Misplaced Pages

#592407

187-508: Land , also known as dry land , ground , or earth , is the solid terrestrial surface of Earth not submerged by the ocean or another body of water . It makes up 29.2% of Earth's surface and includes all continents and islands . Earth's land surface is almost entirely covered by regolith , a layer of rock , soil , and minerals that forms the outer part of the crust . Land plays an important role in Earth's climate system , being involved in

374-461: A cave . They have been important to humans as a place of shelter since the dawn of humanity. Craters are depressions in the ground, but unlike caves, they do not provide shelter or extend underground . There are many kinds of craters, such as impact craters , volcanic calderas , and isostatic depressions . Karst processes can create both solution caves , the most frequent cave type, and craters, as seen in karst sinkholes . The pedosphere

561-533: A circumstellar disk , and then the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides ). According to nebular theory , planetesimals formed by accretion , with the primordial Earth being estimated as likely taking anywhere from 70 to 100 million years to form. Estimates of the age of the Moon range from 4.5 Ga to significantly younger. A leading hypothesis

748-613: A definite article ("the"), a demonstrative adjective ("that"), and demonstrative pronoun . Other demonstratives are þēs ("this"), and ġeon ("that over there"). These words inflect for case, gender, and number. Adjectives have both strong and weak sets of endings, weak ones being used when a definite or possessive determiner is also present. Verbs conjugate for three persons : first, second, and third; two numbers: singular, plural; two tenses : present, and past; three moods : indicative , subjunctive , and imperative ; and are strong (exhibiting ablaut) or weak (exhibiting

935-433: A habitat refers to the environment where a given species or population of organisms lives. Biomes may span more than one continent, and contain a variety of ecosystems and habitats. Land plants evolved from green algae , and are called embryophytes . They include trees , shrubs , ferns , grass , moss , and flowers . Most plants are vascular plants , meaning that their tissues distribute water and minerals throughout

1122-398: A back vowel ( /ɑ/ , /o/ , /u/ ) at the time of palatalization, as illustrated by the contrast between fisċ /fiʃ/ ('fish') and its plural fiscas /ˈfis.kɑs/ . But due to changes over time, a knowledge of the history of the word in question is needed to predict the pronunciation with certainty (for details, see palatalization ). In word-final position, the pronunciation of sċ

1309-619: A coastline may be impacted by the tides , caused by changes in gravitational forces on larger bodies of water. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity . On land, they harbour important ecosystems such as freshwater or estuarine wetlands , which are important for bird populations and other terrestrial animals. In wave-protected areas they harbor saltmarshes , mangroves or seagrasses , all of which can provide nursery habitat for finfish, shellfish , and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for

1496-492: A common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the synodic month , from new moon to new moon, is 29.53 days. Viewed from the celestial north pole , the motion of Earth, the Moon, and their axial rotations are all counterclockwise . Viewed from a vantage point above the Sun and Earth's north poles, Earth orbits in

1683-542: A counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.44 degrees from the perpendicular to the Earth–Sun plane (the ecliptic ), and the Earth-Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses . The Hill sphere , or

1870-406: A dental suffix). Verbs have two infinitive forms: bare and bound; and two participles : present and past. The subjunctive has past and present forms. Finite verbs agree with subjects in person and number. The future tense , passive voice , and other aspects are formed with compounds. Adpositions are mostly before but are often after their object. If the object of an adposition is marked in

2057-517: A following ⟨m⟩ or ⟨n⟩ . Modern editions of Old English manuscripts generally introduce some additional conventions. The modern forms of Latin letters are used, including ⟨g⟩ instead of insular G , ⟨s⟩ instead of insular S and long S , and others which may differ considerably from the insular script, notably ⟨e⟩ , ⟨f⟩ and ⟨r⟩ . Macrons are used to indicate long vowels, where usually no distinction

SECTION 10

#1732838111593

2244-467: A friction that led to the erosion of the complicated inflectional word endings. Simeon Potter notes: No less far-reaching was the influence of Scandinavian upon the inflexional endings of English in hastening that wearing away and leveling of grammatical forms which gradually spread from north to south. It was, after all, a salutary influence. The gain was greater than the loss. There was a gain in directness, in clarity, and in strength. The strength of

2431-420: A full rotation about its axis so that the Sun returns to the meridian . The orbital speed of Earth averages about 29.78 km/s (107,200 km/h; 66,600 mph), which is fast enough to travel a distance equal to Earth's diameter, about 12,742 km (7,918 mi), in seven minutes, and the distance from Earth to the Moon, 384,400 km (238,900 mi), in about 3.5 hours. The Moon and Earth orbit

2618-421: A globe-spanning mid-ocean ridge system. At Earth's polar regions , the ocean surface is covered by seasonally variable amounts of sea ice that often connects with polar land, permafrost and ice sheets , forming polar ice caps . Earth's land covers 29.2%, or 149 million km (58 million sq mi) of Earth's surface. The land surface includes many islands around the globe, but most of

2805-537: A habitat for soil organisms , a recycling system for nutrients and organic wastes , a regulator of water quality , a modifier of atmospheric composition , and a medium for plant growth , making it a critically important provider of ecosystem services . Since soil has a tremendous range of available niches and habitats , it contains a prominent part of the Earth's genetic diversity . A gram of soil can contain billions of organisms, belonging to thousands of species, mostly microbial and largely still unexplored. Soil

2992-453: A large area, it can influence climate and weather patterns. The terrain of a region largely determines its suitability for human settlement: flatter alluvial plains tend to have better farming soils than steeper, rockier uplands. Elevation is defined as the vertical distance between an object and sea level, while altitude is defined as the vertical distance from an object to Earth's surface. The elevation of Earth's land surface varies from

3179-490: A large elevation difference between the highest and lowest points would be deemed "high relief". Most land has relatively low relief. The change in elevation between two points of the terrain is called a slope or gradient. A topographic map is a form of terrain cartography which depicts terrain in terms of its elevation, slope, and the orientation of its landforms. It has prominent contour lines , which connect points of similar elevation, while perpendicular slope lines point in

3366-425: A liquid outer core that generates a magnetosphere capable of deflecting most of the destructive solar winds and cosmic radiation . Earth has a dynamic atmosphere , which sustains Earth's surface conditions and protects it from most meteoroids and UV-light at entry . It has a composition of primarily nitrogen and oxygen . Water vapor is widely present in the atmosphere, forming clouds that cover most of

3553-522: A long time to cause noticeable changes in the landscape—for example, the Grand Canyon was created over the past 70 million years by the Colorado River , which scientists estimate continues to erode the canyon at a rate of 0.3 meters (1 foot) every 200 years. However, humans have caused erosion to be 10–40 times faster than normal, causing half the topsoil of the surface of Earth's land to be lost within

3740-520: A period of 700 years, from the Anglo-Saxon settlement of Britain in the 5th century to the late 11th century, some time after the Norman invasion . While indicating that the establishment of dates is an arbitrary process, Albert Baugh dates Old English from 450 to 1150, a period of full inflections, a synthetic language . Perhaps around 85% of Old English words are no longer in use, but those that survived are

3927-418: A relatively low albedo, meaning that vegetated surfaces are good absorbers of the sun's energy. Forests have an albedo of 10–15 percent while grasslands have an albedo of 15–20 percent. In comparison, sandy deserts have an albedo of 25–40 percent. Land use by humans also plays a role in the regional and global climate. Densely populated cities are warmer and create urban heat islands that have effects on

SECTION 20

#1732838111593

4114-414: A set of practices called sustainable land management . A biome is an area "characterized by its vegetation, soil, climate, and wildlife ." There are five major types of biomes on land: grasslands, forests, deserts, tundras, and freshwater. Other types of biomes include shrublands, wetlands, and polar ice caps . An ecosystem refers to the interaction between organisms within a particular environment, and

4301-737: A solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three- state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate , relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering and erosion . Given its complexity and strong internal connectedness , soil ecologists regard soil as an ecosystem . Soil acts as an engineering medium,

4488-449: A steady growth to the present-day forms or, more likely, a rapid growth early in Earth history followed by a long-term steady continental area. Continents are formed by plate tectonics , a process ultimately driven by the continuous loss of heat from the Earth's interior. On time scales lasting hundreds of millions of years, the supercontinents have formed and broken apart three times. Roughly 750  mya (million years ago), one of

4675-431: A wide range of sessile animals (e.g. mussels , starfish , barnacles ) and various kinds of seaweeds . Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 meters (3.3–164.0 feet). According to a United Nations atlas, 44% of all people live within 150 km (93 mi) of the sea. Because of their importance in society and high concentration of population,

4862-508: Is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in the Solar System . Of the four rocky planets , it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it , taking a year (about 365.25 days) to complete one revolution. Earth rotates around its own axis in slightly less than a day (in about 23 hours and 56 minutes). Earth's axis of rotation

5049-456: Is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity . The thickness of the crust varies from about 6 kilometres (3.7 mi) under the oceans to 30–50 km (19–31 mi) for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as

5236-438: Is a major component of the Earth's ecosystem. The world's ecosystems are impacted in far-reaching ways by the processes carried out in the soil, with effects ranging from ozone depletion and global warming to rainforest destruction and water pollution . With respect to Earth's carbon cycle , soil acts as an important carbon reservoir , and it is potentially one of the most reactive to human disturbance and climate change. As

5423-468: Is a reasonably sharp contrast between the more felsic upper continental crust and the lower continental crust, which is more mafic in character. The composition of land is not uniform across the Earth, varying between locations and between strata within the same location. The most prominent components of upper continental crust include silicon dioxide , aluminium oxide , and magnesium . The continental crust consists of lower density material such as

5610-548: Is also sparse early Northumbrian evidence of a sixth case: the locative . The evidence comes from Northumbrian Runic texts (e.g., ᚩᚾ ᚱᚩᛞᛁ on rodi "on the Cross"). Adjectives agree with nouns in case, gender, and number, and can be either strong or weak. Pronouns and sometimes participles agree in case, gender, and number. First-person and second- person personal pronouns occasionally distinguish dual-number forms. The definite article sē and its inflections serve as

5797-438: Is also used in wetland ecology, where "upland" plants indicate an area that is not a wetland. In addition, the term moorland refers to upland shrubland biomes with acidic soils, while heathlands are lowland shrublands with acidic soils. Geomorphology refers to the study of the natural processes that shape land's surface, creating landforms. Erosion and tectonics , volcanic eruptions , flooding , weathering , glaciation ,

Land - Misplaced Pages Continue

5984-518: Is also used more generally, as in Persian rigestân ( ریگستان ) "place of sand, desert", golestân ( گلستان ) "place of flowers, garden", gurestân ( گورستان ) "graveyard, cemetery", and Hindustân ( هندوستان ) "land of the Indo people". The study of land and its history in general is called geography . Mineralogy is the study of minerals, and petrology is the study of rocks. Soil science

6171-483: Is an island , and a chain of islands is an archipelago . The smaller the island, the larger the percentage of its land area will be adjacent to the water, and subsequently will be coast or beach. Islands can be formed by a variety of processes. The Hawaiian islands , for example, even though they are not near a plate boundary, formed from isolated volcanic activity . Atolls are ring-shaped islands made of coral , created when subsidence causes an island to sink beneath

6358-483: Is approximately 9.8 m/s (32 ft/s ). Local differences in topography, geology, and deeper tectonic structure cause local and broad regional differences in Earth's gravitational field, known as gravity anomalies . The main part of Earth's magnetic field is generated in the core, the site of a dynamo process that converts the kinetic energy of thermally and compositionally driven convection into electrical and magnetic field energy. The field extends outwards from

6545-422: Is as follows. The sounds enclosed in parentheses in the chart above are not considered to be phonemes : The above system is largely similar to that of Modern English , except that [ç, x, ɣ, l̥, n̥, r̥] (and [ʍ] for most speakers ) have generally been lost, while the voiced affricate and fricatives (now also including /ʒ/ ) have become independent phonemes, as has /ŋ/ . The open back rounded vowel [ɒ]

6732-624: Is called the shoreline . The word land is derived from Old English , from the Proto-Germanic word * landą , "untilled land", and then the Proto-Indo-European * lendʰ- , especially in northern regions that were home to languages like Proto-Celtic and Proto-Slavic . Examples include Old Irish land , "land, plot, church building" and Old Irish ithlann , "threshing floor", and Old East Slavic ljadina "wasteland, weeds". A country or nation may be referred to as

6919-517: Is contained in 3.45 billion-year-old Australian rocks showing fossils of microorganisms . During the Neoproterozoic , 1000 to 539 Ma , much of Earth might have been covered in ice. This hypothesis has been termed " Snowball Earth ", and it is of particular interest because it preceded the Cambrian explosion , when multicellular life forms significantly increased in complexity. Following

7106-467: Is divided into two major categories: Mountain ranges and relatively flat interiors called cratons . Both form over millions of years through plate tectonics . Streams – a major part of Earth's water cycle – shape the landscape , carve rocks, transport sediments, and replenish groundwater. At high elevations or latitudes , snow is compacted and recrystallized over hundreds or thousands of years to form glaciers, which can be so heavy that they warp

7293-606: Is evidenced by the continued variation between their successors in Middle and Modern English. In fact, what would become the standard forms of Middle English and of Modern English are descended from Mercian rather than West Saxon, while Scots developed from the Northumbrian dialect. It was once claimed that, owing to its position at the heart of the Kingdom of Wessex, the relics of Anglo-Saxon accent, idiom and vocabulary were best preserved in

7480-452: Is farthest out from its center of mass at its equatorial bulge, the summit of the volcano Chimborazo in Ecuador (6,384.4 km or 3,967.1 mi) is its farthest point out. Parallel to the rigid land topography the ocean exhibits a more dynamic topography . To measure the local variation of Earth's topography, geodesy employs an idealized Earth producing a geoid shape. Such a shape

7667-646: Is followed by Middle English (1150 to 1500), Early Modern English (1500 to 1650) and finally Modern English (after 1650), and in Scotland Early Scots (before 1450), Middle Scots ( c.  1450 to 1700) and Modern Scots (after 1700). Just as Modern English is not monolithic, Old English varied according to place. Despite the diversity of language of the Germanic-speaking migrants who established Old English in England and southeastern Scotland, it

Land - Misplaced Pages Continue

7854-516: Is gained if the ocean is idealized, covering Earth completely and without any perturbations such as tides and winds. The result is a smooth but irregular geoid surface, providing a mean sea level (MSL) as a reference level for topographic measurements. Earth's surface is the boundary between the atmosphere, and the solid Earth and oceans. Defined in this way, it has an area of about 510 million km (197 million sq mi). Earth can be divided into two hemispheres : by latitude into

8041-466: Is important in creating and transforming airflow and precipitation . Large landforms, such as mountain ranges, can divert wind energy and make air parcels less dense and therefore able to hold less heat. As air rises, this cooling effect causes condensation and precipitation. Different types of land cover will influence the land's albedo , a measure of the solar radiation that is reflected, rather than absorbed and transferred to Earth. Vegetation has

8228-482: Is land, most of which is located in the form of continental landmasses within Earth's land hemisphere . Most of Earth's land is at least somewhat humid and covered by vegetation , while large sheets of ice at Earth's polar deserts retain more water than Earth's groundwater , lakes, rivers and atmospheric water combined. Earth's crust consists of slowly moving tectonic plates , which interact to produce mountain ranges, volcanoes , and earthquakes. Earth has

8415-426: Is liquid under normal atmospheric pressure. Differences in the amount of captured energy between geographic regions (as with the equatorial region receiving more sunlight than the polar regions) drive atmospheric and ocean currents , producing a global climate system with different climate regions , and a range of weather phenomena such as precipitation , allowing components such as nitrogen to cycle . Earth

8602-822: Is much freer. The oldest Old English inscriptions were written using a runic system , but from about the 8th century this was replaced by a version of the Latin alphabet . Englisċ , from which the word English is derived, means 'pertaining to the Angles '. The Angles were one of the Germanic tribes who settled in many parts of Britain in the 5th century. By the 9th century, all speakers of Old English, including those who claimed Saxon or Jutish ancestry, could be referred to as Englisċ . This name probably either derives from Proto-Germanic *anguz , which referred to narrowness, constriction or anxiety, perhaps referring to shallow waters near

8789-542: Is now known as Middle English in England and Early Scots in Scotland. Old English developed from a set of Anglo-Frisian or Ingvaeonic dialects originally spoken by Germanic tribes traditionally known as the Angles , Saxons and Jutes . As the Germanic settlers became dominant in England, their language replaced the languages of Roman Britain : Common Brittonic , a Celtic language ; and Latin , brought to Britain by

8976-501: Is now slightly longer than it was during the 19th century due to tidal deceleration , each day varies between 0 and 2 ms longer than the mean solar day. Earth's rotation period relative to the fixed stars , called its stellar day by the International Earth Rotation and Reference Systems Service (IERS), is 86,164.0989 seconds of mean solar time ( UT1 ), or 23 56 4.0989 . Earth's rotation period relative to

9163-415: Is often defined as the solid, dry surface of Earth. The word land may also collectively refer the collective natural resources of Earth, including its land cover , rivers , shallow lakes , its biosphere , the lowest layer of the atmosphere ( troposphere ), groundwater reserves, and the physical results of human activity on land, such as architecture and agriculture. The boundary between land and sea

9350-852: Is possible to reconstruct proto-Old English as a fairly unitary language. For the most part, the differences between the attested regional dialects of Old English developed within England and southeastern Scotland, rather than on the Mainland of Europe. Although from the tenth century Old English writing from all regions tended to conform to a written standard based on Late West Saxon, in speech Old English continued to exhibit much local and regional variation, which remained in Middle English and to some extent Modern English dialects . The four main dialectal forms of Old English were Mercian , Northumbrian , Kentish , and West Saxon . Mercian and Northumbrian are together referred to as Anglian . In terms of geography

9537-453: Is pushed upwards, or subductional events, where Earth's crust is pushed into the mantle, causing the crust to melt, rise due to its low density, and solidify into hardened rock, thickening the crust. A plateau , also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side, creating steep cliffs or escarpments . Both volcanic activity such as

SECTION 50

#1732838111593

9724-612: Is rare, though the alternative spelling Gaia has become common due to the Gaia hypothesis , in which case its pronunciation is / ˈ ɡ aɪ . ə / rather than the more classical English / ˈ ɡ eɪ . ə / . There are a number of adjectives for the planet Earth. The word "earthly" is derived from "Earth". From the Latin Terra comes terran / ˈ t ɛr ə n / , terrestrial / t ə ˈ r ɛ s t r i ə l / , and (via French) terrene / t ə ˈ r iː n / , and from

9911-434: Is replaced by ⟨þ⟩ ). In contrast with Modern English orthography , Old English spelling was reasonably regular , with a mostly predictable correspondence between letters and phonemes . There were not usually any silent letters —in the word cniht , for example, both the ⟨c⟩ and ⟨h⟩ were pronounced ( /knixt ~ kniçt/ ) unlike the ⟨k⟩ and ⟨gh⟩ in

10098-477: Is that it was formed by accretion from material loosed from Earth after a Mars -sized object with about 10% of Earth's mass, named Theia , collided with Earth. It hit Earth with a glancing blow and some of its mass merged with Earth. Between approximately 4.1 and 3.8 Ga , numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of

10285-453: Is the basis for the astronomical unit (AU) and is equal to roughly 8.3 light minutes or 380 times Earth's distance to the Moon . Earth orbits the Sun every 365.2564 mean solar days , or one sidereal year . With an apparent movement of the Sun in Earth's sky at a rate of about 1°/day eastward, which is one apparent Sun or Moon diameter every 12 hours. Due to this motion, on average it takes 24 hours—a solar day—for Earth to complete

10472-429: Is the outermost layer of Earth's continental surface and is composed of soil and subject to soil formation processes . Below it, the lithosphere encompasses both Earth's crust and the uppermost layer of the mantle . The lithosphere rests, or "floats", on top of the mantle below it via isostasy . Above the solid ground, the troposphere and humans' use of land can be considered layers of the land. Land cover refers to

10659-405: Is the study of soils, encompassing the sub-disciplines of pedology , which focuses on soil formation, and edaphology , which focuses on the relationship between soil and life. The earliest material found in the Solar System is dated to 4.5672 ± 0.0006  bya (billion years ago); therefore, the Earth itself must have been formed by accretion around this time. The formation and evolution of

10846-464: Is thicker than oceanic crust , and it is far more varied in terms of composition. About 31% of this continental crust is submerged in shallow water, forming continental shelves. Land provides many ecosystem services , such as mitigating climate change, regulating water supply through drainage basins and river systems, and supporting food production. Land resources are finite, which has led to regulations intended to safeguard these ecosystem services, and

11033-457: Is tied to that of the Sun. Over the next 1.1 billion years , solar luminosity will increase by 10%, and over the next 3.5 billion years by 40%. Earth's increasing surface temperature will accelerate the inorganic carbon cycle , possibly reducing CO 2 concentration to levels lethally low for current plants ( 10  ppm for C4 photosynthesis ) in approximately 100–900 million years . A lack of vegetation would result in

11220-451: Is tilted with respect to the perpendicular to its orbital plane around the Sun, producing seasons . Earth is orbited by one permanent natural satellite , the Moon , which orbits Earth at 384,400 km (1.28 light seconds) and is roughly a quarter as wide as Earth. The Moon's gravity helps stabilize Earth's axis, causes tides and gradually slows Earth's rotation . Tidal locking has made

11407-680: The Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind . The atmosphere and oceans of the Earth continuously shape the land by eroding and transporting solids on the surface. Earth's crust formed when the molten outer layer of the planet Earth cooled to form a solid mass as the accumulated water vapour began to act in the atmosphere. Once land became capable of supporting life, biodiversity evolved over hundreds of millions of years, expanding continually except when punctuated by mass extinctions. The two models that explain land mass propose either

SECTION 60

#1732838111593

11594-628: The Latin alphabet was introduced and adapted for the writing of Old English , replacing the earlier runic system. Nonetheless, the largest transfer of Latin-based (mainly Old French ) words into English occurred after the Norman Conquest of 1066, and thus in the Middle English rather than the Old English period. Another source of loanwords was Old Norse , which came into contact with Old English via

11781-566: The Milky Way and orbits about 28,000  light-years from its center. It is about 20 light-years above the galactic plane in the Orion Arm . The axial tilt of Earth is approximately 23.439281° with the axis of its orbit plane, always pointing towards the Celestial Poles . Due to Earth's axial tilt, the amount of sunlight reaching any given point on the surface varies over the course of

11968-722: The Pacific , North American , Eurasian , African , Antarctic , Indo-Australian , and South American . Other notable plates include the Arabian Plate , the Caribbean Plate , the Nazca Plate off the west coast of South America and the Scotia Plate in the southern Atlantic Ocean. The Australian Plate fused with the Indian Plate between 50 and 55 Ma . The fastest-moving plates are

12155-487: The Roman conquest . Old English had four main dialects, associated with particular Anglo-Saxon kingdoms : Kentish , Mercian , Northumbrian , and West Saxon . It was West Saxon that formed the basis for the literary standard of the later Old English period, although the dominant forms of Middle and Modern English would develop mainly from Mercian, and Scots from Northumbrian. The speech of eastern and northern parts of England

12342-419: The asthenosphere , the solid but less-viscous part of the upper mantle that can flow and move along with the plates. As the tectonic plates migrate, oceanic crust is subducted under the leading edges of the plates at convergent boundaries. At the same time, the upwelling of mantle material at divergent boundaries creates mid-ocean ridges. The combination of these processes recycles the oceanic crust back into

12529-523: The biosphere . Human manipulation of the land, including agriculture and architecture , can also be considered part of land. Land is formed from the continental crust , the layer of rock on which soil . groundwater , and human and animal activity sits. Though modern terrestrial plants and animals evolved from aquatic creatures, Earth's first cellular life likely originated on land. Survival on land relies on fresh water from rivers, streams, lakes, and glaciers, which constitute only three percent of

12716-406: The carbon cycle , nitrogen cycle , and water cycle . One-third of land is covered in trees, another third is used for agriculture , and one-tenth is covered in permanent snow and glaciers . The remainder consists of desert , savannah , and prairie . Land terrain varies greatly, consisting of mountains, deserts, plains, plateaus, glaciers, and other landforms . In physical geology, the land

12903-415: The celestial equator , this is equivalent to an apparent diameter of the Sun or the Moon every two minutes; from Earth's surface, the apparent sizes of the Sun and the Moon are approximately the same. Earth orbits the Sun, making Earth the third-closest planet to the Sun and part of the inner Solar System . Earth's average orbital distance is about 150 million km (93 million mi), which

13090-597: The dialect of Somerset . For details of the sound differences between the dialects, see Phonological history of Old English § Dialects . The language of the Anglo-Saxon settlers appears not to have been significantly affected by the native British Celtic languages which it largely displaced . The number of Celtic loanwords introduced into the language is very small, although dialect and toponymic terms are more often retained in western language contact zones (Cumbria, Devon, Welsh Marches and Borders and so on) than in

13277-594: The kingdom of Northumbria . Other parts of the island continued to use Celtic languages ( Gaelic – and perhaps some Pictish – in most of Scotland, Medieval Cornish all over Cornwall and in adjacent parts of Devon , Cumbric perhaps to the 12th century in parts of Cumbria , and Welsh in Wales and possibly also on the English side of the Anglo-Welsh border ); except in the areas of Scandinavian settlements, where Old Norse

13464-500: The motherland , fatherland , or homeland of its people. Many countries and other places have names incorporating the suffix -land (e.g. England , Greenland , and New Zealand ). The equivalent suffix -stan from Indo-Iranian , ultimately derived from the Proto-Indo-Iranian * sthāna- , is also present in many country and location names, such as Pakistan , Afghanistan , and others throughout Central Asia . The suffix

13651-408: The ocean floor form the top of Earth's crust , which together with parts of the upper mantle form Earth's lithosphere . Earth's crust may be divided into oceanic and continental crust. Beneath the ocean-floor sediments, the oceanic crust is predominantly basaltic , while the continental crust may include lower density materials such as granite , sediments and metamorphic rocks. Nearly 75% of

13838-430: The precessing or moving mean March equinox (when the Sun is at 90° on the equator), is 86,164.0905 seconds of mean solar time (UT1) (23 56 4.0905 ) . Thus the sidereal day is shorter than the stellar day by about 8.4 ms. Apart from meteors within the atmosphere and low-orbiting satellites, the main apparent motion of celestial bodies in Earth's sky is to the west at a rate of 15°/h = 15'/min. For bodies near

14025-413: The sphere of gravitational influence , of Earth is about 1.5 million km (930,000 mi) in radius. This is the maximum distance at which Earth's gravitational influence is stronger than that of the more distant Sun and planets. Objects must orbit Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun. Earth, along with the Solar System, is situated in

14212-433: The upwelling of magma and extrusion of lava, or erosion of mountains caused from water, glaciers, or aeolian processes, can create plateaus. Plateaus are classified according to their surrounding environment as intermontane , piedmont , or continental . A few plateaus may have a small flat top while others are wider. Buttes are smaller, with less extrusive and more intrusive igneous rock, while plateaus or highlands are

14399-643: The whale , that evolved from terrestrial mammals back to an aquatic lifestyle. Many megafauna of the past, such as non-avian dinosaurs , have become extinct due to extinction events, e.g. the Quaternary extinction event . Land is "deeply intertwined with human development." It is a crucial resource for human survival, humans depend on land for subsistence, and can develop strong symbolic attachments to it. Access to land can determine "survival and wealth," particularly in developing countries, giving rise to complex power relationships in production and consumption. Most of

14586-464: The "last ice age", covered large parts of the continents, to the middle latitudes, in ice and ended about 11,700 years ago. Chemical reactions led to the first self-replicating molecules about four billion years ago. A half billion years later, the last common ancestor of all current life arose. The evolution of photosynthesis allowed the Sun's energy to be harvested directly by life forms. The resultant molecular oxygen ( O 2 ) accumulated in

14773-422: The 8th century, the runic system came to be supplanted by a (minuscule) half-uncial script of the Latin alphabet introduced by Irish Christian missionaries. This was replaced by Insular script , a cursive and pointed version of the half-uncial script. This was used until the end of the 12th century when continental Carolingian minuscule (also known as Caroline ) replaced the insular. The Latin alphabet of

14960-479: The Cambrian explosion, 535 Ma , there have been at least five major mass extinctions and many minor ones. Apart from the proposed current Holocene extinction event, the most recent was 66 Ma , when an asteroid impact triggered the extinction of non-avian dinosaurs and other large reptiles, but largely spared small animals such as insects, mammals , lizards and birds. Mammalian life has diversified over

15147-432: The Earth's crust. About 30 percent of land has a dry climate, due to losing more water through evaporation than it gains from precipitation . Since warm air rises, this generates winds, though Earth's rotation and uneven sun distribution also play a part. Land is commonly defined as the solid, dry surface of Earth. It can also refer to the collective natural resources that the land holds, including rivers , lakes , and

15334-637: The Earth. Terra is also the name of the planet in some Romance languages , languages that evolved from Latin , like Italian and Portuguese , while in other Romance languages the word gave rise to names with slightly altered spellings, like the Spanish Tierra and the French Terre . The Latinate form Gæa or Gaea ( English: / ˈ dʒ iː . ə / ) of the Greek poetic name Gaia ( Γαῖα ; Ancient Greek : [ɡâi̯.a] or [ɡâj.ja] )

15521-406: The English language; some of them, such as Pope Gregory I 's treatise Pastoral Care , appear to have been translated by Alfred himself. In Old English, typical of the development of literature, poetry arose before prose, but Alfred chiefly inspired the growth of prose. A later literary standard, dating from the late 10th century, arose under the influence of Bishop Æthelwold of Winchester , and

15708-598: The Great . From that time on, the West Saxon dialect (then in the form now known as Early West Saxon) became standardised as the language of government, and as the basis for the many works of literature and religious materials produced or translated from Latin in that period. The later literary standard known as Late West Saxon (see History , above), although centred in the same region of the country, appears not to have been directly descended from Alfred's Early West Saxon. For example,

15895-581: The Latin Tellus comes tellurian / t ɛ ˈ l ʊər i ə n / and telluric . The oldest material found in the Solar System is dated to 4.5682 +0.0002 −0.0004 Ga (billion years) ago. By 4.54 ± 0.04 Ga the primordial Earth had formed. The bodies in the Solar System formed and evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into

16082-745: The Moon always face Earth with the same side. Earth, like most other bodies in the Solar System, formed 4.5 billion years ago from gas and dust in the early Solar System . During the first billion years of Earth's history , the ocean formed and then life developed within it. Life spread globally and has been altering Earth's atmosphere and surface, leading to the Great Oxidation Event two billion years ago. Humans emerged 300,000 years ago in Africa and have spread across every continent on Earth. Humans depend on Earth's biosphere and natural resources for their survival, but have increasingly impacted

16269-426: The Moon and, by inference, to that of Earth. Earth's atmosphere and oceans were formed by volcanic activity and outgassing . Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids, protoplanets , and comets . Sufficient water to fill the oceans may have been on Earth since it formed. In this model, atmospheric greenhouse gases kept the oceans from freezing when

16456-410: The Northumbrian dialect retained /i(ː)o̯/ , which had merged with /e(ː)o̯/ in West Saxon. For more on dialectal differences, see Phonological history of Old English (dialects) . Some of the principal sound changes occurring in the pre-history and history of Old English were the following: For more details of these processes, see the main article, linked above. For sound changes before and after

16643-857: The Northumbrian region lay north of the Humber River; the Mercian lay north of the Thames and south of the Humber River; West Saxon lay south and southwest of the Thames; and the smallest, Kentish region lay southeast of the Thames, a small corner of England. The Kentish region, settled by the Jutes from Jutland, has the scantest literary remains. The term West Saxon actually is represented by two different dialects: Early West Saxon and Late West Saxon. Hogg has suggested that these two dialects would be more appropriately named Alfredian Saxon and Æthelwoldian Saxon, respectively, so that

16830-462: The Old English period is also often attributed to Norse influence. The influence of Old Norse certainly helped move English from a synthetic language along the continuum to a more analytic word order , and Old Norse most likely made a greater impact on the English language than any other language. The eagerness of Vikings in the Danelaw to communicate with their Anglo-Saxon neighbours produced

17017-478: The Old English period, see Phonological history of English . Nouns decline for five cases : nominative , accusative , genitive , dative , instrumental ; three genders : masculine, feminine, neuter; and two numbers : singular, and plural; and are strong or weak. The instrumental is vestigial and only used with the masculine and neuter singular and often replaced by the dative . Only pronouns and strong adjectives retain separate instrumental forms. There

17204-515: The Scandinavian rulers and settlers in the Danelaw from the late 9th   century, and during the rule of Cnut and other Danish kings in the early 11th   century. Many place names in eastern and northern England are of Scandinavian origin. Norse borrowings are relatively rare in Old English literature, being mostly terms relating to government and administration. The literary standard, however,

17391-578: The Solar System bodies occurred in tandem with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disc , out of which the planets then grow (in tandem with the star). A nebula contains gas, ice grains and dust (including primordial nuclides ). In nebular theory , planetesimals begin to form as particulate matter accumulates by cohesive clumping and then by gravity. The primordial Earth's assembly took 10– 20  myr . By 4.54 ± 0.04 bya ,

17578-458: The Solar System's planetary-sized objects, Earth is the object with the highest density . Earth's mass is approximately 5.97 × 10   kg ( 5.970  Yg ). It is composed mostly of iron (32.1% by mass ), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%), with the remaining 1.2% consisting of trace amounts of other elements. Due to gravitational separation ,

17765-403: The Sun when the star reaches its maximum radius, otherwise, with tidal effects, it may enter the Sun's atmosphere and be vaporized. Earth has a rounded shape , through hydrostatic equilibrium , with an average diameter of 12,742 kilometres (7,918 mi), making it the fifth largest planetary sized and largest terrestrial object of the Solar System . Due to Earth's rotation it has

17952-602: The Viking influence on Old English appears from the fact that the indispensable elements of the language – pronouns , modals , comparatives , pronominal adverbs (like hence and together ), conjunctions and prepositions – show the most marked Danish influence; the best evidence of Scandinavian influence appears in the extensive word borrowings because, as Jespersen indicates, no texts exist in either Scandinavia or Northern England from this time to give certain evidence of an influence on syntax. The effect of Old Norse on Old English

18139-425: The atmosphere and due to interaction with ultraviolet solar radiation, formed a protective ozone layer ( O 3 ) in the upper atmosphere. The incorporation of smaller cells within larger ones resulted in the development of complex cells called eukaryotes . True multicellular organisms formed as cells within colonies became increasingly specialized. Aided by the absorption of harmful ultraviolet radiation by

18326-501: The basic elements of Modern English vocabulary. Old English is a West Germanic language , and developed out of Ingvaeonic (also known as North Sea Germanic) dialects from the 5th century. It came to be spoken over most of the territory of the Anglo-Saxon kingdoms which became the Kingdom of England . This included most of present-day England, as well as part of what is now southeastern Scotland , which for several centuries belonged to

18513-552: The beginnings of the compound tenses of Modern English . Old English verbs include strong verbs , which form the past tense by altering the root vowel, and weak verbs , which use a suffix such as -de . As in Modern English, and peculiar to the Germanic languages, the verbs formed two great classes: weak (regular), and strong (irregular). Like today, Old English had fewer strong verbs, and many of these have over time decayed into weak forms. Then, as now, dental suffixes indicated

18700-488: The borrowing of individual Latin words based on which patterns of sound change they have undergone. Some Latin words had already been borrowed into the Germanic languages before the ancestral Angles and Saxons left continental Europe for Britain. More entered the language when the Anglo-Saxons were converted to Christianity and Latin-speaking priests became influential. It was also through Irish Christian missionaries that

18887-450: The center, the temperature may be up to 6,000 °C (10,830 °F), and the pressure could reach 360  GPa (52 million  psi ). Because much of the heat is provided by radioactive decay, scientists postulate that early in Earth's history, before isotopes with short half-lives were depleted, Earth's heat production was much higher. At approximately 3  Gyr , twice the present-day heat would have been produced, increasing

19074-504: The climate change impacts on habitats and biodiversity, as well as natural resources, in the target areas. Land cover change detection and mapping is a key component of interdisciplinary land change science , which uses it to determine the consequences of land change on climate. Land change modeling is used to predict and analyze changes in land cover and use. Soil is a mixture of organic matter , minerals , gases , liquids , and organisms that together support life . Soil consists of

19261-499: The cluster ending in the palatal affricate is sometimes written ⟨nċġ⟩ (or ⟨nġċ⟩ ) by modern editors. Between vowels in the middle of a word, the pronunciation can be either a palatalized geminate /ʃː/ , as in fisċere /ˈfiʃ.ʃe.re/ ('fisherman') and wȳsċan , /ˈwyːʃ.ʃɑn 'to wish'), or an unpalatalized consonant sequence /sk/ , as in āscian /ˈɑːs.ki.ɑn/ ('to ask'). The pronunciation /sk/ occurs when ⟨sc⟩ had been followed by

19448-636: The coast is important for major parts of the global food and economic system, and they provide many ecosystem services to humankind. For example, important human activities happen in port cities . Coastal fisheries for commercial, recreational, and subsistence purposes, and aquaculture are major economic activities and provide jobs, livelihoods, and protein for the majority of coastal human populations. Other coastal spaces like beaches and seaside resorts generate economic activity through tourism . Marine coastal ecosystems can also provide protection against sea level rise and tsunamis . In many countries,

19635-457: The coast, or else it may derive from a related word *angô which could refer to curve or hook shapes including fishing hooks. Concerning the second option, it has been hypothesised that the Angles acquired their name either because they lived on a curved promontory of land shaped like a fishhook , or else because they were fishermen (anglers). Old English was not static, and its usage covered

19822-418: The coastal mangrove is the primary source of wood for fuel (e.g. charcoal) and building materials. Coastal ecosystems have a much higher capacity for carbon sequestration than many terrestrial ecosystems , and as such can play a critical role in the near future to help mitigate climate change effects by uptake of atmospheric anthropogenic carbon dioxide . A subcontinental area of land surrounded by water

20009-454: The continental crust , particularly during the early stages of Earth's history. New continental crust forms as a result of plate tectonics , a process ultimately driven by the continuous loss of heat from Earth's interior. Over the period of hundreds of millions of years, tectonic forces have caused areas of continental crust to group together to form supercontinents that have subsequently broken apart. At approximately 750 Ma , one of

20196-616: The continental surfaces are covered by sedimentary rocks, although they form about 5% of the mass of the crust. Earth's surface topography comprises both the topography of the ocean surface , and the shape of Earth's land surface. The submarine terrain of the ocean floor has an average bathymetric depth of 4 km, and is as varied as the terrain above sea level. Earth's surface is continually being shaped by internal plate tectonic processes including earthquakes and volcanism ; by weathering and erosion driven by ice, water, wind and temperature; and by biological processes including

20383-419: The core are chaotic; the magnetic poles drift and periodically change alignment. This causes secular variation of the main field and field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago. The extent of Earth's magnetic field in space defines the magnetosphere . Ions and electrons of the solar wind are deflected by

20570-527: The core is primarily composed of the denser elements: iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements. The most common rock constituents of the crust are oxides . Over 99% of the crust is composed of various oxides of eleven elements, principally oxides containing silicon (the silicate minerals ), aluminium, iron, calcium, magnesium, potassium, or sodium. The major heat-producing isotopes within Earth are potassium-40 , uranium-238 , and thorium-232 . At

20757-463: The core, through the mantle, and up to Earth's surface, where it is, approximately, a dipole . The poles of the dipole are located close to Earth's geographic poles. At the equator of the magnetic field, the magnetic-field strength at the surface is 3.05 × 10 T , with a magnetic dipole moment of 7.79 × 10 Am at epoch 2000, decreasing nearly 6% per century (although it still remains stronger than its long time average). The convection movements in

20944-421: The dative case, an adposition may conceivably be located anywhere in the sentence. Remnants of the Old English case system in Modern English are in the forms of a few pronouns (such as I/me/mine , she/her , who/whom/whose ) and in the possessive ending -'s , which derives from the masculine and neuter genitive ending -es . The modern English plural ending -(e)s derives from the Old English -as , but

21131-524: The days shorter. Above the Arctic Circle and below the Antarctic Circle there is no daylight at all for part of the year, causing a polar night , and this night extends for several months at the poles themselves. These same latitudes also experience a midnight sun , where the sun remains visible all day. By astronomical convention, the four seasons can be determined by the solstices—the points in

21318-577: The direction of the steepest slope. Hypsometric tints are colors placed between contour lines to indicate elevation relative to sea level . A difference between uplands, or highlands , and lowlands is drawn in several earth science fields. In river ecology, " upland " rivers are fast-moving and colder than "lowland" rivers, encouraging different species of fish and other aquatic wildlife to live in these habitats. For example, nutrients are more present in slow-moving lowland rivers, encouraging different species of macrophytes to grow there. The term "upland"

21505-605: The earliest known supercontinents, Rodinia , began to break apart. The continents later recombined to form Pannotia at 600–540 Ma , then finally Pangaea , which also began to break apart at 180 Ma . The most recent pattern of ice ages began about 40 Ma , and then intensified during the Pleistocene about 3 Ma . High- and middle-latitude regions have since undergone repeated cycles of glaciation and thaw, repeating about every 21,000, 41,000 and 100,000 years. The Last Glacial Period , colloquially called

21692-975: The earliest known supercontinents, Rodinia , began to break apart. The continents later recombined to form Pannotia , 600– 540 mya , then finally Pangaea , which also broke apart 180 mya . A continuous area of land surrounded by an ocean is called a landmass. Although it is most often written as one word to distinguish it from the usage "land mass"—the measure of land area—it may also be written as two words. There are four major continuous landmasses on Earth: Afro-Eurasia , America (landmass) , Antarctica , and Australia (landmass) , which are subdivided into continents. Up to seven geographical regions are commonly regarded as continents. Ordered from greatest to least land area, these continents are Asia , Africa , North America , South America , Antarctica , Europe , and Australia . Terrain refers to an area of land and its features. Terrain affects travel, mapmaking, ecosystems, and surface water flow and distribution. Over

21879-431: The east. However, various suggestions have been made concerning possible influence that Celtic may have had on developments in English syntax in the post–Old English period, such as the regular progressive construction and analytic word order , as well as the eventual development of the periphrastic auxiliary verb do . These ideas have generally not received widespread support from linguists, particularly as many of

22066-544: The equally large area of land under permafrost ) or deserts (33%). The pedosphere is the outermost layer of Earth's land surface and is composed of soil and subject to soil formation processes. Soil is crucial for land to be arable. Earth's total arable land is 10.7% of the land surface, with 1.3% being permanent cropland. Earth has an estimated 16.7 million km (6.4 million sq mi) of cropland and 33.5 million km (12.9 million sq mi) of pastureland. The land surface and

22253-639: The former diphthong /iy/ tended to become monophthongised to /i/ in EWS, but to /y/ in LWS. Due to the centralisation of power and the destruction wrought by Viking invasions, there is relatively little written record of the non-West Saxon dialects after Alfred's unification. Some Mercian texts continued to be written, however, and the influence of Mercian is apparent in some of the translations produced under Alfred's programme, many of which were produced by Mercian scholars. Other dialects certainly continued to be spoken, as

22440-526: The futhorc. A few letter pairs were used as digraphs , representing a single sound. Also used was the Tironian note ⟨⁊⟩ (a character similar to the digit 7) for the conjunction and . A common scribal abbreviation was a thorn with a stroke ⟨ꝥ⟩ , which was used for the pronoun þæt ( that ). Macrons over vowels were originally used not to mark long vowels (as in modern editions), but to indicate stress, or as abbreviations for

22627-485: The geological continents and the areas of shallow seabed close to their shores, known as continental shelves . This layer is sometimes called sial because its bulk composition is richer in aluminium silicate and has a lower density compared to the oceanic crust , called sima which is richer in magnesium silicate . Changes in seismic wave velocities have shown that at a certain depth (the Conrad discontinuity ), there

22814-638: The growth and decomposition of biomass into soil . Earth's mechanically rigid outer layer of Earth's crust and upper mantle , the lithosphere , is divided into tectonic plates . These plates are rigid segments that move relative to each other at one of three boundaries types: at convergent boundaries , two plates come together; at divergent boundaries , two plates are pulled apart; and at transform boundaries , two plates slide past one another laterally. Along these plate boundaries, earthquakes, volcanic activity , mountain-building , and oceanic trench formation can occur. The tectonic plates ride on top of

23001-405: The growth of coral reefs , and meteorite impacts are among the processes that constantly reshape Earth's surface over geological time . Erosion transports one part of land to another via natural processes, such as wind , water, ice , and gravity . In contrast, weathering wears away rock and other solid land without transporting the land somewhere else. Natural erosional processes usually take

23188-399: The harvest of crops. Floodplains provided agricultural land for some of the earliest civilizations . Erosion is often a main driver for the creation of plains and valleys, with rift valleys being a noticeable exception. Fjords are glacial valleys that can be thousands of meters deep, opening out to the sea. Any natural void in the ground which can be entered by a human can be considered

23375-404: The heat in Earth is lost through plate tectonics, by mantle upwelling associated with mid-ocean ridges . The final major mode of heat loss is through conduction through the lithosphere, the majority of which occurs under the oceans. The gravity of Earth is the acceleration that is imparted to objects due to the distribution of mass within Earth. Near Earth's surface, gravitational acceleration

23562-618: The igneous rocks granite and andesite . Less common is basalt , a denser volcanic rock that is the primary constituent of the ocean floors . Sedimentary rock is formed from the accumulation of sediment that becomes buried and compacted together . Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form about 5% of the crust. The most abundant silicate minerals on Earth's surface include quartz , feldspars , amphibole , mica , pyroxene and olivine . Common carbonate minerals include calcite (found in limestone ) and dolomite . The rock that makes up land

23749-590: The inscriptions on the Franks Casket ) date to the early 8th century. The Old English Latin alphabet was introduced around the 8th century. With the unification of several of the Anglo-Saxon kingdoms (outside the Danelaw ) by Alfred the Great in the later 9th century, the language of government and literature became standardised around the West Saxon dialect (Early West Saxon). Alfred advocated education in English alongside Latin, and had many works translated into

23936-421: The land and the ocean . It migrates each day as tides rise and fall, and moves over long periods of time as sea levels change. The shore extends from the low tide line to the highest elevation that can be reached by storm waves, and the coast stretches out inland until the point where ocean-related features are no longer found. When land is in contact with bodies of water, it can be eroded. The weathering of

24123-406: The land surface is taken by the four continental landmasses , which are (in descending order): Africa-Eurasia , America (landmass) , Antarctica , and Australia (landmass) . These landmasses are further broken down and grouped into the continents . The terrain of the land surface varies greatly and consists of mountains, deserts , plains , plateaus , and other landforms . The elevation of

24310-508: The land surface varies from a low point of −418 m (−1,371 ft) at the Dead Sea , to a maximum altitude of 8,848 m (29,029 ft) at the top of Mount Everest . The mean height of land above sea level is about 797 m (2,615 ft). Land can be covered by surface water , snow, ice, artificial structures or vegetation. Most of Earth's land hosts vegetation, but considerable amounts of land are ice sheets (10%, not including

24497-449: The latter applied only to "strong" masculine nouns in the nominative and accusative cases; different plural endings were used in other instances. Old English nouns had grammatical gender , while modern English has only natural gender. Pronoun usage could reflect either natural or grammatical gender when those conflicted, as in the case of ƿīf , a neuter noun referring to a female person. In Old English's verbal compound constructions are

24684-399: The lithosphere, which is divided into independently moving tectonic plates. Beneath the lithosphere is the asthenosphere , a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 410 and 660 km (250 and 410 mi) below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath

24871-410: The loss of oxygen in the atmosphere, making current animal life impossible. Due to the increased luminosity, Earth's mean temperature may reach 100 °C (212 °F) in 1.5 billion years, and all ocean water will evaporate and be lost to space, which may trigger a runaway greenhouse effect , within an estimated 1.6 to 3 billion years. Even if the Sun were stable, a fraction of the water in

25058-408: The low point of −418 m (−1,371 ft) at the Dead Sea , to a maximum altitude of 8,848 m (29,029 ft) at the top of Mount Everest. The mean height of land above sea level is about 797 m (2,615 ft), with 98.9% of dry land situated above sea level. Relief refers to the difference in elevation within a landscape; for example, flat terrain would have "low relief", while terrain with

25245-456: The lowercase when it is preceded by "the", such as "the atmosphere of the earth". It almost always appears in lowercase in colloquial expressions such as "what on earth are you doing?" The name Terra / ˈ t ɛr ə / occasionally is used in scientific writing and especially in science fiction to distinguish humanity's inhabited planet from others, while in poetry Tellus / ˈ t ɛ l ə s / has been used to denote personification of

25432-497: The magnetosphere. During magnetic storms and substorms , charged particles can be deflected from the outer magnetosphere and especially the magnetotail, directed along field lines into Earth's ionosphere , where atmospheric atoms can be excited and ionized, causing an aurora . Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time ( 86,400.0025 SI seconds ). Because Earth's solar day

25619-409: The magnetosphere; solar wind pressure compresses the day-side of the magnetosphere, to about 10 Earth radii, and extends the night-side magnetosphere into a long tail. Because the velocity of the solar wind is greater than the speed at which waves propagate through the solar wind, a supersonic bow shock precedes the day-side magnetosphere within the solar wind. Charged particles are contained within

25806-478: The magnetosphere; the plasmasphere is defined by low-energy particles that essentially follow magnetic field lines as Earth rotates. The ring current is defined by medium-energy particles that drift relative to the geomagnetic field, but with paths that are still dominated by the magnetic field, and the Van Allen radiation belts are formed by high-energy particles whose motion is essentially random, but contained in

25993-417: The mantle, an extremely low viscosity liquid outer core lies above a solid inner core . Earth's inner core may be rotating at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year, although both somewhat higher and much lower rates have also been proposed. The radius of the inner core is about one-fifth of that of Earth. The density increases with depth. Among

26180-600: The mantle. Due to this recycling, most of the ocean floor is less than 100 Ma old. The oldest oceanic crust is located in the Western Pacific and is estimated to be 200 Ma old. By comparison, the oldest dated continental crust is 4,030 Ma , although zircons have been found preserved as clasts within Eoarchean sedimentary rocks that give ages up to 4,400 Ma , indicating that at least some continental crust existed at that time. The seven major plates are

26367-667: The material physically present on the land surface, for example, woody crops, herbaceous crops, barren land, and shrub-covered areas. Artificial surfaces (including cities) account for about a third of a percent of all land. Land use refers to human allocation of land for various purposes, including farming, ranching, and recreation (e.g. national parks); worldwide, there are an estimated 16.7 million km (6.4 million sq mi) of cropland, and 33.5 million km (12.9 million sq mi) of pastureland. Land cover change detection using remote sensing and geospatial data provides baseline information for assessing

26554-428: The mid-5th century, and the first Old English literary works date from the mid-7th century. After the Norman Conquest of 1066, English was replaced for several centuries by Anglo-Norman (a type of French ) as the language of the upper classes. This is regarded as marking the end of the Old English era, since during the subsequent period the English language was heavily influenced by Anglo-Norman, developing into what

26741-451: The modern knight ( /naɪt/ ). The following table lists the Old English letters and digraphs together with the phonemes they represent, using the same notation as in the Phonology section above. After /n/ , /j/ was realized as [dʒ] and /ɣ/ was realized as [ɡ] . The spellings ⟨ncg⟩ , ⟨ngc⟩ and even ⟨ncgg⟩ were occasionally used instead of

26928-548: The modern oceans will descend to the mantle , due to reduced steam venting from mid-ocean ridges. The Sun will evolve to become a red giant in about 5 billion years . Models predict that the Sun will expand to roughly 1  AU (150 million km; 93 million mi), about 250 times its present radius. Earth's fate is less clear. As a red giant, the Sun will lose roughly 30% of its mass, so, without tidal effects, Earth will move to an orbit 1.7 AU (250 million km; 160 million mi) from

27115-399: The mother of Thor . Historically, "Earth" has been written in lowercase. Beginning with the use of Early Middle English , its definite sense as "the globe" was expressed as "the earth". By the era of Early Modern English , capitalization of nouns began to prevail , and the earth was also written the Earth , particularly when referenced along with other heavenly bodies. More recently,

27302-496: The naive reader would not assume that they are chronologically related. Each of these four dialects was associated with an independent kingdom on the islands. Of these, Northumbria south of the Tyne , and most of Mercia , were overrun by the Vikings during the 9th century. The portion of Mercia that was successfully defended, and all of Kent , were then integrated into Wessex under Alfred

27489-424: The name is sometimes simply given as Earth , by analogy with the names of the other planets , though "earth" and forms with "the earth" remain common. House styles now vary: Oxford spelling recognizes the lowercase form as the more common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name, such as a description of the "Earth's atmosphere", but employs

27676-425: The newly forming Sun had only 70% of its current luminosity . By 3.5 Ga , Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind . As the molten outer layer of Earth cooled it formed the first solid crust , which is thought to have been mafic in composition. The first continental crust , which was more felsic in composition, formed by

27863-586: The ocean may have covered Earth completely. The world ocean is commonly divided into the Pacific Ocean, Atlantic Ocean, Indian Ocean, Antarctic or Southern Ocean , and Arctic Ocean, from largest to smallest. The ocean covers Earth's oceanic crust , with the shelf seas covering the shelves of the continental crust to a lesser extent. The oceanic crust forms large oceanic basins with features like abyssal plains , seamounts , submarine volcanoes , oceanic trenches , submarine canyons , oceanic plateaus , and

28050-435: The ocean surface and leaves a ring of reefs around it. Mountains are features that usually rise at least 300 metres (980 ft) higher than the surrounding terrain. The formation of mountain belts is called orogenesis, and results from plate tectonics . For example, where a plate at a convergent plate boundary pushes one plate above the other, mountains could be formed by either collisional events, such that Earth's crust

28237-648: The oceanic plates, with the Cocos Plate advancing at a rate of 75 mm/a (3.0 in/year) and the Pacific Plate moving 52–69 mm/a (2.0–2.7 in/year). At the other extreme, the slowest-moving plate is the South American Plate, progressing at a typical rate of 10.6 mm/a (0.42 in/year). Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical ( rheological ) properties. The outer layer

28424-581: The orbit of maximum axial tilt toward or away from the Sun—and the equinoxes , when Earth's rotational axis is aligned with its orbital axis. In the Northern Hemisphere, winter solstice currently occurs around 21 December; summer solstice is near 21 June, spring equinox is around 20 March and autumnal equinox is about 22 or 23 September. In the Southern Hemisphere, the situation is reversed, with

28611-625: The ozone layer, life colonized Earth's surface. Among the earliest fossil evidence for life is microbial mat fossils found in 3.48 billion-year-old sandstone in Western Australia , biogenic graphite found in 3.7 billion-year-old metasedimentary rocks in Western Greenland , and remains of biotic material found in 4.1 billion-year-old rocks in Western Australia. The earliest direct evidence of life on Earth

28798-469: The partial melting of this mafic crust. The presence of grains of the mineral zircon of Hadean age in Eoarchean sedimentary rocks suggests that at least some felsic crust existed as early as 4.4 Ga , only 140  Ma after Earth's formation. There are two main models of how this initial small volume of continental crust evolved to reach its current abundance: (1) a relatively steady growth up to

28985-501: The past 66 Mys , and several million years ago, an African ape species gained the ability to stand upright. This facilitated tool use and encouraged communication that provided the nutrition and stimulation needed for a larger brain, which led to the evolution of humans . The development of agriculture , and then civilization , led to humans having an influence on Earth and the nature and quantity of other life forms that continues to this day. Earth's expected long-term future

29172-400: The past 150 years. Plate tectonics refers to the theory that Earth's lithosphere is divided into "tectonic plates" that move over the mantle. This results in continental drift , with continents moving relative to each other. The scientist Alfred Wegener first hypothesized the theory of continental drift in 1912. More researchers gradually developed his idea throughout the 20th century into

29359-512: The past tense of the weak verbs, as in work and worked . Old English syntax is similar to that of modern English . Some differences are consequences of the greater level of nominal and verbal inflection, allowing freer word order . Old English was first written in runes , using the futhorc —a rune set derived from the Germanic 24-character elder futhark , extended by five more runes used to represent Anglo-Saxon vowel sounds and sometimes by several more additional characters. From around

29546-406: The planet warms, it has been predicted that soils will add carbon dioxide to the atmosphere due to increased biological activity at higher temperatures, a positive feedback (amplification). This prediction has, however, been questioned on consideration of more recent knowledge on soil carbon turnover. Continental crust is the layer of igneous , sedimentary , and metamorphic rocks that forms

29733-478: The planet's environment . Humanity's current impact on Earth's climate and biosphere is unsustainable , threatening the livelihood of humans and many other forms of life, and causing widespread extinctions . The Modern English word Earth developed, via Middle English , from an Old English noun most often spelled eorðe . It has cognates in every Germanic language , and their ancestral root has been reconstructed as * erþō . In its earliest attestation,

29920-400: The planet. The water vapor acts as a greenhouse gas and, together with other greenhouse gases in the atmosphere, particularly carbon dioxide (CO 2 ), creates the conditions for both liquid surface water and water vapor to persist via the capturing of energy from the Sun's light . This process maintains the current average surface temperature of 14.76 °C (58.57 °F), at which water

30107-431: The plant. Through photosynthesis , most plants nourish themselves from sunlight and water, breathing in carbon dioxide and breathing out oxygen. Between 20 and 50% of oxygen is produced by land vegetation. Unlike plants, terrestrial animals are not a monophyletic group —that is, a group including all terrestrial animals does not encompass all lineages from a common ancestor . This is because there are organisms, such as

30294-421: The polar Northern and Southern hemispheres; or by longitude into the continental Eastern and Western hemispheres. Most of Earth's surface is ocean water: 70.8% or 361 million km (139 million sq mi). This vast pool of salty water is often called the world ocean , and makes Earth with its dynamic hydrosphere a water world or ocean world . Indeed, in Earth's early history

30481-410: The precipitation, cloud cover , and temperature of the region. A landform is a natural or manmade land feature. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography . Landforms include hills , mountains , canyons , and valleys , as well as shoreline features such as bays , capes , and peninsulas . The shoreline is the interface between

30668-490: The present day, which is supported by the radiometric dating of continental crust globally and (2) an initial rapid growth in the volume of continental crust during the Archean , forming the bulk of the continental crust that now exists, which is supported by isotopic evidence from hafnium in zircons and neodymium in sedimentary rocks. The two models and the data that support them can be reconciled by large-scale recycling of

30855-437: The primordial Earth had formed. Earth's atmosphere and oceans were formed by volcanic activity and outgassing that included water vapour . The origin of the world's oceans was condensation augmented by water and ice delivered by asteroids , protoplanets , and comets . In this model , atmospheric " greenhouse gases " kept the oceans from freezing while the newly formed Sun was only at 70% luminosity . By 3.5 bya ,

31042-493: The rates of mantle convection and plate tectonics, and allowing the production of uncommon igneous rocks such as komatiites that are rarely formed today. The mean heat loss from Earth is 87 mW m , for a global heat loss of 4.42 × 10  W . A portion of the core's thermal energy is transported toward the crust by mantle plumes , a form of convection consisting of upwellings of higher-temperature rock. These plumes can produce hotspots and flood basalts . More of

31229-515: The shape of an ellipsoid , bulging at its Equator ; its diameter is 43 kilometres (27 mi) longer there than at its poles . Earth's shape also has local topographic variations; the largest local variations, like the Mariana Trench (10,925 metres or 35,843 feet below local sea level), shortens Earth's average radius by 0.17% and Mount Everest (8,848 metres or 29,029 feet above local sea level) lengthens it by 0.14%. Since Earth's surface

31416-548: The summer and winter solstices exchanged and the spring and autumnal equinox dates swapped. Old English Old English ( Englisċ or Ænglisc , pronounced [ˈeŋɡliʃ] ), or Anglo-Saxon , was the earliest recorded form of the English language , spoken in England and southern and eastern Scotland in the early Middle Ages . It developed from the languages brought to Great Britain by Anglo-Saxon settlers in

31603-409: The theorized Brittonicisms do not become widespread until the late Middle English and Early Modern English periods, in addition to the fact that similar forms exist in other modern Germanic languages. Old English contained a certain number of loanwords from Latin , which was the scholarly and diplomatic lingua franca of Western Europe. It is sometimes possible to give approximate dates for

31790-564: The time still lacked the letters ⟨j⟩ and ⟨w⟩ , and there was no ⟨v⟩ as distinct from ⟨u⟩ ; moreover native Old English spellings did not use ⟨k⟩ , ⟨q⟩ or ⟨z⟩ . The remaining 20 Latin letters were supplemented by four more: ⟨ æ ⟩ ( æsc , modern ash ) and ⟨ð⟩ ( ðæt , now called eth or edh), which were modified Latin letters, and thorn ⟨þ⟩ and wynn ⟨ƿ⟩ , which are borrowings from

31977-404: The usual ⟨ng⟩ . The addition of ⟨c⟩ to ⟨g⟩ in spellings such as ⟨cynincg⟩ and ⟨cyningc⟩ for ⟨cyning⟩ may have been a means of showing that the word was pronounced with a stop rather than a fricative; spellings with just ⟨nc⟩ such as ⟨cyninc⟩ are also found. To disambiguate,

32164-446: The water on Earth. The vast majority of human activity throughout history has occurred in habitable land areas supporting agriculture and various natural resources . In recent decades, scientists and policymakers have emphasized the need to manage land and its biosphere more sustainably, through measures such as restoring degraded soil , preserving biodiversity , protecting endangered species , and addressing climate change . Land

32351-694: The widely accepted theory of plate tectonics of today. Several key characteristics define modern understanding of plate tectonics. The place where two tectonic plates meet is called a plate boundary , with different geological phenomena occurring across different kinds of boundaries. For example, at divergent plate boundaries , seafloor spreading is usually seen, in contrast with the subduction zones of convergent or transform plate boundaries . Earthquakes and volcanic activity are common in all types of boundaries. Volcanic activity refers to any rupture in Earth's surface where magma escapes, therefore becoming lava . The Ring of Fire , containing two-thirds of

32538-507: The widest, and mesas are a general-sized plateau with horizontal bedrock strata . Wide, flat areas of land are called plains , which cover more than one-third of Earth's land area. When they occur as lowered areas between mountains, they can create valleys , canyons or gorges, and ravines . A plateau can be thought of as an elevated plain. Plains are known to have fertile soils and be important for agriculture due to their flatness supporting grasses suitable for livestock and facilitating

32725-406: The word eorðe was used to translate the many senses of Latin terra and Greek γῆ gē : the ground, its soil , dry land, the human world, the surface of the world (including the sea), and the globe itself. As with Roman Terra /Tellūs and Greek Gaia , Earth may have been a personified goddess in Germanic paganism : late Norse mythology included Jörð ("Earth"), a giantess often given as

32912-423: The word was so nearly the same in the two languages that only the endings would put obstacles in the way of mutual understanding. In the mixed population which existed in the Danelaw, these endings must have led to much confusion, tending gradually to become obscured and finally lost. This blending of peoples and languages resulted in "simplifying English grammar". The inventory of Early West Saxon surface phones

33099-525: The world's philosophies and religions recognize a human duty of stewardship towards land and nature. Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life . This is enabled by Earth being an ocean world , the only one in the Solar System sustaining liquid surface water . Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust . The remaining 29.2% of Earth's crust

33286-610: The world's volcanos, and over 70% of Earth's seismological activity , comprises plate boundaries surrounding the Pacific Ocean . Earth's land interacts with and influences its climate heavily, since the land's surface heats up and cools down faster than air or water. Latitude , elevation , topography , reflectivity , and land use all have varying effects on climate. The latitude of the land will influence how much solar radiation reaches its surface. High latitudes receive less solar radiation than low latitudes. The land's topography

33473-598: The year. This causes the seasonal change in climate, with summer in the Northern Hemisphere occurring when the Tropic of Cancer is facing the Sun, and in the Southern Hemisphere when the Tropic of Capricorn faces the Sun. In each instance, winter occurs simultaneously in the opposite hemisphere. During the summer, the day lasts longer, and the Sun climbs higher in the sky. In winter, the climate becomes cooler and

33660-443: Was an allophone of short /ɑ/ which occurred in stressed syllables before nasal consonants (/m/ and /n/). It was variously spelled either ⟨a⟩ or ⟨o⟩. The Anglian dialects also had the mid front rounded vowel /ø(ː)/ , spelled ⟨œ⟩, which had emerged from i-umlaut of /o(ː)/ . In West Saxon and Kentish, it had already merged with /e(ː)/ before the first written prose. Other dialects had different systems of diphthongs. For example,

33847-439: Was based on the West Saxon dialect , away from the main area of Scandinavian influence; the impact of Norse may have been greater in the eastern and northern dialects. Certainly in Middle English texts, which are more often based on eastern dialects, a strong Norse influence becomes apparent. Modern English contains many, often everyday, words that were borrowed from Old Norse, and the grammatical simplification that occurred after

34034-481: Was either /ʃ/ or possibly /ʃː/ when the preceding vowel was short. Doubled consonants are geminated ; the geminate fricatives ⟨ff⟩ , ⟨ss⟩ and ⟨ðð⟩ / ⟨þþ⟩ / ⟨ðþ⟩ / ⟨þð⟩ are always voiceless [ff] , [ss] , [θθ] . The corpus of Old English literature is small but still significant, with some 400 surviving manuscripts. The pagan and Christian streams mingle in Old English, one of

34221-603: Was followed by such writers as the prolific Ælfric of Eynsham ("the Grammarian"). This form of the language is known as the " Winchester standard", or more commonly as Late West Saxon. It is considered to represent the "classical" form of Old English. It retained its position of prestige until the time of the Norman Conquest, after which English ceased for a time to be of importance as a literary language. The history of Old English can be subdivided into: The Old English period

34408-562: Was made between long and short vowels in the originals. (In some older editions an acute accent mark was used for consistency with Old Norse conventions.) Additionally, modern editions often distinguish between velar and palatal ⟨c⟩ and ⟨g⟩ by placing dots above the palatals: ⟨ċ⟩ , ⟨ġ⟩ . The letter wynn ⟨ƿ⟩ is usually replaced with ⟨w⟩ , but ⟨æ⟩ , ⟨ð⟩ and ⟨þ⟩ are normally retained (except when ⟨ð⟩

34595-411: Was spoken and Danish law applied. Old English literacy developed after Christianisation in the late 7th century. The oldest surviving work of Old English literature is Cædmon's Hymn , which was composed between 658 and 680 but not written down until the early 8th century. There is a limited corpus of runic inscriptions from the 5th to 7th centuries, but the oldest coherent runic texts (notably

34782-649: Was subject to strong Old Norse influence due to Scandinavian rule and settlement beginning in the 9th century. Old English is one of the West Germanic languages , and its closest relatives are Old Frisian and Old Saxon . Like other old Germanic languages, it is very different from Modern English and Modern Scots, and largely incomprehensible for Modern English or Modern Scots speakers without study. Within Old English grammar nouns, adjectives, pronouns and verbs have many inflectional endings and forms, and word order

34969-425: Was substantive, pervasive, and of a democratic character. Old Norse and Old English resembled each other closely like cousins, and with some words in common, speakers roughly understood each other; in time the inflections melted away and the analytic pattern emerged. It is most important to recognize that in many words the English and Scandinavian language differed chiefly in their inflectional elements. The body of

#592407