Headlands and bays

Both headland and bay are two coastal features that are related and often found on the same coastline. A bay is a body of water—usually seawater (salt water) and sometimes fresh water— mostly surrounded by land, whereas a headland is surrounded by water on three sides. Headlands are characterized by breaking waves, rocky shores, intense erosion and steep sea cliffs. Bays generally have less wave activity and typically have sandy beaches. Headlands and bays form on discordant coastlines, where the land consists of bands of rock of alternating resistance that run perpendicular to the coast.

Geology and geography

Bays form where less resistant rocks, such as sands and clays, are eroded, leaving bands of stronger, or more resistant rocks, (such as chalk, limestone, and granite), which form a headland or peninsula. Refraction of waves occurs on headlands concentrating wave energy on them, so many other landforms, such as caves, natural arches, and stacks, form on headlands. Wave energy is directed at right angles to the wave crest, and lines drawn at right angles to the wave crest (orthogonals) represent the direction of energy expenditure. Orthogonals converge on headlands and diverge in bays, which concentrates wave energy on the headlands and dissipates wave energy in the bays.[1]

In the formation of sea cliffs, wave erosion undercuts the slopes at the shoreline, which retreat landward. This increases the shear stress in the cliff-forming material and accelerates mass movement.[1] The debris from these landslides collects at the base of the cliff and is also removed by the waves, usually during storms, when wave energy is greatest. This debris provides sediment, which is transported through longshore current for the nearby bay. Joints in the headlands are eroded back to form caves, which erode further to form arches. These gaps eventually collapse and leave tall stacks at the ends of the headlands. Eventually these too are eroded by the waves.[2]

Wave refraction disperses wave energy through the bay, and along with the sheltering effect of the headlands, this protects bays from storms. This effect means that the waves reaching the shore in a bay are weaker than the waves reaching the headland, and the bay is thus a safer place for water activities like surfing or swimming. Through the deposition of sediment within the bay and the erosion of the headlands, coastlines eventually straighten out. But then the same process starts all over again.

Beach stability

A beach is a dynamic geologic feature that can fluctuate between advancement and retreat of sediment. The natural agents of fluctuation include waves, tides, currents, and winds. Man-made elements such as the interruption of sediment supply, such as a dam, and withdrawal of fluid can also affect beach stabilization.[3] Static equilibrium refers to a beach that is stable and experiences neither littoral drift nor sediment deposition nor erosion.[4] Waves generally diffract around the headland(s) and near the beach when the beach is in a state of static equilibrium. Dynamic equilibrium occurs when the beach sediments are deposited and eroded at approximately equal rates.[4] Beaches that have dynamic equilibrium are usually near a river that supplies sediment and would otherwise erode away without the river supply. Unstable beaches are usually a result of human interaction, such as a breakwater or dammed river.[4] Unstable beaches are reshaped by continual erosion or deposition and will continue to erode or deposit until a state of equilibrium is reached in the bay.

References

  1. ^ a b Easterbrook, Don (1999). Surface Processes and Landforms (2nd ed.). Prentice Hall.
  2. ^ "Erosion and Deposition in Coastal Headlands". 2001. Retrieved 28 January 2016.
  3. ^ Schwartz, M. (2005). "Encyclopedia of Coastal Science" . Springer. ISBN 978-1-4020-1903-6 p399
  4. ^ a b c Benedet, L.; Klein, A. H. F.; Hsu, J. R.-C. (2004). Practical Insights and Applications of Empirical Bay Shape Equations. International Conference on Coastal Engineering 2004. Lisbon: American Society of Civil Engineers. pp. 2181–2193. doi:10.1142/9789812701916_0175. ISBN 978-981-256-298-2.

External links

Aberlady Bay

Aberlady Bay in East Lothian, Scotland lies between Aberlady and Gullane.

In 1952, Aberlady Bay became the UK's first Local Nature Reserve (LNR) and is served by the East Lothian Council Rangers.

The Scottish Ornithologists' Club has Waterston House as its headquarters at Aberlady, with panoramic views of the bay.

Aberlady Bay is part of the John Muir Way, a long distance footpath from Fisherrow (Musselburgh) to Dunglass. It is also the East Lothian Section of the transnational North Sea Trail, a path network connecting seven countries and 26 areas.

Bay

A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a type of smaller bay with a circular inlet and narrow entrance. A fjord is a particularly steep bay shaped by glacial activity.

A bay can be the estuary of a river, such as the Chesapeake Bay, an estuary of the Susquehanna River. Bays may also be nested within each other; for example, James Bay is an arm of Hudson Bay in northeastern Canada. Some large bays, such as the Bay of Bengal and Hudson Bay, have varied marine geology.

The land surrounding a bay often reduces the strength of winds and blocks waves. Bays may have as wide a variety of shoreline characteristics as other shorelines. In some cases, bays have beaches, which "are usually characterized by a steep upper foreshore with a broad, flat fronting terrace". Bays were significant in the history of human settlement because they provided safe places for fishing. Later they were important in the development of sea trade as the safe anchorage they provide encouraged their selection as ports.

Charlevoix

Charlevoix (English: ) is a cultural and natural region located in Quebec, on the north shore of the Saint Lawrence River as well as in the Laurentian Mountains area of the Canadian Shield. This dramatic landscape includes rolling terrain, fjords, headlands and bays; the region was designated a World Biosphere Reserve by UNESCO in 1989.

Coastal geography

Coastal geography is the study of the constantly changing region between the ocean and the land, incorporating both the physical geography (i.e. coastal geomorphology, geology and oceanography) and the human geography (sociology and history) of the coast. It includes understanding coastal weathering processes, particularly wave action, sediment movement and weather, and the ways in which humans interact with the coast

Discordant coastline

A discordant coastline occurs where bands of different rock type run perpendicular to the coast.

The differing resistance to erosion leads to the formation of headlands and bays. A hard rock type such as granite is resistant to erosion and creates a promontory whilst a softer rock type such as the clays of Bagshot Beds is easily eroded creating a bay.

Part of the Dorset coastline running north from the Portland limestone of Durlston Head is a clear example of a discordant coastline. The Portland limestone is resistant to erosion; then to the north there is a bay at Swanage where the rock type is a softer greensand. North of Swanage, the chalk outcrop creates the headland which includes Old Harry Rocks.

The converse of a discordant coastline is a concordant coastline.

Dock Tarn

Dock Tarn is a small tarn located within the Lake District National Park in Cumbria, England at grid reference NY273143. It is situated on moorland at 400 metres above sea level near the summit of Great Crag, midway between Watendlath, the Stonethwaite valley and Borrowdale. It measures approximately 300 by 200 metres, and the shoreline is indented with rocky headlands and bays. There is a tiny island in the tarn with a few small Rowan trees growing on it. Many Lake District writers rate Dock Tarn and the walk to it very highly because of its quiet beauty.

The tarn can be reached from Watendlath by a 2.5 kilometre walk along a path that climbs very close to the summit of Great Crag; many walkers include the ascent of this fell in the outing. The approach from Stonethwaite is of a similar distance but is more arduous, going steeply through the deciduous woodland in the valley before following the stream of Willygrass Gill, which is the outflow of Dock Tarn.

Dumfriesshire

Dumfriesshire or the County of Dumfries (Siorrachd Dhùn Phris in Gaelic) is a historic county, registration county and lieutenancy area of Scotland.

It borders Kirkcudbrightshire to the west, Ayrshire to the north-west, Lanarkshire, Peeblesshire and Selkirkshire to the north, and Roxburghshire to the east. To the south is the coast of the Solway Firth, and the English county of Cumberland.

Dumfries has three subdivisions: Annandale, Eskdale and Nithsdale.

For purposes of modern local government, it is combined with Galloway to form the council area of Dumfries and Galloway.

East Lothian

East Lothian (; Scottish Gaelic: Lodainn an Ear) is one of the 32 council areas of Scotland, a historic county, registration county and lieutenancy area. The county was also known as Haddingtonshire.

East Lothian lies south of the Firth of Forth in the eastern central Lowlands of Scotland, east of the City of Edinburgh (historically within Midlothian) and also bordering Midlothian and Berwickshire within the modern Scottish Borders area. Its administrative centre and county town is Haddington and the largest town is Musselburgh which was historically in Midlothian. In 1975, the historic county was incorporated for local government purposes into the Lothian region as East Lothian District, with some slight alterations of its boundaries. The Local Government etc. (Scotland) Act 1994 later created East Lothian as one of 32 modern council areas.

Haddingtonshire has ancient origins and is named in a charter of 1139 as Hadintunschira and in another of 1141 as Hadintunshire. Three of the county's towns were designated as royal burghs: Haddington, Dunbar, and North Berwick.

As with the rest of Lothian, it formed part of the Anglo-Saxon kingdom of Bernicia and later the Kingdom of Northumbria. Popular legend suggests that it was at a battle between the Picts and Angles in the East Lothian village of Athelstaneford in 823 that the flag of Scotland was conceived. From the 10th century, Lothian transferred from the Kingdom of England to the authority of the monarchs of Scotland. It was a cross-point in battles between England and Scotland and later the site of a significant Jacobite victory against Government forces in the Battle of Prestonpans. In the 19th century, the county is mentioned in the Gazetteer for Scotland as chiefly agricultural, with farming, fishing and coal-mining forming significant parts of the local economy.

Geography of Cambodia

Cambodia is a country in mainland Southeast Asia, bordering Thailand, Laos, Vietnam, the Gulf of Thailand and covers a total area of 181,035 km2 (69,898 sq mi). The country is situated in its entirety inside the tropical Indomalayan ecozone and the Indochina Time zone (ICT).Cambodia's main geographical features are the low lying Central Plain that includes the Tonlé Sap basin, the lower Mekong River flood-plains and the Bassac River plain surrounded by mountain ranges to the north, east, in the south-west and south. The central lowlands extend into Vietnam to the south-east. The south and south-west of the country constitute a 443 km (275 mi) long coast at the Gulf of Thailand, characterized by sizable mangrove marshes, peninsulas, sandy beaches and headlands and bays. Cambodia's territorial waters account for over 50 islands. The highest peak is Phnom Aural, sitting 1,810 metres (5,938 ft) above sea level.The landmass is bisected by the Mekong river, which at 486 km (302 mi) is the longest river in Cambodia. After extensive rapids, turbulent sections and cataracts in Laos, the river enters the country at Stung Treng province, is predominantly calm and navigable during the entire year as it widens considerably in the lowlands. The Mekong's waters disperse into the surrounding wetlands of central Cambodia and strongly affect the seasonal nature of the Tonlé Sap lake.Two third of the country's population live in the lowlands, where the rich sediment deposited during the Mekong's annual flooding makes the agricultural lands highly fertile. As deforestation and over-exploitation affected Cambodia only in recent decades, forests, low mountain ranges and local eco-regions still retain much of their natural potential and although still home to the largest areas of contiguous and intact forests in mainland Southeast Asia, multiple serious environmental issues persist and accumulate, which are closely related to rapid population growth, uncontrolled globalization and inconsequential administration.The majority of the country lies within the Tropical savanna climate zone, as the coastal areas in the South and West receive noticeably more and steady rain before and during the wet season. These areas constitute the easternmost fringes of the south-west monsoon, determined to be inside the Tropical monsoon climate. Countrywide there are two seasons of relatively equal length, defined by varying precipitation as temperatures and humidity are generally high and steady throughout the entire year.

Geography of Ireland

Ireland is an island in Northwestern Europe in the north Atlantic Ocean. The island lies on the European continental shelf, part of the Eurasian Plate. The island's main geographical features include low central plains surrounded by coastal mountains. The highest peak is Carrauntoohil (Irish: Corrán Tuathail), which is 1,041 meters (3,415 ft) above sea level. The western coastline is rugged, with many islands, peninsulas, headlands and bays. The island is bisected by the River Shannon, which at 360.5 km (224 mi) with a 102.1 km (63 mi) estuary is the longest river in Ireland and flows south from County Cavan in Ulster to meet the Atlantic just south of Limerick. There are a number of sizeable lakes along Ireland's rivers, of which Lough Neagh is the largest.

Politically, the island consists of the Republic of Ireland, with jurisdiction over about five-sixths of the island; and Northern Ireland, a constituent country (and an unconfirmed "practical" exclave) of the United Kingdom, with jurisdiction over the remaining sixth. Located west of the island of Great Britain, it is located at approximately 53°N 8°W. It has a total area of 84,421 km2 (32,595 sq mi). It is separated from Great Britain by the Irish Sea and from mainland Europe by the Celtic Sea.

Ireland and Great Britain, together with nearby islands, are known collectively as the British Isles; as the term British Isles is controversial in relation to Ireland, the alternative term 'Britain and Ireland' is increasingly preferred.

Golding Island

Golding Island (sometimes seen spelt as "Goulding Island") is one of the Falkland Islands, just to the north of West Falkland in Keppel Sound and near Keppel and Pebble Islands. It has a complex shape, with narrow headlands and bays, and a pond in the middle.

Golding Island is a sheep farm, and was previously farmed together with Pebble Island and Keppel Island by the Dean Brothers. It is now owned by the Hirtle family. The settlement is in the south east, near Hummock Point.

After a raid on San Carlos Water during the Falklands War, Capitan Garcia, an Argentine airman, ejected from his aircraft, an Argentine A-4C Skyhawk . At the time, his body was not recovered, but was washed ashore in a dinghy in 1983. The island was also bombed during the War by the Argentines who thought that they picked up a radio transmission from here.

Headland

A headland is a coastal landform, a point of land usually high and often with a sheer drop, that extends into a body of water. It is a type of promontory. A headland of considerable size often is called a cape. Headlands are characterised by high, breaking waves, rocky shores, intense erosion, and steep sea cliff.

Headlands and bays are often found on the same coastline. A bay is flanked by land on three sides, whereas a headland is flanked by water on three sides. Headlands and bays form on discordant coastlines, where bands of rock of alternating resistance run perpendicular to the coast. Bays form when weak (less resistant) rocks (such as sands and clays) are eroded, leaving bands of stronger (more resistant) rocks (such as chalk, limestone, granite) forming a headland, or peninsula. Through the deposition of sediment within the bay and the erosion of the headlands, coastlines eventually straighten out then start the same process all over again.

Headland (disambiguation)

A headland is a point of land, usually high and often with a sheer drop, that extends out into a body of water.

Headland can also refer to:

Headlands and bays

headLand, an Australian television series

Headland (agriculture), the area at each end of a planted field used for turning farm machinery

Headland, Alabama, a small city in the United States

Headland, Hartlepool, a village in County Durham, UK

Headlands Center for the Arts

Headlands Beach State Park

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, such as the Philippines.

An island may be described as such, despite the presence of an artificial land bridge; examples are Singapore and its causeway, and the various Dutch delta islands, such as IJsselmonde. Some places may even retain "island" in their names for historical reasons after being connected to a larger landmass by a land bridge or landfill, such as Coney Island and Coronado Island, though these are, strictly speaking, tied islands. Conversely, when a piece of land is separated from the mainland by a man-made canal, for example the Peloponnese by the Corinth Canal or Marble Hill in northern Manhattan during the time between the building of the United States Ship Canal and the filling-in of the Harlem River which surrounded the area, it is generally not considered an island.

There are two main types of islands in the sea: continental and oceanic. There are also artificial islands.

Kongsøya

Kongsøya is an island in Svalbard, Norway. It is the largest of the islands in King Charles Land (Kong Karls Land). Its area is 191 square kilometres (74 sq mi). The other main island in the chain is Svenskøya.

Mudflat

Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A recent global analysis suggested they are as extensive globally as mangroves. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily.

In the past tidal flats were considered unhealthy, economically unimportant areas and were often dredged and developed into agricultural land. Several especially shallow mudflat areas, such as the Wadden Sea, are now popular among those practising the sport of mudflat hiking.

On the Baltic Sea coast of Germany in places, mudflats are exposed not by tidal action, but by wind-action driving water away from the shallows into the sea. These wind-affected mudflats are called windwatts in German.

Promontory

A promontory is a raised mass of land that projects into a lowland or a body of water (in which case it is a peninsula).

Most promontories either are formed from a hard ridge of rock that has resisted the erosive forces that have removed the softer rock to the sides of it, or are the high ground that remains between two river valleys where they form a confluence.

Throughout history many forts and castles have been built on promontories because of their inherent defensibility. The promontory forts in Ireland are examples of this. Similarly, the ancient town of Ras Bar Balla in southern Somalia, which in the Middle Ages was part of the Ajuran Sultanate's domain, was built on a small promontory.River confluences consistently provide an added defensive advantage to promontories, acting as a reliable natural moat for the enemy to overcome. The Citadel of Namur, a prime fortified location from the 10th century to this day, lies on the promontory at the confluence of the Meuse and Sambre rivers in the Walloon capital city of Namur, Belgium. Another good example of a confluence promontory fort is Fort Pitt, an English fort during the American Revolution that had previously belonged to the French as Fort Duquesne during the French and Indian War. The surrounding location is known as the city of Pittsburgh, Pennsylvania.

Surf zone

As ocean surface waves come closer to shore they break, forming the foamy, bubbly surface called surf. The region of breaking waves defines the surf zone. After breaking in the surf zone, the waves (now reduced in height) continue to move in, and they run up onto the sloping front of the beach, forming an uprush of water called swash. The water then runs back again as backswash. The nearshore zone where wave water comes onto the beach is the surf zone. The water in the surf zone, or breaker zone, is shallow, usually between 5 and 10 m (16 and 33 ft) deep; this causes the waves to be unstable.

West Nusa Tenggara

West Nusa Tenggara (Indonesian: Nusa Tenggara Barat – NTB) is a province of Indonesia. It comprises the western portion of the Lesser Sunda Islands, with the exception of Bali which is its own province. Mataram, on Lombok, is the capital and largest city of the province. The 2010 census recorded the population at 4,496,855; the latest estimate (for January 2014) is 4,702,389. The province's area is 19,708.79 km2.

The two largest islands in the province are Lombok in the west and the larger Sumbawa island in the east. The islands of Flores and Sumba are part of East Nusa Tenggara.

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