Cliffed coast

A cliffed coast, also called an abrasion coast, is a form of coast where the action of marine waves has formed steep cliffs that may or may not be precipitous. It contrasts with a flat or alluvial coast.

Cliffed coast (shematic view)
Section through a cliffed coast.

Formation

Klippenküste
Crags on the southwestern coast of Portugal
The cliff-top, hilly suburb of Dover Heights (Sydney, Australia)
A cliffed coast in Sydney with houses and apartments.
大连国家地质公园9-海蚀崖
Abrasion cliff in Jinshitan Coastal National Geopark, Dalian, Liaoning Province, China. Wave-like texture was produced by coastal erosion

In coastal areas in which the land surface dips at a relatively steep angle below the water table, the continuous action of marine waves on the coastline, known as abrasion, may create a steep declivity known as a cliff, the slope angle of which depends on a variety of factors including the jointing, bedding and hardness of the materials making up the cliff as well as the erosional processes themselves.[1][2] The slope is constantly being eroded. The waves attacking the cliff-foot form a wave-cut notch by constant abrasion action producing an overhang. This overhang grows in size as the cliff is undercut, until it collapses under its own weight. The loose debris that has broken off is gradually carried away from the area in front of the cliff by the action of the sea. As the coastal cliffs collapse, the shoreline recedes inland. The speed at which this happens depends, in particular, on the strength of the surf, the height of the cliff, the frequency of storm surges and the hardness of the bedrock. Thus, the Mecklenburg coast in Germany recedes by about 25 centimetres per year, whereas the chalk cliffs of southern England retreat by just ½ a centimetre each year. A cliffed coast is made of a loose bedrock material, such as at the Red Cliff on the German island of Sylt, but can also occur in hard rock like the red sandstone cliffs on Heligoland. There are, however, differences between the former and the latter regarding some peculiarities of the coast line.

Rocky cliffed coast

On a rocky cliffed coast made up of material which is relatively resistant to erosion such as sandstone, limestone or granite, a flat rocky wave-cut platform or abrasion platform is formed in front of the cliff. It represents the foot of the cliff preserved at and below the level of water table. If there is a tectonic uplift of the coast, these abrasion platforms can be raised to form coastal terraces, from which the amount of uplift can be calculated from their elevation relative to the sea level, taking into account any eustatic sea level changes. On a cliffed coast made up of material which is only fairly or even hardly resistant to erosion no wave-cut platform but a beach is formed in front of the sea cliff.

If waves carve notches at a narrow point on both sides of a promontory on the rocky cliffed coast, a natural arch may be formed.[3] When the arch collapses as the coastline recedes further a stack is left behind on the wave-cut platform. The best-known example in Germany is the Lange Anna on Heligoland.

Furthermore, on a rocky cliffed coast wave action is not the only driving force for coastline retreat. General weathering of the bedrock is almost equally important.[2]

Living and dead cliffs

"Living cliffs" are those on a coast that is still active, i.e. that is being eroded and is receding. A "dead cliff", by contrast, is only reached by very high marine waves and is therefore subjected to very little change. A clear indication of a lack of activity at a dead cliff is a covering of vegetation that appears on the cliff as wave action against it subsides.

Well-known coasts with living cliffs in Germany are the Red Cliff (Rote Kliff) in Kampen on the island of Sylt or the chalk cliffs on the Jasmund Peninsula. The Königsstuhl on the island of Rügen is a good example of a dead cliff. Others may be found in the regions of the present-day Wadden Sea coast of the North Sea a few kilometres inland. These show the former coastline from which the sea retreated as the level of water in the North Sea fell.

Other processes

Steep sea cliffs can also be caused by catastrophic debris avalanches. These have been common on the submerged flanks of ocean island volcanos such as the Hawaiian Islands and the Cape Verde Islands.[4][5]

References

  1. ^ Whittow, John (1984). Dictionary of Physical Geography. London: Penguin, 1984, p. 97. ISBN 0-14-051094-X.
  2. ^ a b Herbert Louis and Klaus Fischer: Allgemeine Geomorphologie, de Gruyter, 4th ed., Berlin 1979, pp. 532-537
  3. ^ Hans Georg Wunderlich: Einführung in die Geologie, Band I, Exogene Dynamik, Bibliographisches Institut Mannheim/Wien/Zürich, B.I.-Wissenschaftsverlag, Mannheim, 1968, p. 116
  4. ^ Le Bas, T.P. (2007), "Slope Failures on the Flanks of Southern Cape Verde Islands", in Lykousis, Vasilios, Submarine mass movements and their consequences: 3rd international symposium, Springer, ISBN 978-1-4020-6511-8
  5. ^ Mitchell, N. (2003) Susceptibility of mid-ocean ridge volcanic islands and seamounts to large scale landsliding. Journal of Geophysical Research, 108, 1-23.

External links

Basque Coast Geopark

The Basque Coast Geopark (Basque language: Euskal Kostaldeko Geoparkeak), formally the Basque Coast UNESCO Global Geopark, is an area of the Basque Country in the north of Spain which became a member of the European Geoparks Network in 2010, one of several Global Geoparks in Spain. It comprises 89 square kilometres of countryside with a 23km long cliffed coast fronting the Bay of Biscay. Inland it comprises hilly country which reaches up to Sesiarte which is 755m above sea level. The main communities within the Geopark are Zumaia, Deba and Mutriku. The A8 Cantabrian motorway runs east-west through the Geopark.

Brighton to Newhaven Cliffs

Brighton to Newhaven Cliffs is a 165.4-hectare (409-acre) biological and geological Site of Special Scientific Interest and Geological Conservation Review site, which stretches along the coast between Brighton and Newhaven in East Sussex. An area of 16.4 hectares (41 acres) is the Castle Hill, Newhaven Local Nature Reserve

Cliff

In geography and geology, a cliff is a vertical, or nearly vertical, rock exposure. Cliffs are formed as erosion landforms by the processes of weathering and erosion. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually formed by rock that is resistant to weathering and erosion. Sedimentary rocks most likely to form cliffs include sandstone, limestone, chalk, and dolomite. Igneous rocks such as granite and basalt also often form cliffs.

An escarpment (or scarp) is a type of cliff, formed by the movement of a geologic fault or landslide, or by differential erosion of rock layers of differing hardness.

Most cliffs have some form of scree slope at their base. In arid areas or under high cliffs, they are generally exposed jumbles of fallen rock. In areas of higher moisture, a soil slope may obscure the talus. Many cliffs also feature tributary waterfalls or rock shelters. Sometimes a cliff peters out at the end of a ridge, with tea tables or other types of rock columns remaining. Coastal erosion may lead to the formation of sea cliffs along a receding coastline.

The Ordnance Survey distinguishes between cliffs (continuous line along the top edge with projections down the face) and outcrops (continuous lines along lower edge).

Cliffs of Moher

The Cliffs of Moher (; Irish: Aillte an Mhothair) are sea cliffs located at the southwestern edge of the Burren region in County Clare, Ireland. They run for about 14 kilometres. At their southern end, they rise 120 metres (390 ft) above the Atlantic Ocean at Hag's Head, and, eight kilometres to the north, they reach their maximum height of 214 metres (702 ft) just north of O'Brien's Tower, a round stone tower near the midpoint of the cliffs, built in 1835 by Sir Cornelius O'Brien, then continue at lower heights. The closest settlements are Liscannor (6 km south) and Doolin (7 km north).

From the cliffs, and from atop the tower, visitors can see the Aran Islands in Galway Bay, the Maumturks and Twelve Pins mountain ranges to the north in County Galway, and Loop Head to the south. The cliffs rank among the most visited tourist sites in Ireland, with around 1.5 million visits per annum.

Coast

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; for example, New Zealand's West Coast, or the East and West Coasts of the United States. Edinburgh for example is a city on the coast of Great Britain.

A pelagic coast refers to a coast which 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 (sea shore) and lakes (lake shore). Similarly, the somewhat related term "[stream bed/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 kilometres (93 miles) 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

Dornbusch (Hiddensee)

The Dornbusch is a region of low rolling hills in the northern part of the German Baltic Sea island of Hiddensee. It consists mainly of ice age depositions, that were left behind after the glacier thawed. It is one of three island cores of the Hiddensee responsible for the emergence of the lowland.

The Dornbusch measures about 2.45 kilometres from north to south and about 2.85 kilometres from east to west. Its highest point, at 72 metres above sea level, is the Schluckswiekberg, on which the Dornbusch Lighthouse, the symbol of Hiddensee, stands.

With much of its cliffed coast still active it represents an important landscape in the West Pomeranian Lagoon Area National Park and is part of protection zone II. Numerous footpaths run through its varied countryside.

Fischland

Fischland (literally "fish land") is an isthmus on the southern Baltic Sea coast on the Bay of Mecklenburg in northeastern Germany. It is part of the peninsula of Fischland-Darß-Zingst. Fischland was an island until the 14th century and was bounded by the navigable estuarine branches of the River Recknitz: the Permin in the south and the Loop in the north. In more recent times its southern boundary has usually been considered to be the Recknitz Meadowland (Recknitzer Stadtwiesen) and the Rostock Heath (Rostocker Heide). To the west and east its boundaries are more obvious: on the one side is its active cliffed coast on the Baltic, and on the other the coastline alongside the Saaler Bodden, only a few centimetres above sea level. Fischland is about 5 km long, between 500 metres and 2 km wide and runs from southwest to northeast.

The Pleistocene island core, which is subjected to marked changes as a result of water and wind action, consists of glacial sands (Geschiebesanden) and till and forms part of a graded shoreline. Not until the end of the 14th century were the two existing channels between the Baltic Sea and the lagoon or bodden filled in by the Hanseatic League in order to make access to the sea more difficult for their rival, Ribnitz. As a result, Fischland and Darß became a peninsula.

Today storms carry away an average of half a metre of coast per year from Fischland, depositing it again further north at Darßer Ort. Without major coastal defence measures the narrow isthmus would probably have long since been destroyed.

Near the steep coastline of Althagen/Niehagen lies the eminence of Bakelberg. At 17.9 metres above sea level (NN) it is the highest elevation on Fischland.

There is a total of just four settlements on Fischland, which have largely merged with one another today: the Ahrenshoop villages of Althagen and Niehagen as the municipality of Wustrow with the village of Barnstorf. The village of Ahrenshoop, well known as a residence and holiday resort for artists, on West Pomeranian soil is not on Fischland, however, but on the Vordarß. To the north Fischland is bounded by the present-day boundary trail (Grenzweg) in the municipality of Ahrenshoop. This used to be the site of the Loop, an inlet that marked the border between Mecklenburg and Pomerania; until recent times it continued to form the border between the Mecklenburg and Pomeranian State Churches.

Granitz

The Granitz is a wooded ridge in the southeast of Germany's largest island, Rügen, between the Baltic Sea resorts of Binz and Sellin. The woods cover an area of 982 hectares and are designated as a nature reserve. Since 1991 they have been part of the Southeast Rügen Biosphere Reserve.

Characteristic of the Granitz are its rich stands of beech and sessile oak and its rolling landscape of push end moraines, which in some ways resemble a mountain landscape. To the north and east the Granitz is bounded by a cliffed coast on the Baltic Sea. In the south it adjoins the Mönchgut region and in the north, the narrow bar of the Schmale Heide. The 23-acre (9.3 ha) Black Lake (Schwarzer See) lies in the Granitz as do several kettle bogs. A number of non-native stands of conifers are being turned into a near-natural forest.

No roads of any description run through the Granitz, but there are many cycle and footpaths. Local transport and access to the area is provided by the Rügen Light Railway and Binz Seaside Railway (Binzer Bäderbahn).

On the highest point, the Tempelberg (107 m above sea level (NN)), Prince Wilhelm Malte I of Putbus had the Granitz hunting lodge constructed in the 19th century. Other landmarks include Granitz House, the grave site of Finnish warriors and the Cross Oak (Kreuzeiche).

The name is probably of Slavic origin and comes from the personal name, Granza, used by the Rani tribe, which first appears as a prince's name in the Saxo Grammaticus in 1168. In 1888, the Waldhalle, a tourist restaurant, was built on the hill of Falkenberg on the clifftop path from Binz to Sellin near the coast. The building had to be abandoned and demolished in the 1980s as a result of coast collapse. Only a few remains of foundations on the cliff face of the Baltic Sea coast recall the existence of the building.

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.

Jaromarsburg

The Jaromarsburg was a cult site for the Slavic tribe of Rani dedicated to the god Svantovit and used from the 9th to the 12th century. It was located on the northeastern tip of the Baltic Sea island of Rügen at Cape Arkona, and was protected on two sides by the cliffed coast and from the land side by a Slavic burgwall. The name of the temple hill is derived from the Rani prince, Jaromar I, who became a vassal of the Danish king, Valdemar I in 1168 after Rügen was conquered by Denmark.

At Cape Arkona in recent centuries, sections of the cliff tops have continually collapsed into the sea, which is why the remnants of the Jaromarsburg today mainly comprise the castle ramparts. Based on a loss of 10 to 20 metres per century, it is believed that the current area within the ramparts represents only a third of the original total. As a result, for several years urgent archaeological excavations have taken place, which have uncovered the site of the Svetovid temple, which had been thought for a long time had been lost to coastal collapse. It is a rectangular area that was completely free of artifacts, but to find around which, however, articles were discovered that may have been offerings, including parts of broken weapons. This is consistent with the historical account by Saxo Grammaticus, who states that the priests inside the temple were not even allowed to breathe within its confines, so as not to defile it.

Mudflat

Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. 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.

North Northumberland Coastal Plain

The North Northumberland Coastal Plain is a major natural region that lies on England's northeasternmost stretch of coastline on the North Sea. To the west lie the Cheviot Fringe, the Northumberland Sandstone Hills and Mid Northumberland; to the south it is continued by the South East Northumberland Coastal Plain.

The North Northumberland Coastal Plain lies along the coast of the county of Northumberland and is listed as Natural Area No. 1 and also as National Character Area 1 by Natural England, the UK government's advisor on the natural environment in England. The region is a coastal strip, around 70 kilometres long and 3 to 10 kilometres wide, that runs from the Scottish Border to Amble on the River Coquet. Its narrow, low lying, windswept terrain has wide views east towards the sea and west towards the Cheviots. Coastal scenery is diverse. The northern part has a 'hard' cliffed coast of spectacular high cliffs, offshore islands and rocky headlands, whilst the southern strip is a 'soft' alluvial coast of wide, sweeping sandy bays backed by sand dunes and intertidal flats backed by saltmarsh. Inland, the plain is intensively farmed, typically with open, mixed arable land and few trees. The valleys and coastal fringes are characterized by woodland and permanent pasture or semi-natural grassland.Roughly a quarter of the NCA lies within the Northumberland Coast Area of Outstanding Natural Beauty and also within the North Northumberland Heritage Coast.

The region contains 4 Special Areas of Conservation - Berwickshire and North Northumberland Coast SAC; Newham Fen SAC; River Tweed SAC; and Tweed Estuary SAC - three national nature reserves - Lindisfarne NNR, Farne Islands NNR and Newham Bog NNR - and 15 Sites of Special Scientific Interest, the latter totalling 1,296 hectares. Its major watercourses are the River Tweed, which forms the border with Scotland in the north, the River Coquet in the far south, Whiteadder Water and the River Aln.The Holy Island of Lindisfarne is an important historic site which incorporates Lindisfarne Castle. Other historic sites include: Bamburgh, Dunstanburgh and Warkworth Castles.

Reddevitz Höft

The Reddevitz Höft or Reddevitzer Höft is a peninsular forming part of the German Baltic Sea island of Rügen. It is part of the Mönchgut peninsula, with which it is linked in the southeast by a good 130 metre wide isthmus. The Reddevitzer Höft is over four kilometres long and up to 500 metres wide. In its western part, which end in a cliffed coast, the land climbs to a height of over 33 metres. At the eastern end is the village of Alt Reddevitz, part of the municipality of Middelhagen. The namen is derived from the Low German word höft for "head".

In the north the Reddevitzer Höft borders on the Having and in the south on the Hagensche Wiek, to the west and southwest lies the Bay of Greifswald.

The peninsula, which lies within the Southeast Rügen Biosphere Reserve, is the largest contiguous stretch of heathland on the island of Rügen and is classed as a natural monument.

Rotes Kliff

The Rotes Kliff is a 52-metre high line of sea cliffs between the villages of Wenningstedt and Kampen on the German North Sea island of Sylt. It is located on the west side of the island facing the open sea, beginning in the south at the car park of "Risgap" in Wenningstedt and ending in the north at Haus Kliffende on the Kampen West Heath.

For centuries these striking cliffs have acted as an unmistakable recognition mark of the island for ships. Nowhere on the German and Dutch North Sea shores is there such a striking cliffed coast.

About 120,000 years ago, glaciers of the Saale glaciation deposited thick, unsorted rock debris in the region of the present-day island of Sylt. As a result of rising sea levels in the post-glacial period, these formed an abrasion coastline. The rusty-red glacial till, which gives the cliffs their name, is caused by colouration arising from the oxidation of ferrous elements.

Even in the 19th century, geologists suspected there was a geological connexion between Sylt and Heligoland, whose rocks have a similar coloration but are considerably older and have a different genesis. The rocks that break off the Rotes Kliff - such as flint, rhomb porphyry or Rapakivi granite - still enable an accurate determination of their origin to be made.

The Rotes Kliff has always been at great risk from storm surges and erosion. Since the end of the 1970s, coastal defence measures have been taken, however, in the shape of extensive sand replenishment of the entire west beach of the island and this has proved an important protection against the loss of land. However this has also resulted in the Rotes Kliff in the municipality of Wenningstedt becoming largely invisible from the sea, because it is now hidden behind beach grass-covered sand dunes.

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.

Vitt

The fishing village of Vitt lies on the German Baltic Sea island of Rügen, more precisely on the Wittow peninsula near Cape Arkona. The village is part of the municipality of Putgarten. Because of its location in a coastal gully on the cliffed coast, called Liete, Vitt is not visible from afar. However, from the edge of the gully there is a view over the thatched roofs of the village. It is a popular tourist destination; often described as "the most romantic place on Rügen". The Marco Polo guide rates it as one of the top 15 highlights on the island of Rügen.

West Mecklenburg

West Mecklenburg (German: Westmecklenburg) is the western part of the German federal state of Mecklenburg-Vorpommern, covering an area of ca. 7,000 km². It incorporates parts of the historic territories of Mecklenburg-Schwerin and Mecklenburg-Strelitz (parts of the former Principality of Ratzeburg around the town of Schönberg (Mecklenburg)) and of Saxe-Lauenburg (the Prussian municipalities allocated to the former Soviet Zone of Occupation by the Barber-Lyashchenko Agreement).

The region of West Mecklenburg consists of the districts of Nordwestmecklenburg and Ludwigslust-Parchim as well as the independent city of Schwerin and is legally defined as a planning region, i. e. a sub-region for regional spatial planning that is carried out by a regional planning association.The region had a population of 483,939 on 30 June 2008. The centre for the region is the state capital of Schwerin; other important towns are Parchim, Ludwigslust, Wismar, Gadebusch, Klütz, Grevesmühlen and Hagenow.

West Mecklenburg is an undulating morainic terrain in the Baltic Uplands interspersed with inland lakes and formed by the Weichsel glaciation. On the Baltic Sea rim is a cliffed coast with the Bay of Lübeck and Bay of Wismar with the island of Poel and the seaside resort of Boltenhagen. In the northeast West Mecklenburg gives way to the region of Middle Mecklenburg; in the southeast it merges gradually into the Mecklenburg Lake District.

Whale Cave

The Whale Cave (Chinese: 澎湖逍遙遊; pinyin: Pēnghú Xiāoyáoyóu) is a wave-cut platform in Xiaomen Village, Xiyu Township, Penghu County, Taiwan.

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