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67-619: The four species of avocets / ˈ æ v ə s ɛ t / are a genus, Recurvirostra , of waders in the same avian family as the stilts . The genus name comes from Latin recurvus , 'curved backwards' and rostrum , 'bill'. The common name is thought to derive from the Italian ( Ferrarese ) word avosetta . Francis Willughby in 1678 noted it as the "Avosetta of the Italians". Avocets have long legs and long, thin, upcurved bills which they sweep from side to side when feeding in

134-534: A navy and some form of coast guard . Coasts, especially those with beaches and warm water, attract tourists often leading to the development of seaside resort communities. In many island nations such as those of the Mediterranean , South Pacific Ocean and Caribbean , tourism is central to the economy . Coasts offer recreational activities such as swimming, fishing, surfing, boating, and sunbathing . Growth management and coastal management can be

201-465: A paraphyletic assemblage. However, it indicated that the plains wanderer actually belonged into one of them. Following recent studies (Ericson et al., 2003; Paton et al., 2003; Thomas et al., 2004a, b; van Tuinen et al., 2004; Paton & Baker, 2006), the waders may be more accurately subdivided as follows, with Charadrii being repurposed into a monophyletic suborder of plovers, oystercatchers, and their close relatives. The waders are traditionally

268-478: 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 and sea level rise . In many of these communities, management practices such as beach nourishment or when the coastal infrastructure is no longer financially sustainable, managed retreat to remove communities from

335-576: A greatly enlarged order Ciconiiformes . However, the classification of the Charadriiformes is one of the weakest points of the Sibley-Ahlquist taxonomy, as DNA–DNA hybridization has turned out to be incapable of properly resolving the interrelationships of the group. Formerly, the waders were united in a single suborder Charadrii , but this has turned out to be a " wastebasket taxon ", uniting no fewer than four charadriiform lineages in

402-534: A group of two Charadriiform suborders which include 13 families . Species in the third Charadriiform suborder, Lari , are not universally considered as waders, though the Larine families which may variously be included are listed below as well. Shorebirds is a blanket term used to refer to multiple bird species that live in wet, coastal environments. Because most these species spend much of their time near bodies of water, many have long legs suitable for wading (hence

469-486: A long time because of land reclamation of their habitat and persecution by skin and egg collectors , but during or soon after World War II , they started breeding on reclaimed land near the Wash , which was returned to salt marsh to make difficulties for any landing German invaders . Avocets use Titchfield Haven National Nature Reserve as a summer breeding ground. Wader Waders or shorebirds are birds of

536-655: A much higher capacity for 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 and sea level rise, as well as related issues like coastal erosion , saltwater intrusion , and coastal flooding . Other coastal issues, such as marine pollution , marine debris , coastal development, and marine ecosystem destruction, further complicate

603-653: A proper name to the coast of the Ligurian Sea , in the form riviera ligure , then shortened to riviera . Historically, the Ligurian Riviera extended from Capo Corvo (Punta Bianca) south of Genoa , north and west into what is now French territory past Monaco and sometimes as far as Marseilles . Today, this coast is divided into the Italian Riviera and the French Riviera , although

670-435: 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 's natural processes, particularly sea level rises , waves and various weather phenomena, have resulted in the erosion , accretion and reshaping of coasts as well as flooding and creation of continental shelves and drowned river valleys ( rias ). More and more of

737-403: A result, an increase in dimorphism. Bigger males tend to have greater access (and appeal) to female mates because their larger size aids them in defeating other competitors. Likewise, if the species exhibits gender role reversal (where males take on roles traditionally done by females such as childcare and feeding), then males will select female mates based on traits that are the most appealing. In

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804-456: A shoreline configuration. Swash is the shoreward flow after the break, backwash is the water flow back down the beach. The relative strength of flow in the swash and backwash determines what size grains are deposited or eroded. This is dependent on how the wave breaks and the slope of the shore. Depending on the form of the breaking wave, its energy can carry granular material up the beach and deposit it, or erode it by carrying more material down

871-443: A single female partner, males typically do not have distinctive dimorphic characteristics such as colored feathers, but they still tend to be larger in size compared to females. The suborder Charadrii displays the widest range of sexual dimorphisms seen in the order Charadriiformes. However, cases of sexual monomorphism, where there are no distinguishing physical features besides external genitalia, are also seen in this order. One of

938-425: A slightly different way in discussions of legal and economic boundaries (see territorial waters and international waters ) or when considering the geography of coastal landforms or the ecological systems operating through the continental shelf ( marine coastal ecosystems ). The research on coastal waters often divides into these separate areas too. The dynamic fluid nature of the ocean means that all components of

1005-529: A wide range of sessile animals (e.g. mussels , starfish , barnacles ) and various kinds of seaweeds . In physical oceanography , a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore, representing the intertidal zone where there is one. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 m (3.3–164.0 ft). According to an atlas prepared by

1072-541: 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 landforms , which are above the high tide mark, such as raised beaches . In contrast, a submergent coastline is one where the sea level has risen, due to a global sea-level change, local subsidence , or isostatic rebound . Submergent coastlines are identifiable by their submerged, or "drowned" landforms, such as rias (drowned valleys) and fjords According to

1139-528: Is connected to marine pollution which can occur from a number of sources: Marine debris (garbage and industrial debris); the transportation of petroleum in 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 occurs when substances used or spread by humans, such as industrial , agricultural and residential waste , particles , noise , excess carbon dioxide or invasive organisms enter

1206-415: 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

1273-408: Is more important. Macrotidal coasts lack barrier islands and lagoons , and are characterized by funnel-shaped estuaries containing sand ridges aligned with tidal currents. Wave action is much more important for determining bedforms 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

1340-423: Is moved along the coastline by the waves. This forms an abrasion or cliffed coast . 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

1407-584: Is the least sandpiper , small adults of which can weigh as little as 15.5 grams (0.55 oz) and measure just over 13 centimetres (5 inches). The largest species is believed to be the Far Eastern curlew , at about 63 cm (25 in) and 860 grams (1 pound 14 ounces), although the beach thick-knee is the heaviest at about 1 kg (2 lb 3 oz). In the Sibley-Ahlquist taxonomy , waders and many other groups are subsumed into

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1474-412: 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 fractal dimension . Although the "paradox of length" was previously noted by Hugo Steinhaus , the first systematic study of this phenomenon was by Lewis Fry Richardson , and it

1541-462: The Aegean Sea . The following articles describe some coastal landforms: "Coastal waters" (or "coastal seas") is a rather general term used differently in different contexts, ranging geographically from the waters within a few kilometers of the coast, through to the entire continental shelf which may stretch for more than a hundred kilometers from land. Thus the term coastal waters is used in

1608-466: The Jacana species, females compete with each other for access to male mates, so females are larger in size. Males choose female mates based on who presents herself as the strongest and who 'owns' the most territory. Another factor that leads to the development of dimorphisms in species is natural selection . Natural selection focuses on traits and the environment's response to the traits in question; if

1675-603: The Latin recurvus meaning 'bent' or 'curved backwards' with rostrum meaning 'bill'. The genus contains four species. One fossil species, R. sanctaneboulae Mourer-Chauviré, 1978, dates from the late Eocene of France. In a large colony, they are aggressively defensive and chase off any other species of birds that try to nest among or near them. That causes the annoyed remark " Avocet: Exocet " from some British birdwatchers . They had been extirpated in Britain for

1742-456: The US EPA considers this region to extend much further offshore. "Coastal waters" has specific meanings in the context of commercial coastal shipping , and somewhat different meanings in the context of naval littoral warfare . Oceanographers and marine biologists have yet other takes. Coastal waters have a wide range of marine habitats from enclosed estuaries to the open waters of

1809-617: The United Nations , about 44% of the human population lives within 150 km (93 mi) of the sea as of 2013 . Due to its importance in society and its high population concentrations, the coast is important for major parts of the global food and economic system, and they provide many ecosystem services to humankind. For example, important human activities happen in port cities. Coastal fisheries (commercial, recreational, and subsistence) and aquaculture are major economic activities and create jobs, livelihoods, and protein for

1876-686: The Western Interior Seaway , a shallow sea that flooded central North America during the late Cretaceous Period (about 100 to 66 million years ago). These are beautifully exposed along the Book Cliffs of Utah and Colorado . The following articles describe the various geologic processes that affect a coastal zone: Larger animals that live in coastal areas include puffins , sea turtles and rockhopper penguins , among many others. Sea snails and various kinds of barnacles live on rocky coasts and scavenge on food deposited by

1943-469: The ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. It is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide. Since most inputs come from land, either via

2010-596: The ocean . Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping . Naturally occurring debris, such as driftwood and drift seeds , are also present. With the increasing use of plastic , human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10%) and majority of large plastic in

2077-444: The rivers , sewage or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor by carrying off iron, carbonic acid, nitrogen , silicon, sulfur, pesticides or dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff , wind-blown debris , and dust. These nonpoint sources are largely due to runoff that enters

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2144-485: The Arctic species, such as the little stint , are amongst the longest distance migrants, spending the non- breeding season in the southern hemisphere . Many of the smaller species found in coastal habitats, particularly but not exclusively the calidrids , are often named as "sandpipers", but this term does not have a strict meaning, since the upland sandpiper is a grassland species. The smallest member of this group

2211-773: The French use the term "Riviera" to refer to the Italian Riviera and call the French portion the "Côte d'Azur". As a result of the fame of the Ligurian rivieras, the term came into English to refer to any shoreline, especially one that is sunny, topographically diverse and popular with tourists. Such places using the term include the Australian Riviera in Queensland and the Turkish Riviera along

2278-546: The United Nations has declared 2021–2030 the UN Decade on Ecosystem Restoration , but restoration of coastal ecosystems has received insufficient attention. Since coasts are constantly changing, a coastline's exact perimeter cannot be determined; this measurement challenge is called the coastline paradox . The term coastal zone is used to refer to a region where interactions of sea and land processes occur. Both

2345-571: The average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This was faster than the sea level had ever risen over at least the past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities is the main cause. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise , with another 42% resulting from thermal expansion of water . International attention to address

2412-417: The average wind wave and swell conditions are relatively mild. Low energy coasts typically change slowly, and tend to be depositional environments. High energy coasts are exposed to the direct impact of waves and storms, and are generally erosional environments. High energy storm events can make large changes to a coastline, and can move significant amounts of sediment over a short period, sometimes changing

2479-489: The biggest factors that leads to the development of sexual dimorphism in shorebirds is sexual selection . Males with ideal characteristics favored by females are more likely to reproduce and pass on their genetic information to their offspring better than the males who lack such characteristics. Mentioned earlier, male shorebirds are typically larger in size compared to their female counterparts. Competition between males tends to lead to sexual selection toward larger males and as

2546-406: The brackish or saline wetlands they prefer. Their plumage is pied , sometimes also with some red. Members of this genus have webbed feet and readily swim. Their diet consists of aquatic insects and other small creatures. Avocets nest on the ground in loose colonies. In estuarine settings, they may feed on exposed bay muds or mudflats . The nest is simply a lining of grass in a hollow in

2613-461: The coast of Wales and other countries. Coastal fish , also called inshore fish or neritic fish, inhabit the sea between the shoreline and the edge of the continental shelf . Since the continental shelf is usually less than 200 metres (660 ft) deep, it follows that pelagic coastal fish are generally epipelagic fish , inhabiting the sunlit epipelagic zone . Coastal fish can be contrasted with oceanic fish or offshore fish , which inhabit

2680-812: The coast. Estuarine and marine coastal ecosystems are both marine ecosystems . Together, these ecosystems perform the four categories of ecosystem services in a variety of ways: The provisioning services include forest products, marine products, fresh water , raw materials, biochemical and genetic resources. Regulating services include carbon sequestration (contributing to climate change mitigation ) as well as waste treatment and disease regulation and buffer zones. Supporting services of coastal ecosystems include nutrient cycling , biologically mediated habitats and primary production . Cultural services of coastal ecosystems include inspirational aspects, recreation and tourism , science and education. According to one principle of classification, an emergent coastline

2747-567: The continental shelf. Similarly, the term littoral zone has no single definition. It is the part of a sea , lake , or river that is close to the shore . In coastal environments, the littoral zone extends from the high water mark , which is rarely inundated, to shoreline areas that are permanently submerged . Coastal waters can be threatened by coastal eutrophication and harmful algal blooms . The identification of bodies of rock formed from sediments deposited in shoreline and nearshore environments (shoreline and nearshore facies )

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2814-555: The deep seas beyond the continental shelves. 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 , seagrasses , macroalgal beds, and salt marsh are important coastal vegetation types in tropical and temperate environments respectively. Restinga is another type of coastal vegetation. Coasts also face many human-induced environmental impacts and coastal development hazards . The most important ones are: The pollution of coastlines

2881-566: The ground. They lay three or four eggs of a dark greenish or brownish buff color, boldly marked with brown and black. The pied avocet is the emblem of the Royal Society for the Protection of Birds . The genus Recurvirostra was introduced in 1758 by Swedish naturalist Carl Linnaeus in the 10th edition of his Systema Naturae to contain a single species, the pied avocet , Recurvirostra avosetta . The genus name combines

2948-789: The human uses of the coast and threaten coastal ecosystems. The interactive effects of climate change, habitat destruction , overfishing , and water pollution (especially eutrophication ) have led to the demise of coastal ecosystem around the globe. This has resulted in population collapse of fisheries stocks, loss of biodiversity , increased invasion of alien species , and loss of healthy habitats. International attention to these issues has been captured in Sustainable Development Goal 14 "Life Below Water", which sets goals for international policy focused on preserving marine coastal ecosystems and supporting more sustainable economic practices for coastal communities. Likewise,

3015-410: The majority of coastal human populations. Other coastal spaces like beaches and seaside resorts generate large revenues through tourism . Marine coastal ecosystems can also provide protection against sea level rise and tsunamis . In many countries, mangroves are the primary source of wood for fuel (e.g. charcoal ) and building material. Coastal ecosystems like mangroves and seagrasses have

3082-673: The margins of the continental shelves , 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 . The definition of coasts varies. Marine scientists think of the "wet" (aquatic or intertidal ) vegetated habitats as being coastal ecosystems (including seagrass, salt marsh etc.) whilst some terrestrial scientists might only think of coastal ecosystems as purely terrestrial plants that live close to

3149-587: The microplastics go through the water filtration system and into the ocean, but because of their small size they are likely to escape capture by the preliminary treatment screens on wastewater plants. These beads are harmful to the organisms in the ocean, especially filter feeders, because they can easily ingest the plastic and become sick. The microplastics are such a concern because it is difficult to clean them up due to their size, so humans can try to avoid using these harmful plastics by purchasing products that use environmentally safe exfoliates. Between 1901 and 2018,

3216-507: The more resistant rocks erode more slowly, remaining as headlands or outcroppings . Parts of a coastline can be categorised as high energy coast or low energy coast. The distinguishing characteristics of a high energy coast are that the average wave energy is relatively high so that erosion of small grained material tends to exceed deposition, and consequently landforms like cliffs, headlands and wave-cut terraces develop. Low energy coasts are generally sheltered from waves, or in regions where

3283-477: The name 'Waders'). Some species prefer locations with rocks or mud. Many shorebirds display migratory patterns and often migrate before breeding season. These behaviors explain the long wing lengths observed in species, and can also account for the efficient metabolisms that give the birds energy during long migrations . The majority of species eat small invertebrates picked out of mud or exposed soil. Different lengths of bills enable different species to feed in

3350-441: The ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution , bilge pollution , atmospheric pollution and, potentially, deep sea mining . Marine debris , also known as marine litter, is human-created solid material that has deliberately or accidentally been released in seas or

3417-485: The oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish , seabirds , marine reptiles , and marine mammals , as well as to boats and coasts. A growing concern regarding plastic pollution in the marine ecosystem is the use of microplastics. Microplastics are beads of plastic less than 5 millimeters wide, and they are commonly found in hand soaps, face cleansers, and other exfoliators. When these products are used,

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3484-792: The order Charadriiformes commonly found wading along shorelines and mudflats in order to forage for food crawling or burrowing in the mud and sand, usually small arthropods such as aquatic insects or crustaceans . The term "wader" is used in Europe, while "shorebird" is used in North America, where "wader" may be used instead to refer to long-legged wading birds such as storks and herons . There are about 210 species of wader, most of which live in wetland or coastal environments. Many species of Arctic and temperate regions are strongly migratory , but tropical birds are often resident, or move only in response to rainfall patterns. Some of

3551-435: The said trait increases the overall fitness of the individual possessing it, then it will be 'selected' and eventually become a permanent part of the population's gene pool. For example, depending on the food available in a shorebird specie's respective niche , bigger bill sizes may be favored in all individuals. This would essentially lead to monomorphism within the species but is subject to change once sexual selection acts on

3618-818: The same habitat, particularly on the coast, without direct competition for food. Many waders have sensitive nerve endings at the end of their bills which enable them to detect prey items hidden in mud or soft soil. Some larger species, particularly those adapted to drier habitats will take larger prey including insects and small reptiles . Shorebirds, like many other animals, exhibit phenotypic differences between males and females, also known as sexual dimorphism . In shorebirds, various sexual dimorphisms are seen, including, but not limited to, size (e.g. body size, bill size), color, and agility. In polygynous species, where one male individual mates with multiple female partners over his lifetime, dimorphisms tend to be more diverse. In monogamous species, where male individuals mate with

3685-416: 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 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

3752-579: The sea. Some coastal animals are used to humans in developed areas, such as 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 sessile animals such as corals , sponges, starfish, mussels, seaweeds, fishes, and 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

3819-401: The seashore (see also estuaries and coastal ecosystems ). 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. The coastline paradox

3886-427: 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 , so the coastline forms distinctive landforms, such as coves. Discordant coastlines feature distinctive landforms because the rocks are eroded by the ocean waves . The less resistant rocks erode faster, creating inlets or bay ;

3953-404: The slope than up it. Steep waves that are close together and break with the surf plunging down onto the shore slope expend much of their energy lifting the sediment. The weak swash does not carry it far up the slope, and the strong backwash carries it further down the slope, where it either settles in deeper water or is carried along the shore by a longshore current induced by an angled approach of

4020-758: 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 Coast , or the East , West , and Gulf Coast of the 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 or bay . A 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). The Earth has approximately 620,000 kilometres (390,000 mi) of coastline. Coastal habitats, which extend to

4087-811: The trait. Sexual selection could give rise to males with relatively larger bills than females if males used their bills to compete with other males. If larger bill size assisted the male in gathering resources, it would also make him more attractive to female mates. Coastal Coasts are important zones in natural ecosystems , often home to a wide range of biodiversity . On land, they harbor important ecosystems such as freshwater or estuarine wetlands , which are important for bird populations and other terrestrial animals . In wave-protected areas, they harbor salt marshes , mangroves or seagrasses , all of which can provide nursery habitat for fin fish , shellfish , and other aquatic animals . Rocky shores are usually found along exposed coasts and provide habitat for

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4154-487: 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

4221-476: The wave-front to the shore. These waves which erode the beach are called destructive waves. Low waves that are further apart and break by spilling , expend more of their energy in the swash which carries particles up the beach, leaving less energy for the backwash to transport them downslope, with a net constrictive influence on the beach. Riviera is an Italian word for "shoreline", ultimately derived from Latin ripa ("riverbank"). It came to be applied as

4288-407: The waves surge up the river estuaries from the ocean. Geologists classify coasts on the basis of tidal range into macrotidal coasts with a tidal range greater than 4 m (13 ft); mesotidal coasts with a tidal range of 2 to 4 m (6.6 to 13 ft); and microtidal coasts with a tidal range of less than 2 m (7 ft). The distinction between macrotidal and mesotidal coasts

4355-469: The whole ocean system are ultimately connected, although certain regional classifications are useful and relevant. The waters of the continental shelves represent such a region. The term "coastal waters" has been used in a wide variety of different ways in different contexts. In European Union environmental management it extends from the coast to just a few nautical miles while in the United States

4422-482: The world's people live in coastal regions. According to a United Nations atlas, 44% of all people live within 150 km (93 mi) of the sea. Many major cities are on or near good harbors and have port facilities. Some landlocked places have achieved port status by building canals . 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

4489-441: Was expanded upon by Benoit Mandelbrot . Tides often determine the range over which 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 bores can erode as

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