The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period and with the end of the Paleolithic age used in archaeology; the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, the Gelasian, Middle Pleistocene and Upper Pleistocene. In addition to this international subdivision, various regional subdivisions are used. Before a change confirmed in 2009 by the International Union of Geological Sciences, the time boundary between the Pleistocene and the preceding Pliocene was regarded as being at 1.806 million years Before Present, as opposed to the accepted 2.588 million years BP: publications from the preceding years may use either definition of the period. Charles Lyell introduced the term "Pleistocene" in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today.
This distinguished it from the older Pliocene epoch, which Lyell had thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" from the Greek πλεῖστος, pleīstos, "most", καινός, kainós, "new"; the Pleistocene has been dated from 2.588 million to 11,700 years BP with the end date expressed in radiocarbon years as 10,000 carbon-14 years BP. It covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell; the end of the Younger Dryas has been dated to about 9640 BC. The end of the Younger Dryas is the official start of the current Holocene Epoch. Although it is considered an epoch, the Holocene is not different from previous interglacial intervals within the Pleistocene, it was not until after the development of radiocarbon dating, that Pleistocene archaeological excavations shifted to stratified caves and rock-shelters as opposed to open-air river-terrace sites. In 2009 the International Union of Geological Sciences confirmed a change in time period for the Pleistocene, changing the start date from 1.806 to 2.588 million years BP, accepted the base of the Gelasian as the base of the Pleistocene, namely the base of the Monte San Nicola GSSP.
The IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75° 06' N 42° 18' W; the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils: Discoaster pentaradiatus and Discoaster surculus; the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age; the revised definition of the Quaternary, by pushing back the start date of the Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. The modern continents were at their present positions during the Pleistocene, the plates upon which they sit having moved no more than 100 km relative to each other since the beginning of the period.
According to Mark Lynas, the Pleistocene's overall climate could be characterized as a continuous El Niño with trade winds in the south Pacific weakening or heading east, warm air rising near Peru, warm water spreading from the west Pacific and the Indian Ocean to the east Pacific, other El Niño markers. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places, it is estimated. In addition, a zone of permafrost stretched southward from the edge of the glacial sheet, a few hundred kilometres in North America, several hundred in Eurasia; the mean annual temperature at the edge of the ice was −6 °C. Each glacial advance tied up huge volumes of water in continental ice sheets 1,500 to 3,000 metres thick, resulting in temporary sea-level drops of 100 metres or more over the entire surface of the Earth. During interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions.
The effects of glaciation were global. Antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene; the Andes were covered in the south by the Patagonian ice cap. There were glaciers in New Tasmania; the current decaying glaciers of Mount Kenya, Mount Kilimanjaro, the Ruwenzori Range in east and central Africa were larger. Glaciers existed to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one; the Cordilleran ice sheet covered the North American northwest. The Fenno-Scandian ice sheet rested including much of Great Britain. Scattered domes stretched across Siberi
Marine debris known as marine litter, is human-created waste that has deliberately or accidentally been released in a lake, ocean, or waterway. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Occurring debris, such as driftwood, are present. With the increasing use of plastic, human influence has become an issue as many types of plastics do not biodegrade. Waterborne plastic poses a serious threat to fish, marine reptiles, marine mammals, as well as to boats and coasts. Dumping, container spillages, litter washed into storm drains and waterways and wind-blown landfill waste all contribute to this problem. In efforts to prevent and mediate marine debris and pollutants and policies have been adopted internationally. Depending on relevance to the issues and various levels of contribution, some countries have introduced more specified protection policies.
Researchers classify debris as either land- or ocean-based. More recent studies have found that more than half of plastic debris found on Korean shores is ocean-based. A wide variety of man-made objects can become marine debris. Six pack rings, in particular, are considered emblematic of the problem; the US military used ocean dumping for unused weapons and bombs, including ordinary bombs, UXO, landmines and chemical weapons from at least 1919 until 1970. Millions of pounds of ordnance were disposed of in the Gulf of Mexico and off the coasts of at least 16 states, from New Jersey to Hawaii. Eighty percent of marine debris is plastic. Plastics accumulate because they do not biodegrade as many other substances do, they photodegrade on exposure to sunlight, although they do so only under dry conditions, as water inhibits photolysis. In a 2014 study using computer models, scientists from the group 5 Gyres, estimated 5.25 trillion pieces of plastic weighing 269,000 tons were dispersed in oceans in similar amount in the Northern and Southern Hemispheres, one-hundredth of them are particles the scale of a sand.
Fishing nets left or lost in the ocean by fishermen – ghost nets – can entangle fish, sea turtles, dugongs, seabirds and other creatures. These nets restrict movement, causing starvation and infection, and, in animals that breathe air, suffocation. 8.8 million metric tons of plastic waste are dumped in the world's oceans each year. Asia was the leading source of mismanaged plastic waste, with China alone accounting for 2.4 million metric tons. Plastic waste has reached all the world's oceans; this plastic pollution harms an estimated 100,000 sea turtles and marine mammals and 1,000,000 sea creatures each year. Larger plastics such as plastic shopping bags can clog the digestive tracts of larger animals when consumed by them and can cause starvation through restricting the movement of food, or by filling the stomach and tricking the animal into thinking it is full. Microplastics on the other hand harm smaller marine life. For example, pelagic plastic pieces in the center of our ocean’s gyres outnumber live marine plankton, are passed up the food chain to reach all marine life.
A 1994 study of the seabed using trawl nets in the North-Western Mediterranean around the coasts of Spain and Italy reported mean concentrations of debris of 1,935 items per square kilometre. Plastic debris accounted for 77 %. Nurdles known as "mermaids' tears", are plastic pellets under five millimetres in diameter, that are a major component of marine debris, they are a raw material in plastics manufacturing, enter the natural environment when spilled. Weathering produces smaller pieces. Nurdles resemble fish eggs. Litter, made from diverse materials that are denser than surface water, have been found to spread over the floor of seas and open oceans, where it can become entangled in corals and interfere with other sea-floor life, or become buried under sediment, making clean-up difficult due to the wide area of its dispersal compared to shipwrecks. Research performed by MBARI found items including plastic bags below 2000 m depth off the west coast of North America and around Hawaii; the 10 largest emitters of oceanic plastic pollution worldwide are, from the most to the least, Indonesia, Vietnam, Sri Lanka, Egypt, Malaysia and Bangladesh through the rivers Yangtze, Yellow, Nile, Pearl, Amur and the Mekong, accounting for "90 percent of all the plastic that reaches the world's oceans."An estimated 10,000 containers at sea each year are lost by container ships during storms.
One spillage occurred in the Pacific Ocean in 1992, when thousands of rubber ducks and other toys went overboard during a storm. The toys have since been found all over the world, providing a better understanding of ocean currents. Similar incidents have happened before, such as when Hansa Carrier dropped 21 c
The North Sea is a marginal sea of the Atlantic Ocean located between the United Kingdom, Norway, Germany, the Netherlands and France. An epeiric sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north, it is more than 970 kilometres long and 580 kilometres wide, with an area of 570,000 square kilometres. The North Sea has long been the site of important European shipping lanes as well as a major fishery; the sea is a popular destination for recreation and tourism in bordering countries and more has developed into a rich source of energy resources including fossil fuels and early efforts in wave power. The North Sea has featured prominently in geopolitical and military affairs in Northern Europe, it was important globally through the power northern Europeans projected worldwide during much of the Middle Ages and into the modern era. The North Sea was the centre of the Vikings' rise. Subsequently, the Hanseatic League, the Netherlands, the British each sought to dominate the North Sea and thus access to the world's markets and resources.
As Germany's only outlet to the ocean, the North Sea continued to be strategically important through both World Wars. The coast of the North Sea presents a diversity of geographical features. In the north, deep fjords and sheer cliffs mark the Norwegian and Scottish coastlines, whereas in the south, the coast consists of sandy beaches and wide mudflats. Due to the dense population, heavy industrialization, intense use of the sea and area surrounding it, there have been various environmental issues affecting the sea's ecosystems. Adverse environmental issues – including overfishing and agricultural runoff and dumping, among others – have led to a number of efforts to prevent degradation of the sea while still making use of its economic potential; the North Sea is bounded by the Orkney Islands and east coast of Great Britain to the west and the northern and central European mainland to the east and south, including Norway, Germany, the Netherlands and France. In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean.
In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively. In the north it is bordered by the Shetland Islands, connects with the Norwegian Sea, which lies in the north-eastern part of the Atlantic; the North Sea is more than 970 kilometres long and 580 kilometres wide, with an area of 570,000 square kilometres and a volume of 54,000 cubic kilometres. Around the edges of the North Sea are sizeable islands and archipelagos, including Shetland and the Frisian Islands; the North Sea receives freshwater from a number of European continental watersheds, as well as the British Isles. A large part of the European drainage basin empties into the North Sea, including water from the Baltic Sea; the largest and most important rivers flowing into the North Sea are the Elbe and the Rhine – Meuse watershed. Around 185 million people live in the catchment area of the rivers discharging into the North Sea encompassing some industrialized areas.
For the most part, the sea lies on the European continental shelf with a mean depth of 90 metres. The only exception is the Norwegian trench, which extends parallel to the Norwegian shoreline from Oslo to an area north of Bergen, it has a maximum depth of 725 metres. The Dogger Bank, a vast moraine, or accumulation of unconsolidated glacial debris, rises to a mere 15 to 30 m below the surface; this feature has produced the finest fishing location of the North Sea. The Long Forties and the Broad Fourteens are large areas with uniform depth in fathoms; these great banks and others make the North Sea hazardous to navigate, alleviated by the implementation of satellite navigation systems. The Devil's Hole lies 200 miles east of Scotland; the feature is a series of asymmetrical trenches between 20 and 30 kilometres long and two kilometres wide and up to 230 metres deep. Other areas which are less deep are Fisher Bank and Noordhinder Bank; the International Hydrographic Organization defines the limits of the North Sea as follows: On the Southwest.
A line joining the Walde Lighthouse and Leathercoat Point. On the Northwest. From Dunnet Head in Scotland to Tor Ness in the Island of Hoy, thence through this island to the Kame of Hoy on to Breck Ness on Mainland through this island to Costa Head and to Inga Ness in Westray through Westray, to Bow Head, across to Mull Head and on to Seal Skerry and thence to Horse Island. On the North. From the North point of the Mainland of the Shetland Islands, across to Graveland Ness in the Island of Yell, through Yell to Gloup Ness and across to Spoo Ness in Unst island, through Unst to Herma Ness, on to the SW point of the Rumblings and to Muckle Flugga all these being included in the North Sea area.
SMS Baden was a Bayern-class dreadnought battleship of the German Imperial Navy built during World War I. Launched in October 1915 and completed in March 1917, she was the last battleship completed for use in the war; the ship mounted eight 38-centimeter guns in four twin turrets, displaced 32,200 metric tons at full combat load, had a top speed of 21 knots. Along with her sister Bayern, Baden was the largest and most powerfully armed battleship built by the Imperial Navy. Upon commissioning into the High Seas Fleet, Baden was made the fleet flagship, replacing Friedrich der Grosse. Baden saw little action during her short career. Following the German collapse in November 1918, Baden was interned with the majority of the High Seas Fleet at Scapa Flow by the British Royal Navy. On 21 June 1919, Rear Admiral Ludwig von Reuter ordered the scuttling of the fleet. However, British sailors in the harbor managed to board beach her to prevent her sinking; the ship was refloated examined, sunk in extensive gunnery testing by the Royal Navy in 1921.
Baden was 179.4 m long at the waterline, 180 m long overall. She had a draft of between 9.3–9.4 m. Baden displaced 28,530 metric tons at her designed displacement, which did not include a full load of combat supplies and other operational necessities. Baden's displacement was more than 3,000 t greater than that of the preceding König-class ships, making her the largest battleship built by the Imperial Navy. Baden was powered by three sets of Schichau steam turbines, which were rated at 34,521 shaft horsepower, produced a maximum of 55,500 shaft horsepower, her design speed was 21 knots. Upon commissioning, she carried a crew of 1,129 enlisted men; the ship was the first German warship armed with eight 38 cm SK L/45 guns. The main battery guns were arranged in four twin gun turrets: two superfiring turrets each fore and aft, her secondary armament consisted of sixteen 15 cm SK L/45 guns, six 8.8 cm SK L/45 guns and five 60 cm underwater torpedo tubes, one in the bow and two on each beam. The ship had an armored belt, 170–350 mm thick and an armored deck, 60–100 mm thick.
Her forward conning tower had 400 mm sides, the main battery turrets had 350 mm thick sides and 200 mm thick roofs. Baden was ordered under the provisional name Ersatz Wörth in 1912, under the fourth and final Naval Law, passed that year. Construction began at the Schichau-Werke dockyard in Danzig under construction number 913; the ship was laid down on 20 December 1913 and launched on 30 October 1915. After fitting-out, sea trials were conducted. Baden's two sisterships, Sachsen and Württemberg, both lay incomplete at the end of World War I and were subsequently scrapped, leaving Baden the last battleship built for the Imperial Navy. After her commissioning into the High Seas Fleet, Baden was placed in the role of flagship for the commander of the fleet, Vice Admiral Franz von Hipper, a position she held until the end of the war. At the end of August 1917, Baden took Kaiser Wilhelm II to visit the fortified island of Helgoland. After the conclusion of the visit, Baden returned the Kaiser to Cuxhaven.
The ship struck the sea bottom outside Cuxhaven. In late 1917, light forces of the High Seas Fleet began interdicting British convoys to Norway. On 17 October the light cruisers Brummer and Bremse intercepted one of the convoys, sinking nine of the twelve cargo ships and the two escorting destroyers before turning back to Germany. On 12 December, four German destroyers ambushed a second British convoy of five cargo vessels and two British destroyers. All five transports were sunk. Following these two raids, Admiral David Beatty, the commander of the Grand Fleet, detached battleships from the battle fleet to protect the convoys; the German Imperial Navy was now presented with an opportunity for which it had been waiting the entire war: a portion of the numerically stronger Grand Fleet was separated and could be isolated and destroyed. Hipper planned the operation: the battlecruisers of the I Scouting Group, along with light cruisers and destroyers, would attack one of the large convoys, while the rest of the High Seas Fleet would stand by, ready to attack the British dreadnought battleship squadron.
At 05:00 on 23 April 1918, the German fleet departed from the Schillig roadstead. Hipper, aboard Baden, ordered wireless transmissions be kept to a minimum, to prevent radio intercepts by British intelligence. At 06:10 the German battlecruisers had reached a position 60 kilometers southwest of Bergen when the battlecruiser Moltke lost her inner starboard propeller, which damaged the ship's engines; the crew effected temporary repairs that allowed the ship to steam at 4 kn, but it was decided to take the ship under tow. Despite this setback, Hipper continued northward. By 14:00, Hipper's force had found nothing. At 14:10, Hipper turned. By 18:37, the German fleet had made it back to the defensive
Ocean disposal of radioactive waste
From 1946 through 1993, thirteen countries used ocean disposal or ocean dumping as a method to dispose of nuclear/radioactive waste. The waste materials included both liquids and solids housed in various containers, as well as reactor vessels and without spent or damaged nuclear fuel. Since 1993, ocean disposal has been banned by international treaties. However, according to the United Nations, some companies have been dumping radioactive waste and other hazardous materials into the coastal waters of Somalia, taking advantage of the fact that the country had no functioning government from the early 1990s onwards. According to one official at the United Nations, this caused health problems for locals in the coastal region and posed a significant danger to Somalia's fishing industry and local marine life."Ocean floor disposal" —a more deliberate method of delivering radioactive waste to the ocean floor and depositing it into the seabed—was studied by the UK and Sweden, but never implemented.
Data are from IAEA-TECDOC-1105. Page 3-4 1946 First dumping operation at Northeast Pacific Ocean 1957 First IAEA Advisory Group Meeting on Radioactive Waste Disposal into the Sea 1958 First United Nations Conference on the Law of the Sea 1972 Adoption of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1975 The London Convention 1972 entered into force 1983 Moratorium on low-level waste dumping 1988 Assessing the Impact of Deep Sea Disposal of Low-level Radioactive Waste on Living Marine Resources. IAEA Technical Reports Series No. 288 1990 Estimation of Radiation Risks at Low Dose. IAEA-TECDOC-557 1993 Russia reported the dumping of high level nuclear waste including spent fuel by former USSR. 1994 Feb-20 Total prohibition of disposal at sea came into force Data are from IAEA-TECDOC-1105. Summary of pages 27–120: Disposal projects attempted to locate ideal dumping sites based on depth and currents, to treat and contain the waste. However, some dumping only involved diluting the waste with surface water, or used containers that imploded at depth.
Containers that survived the pressure could physically decay over time. The countries involved — listed in order of total contributions measured in TBq — were the USSR, the UK, the US, France, the Netherlands, Sweden, New Zealand, Germany and South Korea. Together, they dumped a total of 85,100 TBq of radioactive waste at over 100 ocean sites, as measured in initial radioactivity at the time of dump. For comparison: Global fallout of nuclear weapon tests — 2,566,087x1015 Bq. 1986 Chernobyl disaster total release — 12,060x1015 Bq. 2011 Fukushima Daiichi nuclear disaster, estimated total aerial release — 11,346x1015 Bq. Fukishima Daiichi nuclear plant cooling water dumped to the sea — TEPCO estimate 4.7x1015 Bq, Japanese Nuclear Safety Commission estimate 15x1015 Bq, French Nuclear Safety Committee estimate 27x1015 Bq. Occurring Potassium 40 in all oceans — 14,000,000x1015 Bq. One container of vitrified high-level radioactive waste has an average radioactivity of 4x1015 Bq. Data are from IAEA-TECDOC-1105.
Unpackaged and diluted in surface waters contained in package but not solidified low level waste like resins, material used for decontamination processes, etc. solidified with cement or bitumen and packaged in metal containers unpackaged solid waste large parts of nuclear installations without nuclear fuel containing damaged spent nuclear fuel solidified with polymer agent special container with damaged spent nuclear fuel Data are from IAEA-TECDOC-1105. At the east coast of Novaya Zemlya at Kara Sea and small proportion at Barents Sea by USSR. Dumped at 20 sites from 1959–92, total of 222,000 m3 including reactors and spent fuel. Dumping occurred from 1948 to 1982. Seventy-eight percent of dumping in the Atlantic was done by UK, followed by Switzerland, USA and Belgium. Sunken USSR nuclear submarines are not included. See List of sunken nuclear submarines There were 137,000 tonnes dumped by eight European countries. USA reported neither volume for 34,282 containers. USSR 874 TBq, USA 554 TBq, Japan 15.1 TBq, New Zealand 1 + unknown amount by South Korea.
751,000 m3 were dumped by Japan and USSR. USA reported neither volume of 56,261 containers. Dumping of contaminated water at 2011 Fukushima Nuclear accident is not included. USSR dumped 749 TBq. Japan dumped 15.1 TBq south of main island. South Korea dumped 45 tonnes. Data are from IAEA-TECDOC-1105. Joint Russian-Norwegian expeditions collected samples from four dump sites. At immediate vicinity of waste containers, elevated levels of radionuclide were found, but had not contaminated the surrounding area. Dumping was undertaken by UK, Belgium, the Netherlands, Sweden and Italy. IAEA had been studying since 1977; the report of 1996, by CRESP suggests measurable leakages of radioactive material, concluded that environmental impact is negligible. These sites are monitored by the United States Environmental Protection Agency and US National Oceanic and Atmospheric Administration. So far, no excess level of radionuclides was found in samples collected in the area, except the sample tak
Strait of Dover
The Strait of Dover or Dover Strait known as the Dover Narrows. The shortest distance across the strait, 33.3 kilometres, is from the South Foreland, northeast of Dover in the English county of Kent, to Cap Gris Nez, a cape near to Calais in the French département of Pas-de-Calais. Between these points lies the most popular route for cross-channel swimmers; the entire strait is within the territorial waters of France and the United Kingdom, but a right of transit passage under the UNCLOS exists allowing unrestricted shipping. On a clear day, it is possible to see the opposite coastline of England from France and vice versa with the naked eye, with the most famous and obvious sight being the white cliffs of Dover from the French coastline and shoreline buildings on both coastlines, as well as lights on either coastline at night, as in Matthew Arnold's poem "Dover Beach". Most maritime traffic between the Atlantic Ocean and the North Sea and Baltic Sea passes through the Strait of Dover, rather than taking the longer and more dangerous route around the north of Scotland.
The strait is the busiest international seaway in the world, used by over 400 commercial vessels daily. This has made traffic safety a critical issue, with HM Coastguard and the Maritime Gendarmerie maintaining a 24-hour watch over the strait and enforcing a strict regime of shipping lanes. In addition to the intensive east–west traffic, the strait is crossed from north to south by ferries linking Dover to Calais and Dunkirk; until 1994 these provided the only route across it for land transport. The Channel Tunnel now provides an alternative route, crossing beneath the strait at an average depth of 45 m below the seabed; the town of Dover gives its name to one of the sea areas of the British Shipping Forecast. The strait is believed to have been created by the erosion of a land bridge that linked the Weald in Great Britain to the Boulonnais in the Pas de Calais; the predominant geology on both the British and French sides and on the seafloor is chalk. Although somewhat resistant to erosion, erosion of both coasts has created the famous white cliffs of Dover in the UK and the Cap Blanc Nez in France.
The Channel Tunnel was bored through solid chalk. The Rhine flowed northwards into the North Sea as the sea level fell during the start of the first of the Pleistocene Ice Ages; the ice created a dam from Scandinavia to Scotland, the Rhine, combined with the Thames and drainage from much of north Europe, created a vast lake behind the dam, which spilled over the Weald into the English Channel. This overflow channel became the Strait of Dover about 425,000 years ago. A narrow deep channel along the middle of the strait was the bed of the Rhine in the last Ice Age. A geological deposit in East Anglia marks the old preglacial northward course of the Rhine. A 2007 study concluded; the first was about 425,000 years ago, when an ice-dammed lake in the southern North Sea overflowed and broke the Weald-Artois chalk range in a catastrophic erosion and flood event. Afterwards, the Thames and Scheldt flowed through the gap into the English Channel, but the Meuse and Rhine still flowed northwards. In a second flood about 225,000 years ago the Meuse and Rhine were ice-dammed into a lake that broke catastrophically through a high weak barrier.
Both floods cut massive flood channels in the dry bed of the English Channel, somewhat like the Channeled Scablands or the Wabash River in the USA. A further update in 2017, attributed a series of described underwater holes in the Channel floor -"100m deep" and in places "several kilometres in diameter" to lake water plunging over a rock ridge causing isolated depressions or plunge pools; the melting ice and rising sea levels submerged Doggerland, the area linking Britain to France 6,500–6,200 BCE. The Lobourg strait, a major feature of the strait's seafloor, runs its 6 km wide slash on a NNE–SSW axis. Nearer to the French coast than to the English coast, it runs along the Varne sandbank where it plunges to 68 m at its deepest, along the latter's south-east neighbour the Ridge bank with a maximum depth of 62 m; the submarine depth of the strait varies between 68 m at the Lobourg strait and 20 m at the highest banks. It presents a succession of rocky areas deserted by ships wanting to spare their nets, of sandy flats and sub-aqueous dunes.
The strong currents of the Channel are slowed down around the rocky areas of the strait, with formation of countercurrents and calmer zones where many species can find shelter. In these calmer zones, the water is clearer than in the rest of the strait. Moreover, this is a transition zone for the species of the Atlantic Ocean and those of the southern part of the North Sea; this mix of various environments promotes a wide variety of wildlife. The Ridens de Boulogne, a 10–20 m deep rocky high ground covered with sand located 15 nmi to the west of Boulogne, boasts the highest production of maerl in the strait. A 682 km2 area of the strait is classified as a Natura 2000 protection zone listed under the name Ridens et dunes hydrauliques du Pas de Calais (Ridens and sub-aqueous dunes of the Dov
The Channel Islands are an archipelago in the English Channel, off the French coast of Normandy. They include two Crown dependencies: the Bailiwick of Jersey, the largest of the islands, they are considered the remnants of the Duchy of Normandy and, although they are not part of the United Kingdom, the UK is responsible for the defence and international relations of the islands. The Crown dependencies are not members of the European Union, they have a total population of about 164,541, the bailiwicks' capitals, Saint Helier and Saint Peter Port, have populations of 33,500 and 18,207, respectively. The total area of the islands is 198 km2. "Channel Islands" is a geographical term, not a political unit. The two bailiwicks have been administered separately since the late 13th century; each has its own independent laws and representative bodies. Any institution common to both is the exception rather than the rule; the Bailiwick of Guernsey is divided into three jurisdictions – Guernsey and Sark – each with its own legislature.
Although there are a few pan-island institutions, these tend to be established structurally as equal projects between Guernsey and Jersey. Otherwise, entities proclaiming membership of both Guernsey and Jersey might in fact be from one bailiwick only, for instance the Channel Islands Securities Exchange is in Saint Peter Port; the term "Channel Islands" began to be used around 1830 first by the Royal Navy as a collective name for the islands. The term refers only the archipelago to the west of the Cotentin Peninsula; the Isle of Wight, for example, is not a "Channel Island". The two major islands are Guernsey, they make up 92 % of the area. The permanently inhabited islands of the Channel Islands and their population and area are: Jersey 100,080 Guernsey 63,026 Alderney 2,000 Sark 600 Herm 60 Jethou 3 Brecqhou There are several uninhabited islets. Four are part of the Bailiwick of Jersey: The Minquiers Écréhous Les Dirouilles Les Pierres de Lecq These lie off Alderney: Burhou Casquets Ortac RenonquetThese lie off Guernsey: Caquorobert Crevichon Grande Amfroque Les Houmets Lihou The names of the larger islands in the archipelago in general have the -ey suffix, whilst those of the smaller ones have the -hou suffix.
These are believed to be from holmr. The Chausey Islands south of Jersey are not included in the geographical definition of the Channel Islands but are described in English as'French Channel Islands' in view of their French jurisdiction, they were linked to the Duchy of Normandy, but they are part of the French territory along with continental Normandy, not part of the British Isles or of the Channel Islands in a political sense. They are an incorporated part of the commune of Granville. While they are popular with visitors from France, Channel Islanders visit them as there are no direct transport links from the other islands. In official Jersey French, the islands are called'Îles de la Manche', while in France, the term'Îles Anglo-normandes' is used to refer to the British'Channel Islands' in contrast to other islands in the Channel. Chausey is referred to as an'Île normande'.'Îles Normandes' and'Archipel Normand' have historically, been used in Channel Island French to refer to the islands as a whole.
The large tidal variation provides an environmentally rich inter-tidal zone around the islands, some islands such as Burhou, the Écréhous, the Minquiers have been designated Ramsar sites. The waters around the islands include the following: The Swinge The Little Swinge La Déroute Le Raz Blanchard, or Race of Alderney The Great Russel The Little Russel Souachehouais Le Gouliot La Percée The highest point in the islands is Les Platons in Jersey at 143 metres above sea level; the lowest point is the English Channel. The earliest evidence of human occupation of the Channel Islands has been dated to 250,000 years ago when they were attached to the landmass of continental Europe; the islands became detached by rising sea levels in the Neolithic period. The numerous dolmens and other archaeological sites extant and recorded in history demonstrate the existence of a population large enough and organised enough to undertake constructions of considerable size and sophistication, such as the burial mound at La Hougue Bie in Jersey or the statue menhirs of Guernsey.
Hoards of Armorican coins have been excavated, providing evidence of trade and contact in the Iron Age period. Evidence for Roman settlement is sparse, although evidently the islands were visited by Roman officials and traders; the Roman name for the Channel Islands was I. Lenuri and is included in the Peutinger Table The traditional Latin na