Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago. The lake measured about 7,770 square kilometres and contained about 2,100 cubic kilometres of water, half the volume of Lake Michigan; the Glacial Lake Missoula National Natural Landmark is located about 110 kilometres northwest of Missoula, Montana, at the north end of the Camas Prairie Valley, just east of Montana Highway 382 and Macfarlane Ranch. It was designated as a National Natural Landmark in 1966 because it contains the great ripples that served as a strong supporting element for J Harlen Bretz's contention that Washington State's Channeled Scablands were formed by repeated cataclysmic floods over only about 2,000 years, rather than through the millions of years of erosion, assumed; the lake was the result of an ice dam on the Clark Fork caused by the southern encroachment of a finger of the Cordilleran Ice Sheet into the Idaho Panhandle.
The height of the ice dam approached 610 metres, flooding the valleys of western Montana 320 kilometres eastward. It was the largest ice-dammed lake known to have occurred; the periodic rupturing of the ice dam resulted in the Missoula Floods – cataclysmic floods that swept across eastern Washington and down the Columbia River Gorge 40 times during a 2,000 year period. The cumulative effect of the floods was to excavate 210 cubic kilometres of loess and basalt from the channeled scablands of eastern Washington and to transport it downstream; these floods are noteworthy for producing canyons and other large geologic features through cataclysms rather than through more typical gradual processes. In addition and Early Pleistocene Missoula flood deposits have been documented to comprise parts of the glaciofluvial deposits, informally known as the Hanford formation that are found in parts of the Othello Channels, Columbia River Gorge, Channeled Scabland, Quincy Basin, Pasco Basin, the Walla Walla Valley.
The age of these deposits is demonstrated by the presence of multiple interglacial calcretes interbedded in these glaciofluvial deposits, sequences of sediments with normal and reverse magnetostratigraphy, optically stimulated luminescence dating, unconformity truncated clastic dikes. Based upon these criteria, Quaternary geologists estimated that the oldest of the Pleistocene Missoula floods happened before 1.5 million years ago. The older Pleistocene glaciofluvial deposits within the Hanford formation are fragmentary in nature because they have been eroded and removed by subsequent Missoula floods; because of the fragmentary nature of older glaciofluvial deposits, the exact number of older Missoula floods, which are known as Ancient Cataclysmic Floods, that occurred during the Pleistocene cannot be estimated with any confidence. Although Lake Missoula was the source of many of the Ancient Cataclysmic Floods, the fragmentary nature of the older deposits within the Hanford formation makes precise determination of the precise origin of the floods that deposited them difficult.
Missoula Floods – Cataclysmic floods at the end of the last ice age, in eastern Washington state, USA Glacial lake outburst flood – A type of outburst flood that occurs when the dam containing a glacial lake fails Giant current ripples – Depositional forms in diluvial plain and mountain scablands Ice Age Floods National Geologic Trail List of prehistoric lakes USGS Site on Glacial Lake Missoula US Park Service Site for Glacial Lake Missoula National Natural Landmark PBS's NOVA: Mystery of the Megaflood for information on the Missoula Floods The Seattle Times' Pacific NW magazine - "Trailing an Apocalypse" - 30-Sep-2007 The Ice Age Floods Institute U of Montana publication, The Montanan, "Sedimental Journey: Following the Path of Glacial Lake Missoula's Flood Waters." Pazynych V. Missoula floods - Subglacial Artesian Basin and its Full Physical pattern https://www.academia.edu/36805879/Missoula_floods_-_Subglacial_Artesian_Basin_and_its_Full_Physical_pattern
Waders are birds found along shorelines and mudflats that wade in order to forage for food in the mud or sand. They are called shorebirds in North America, where the term "wader" is used to refer to long-legged wading birds such as storks and herons. Waders are members of the order Charadriiformes, which includes gulls and their allies. There are about 210 species of wader, most of which live in coastal environments. Many species of Arctic and temperate regions are migratory, but tropical birds are resident, or move only in response to rainfall patterns; some of the Arctic species, such as the little stint, are amongst the longest distance migrants, spending the non-breeding season in the southern hemisphere. Many of the smaller species found in coastal habitats but not the calidrids, are named as "sandpipers", but this term does not have a strict meaning, since the upland sandpiper is a grassland species; the smallest member of this group is the least sandpiper, small adults of which can weigh as little as 15.5 grams and measure just over 13 cm.
The largest species is believed to be the Far Eastern curlew, at about 63 cm and 860 grams, although the beach thick-knee is the heaviest at about 1 kg. In the Sibley-Ahlquist taxonomy and many other groups are subsumed into a enlarged Ciconiiformes order. However, the classification of the Charadriiformes is one of the weakest points of the Sibley-Ahlquist taxonomy, as DNA–DNA hybridization has turned out to be incapable of properly resolving the interrelationships of the group; the waders were united in a single suborder Charadrii, but this has turned out to be a "wastebasket taxon", uniting no less than four charadriiform lineages in a paraphyletic assemblage. However, it indicated that the plains wanderer belonged into one of them. Following recent studies, the waders may be more subdivided as follows: Suborder Scolopaci Family Scolopacidae: snipe, sandpipers and allies Suborder Thinocori Family Rostratulidae: painted snipe Family Jacanidae: jacanas Family Thinocoridae: seedsnipe Family Pedionomidae: plains wanderer Suborder Chionidi Family Burhinidae: thick-knees Family Chionididae: sheathbills Family Pluvianellidae: Magellanic plover Suborder Charadrii Family Ibidorhynchidae: ibisbill Family Recurvirostridae: avocets and stilts Family Haematopodidae: oystercatchers Family Charadriidae: plovers and lapwingsIn keeping more in line with the traditional grouping, the Thinocori could be included in the Scolopaci, the Chionidi in the Charadrii.
However, the increasing knowledge about the early evolutionary history of modern birds suggests that the assumption of Paton et al. and Thomas et al. of 4 distinct "wader" lineages being present around the Cretaceous–Paleogene boundary is correct. Shorebirds is a blanket term used to refer to multiple species of birds that live in wet, coastal environments; because most these species spend much of their time near bodies of water, many have long legs suitable for wading. Some species prefer locations with rocks or mud. Many shorebirds display migratory patterns and migrate before breeding season; these behaviors explain the long wing lengths observed in species, can account for the efficient metabolisms that give the birds energy during long migrations. The majority of species eat. Different lengths of bills enable different species to feed in the same habitat on the coast, without direct competition for food. Many waders have sensitive nerve endings at the end of their bills which enable them to detect prey items hidden in mud or soft soil.
Some larger species those adapted to drier habitats will take larger prey including insects and small reptiles. Shorebirds, like many other animals, exhibit phenotypic differences between males and females known as sexual dimorphism. In shorebirds, various sexual dimorphisms are seen, but not limited to, size and agility. In polygynous species, where one male individual mates with multiple female partners over his lifetime, dimorphisms tend to be more diverse. In monogamous species, where male individuals mate with a single female partner, males do not have distinctive dimorphic characteristics such as colored feathers, but they still tend to be larger in size compared to females; the suborder of Charadrii displays the widest range of sexual dimorphisms seen in the Charadriiformes order. However, cases of sexual monomorphism, where there are no distinguishing physical features besides external genitalia, are seen in this order. One of the biggest factors that leads to the development of sexual dimorphism in shorebirds is sexual selection.
Males with ideal characteristics favored by females are more to reproduce and pass on their genetic information to their offspring better than the males who lack such characteristics. Mentioned earlier, male shorebirds are larger in size compared to their female counterparts. Competition between males tends to lead to sexual selection toward larger males and as a result, an increase in dimorphism. Bigger males tend to have greater access to female mates because their larger size aids them in defeating other competitors. If the species exhibits gender role reversal males will select female mates based on traits that are the most appealing. In the Jacana species, fe
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, the rotation of the Earth. Tide tables can be used for any given locale to find the predicted times and amplitude; the predictions are influenced by many factors including the alignment of the Sun and Moon, the phase and amplitude of the tide, the amphidromic systems of the oceans, the shape of the coastline and near-shore bathymetry. They are however only predictions, the actual time and height of the tide is affected by wind and atmospheric pressure. Many shorelines experience low tides each day. Other locations have a diurnal tide -- one low tide each day. A "mixed tide" – two uneven magnitude tides a day – is a third regular category. Tides vary on timescales ranging from hours to years due to a number of factors, which determine the lunitidal interval. To make accurate records, tide gauges at fixed stations measure water level over time. Gauges ignore; these data are compared to the reference level called mean sea level.
While tides are the largest source of short-term sea-level fluctuations, sea levels are subject to forces such as wind and barometric pressure changes, resulting in storm surges in shallow seas and near coasts. Tidal phenomena are not limited to the oceans, but can occur in other systems whenever a gravitational field that varies in time and space is present. For example, the shape of the solid part of the Earth is affected by Earth tide, though this is not as seen as the water tidal movements. Tide changes proceed via the following stages: Sea level rises over several hours, covering the intertidal zone; the water rises to its highest level. Sea level falls over several hours; the water stops reaching low tide. Oscillating currents produced by tides are known as tidal streams; the moment that the tidal current ceases is called slack tide. The tide reverses direction and is said to be turning. Slack water occurs near high water and low water, but there are locations where the moments of slack tide differ from those of high and low water.
Tides are semi-diurnal, or diurnal. The two high waters on a given day are not the same height; the two low waters each day are the higher low water and the lower low water. The daily inequality is not consistent and is small when the Moon is over the Equator. From the highest level to the lowest: Highest astronomical tide – The highest tide which can be predicted to occur. Note that meteorological conditions may add extra height to the HAT. Mean high water springs – The average of the two high tides on the days of spring tides. Mean high water neaps – The average of the two high tides on the days of neap tides. Mean sea level – This is the average sea level; the MSL is constant for any location over a long period. Mean low water neaps – The average of the two low tides on the days of neap tides. Mean low water springs – The average of the two low tides on the days of spring tides. Lowest astronomical tide and Chart Datum – The lowest tide which can be predicted to occur. Modern charts use this as the chart datum.
Note that under certain meteorological conditions the water may fall lower than this meaning that there is less water than shown on charts. Tidal constituents are the net result of multiple influences impacting tidal changes over certain periods of time. Primary constituents include the Earth's rotation, the position of the Moon and Sun relative to the Earth, the Moon's altitude above the Earth's Equator, bathymetry. Variations with periods of less than half a day are called harmonic constituents. Conversely, cycles of days, months, or years are referred to as long period constituents. Tidal forces affect the entire earth. In contrast, the atmosphere is much more fluid and compressible so its surface moves by kilometers, in the sense of the contour level of a particular low pressure in the outer atmosphere. In most locations, the largest constituent is the "principal lunar semi-diurnal" known as the M2 tidal constituent, its period is about 12 hours and 25.2 minutes half a tidal lunar day, the average time separating one lunar zenith from the next, thus is the time required for the Earth to rotate once relative to the Moon.
Simple tide clocks track this constituent. The lunar day is longer than the Earth day because the Moon orbits in the same direction the Earth spins; this is analogous to the minute hand on a watch crossing the hour hand at 12:00 and again at about 1:05½. The Moon orbits the Earth in the same direction as the Earth rotates on its axis, so it takes more than a day—about 24 hours and 50 minutes—for the Moon to return to the same location in the sky. During this time, it has passed overhead once and underfoot once, so in many places the period of strongest tidal forcing is the above-mentioned, about 12 hours and 25 minutes; the moment of highest tide is not when the Moon is nearest to zenith or nadir, but the period of the forcing still determines the time between high tides. Because the gravitational field created by the Moon weakens
A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying passengers or goods, or in support of specialized missions, such as defense and fishing. A "ship" was a sailing vessel with at least three square-rigged masts and a full bowsprit. Ships are distinguished from boats, based on size, load capacity, tradition. Ships have been important contributors to human commerce, they have supported the spread of colonization and the slave trade, but have served scientific and humanitarian needs. After the 15th century, new crops that had come from and to the Americas via the European seafarers contributed to the world population growth. Ship transport is responsible for the largest portion of world commerce; as of 2016, there were more than 49,000 merchant ships, totaling 1.8 billion dead weight tons. Of these 28% were oil tankers, 43% were bulk carriers, 13% were container ships. Ships are larger than boats, but there is no universally accepted distinction between the two.
Ships can remain at sea for longer periods of time than boats. A legal definition of ship from Indian case law is a vessel. A common notion is, but not vice versa. A US Navy rule of thumb is that ships heel towards the outside of a sharp turn, whereas boats heel towards the inside because of the relative location of the center of mass versus the center of buoyancy. American and British 19th Century maritime law distinguished "vessels" from other craft. In the Age of Sail, a full-rigged ship was a sailing vessel with at least three square-rigged masts and a full bowsprit. A number of large vessels are referred to as boats. Submarines are a prime example. Other types of large vessel which are traditionally called boats are Great Lakes freighters and ferryboats. Though large enough to carry their own boats and heavy cargoes, these vessels are designed for operation on inland or protected coastal waters. In most maritime traditions ships have individual names, modern ships may belong to a ship class named after its first ship.
In the northern parts of Europe and America a ship is traditionally referred to with a female grammatical gender, represented in English with the pronoun "she" if named after a man. This is not universal usage and some English language journalistic style guides advise using "it" as referring to ships with female pronouns can be seen as offensive and outdated. In many documents the ship name is introduced with a ship prefix being an abbreviation of the ship class, for example "MS" or "SV", making it easier to distinguish a ship name from other individual names in a text; the first known vessels could not be described as ships. The first navigators began to use animal skins or woven fabrics as sails. Affixed to the top of a pole set upright in a boat, these sails gave early ships range; this allowed men to explore allowing for the settlement of Oceania for example. By around 3000 BC, Ancient Egyptians knew, they used woven straps to lash the planks together, reeds or grass stuffed between the planks helped to seal the seams.
The Greek historian and geographer Agatharchides had documented ship-faring among the early Egyptians: "During the prosperous period of the Old Kingdom, between the 30th and 25th centuries BC, the river-routes were kept in order, Egyptian ships sailed the Red Sea as far as the myrrh-country." Sneferu's ancient cedar wood ship Praise of the Two Lands is the first reference recorded to a ship being referred to by name. The ancient Egyptians were at ease building sailboats. A remarkable example of their shipbuilding skills was the Khufu ship, a vessel 143 feet in length entombed at the foot of the Great Pyramid of Giza around 2500 BC and found intact in 1954, it is known that ancient Nubia/Axum traded with India, there is evidence that ships from Northeast Africa may have sailed back and forth between India/Sri Lanka and Nubia trading goods and to Persia and Rome. Aksum was known by the Greeks for having seaports for ships from Yemen. Elsewhere in Northeast Africa, the Periplus of the Red Sea reports that Somalis, through their northern ports such as Zeila and Berbera, were trading frankincense and other items with the inhabitants of the Arabian Peninsula well before the arrival of Islam as well as with Roman-controlled Egypt.
A panel found at Mohenjodaro depicted a sailing craft. Vessels were of many types; this treatise gives a technical exposition on the techniques of shipbuilding. It sets forth minute details about the various types of ships, their sizes, the materials from which they were built; the Yukti Kalpa Taru sums up in a condensed form all the available information. The Yukti Kalpa Taru gives sufficient information and dates to prove that, in ancient times, Indian shipbuilders had a good knowledge of the materials which were used in building ships. In addition to describing the qualities of the different types of wood and their suitability for shipbuilding, the Yukti Kalpa Taru gives an elaborate classification of ships based on their size; the oldest discovered sea faring hulled boat is the Late Bronze Age Uluburun shipwreck off the coast of Turkey, dating back to 1300 BC. The Phoenicians, the first to sail around
Seaweed or macroalgae refers to several species of macroscopic, marine algae. The term includes some types of Rhodophyta and Chlorophyta macroalgae. Marine algae species such as kelps provide essential nursery habitat for fisheries and other marine species and thus protect food sources. Understanding these roles provides guiding principles for conservation and sustainable use of seaweeds to take precedence over industrial exploitation. Mechanical dredging of kelp, for instance, destroys dependent fisheries. Seaweed are a rich source of multiple biologically active compounds including proteins and polysaccharides with promising uses in nutrition, biomedicine and other uses. "Seaweed" lacks a formal definition. A seaweed may belong to one of several groups of multicellular algae: the red algae, green algae, brown algae; as these three groups do not have a common multicellular ancestor, the seaweed are in a polyphyletic group. In addition, some tuft-forming bluegreen algae are sometimes considered to be seaweed.
Seaweed's appearance somewhat resembles non-arboreal terrestrial plants. Thallus: the algal body lamina or blade: a flattened structure, somewhat leaf-like sorus: a spore cluster on Fucus, air bladder: a flotation-assisting organ on the blade on kelp, float: a flotation-assisting organ between the lamina and stipe stipe: a stem-like structure, may be absent holdfast: a specialized basal structure providing attachment to a surface a rock or another alga haptera: a finger-like extension of the holdfast anchoring to a benthic substrateThe stipe and blade are collectively known as the frond. Two specific environmental requirements dominate seaweed ecology; these are the presence of light sufficient to drive photosynthesis. Another common requirement is a firm attachment point, although some genera such as Sargassum and Gracilaria have species that float freely; as a result, seaweed most inhabit the part of a sea, close to the shore and within that zone more on rocky shores than on sand or shingle.
Seaweed occupy a wide range of ecological niches. The highest elevation is only wetted by the tops of sea spray, the lowest is several meters deep. In some areas, littoral seaweed can extend several miles out to sea; the limiting factor in such cases is sunlight availability. The deepest living seaweed are some species of red algae. Others have adapted to live in tidal rock pools. In this habitat, seaweed must withstand changing temperature and salinity and occasional drying. Seaweed has a variety of purposes, for which it is foraged from the wild. At the beginning of 2011, Indonesia produced 3 million tonnes of seaweed and surpassed the Philippines as the world's largest seaweed producer. By 2011, the production was estimated to have reached 10 million tonnes. Seaweed is consumed by coastal people in East Asia, e.g. Japan, Korea and Southeast Asia, e.g. Brunei, Thailand, Cambodia, Indonesia and Malaysia, in South Africa, Peru, the Canadian Maritimes, South West England, Wales and Scotland. In Asia, nori, zicai are sheets of dried Porphyra used in soups, sushi wrap or onigiri.
Chondrus crispus is another red alga used in producing food additives, along with Kappaphycus and gigartinoid seaweed. Porphyra is a red alga used in Wales to make laverbread. Laverbread, made from the seaweed, sometimes with oat flour, is a popular dish there. In northern Belize, edible seaweed are mixed with milk, nutmeg and vanilla to make a common beverage affectionately called "dulce". Seaweed are harvested or cultivated for the extraction of alginate and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance as food additives; the food industry exploits their gelling, water-retention and other physical properties. Agar is used in foods such as confectionery and poultry products and beverages and moulded foods. Carrageenan is used in salad dressings and sauces, dietetic foods, as a preservative in meat and fish products, dairy items and baked goods; the development of seaweed as an alternative and sustainable source of food and animal feed ingredients depends on the sustainability of the natural resource of raw biomass and on moving the process of feed development from laboratory to industrial scale.
Alginates are used in wound dressings, production of dental moulds. In microbiology research, agar – a plant-based jelly similar to gelatin and made from seaweed – is extensively used as culture medium. Carrageenans and agaroses, with other lesser-known macroalgal polysaccharides, have several important biological activities or applications in biomedicine. Research suggests that the Australian seaweed Delisea pulchra may interfere with bacterial colonization. Sulfated saccharides from both red and green algae have been known to inhibit some DNA and RNA enveloped viruses. Seaweed extract is used in some diet pills. Other seaweed pills exploit the same effect as gastric banding, expanding in the stomach to make the body feel more full; the strong photosynthesis of algae creates a large affinity for nutrients.
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
The United Kingdom the United Kingdom of Great Britain and Northern Ireland, sometimes referred to as Britain, is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west, giving it the 12th-longest coastline in the world; the Irish Sea lies between Great Ireland. With an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world, it is the 22nd-most populous country, with an estimated 66.0 million inhabitants in 2017. The UK is constitutional monarchy; the current monarch is Queen Elizabeth II, who has reigned since 1952, making her the longest-serving current head of state.
The United Kingdom's capital and largest city is London, a global city and financial centre with an urban area population of 10.3 million. Other major urban areas in the UK include Greater Manchester, the West Midlands and West Yorkshire conurbations, Greater Glasgow and the Liverpool Built-up Area; the United Kingdom consists of four constituent countries: England, Scotland and Northern Ireland. Their capitals are London, Edinburgh and Belfast, respectively. Apart from England, the countries have their own devolved governments, each with varying powers, but such power is delegated by the Parliament of the United Kingdom, which may enact laws unilaterally altering or abolishing devolution; the nearby Isle of Man, Bailiwick of Guernsey and Bailiwick of Jersey are not part of the UK, being Crown dependencies with the British Government responsible for defence and international representation. The medieval conquest and subsequent annexation of Wales by the Kingdom of England, followed by the union between England and Scotland in 1707 to form the Kingdom of Great Britain, the union in 1801 of Great Britain with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland.
Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain and Northern Ireland. There are fourteen British Overseas Territories, the remnants of the British Empire which, at its height in the 1920s, encompassed a quarter of the world's land mass and was the largest empire in history. British influence can be observed in the language and political systems of many of its former colonies; the United Kingdom is a developed country and has the world's fifth-largest economy by nominal GDP and ninth-largest economy by purchasing power parity. It has a high-income economy and has a high Human Development Index rating, ranking 14th in the world, it was the world's first industrialised country and the world's foremost power during the 19th and early 20th centuries. The UK remains a great power, with considerable economic, military and political influence internationally, it is sixth in military expenditure in the world. It has been a permanent member of the United Nations Security Council since its first session in 1946.
It has been a leading member state of the European Union and its predecessor, the European Economic Community, since 1973. The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the G20, NATO, the Organisation for Economic Co-operation and Development and the World Trade Organization; the 1707 Acts of Union declared that the kingdoms of England and Scotland were "United into One Kingdom by the Name of Great Britain". The term "United Kingdom" has been used as a description for the former kingdom of Great Britain, although its official name from 1707 to 1800 was "Great Britain"; the Acts of Union 1800 united the kingdom of Great Britain and the kingdom of Ireland in 1801, forming the United Kingdom of Great Britain and Ireland. Following the partition of Ireland and the independence of the Irish Free State in 1922, which left Northern Ireland as the only part of the island of Ireland within the United Kingdom, the name was changed to the "United Kingdom of Great Britain and Northern Ireland".
Although the United Kingdom is a sovereign country, Scotland and Northern Ireland are widely referred to as countries. The UK Prime Minister's website has used the phrase "countries within a country" to describe the United Kingdom; some statistical summaries, such as those for the twelve NUTS 1 regions of the United Kingdom refer to Scotland and Northern Ireland as "regions". Northern Ireland is referred to as a "province". With regard to Northern Ireland, the descriptive name used "can be controversial, with the choice revealing one's political preferences"; the term "Great Britain" conventionally refers to the island of Great Britain, or politically to England and Wales in combination. However, it is sometimes used as a loose synonym for the United Kingdom as a whole; the term "Britain" is used both as a synonym for Great Britain, as a synonym for the United Kingdom. Usage is mixed, with the BBC preferring to use Britain as shorthand only for Great Britain and the UK Government, while accepting that both terms refer to the United K