts are more sheltered coast in a
gulf A gulf is a large inlet from the ocean into the landmass, typically with a narrower opening than a bay (geography), bay, but that is not observable in all geographic areas so named. The term gulf was traditionally used for large highly-indented ...

gulf
or
bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface ...

bay
. A
shore A shore or a shoreline is the fringe of land Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situated at elevations above sea level (variable over geologic time frames) and consist ...

shore
, on the other hand, may refer to parts of land adjoining any large body of water, including oceans (sea shore) and lakes (lake shore).


Size

The
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
has around of coastline. Coastal habitats, which extend to the margins of the , make up about 7 percent of the Earth's oceans, but at least 85% of commercially harvested fish depend on coastal environments during at least part of their life cycle. As of October 2010, about 2.86% of exclusive economic zones were part of
marine protected areas Marine protected areas (MPA) are protected areas of seas, oceans, estuary, estuaries or in the US, the Great Lakes. These marine areas can come in many forms ranging from wildlife refuges to research facilities. MPAs restrict human activity for a ...

marine protected areas
. The definition of coasts varies. Marine scientists think of the "wet" (aquatic or
intertidal The intertidal zone, also known as the foreshore or seashore, is the area above water level Water level, also known as gauge height or stage, is the elevation of the free surface of a sea, stream, lake or reservoir relative to a specified ver ...
) vegetated habitats as being
coastal ecosystems A marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Marine coastal ecosystems include many different types of marine habitats, such as estuaries and lagoons, salt marshes and mangrove forests, seagrass mea ...
(e.g. seagrass, salt marsh etc.) whilst some terrestrial scientist might only think of coastal ecosystems as purely terrestrial plants that live close to the seashore (see also estuaries and coastal ecosystems).


Formation

Tide Tides are the rise and fall of sea level Mean sea level (MSL) (often shortened to sea level) is an average In colloquial, ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of ...

Tide
s often determine the range over which
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. ...

sediment
is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deposition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however,
tidal bore Tidal is the adjectival form of tide (U.S.), low tide occurs roughly at moonrise and high tide with a high Moon, corresponding to the simple gravity model of two tidal bulges; at most places however, the Moon and tides have a phase shift. Tid ...

tidal bore
s can erode as the waves surge up the river
estuaries An estuary is a partially enclosed coastal body of brackish water Brackish water, also sometimes termed brack water, is water occurring in a natural environment having more salinity File:IAPSO Standard Seawater.jpg, upInternational Associatio ...

estuaries
from the ocean. Geologists classify coasts on the basis of
tidal range Tidal range is the height difference between high tide and low tide (U.S.), low tide occurs roughly at moonrise and high tide with a high Moon, corresponding to the simple gravity model of two tidal bulges; at most places however, the Moon an ...
into ''macrotidal coasts'' with a tidal range greater than 4 meters (13 feet); ''mesotidal coasts'' with a tidal range of 2 to 4 meters (7 to 13 feet); and ''microtidal coasts'' with a tidal range of less than 2 meters (7 feet). The distinction between macrotidal and mesotidal coasts is more important. Macrotidal coasts lack
barrier islands Barrier islands are Coast#Landforms, coastal landforms and a type of dune system that are exceptionally flat or lumpy areas of sand that form by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of a ...
and
lagoons Garabogaz-Göl lagoon in Turkmenistan A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coast ...
, and are characterized by funnel-shaped estuaries containing sand ridges aligned with tidal currents. Wave action is much more important for determining
bedforms A bedform is a feature that develops at the interface of fluid and a moveable bed, the result of bed material being moved by fluid flow. Examples include ripples and dune A dune is a landform A landform is a natural or artificial featur ...
of sediments deposited along mesotidal and microtidal coasts than in macrotidal coasts. Waves erode coastline as they break on shore releasing their energy; the larger the wave the more energy it releases and the more sediment it moves. Coastlines with longer shores have more room for the waves to disperse their energy, while coasts with cliffs and short shore faces give little room for the wave energy to be dispersed. In these areas, the wave energy breaking against the cliffs is higher, and air and water are compressed into cracks in the rock, forcing the rock apart, breaking it down. Sediment deposited by waves comes from eroded cliff faces and is moved along the coastline by the waves. This forms an abrasion or
cliffed coast A cliffed coast, also called an abrasion coast, is a form of coast The coast, also known as the coastline or seashore, is defined as the area where land meets the sea or ocean, or as a line that forms the boundary between the land and the ocea ...
. Sediment deposited by rivers is the dominant influence on the amount of sediment located in the case of coastlines that have estuaries. Today riverine deposition at the coast is often blocked by dams and other human regulatory devices, which remove the sediment from the stream by causing it to be deposited inland. Coral reefs are a provider of sediment for coastlines of tropical islands. Like the ocean which shapes them, coasts are a dynamic environment with constant change. The
Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is Water distribution on Earth, covered wi ...

Earth
's natural processes, particularly
sea level rise Tide gauge measurements show that the current global sea level rise began at the start of the 20th century. Between 1900 and 2017, the globally averaged sea level Mean sea level (MSL) (often shortened to sea level) is an average In colloqu ...

sea level rise
s, waves and various
weather Weather is the state of the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a p ...

weather
phenomena, have resulted in the
erosion In earth science Earth science or geoscience includes all fields of natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

erosion
,
accretion Accretion may refer to: Science * Accretion (astrophysics), the formation of planets and other bodies by collection of material through gravity * Accretion (meteorology), the process by which water vapor in clouds forms water droplets around nucle ...
and reshaping of coasts as well as flooding and creation of and drowned river valleys (
ria A ria (; gl, ría) is a coastal inlet An inlet is an indentation of a shoreline, usually long and narrow, such as a small bay or arm, that often leads to an enclosed body of salt water, such as a sound In physics, sound is a vibration th ...

ria
s).


Importance for humans and ecosystems


Human settlements

More and more of the world's people live in coastal regions. According to a
United Nations The United Nations (UN) is an intergovernmental organization aiming to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be a centre for harm ...

United Nations
atlas, 44% of all people live within 150 km (93 mi) of the sea. Many major cities are on or near good
harbor A harbor (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Engl ...

harbor
s and have
port A port is a maritime Maritime may refer to: Geography * Maritime Alps, a mountain range in the southwestern part of the Alps * Maritime Region, a region in Togo * Maritime Southeast Asia * The Maritimes, the Canadian provinces of ...

port
facilities. Some
landlocked A landlocked country is a country that does not have territory connected to an ocean or whose coastlines lie on endorheic basin, endorheic basins. There are currently 44 landlocked countries and 5 list of states with limited recognition, partial ...
places have achieved port status by building
canal Canals are waterways channels Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * ...

canal
s. Nations defend their coasts against military invaders, smugglers and illegal migrants. Fixed coastal defenses have long been erected in many nations, and coastal countries typically have a
navy A navy, naval force, or maritime force is the branch of a nation's armed forces A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare War is an intense ...

navy
and some form of
coast guard A coast guard or coastguard is a maritime security Maritime may refer to: Geography * Maritime Alps, a mountain range in the southwestern part of the Alps * Maritime Region, a region in Togo * Maritime Southeast Asia * The Maritimes ...

coast guard
. File:花蓮新社梯田.jpg,
Paddy field fields in Hanalei Valley, Kaua'i, Hawaii Hawaii ( ; haw, Hawaii or ) is a U.S. state, state in the Western United States, located in the Pacific Ocean about 2,000 miles from the U.S. mainland. It is the only state outside North ...

Paddy field
s by the coast of
Fengbin, Hualien Fengbin TownshipBarcelona Barcelona ( , , ) is a city on the coast of northeastern Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second most populous municipality of Spain. With a population of 1.6 million within ci ...

Barcelona
as viewed from Port Fòrum, with
Montjuïc Montjuïc () is a hill in Barcelona Barcelona ( , , ) is a city on the coast of northeastern Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second most populous municipality of Spain. ...

Montjuïc
and
Port Vell Port Vell at night, right Port Vell (, literally in English 'Old Harbor') is a waterfront harbor in Barcelona Barcelona ( , , ) is a city on the coast of northeastern Spain. It is the capital and largest city of the autonomous community of ...

Port Vell
can also be seen.


Tourism

Coasts, especially those with beaches and warm water, attract tourists often leading to the development of
seaside resort A seaside resort is a resort town, town, village, or hotel that serves as a Resort, vacation resort and is located on a coast. Sometimes the concept includes an aspect of official accreditation based on the satisfaction of certain requirements, such ...
communities. In many
island nation An island country or an island nation is a country A country is a distinct territorial body or political entity A polity is an identifiable political entity—any group of people who have a collective identity, who are organized by some ...
s such as those of the
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western Europe, Western and Southern Europe and Anatolia, on the south by North Africa ...

Mediterranean
,
South Pacific Ocean South is one of the cardinal directions or compass points. South is the opposite of north and is perpendicular to the east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic language, Proto-Germa ...
and
Caribbean The Caribbean (, ; es, Caribe; french: Caraïbes; ht, Karayib; also gcf, label=Antillean Creole Antillean Creole (Antillean French Creole, Kreyol, Kwéyòl, Patois) is a French-based creole, which is primarily spoken in the Lesser Antilles ...
, . Coasts offer recreational activities such as swimming, fishing, surfing, boating, and
sunbathing Sun tanning or simply tanning is the process whereby skin color is darkened or tanned. It is most often a result of exposure to ultraviolet (UV) radiation from sunlight Sunlight is a portion of the electromagnetic radiation given off b ...

sunbathing
.
Growth management Growth management, in the United States, is a set of techniques used by the government to ensure that as the population grows that there are services available to meet their demands. Growth management goes beyond traditional land use planning, zoni ...
and
coastal management Coastal management is defence against flooding A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide (U.S.), low tide occurs r ...
can be a challenge for coastal local authorities who often struggle to provide the infrastructure required by new residents, and poor management practices of construction often leave these communities and infrastructure vulnerable to processes like
coastal erosion Coastal erosion is the loss or displacement of land, or the long-term removal of sediment Sediment is a naturally occurring material that is broken down by processes of weathering Weathering is the deterioration of rocks A roc ...
and
sea level rise Tide gauge measurements show that the current global sea level rise began at the start of the 20th century. Between 1900 and 2017, the globally averaged sea level Mean sea level (MSL) (often shortened to sea level) is an average In colloqu ...

sea level rise
. In many of these communities, management practices such as
beach nourishment Beach nourishment (also referred to as beach renourishment, beach replenishment, or sand replenishment) describes a process by which sediment Sediment is a naturally occurring material that is broken down by processes of weathering Weat ...
or when the coastal infrastructure is no longer financially sustainable,
managed retreat Managed retreat involves the purposeful, coordinated movement of people and buildings away from risks. This may involve the movement of a person, infrastructure (e.g., building or road), or community. It can occur in response to a variety of hazard ...
to remove communities from the coast. File:Maarianhamina SNV10312 -2B.jpg, A passenger car ferry arrives at the coast of
Mariehamn Mariehamn (, ; fi, Maarianhamina ; la, Portus Mariae) is the capital Capital most commonly refers to: * Capital letter Letter case (or just case) is the distinction between the letters that are in larger uppercase or capitals (or mo ...

Mariehamn
,
Åland Åland (; fi, Ahvenanmaa: ; ; ) is an Federacy, autonomous and Demilitarized zone, demilitarised region of Finland since 1920 by a decision of the League of Nations. It is the smallest region of Finland, constituting 0.51% of its land area an ...
. File:Tiburon.jpg, Houses close to the coast, like these in
Tiburon, California Tiburon (; es, Tiburón, ) is an incorporated town An incorporated town is a town A town is a human settlement. Towns are generally larger than villages and smaller than city, cities, though the criteria to distinguish between the ...
, may be especially desirable properties.


Ecosystem services


Types


Emergent coastline

According to one principle of classification, an emergent coastline is a coastline that has experienced a fall in sea level, because of either a global sea-level change, or local uplift. Emergent coastlines are identifiable by the coastal
landform A landform is a natural or artificial feature of the solid surface of the Earth or other planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws ...

landform
s, which are above the high tide mark, such as
raised beach A raised beach, coastal terrace,Pinter, N (2010): 'Coastal Terraces, Sealevel, and Active Tectonics' (educational exercise), from 2/04/2011/ref> or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin,P ...
es. In contrast, a submergent coastline is one where the sea level has risen, due to a global sea-level change, local
subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope move ...
, or
isostatic reboundThe term isostatic may refer to: * Isostatic depression in geodynamics * Isostatic powder compaction in metallurgy and ceramic engineering * Isostatic press in manufacturing See also

*Isostasy in geology: gravitational equilibrium between th ...

isostatic rebound
. Submergent coastlines are identifiable by their submerged, or "drowned" landforms, such as
ria A ria (; gl, ría) is a coastal inlet An inlet is an indentation of a shoreline, usually long and narrow, such as a small bay or arm, that often leads to an enclosed body of salt water, such as a sound In physics, sound is a vibration th ...

ria
s (drowned valleys) and
fjord In physical geography Physical geography (also known as physiography) is one of the two fields of geography Geography (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδ ...

fjord
s


Concordant coastline

According to the second principle of classification, a concordant coastline is a coastline where bands of different rock types run parallel to the shore. These rock types are usually of varying
resistance Resistance may refer to: Arts, entertainment, and media Comics * Either of two similarly named but otherwise unrelated comic book series, both published by Wildstorm: ** ''Resistance'' (comics), based on the video game of the same title ** ''Th ...
, so the coastline forms distinctive landforms, such as coves. Discordant coastlines feature distinctive landforms because the rocks are
eroded In earth science Earth science or geoscience includes all fields of natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

eroded
by the ocean
wave In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular su ...

wave
s. The less resistant rocks erode faster, creating
inlet An inlet is an indentation of a shoreline, usually long and narrow, such as a small bay or arm, that often leads to an enclosed body of water, body of salt water, such as a Sound (geography), sound, bay, lagoon, or marsh. Overview In sea coasts, ...

inlet
s or
bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface ...

bay
; the more resistant rocks erode more slowly, remaining as
headland A headland, also known as a head, is a coast The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean The ocean (also the or the world ocean) is the body of that covers approximately 70.8 ...

headland
s or
outcrop An outcrop or rocky outcrop is a visible exposure of bedrock Bedrock in geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the soli ...

outcrop
pings.


Other coastal categories

* A
cliffed coast A cliffed coast, also called an abrasion coast, is a form of coast The coast, also known as the coastline or seashore, is defined as the area where land meets the sea or ocean, or as a line that forms the boundary between the land and the ocea ...
or abrasion coast is one where marine action has produced steep declivities known as
cliff In geography and geology, a cliff is an area of rock Rock most often refers to: * Rock (geology) A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included ...

cliff
s. * A
flat coast At a flat coast or flat shoreline, the land descends gradually into the sea. Flat coasts can be formed either as a result of the sea advancing into gently-sloping terrain or through the Abrasion (geology), abrasion of loose rock. They may be basica ...
is one where the land gradually descends into the sea. * A graded shoreline is one where wind and water action has produced a flat and straight coastline.


Landforms

The following articles describe some coastal landforms: *
Bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface ...

Bay
*
Headland A headland, also known as a head, is a coast The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean The ocean (also the or the world ocean) is the body of that covers approximately 70.8 ...

Headland
*
Cove A cove is a small type of bay or coast The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean ...

Cove
*
Peninsula A peninsula ( la, paeninsula from 'almost' and 'island') is a landform A landform is a natural or artificial feature of the solid surface of the Earth or other planetary body A planet is an astronomical body Astronomy (from el ...

Peninsula


Cliff erosion

* Much of the sediment deposited along a coast is the result of erosion of a surrounding
cliff In geography and geology, a cliff is an area of rock Rock most often refers to: * Rock (geology) A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included ...

cliff
, or bluff.
Sea cliff A cliffed coast, also called an abrasion coast, is a form of coast The coast, also known as the coastline or seashore, is defined as the area where land meets the sea or ocean, or as a line that forms the boundary between the land and the ocea ...
s retreat landward because of the constant undercutting of slopes by waves. If the slope/cliff being undercut is made of unconsolidated sediment it will erode at a much faster rate than a cliff made of bedrock. * A
natural arch A natural arch, natural bridge, or (less commonly) rock arch is a natural rock formation where an arch An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a h ...

natural arch
is formed when a headland is eroded through by waves. *
Sea cave A sea cave, also known as a littoral cave, is a type of cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering Weathering is the breaking down of roc ...
s are made when certain rock beds are more susceptible to erosion than the surrounding rock beds because of different areas of weakness. These areas are eroded at a faster pace creating a hole or crevice that, through time, by means of wave action and erosion, becomes a cave. * A stack is formed when a headland is eroded away by wave and wind action. * A stump is a shortened sea stack that has been eroded away or fallen because of instability. * Wave-cut notches are caused by the undercutting of overhanging slopes which leads to increased stress on cliff material and a greater probability that the slope material will fall. The fallen debris accumulates at the bottom of the cliff and is eventually removed by waves. * A
wave-cut platform A wave-cut platform, shore platform, coastal bench, or wave-cut cliff is the narrow flat area often found at the base of a sea cliff or along the shoreline of a lake, bay, or sea that was created by erosion. Wave-cut platforms are often most obvio ...

wave-cut platform
forms after erosion and retreat of a sea cliff has been occurring for a long time. Gently sloping wave-cut platforms develop early on in the first stages of cliff retreat. Later, the length of the platform decreases because the waves lose their energy as they break further offshore.


Coastal features formed by sediment

*
Beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from Rock (geology), rock, such as sand, gravel, shingle beach, shingle, pebbles, etc., or biological so ...

Beach
*
Beach cusps Beach cusps are shoreline formations made up of various grades of sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action ...
*
Cuspate foreland , stabilised by vegetation Cuspate forelands, also known as cuspate barriers or nesses in Great Britain, Britain, are geographical features found on coastlines and lakeshores that are created primarily by longshore drift.Craig-Smith, S. J., Cuspate ...
* *
Mudflat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetland A wetland is a distinct ecosystem that is flooded by water, either permanently or seasonally, where oxygen-free processes prevail. The primary ...
*
Raised beach A raised beach, coastal terrace,Pinter, N (2010): 'Coastal Terraces, Sealevel, and Active Tectonics' (educational exercise), from 2/04/2011/ref> or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin,P ...
*
Ria A ria (; gl, ría) is a coastal inlet An inlet is an indentation of a shoreline, usually long and narrow, such as a small bay or arm, that often leads to an enclosed body of salt water, such as a sound In physics, sound is a vibration th ...

Ria
*
Shoal In oceanography Oceanography (from the Ancient Greek Ancient Greek includes the forms of the used in and the from around 1500 BC to 300 BC. It is often roughly divided into the following periods: (), Dark Ages (), the peri ...
* Spit * Strand plain *
Surge channel Surge channel on the West Coast Trail, Vancouver Island. A surge channel is a narrow inlet, usually on a rocky shoreline, and is formed by differential erosion of those rocks by coastal wave action. As waves strike the shore, water fills the cha ...
*
Tombolo A tombolo is a sandy isthmus. A tombolo, from the Italian ''tombolo'', meaning 'pillow' or 'cushion', and sometimes translated as '' ayre'', is a deposition landform A landform is a natural or artificial feature of the solid surface of the E ...


Coastal features formed by another feature

*
Lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' and ''atoll lagoons''. They ...

Lagoon
*
Salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh A tidal marsh (also known as a type of "tidal wetland") is a marsh found along rivers, coasts and estuary, estuaries which floods and drains by the tide, tidal move ...

Salt marsh
* *
Kelp forests Kelp forests are under water areas with a high density of kelp, which covers a large part of the world's coastlines. They are recognized as one of the most productive and dynamic ecosystems on Earth.Mann, K.H. 1973. Seaweeds: their productivity and ...

Kelp forests
*
Coral reefs ''Coral Reefs'' is a quarterly peer-reviewed scientific journal dedicated to the study of coral reefs. It was established in 1982 and is published by Springer Science+Business Media on behalf of the International Society for Reef Studies, of which ...

Coral reefs
* Oyster reefs


Other features on the coast

*
Concordant coastline A concordant, longitudinal, or Pacific type coastline occurs where beds, or layers, of differing Rock (geology), rock types are folded into ridges that run parallel to the coast. The outer hard rock (for example, granite) provides a protective bar ...
*
Discordant coastline Discord may refer to: Entertainment * ''Discord'' (film), a 1933 British drama * Discord (My Little Pony), Discord (''My Little Pony''), a television character * Discord (album), ''Discord'' (album), or its title track, by Bomb Factory * ''Discor ...
* Fjord * Island * Island arc * Machair


In geology

The identification of bodies of rock formed from sediments deposited in shoreline and nearshore environments (shoreline and nearshore ''Facies (geology), facies'') is extremely important to geologists. These provide vital clues for reconstructing the geography of ancient continents (''paleogeography''). The locations of these beds show the extent of ancient seas at particular points in geological time, and provide clues to the magnitudes of tides in the distant past. Sediments deposited in the shoreface are preserved as lenses of sandstone in which the upper part of the sandstone is coarser than the lower part (a ''coarsening upwards sequence''). Geologists refer to these are ''parasequences''. Each records an episode of retreat of the ocean from the shoreline over a period of 10,000 to 1,000,000 years. These often show Lamination (geology), laminations reflecting various kinds of tidal cycles. Some of the best-studied shoreline deposits in the world are found along the former western shore of the Western Interior Seaway, a shallow sea that flooded central North America during the late Cretaceous Period (geology), Period (about 100 to 66 million years ago). These are beautifully exposed along the Book Cliffs of Utah and Colorado.


Geologic processes

The following articles describe the various geologic processes that affect a coastal zone: * Attrition (weathering), Attrition * Ocean current, Currents * Denudation * Deposition (geology), Deposition * Erosion * Flooding * Longshore drift * Marine sediments * Saltation (geology), Saltation * Sea level change ** eustatic ** isostasy, isostatic * Sedimentation * Coastal sediment supply ** sediment transport ** Solution (chemistry), solution ** subaerial processes ** Suspension (chemistry), suspension *
Tide Tides are the rise and fall of sea level Mean sea level (MSL) (often shortened to sea level) is an average In colloquial, ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of ...

Tide
s * Wind wave, Water waves ** diffraction ** refraction ** wave breaking ** wave shoaling * Weathering


Wildlife


Animals

Larger animals that live in coastal areas include Puffin, puffins, Sea turtle, sea turtles and Rockhopper penguin, rockhopper penguins, among many others. Gastropoda, Sea snails and various kinds of
barnacles A barnacle is a type of arthropod An arthropod (, (gen. ποδός)) is an invertebrate animal having an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda,Reference sh ...

barnacles
live on rocky coasts and scavenge on food deposited by the sea. Some coastal animals are used to humans in developed areas, such as Dolphin, dolphins and seagulls who eat food thrown for them by tourists. Since the coastal areas are all part of the littoral zone, there is a profusion of marine life found just off-coast, including Sessility (motility), sessile animals such as Coral, corals, sponges, starfish, mussels, seaweeds, fishes, and Sea anemone, sea anemones. There are many kinds of seabirds on various coasts. These include pelicans and cormorants, who join up with terns and oystercatchers to forage for fish and shellfish. There are sea lions on the coast of Wales and other countries.


Coastal fish


Plants

Many coastal areas are famous for their kelp beds. Kelp is a fast-growing seaweed that can grow up to half a meter a day in ideal conditions. Mangroves, Seagrass, seagrasses, macroalgal beds, and salt marsh are important coastal vegetation types in tropical and temperate environments respectively. Restinga is another type of coastal vegetation.


Threats

Coasts also face many Human impact on the environment, human-induced environmental impacts and coastal development hazards. The most important ones are sea level rise, and associated issues like
coastal erosion Coastal erosion is the loss or displacement of land, or the long-term removal of sediment Sediment is a naturally occurring material that is broken down by processes of weathering Weathering is the deterioration of rocks A roc ...
and
saltwater intrusion Saltwater intrusion is the movement of saline water Saline water (more commonly known as salt water) is water that contains a high concentration of solvation, dissolved salts (mainly sodium chloride). The salt concentration is usually expressed i ...
, and
water pollution Water pollution (or aquatic pollution) is the contamination of water bodies ( Lysefjord) in Norway Norway ( nb, ; nn, ; se, Norga; smj, Vuodna; sma, Nöörje), officially the Kingdom of Norway, is a Nordic countries, Nordic c ...

water pollution
, such as Oil spill, oil spills or
marine debris Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing a ...

marine debris
contaminating coasts with plastic and other trash.


Sea level rise due to climate change


Pollution

The pollution of coastlines is connected to
marine pollution Marine pollution occurs when substances used or spread by humans, such as industrial Industrial may also refer to: Industry * Industrial archaeology, the study of the history of the industry * Industrial engineering, engineering dealing with ...
which can occur from a number of sources: Marine debris (garbage and industrial debris); the Petroleum transport, transportation of petroleum in tanker (ship), tankers, increasing the probability of large oil spills; small oil spills created by large and small vessels, which flush bilge water into the ocean.


Marine pollution


Marine debris


Microplastics


Global goals

International attention to address the threats of coasts has been captured in
Sustainable Development Goal 14 Sustainable Development Goal 14 (Goal 14 or SDG 14) is about "Life below water" and is one of the 17 Sustainable Development Goals The Sustainable Development Goals (SDGs) or Global Goals are a collection of 17 interlinked global goals designed ...

Sustainable Development Goal 14
"Life Below Water" which sets goals for international policy focused on preserving coastal ecosystems and supporting more for coastal communities. Likewise, the United Nations has declared 2021-2030 the
UN Decade on Ecosystem Restoration The United Nations Decade on Ecosystem Restoration runs from 2021–2030. Similar to other nature related international decades, its purpose is to promote the United Nation's enviromental goals. Specifically, to facilitate global cooperation for the ...
, but restoration of coastal ecosystems has received insufficient attention.


Statistics

While there is general agreement in the scientific community regarding the definition of coast, in the political sphere, the delineation of the extents of a coast differ according to jurisdiction. Government authorities in various countries may define coast differently for economic and social policy reasons.


Length of coastline


See also

* Beach cleaning * Coastal and Estuarine Research Federation * Coastline of the North Sea * European Atlas of the Seas * Intertidal zone * Land reclamation * List of countries by length of coastline * List of U.S. states by coastline * Marine coastal ecosystem * Nautical chart


References


External links


Woods Hole Oceanographic Institution
- organization dedicated to ocean research, exploration, and education {{Authority control Coasts, Coastal and oceanic landforms Coastal geography Oceanographical terminology category:Articles containing video clips