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 of loose rock. They may be basically divided into two parallel strips: the shoreface and the beach.

Flat coasts consist of loose material such as sand and gravel. Wind transports finer grains of sand inland over the dunes. The sea washes pebbles and sand away from the coast and dumps it at other locations.

Flat coast (shematic view)
Schematic diagram of a flat coast.

Flat coast littoral series

Litorale Serie Flachküste
Diagram of a flat coast littoral series. Key: B: bar, TNW: average low tide, THW: average high tide, US: shoreface; GS: foreshore, SW: berm, SR: runnel, HS: backshore, DG: dune belt, SK: dune cliff

The typical sequence of landforms created by the sea is described as a "littoral series".

Sandbars, runnels and creeks

Priel im Sahlenburger Watt
Wadden creek with exposed sandbar during an ebb tide

The littoral series of a flat coast starts in the permanently flooded shallow water region, or shoreface, with a sand or gravel reef (also called a bar). The longshore bar is an elongated ridge of sand found parallel to the shore in the surf zone on many flat coasts. It consists mainly of sand or gravel, depending on the material available along the coast. The sides of the sandbar fall gently away. The basin between a sandbar and the shore zone is called the runnel or swale. The presence of a bar clearly indicates that the movement of waves is transporting and depositing material on the seabed. There may be several bars whose longitudinal axes all run parallel to the beach and which are separated by equally parallel runnels or creeks. The drainage troughs in areas of tidal flats also run parallel to the coast.

Shoreface and beach

Quinta do Lago beach 1
Start of the dune belt by the sand cliff

The shoreface (or underwater platform) on flat coasts encompasses in its narrow sense that area which is subject to the constant action of moving water. This means that the landward boundary between shoreface and beach is the line of the average low-water mark. However this definition is not universal and frequently varies from author to author in the literature. Whilst some define the beach as the landward transition to the shoreface that extends from the low-water mark to the highest high-water mark, i.e. the zone that is only periodically or episodically (after a storm surge) flooded by water; other authors do not use the term "beach" for the landward element of a flat coast at all. They describe the region between the mean low-water mark and the mean high-water mark of the tides as the intertidal zone or foreshore and that area above the average high-water mark as the supratidal zone or backshore that is only directly attacked by water during storms. Because the backshore is often considerably flatter in appearance than the foreshore, which slopes clearly down towards the sea, it is also often referred to as a beach platform, which is why this part of the shore can be considered in practice to be the actual beach. The farthest point inland that is reached by storm surges is bounded by a belt of dunes, where floods can form a dune cliff.


The berm: where the gravel is no longer washed back into the sea by the backwash

On the beach (the beach platform) there is very often a bank of sand or a gravel ridge parallel to the shoreline and a few tens of centimetres high, known as the berm. On its landward side there is often a shallow runnel. The berm is formed by material transported by the breaking waves that is thrown beyond the average level of the sea. The coarse-grained material that can no longer be washed away by the backwash remains behind. The location and size of the berm is subject to seasonal changes. For example, a winter berm that has been thrown up by storm surges in winter is usually much more prominent and higher up the beach than berms formed by summer high tides.

A similar landform is a beach ridge.

Beach losses and gains

Noel2007 erosion
Beach losses after a hurricane

Beaches are usually heavily eroded during storm surges and the beach profile steepened, whereas normal wave action on flat coasts tends to raise the beach. Not infrequently a whole series of parallel berms is formed, one behind the other. There is a consequent gradual increase in height with the result that, over time, the shoreline advances seawards. A striking example of land-forming system of berms is Skagen Odde on the northern tip of Vendsyssel in the extreme north of Denmark. This headland is still growing today as more berms are added.

Coastal defences against erosion are groynes, stone walls, or tetrapods of concrete, which act as breakwaters. The first plants to colonise the dunes include sea buckthorn or beach grass which prevent wind erosion.


  • Klaus Duphorn et al.: Die deutsche Ostseeküste. Sammlung geologischer Führer, Vol. 88, 281 p., numerous diagrams and maps, Bornträger, Berlin, 1995
  • Heinz Klug, Horst Sterr, Dieter Boedecker: Die deutsche Ostseeküste zwischen Kiel und Flensburg. Morphologischer Charakter und rezente Entwicklung. Geographische Rundschau 5, p. 6–14. Brunswick, 1988
  • Harald Zepp: Grundriss Allgemeine Geographie – Geomorphologie. UTB 2008, ISBN 3-8252-2164-4
  • Frank Ahnert: Einführung in die Geomorphologie. UTB 2003, ISBN 3-8252-8103-5

Alrø is a small Danish island in Horsens Fjord on the east coast of Jutland within Odder Municipality.The island is 7.52 km long with a coastline of 14 km, and stretches a little over 5 km wide from east to west. With a population of 147 as of January 2013, the island can be reached by road over an artificial causeway which connects it to the mainland on the northern side of the fjord. Alrø has been inhabited continuously since the Stone Age up to modern times, with possible additional usage during the Viking Age as a landing site.


The coast, also known as the coastline or seashore, is the area where land meets the sea or ocean, or a line that forms the boundary between the land and the ocean or a lake. A precise line that can be called a coastline cannot be determined due to the coastline paradox.

The term coastal zone is a region where interaction of the sea and land processes occurs. Both the terms coast and coastal are often used to describe a geographic location or region (e.g., New Zealand's West Coast, or the East and West Coasts of the United States). Edinburgh is an example city on the coast of Great Britain.

The term pelagic coast refers to a coast that fronts the open ocean, as opposed to a more sheltered coast in a gulf or bay. A shore, on the other hand, can refer to parts of land adjoining any large body of water, including oceans (seashore) and lakes (lake shore). Similarly, the somewhat related term stream bed or stream bank refers to the land alongside or sloping down to a river (riverbank) or body of water smaller than a lake. Bank is also used in some parts of the world to refer to an artificial ridge of earth intended to retain the water of a river or pond; in other places this may be called a levee.

While many scientific experts might agree on a common definition of the term coast, the delineation of the extents of a coast differ according to jurisdiction, with many scientific and government authorities in various countries differing for economic and social policy reasons. According to the UN atlas, 44% of people live within 150 km (93 mi) of the sea.

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


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.


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.

Outline of oceanography

The following outline is provided as an overview of and introduction to Oceanography.


Quintes is one of the westernmost towns of the municipality of Villaviciosa. It is located on the left side of the river called río España, 17 km from Villaviciosa and 14 km from Gijón. It is a coastal town with beautiful cliffs that look out over the Cantábrico from considerable heights. The Spanish beach, in the estuary of the Rio España, receives a large number of visitors throughout the year, especially during the peak holiday season.


Quintueles (variant: San Clemente de Quintueles) is one of 41 parishes in Villaviciosa, a municipality within the province and autonomous community of Asturias, in northern Spain.Situated at 88 m (289 ft) above sea level, the parroquia is 9.81 km2 (3.79 sq mi) in area, with a population of 663 (INE 2008).

Fossilised pterosaur tracks have been uncovered at Quintueles' Lastres Formation.

Steep coast

A steep coast is a stretch of coastline where the mainland descends abruptly into the sea. There is a sharp transition from the land to sea as opposed to that on a flat coast where the land descends gradually seawards. The height of the land on a steep coast is well above sea level.

Most steep coast are rocky cliffed coasts (also called abrasion coasts), where the erosion processes of wave action result in a steep declivity. Another type of steep coast is the fjord which is formed when a glacial valley lies partially under water as a result of a rise in sea levels. In Norway, New Zealand or Alaska there are fjords whose almost vertical sides tower over 1,000 metres above the water and plunge 300 metres below it.

On volcanic islands the sea can enter the caldera and the face of the volcanic pipe can form a steep coastline. The best-known example of that is Santorini in the archipelago of the Cyclades in Greeces. The main town of Thira lies on the rim of the caldera which is around 300 metres above the sea and drops below it for another 200 metres.

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.

Wadden Sea National Park, Denmark

Wadden Sea National Park (Nationalpark Vadehavet) was designated a Danish national park on 17 January 2008, effective 2010. Since June 2014 it has constituted the Danish part of the UNESCO's Wadden Sea World Heritage Site. Prince Joachim of Denmark is Patron of the Wadden Sea Centre.

The Wadden Sea National Park is - except Greenland by far the largest of Denmark's national parks and covers the Danish part of the Wadden Sea from Ho Bugt to the German border, and includes the islands of Fanø, Mandø and Rømø, as well as Skallingen, the Varde Å valley, and many of the marshlands of Tjæreborgmarsken, Ribemarsken, Margrethekogen and De Ydre Diger in Tøndermarsken.

The Wadden Sea is internationally known as a resting place for millions of migratory birds, and more than 10 million of them pass through the Wadden Sea twice a year. Large flocks of European starlings can be found which fly in formations known as the sort sol.

The Wadden Sea also has large numbers of breeding birds, fish, and invertebrates such as starfish and blue mussels. It provides habitat for more than 500 species of plants and animals.

97% of the national park is part of Natura 2000, divided into several projects: a bird sanctuary, a wildlife sanctuary, and Ramsar wetlands of international importance. The areas comprise biomes like the low-lying flat coast, tidal channels, tidal flats, stream mouths, beach meadows, sandplains and dunes.



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