Land, also known asdry land,ground, orearth, is the solid terrestrial surface ofEarth not submerged by theocean or anotherbody of water. It makes up 29.2% of Earth's surface and includes allcontinents andislands. Earth's land surface is almost entirely covered byregolith, a layer ofrock,soil, andminerals that forms the outer part of thecrust. Land plays an important role in Earth'sclimate system, being involved in thecarbon cycle,nitrogen cycle, andwater cycle. One-third of land is covered intrees, another third is used foragriculture, and one-tenth is covered in permanent snow andglaciers. The remainder consists ofdesert,savannah, andprairie.
Landterrain varies greatly, consisting of mountains, deserts, plains, plateaus, glaciers, and otherlandforms. In physical geology, the land is divided into two major categories:Mountain ranges and relatively flat interiors calledcratons. Both form over millions of years throughplate tectonics.Streams – a major part of Earth's water cycle – shape thelandscape, carve rocks, transport sediments, and replenish groundwater. At high elevations orlatitudes,snow is compacted and recrystallized over hundreds or thousands of years to form glaciers, which can be so heavy that they warp the Earth's crust. About 30 percent of land has a dry climate, due to losing more water through evaporation than it gains fromprecipitation. Since warm air rises, this generates winds, thoughEarth'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 collectivenatural resources that the land holds, includingrivers,lakes, and thebiosphere. Human manipulation of the land, includingagriculture andarchitecture, can also be considered part of land. Land is formed from thecontinental crust, the layer of rock on whichsoil,groundwater, and human and other animal activity sits.
Though modern terrestrialplants andanimals evolved from aquatic creatures, Earth'sfirst cellular life likely originated on land. Survival on land relies onfresh water from rivers, streams, lakes, and glaciers, which constitute only three percent of the water on Earth. The vast majority of human activity throughout history has occurred inhabitable land areas supporting agriculture and variousnatural resources. In recent decades, scientists and policymakers have emphasized the need tomanage land and its biosphere more sustainably, through measures such as restoringdegraded soil, preservingbiodiversity, protectingendangered species, and addressingclimate change.
Land is often defined as the solid, dry surface of Earth.[1] The wordland may also collectively refer the collectivenatural resources of Earth,[2] including itsland cover,rivers, shallowlakes, itsbiosphere, the lowest layer of the atmosphere (troposphere),groundwater reserves, and the physical results of human activity on land, such asarchitecture and agriculture.[3] The boundary between land and sea is called theshoreline.[4]: 625 [5]
The wordland is derived fromOld English, from theProto-Germanic word*landą, "untilled land", and then theProto-Indo-European*lendʰ-, especially in northern regions that were home to languages likeProto-Celtic andProto-Slavic. Examples includeOld Irishland, "land, plot, church building" andOld Irishithlann, "threshing floor", andOld East Slavicljadina "wasteland, weeds".[2]
Acountry ornation may be referred to as themotherland,fatherland, orhomeland of its people.[6]: 43 Many countries and other places have names incorporating the suffix-land (e.g.England,[7]Greenland,[8] andNew Zealand[9]). The equivalent suffix-stan fromIndo-Iranian, ultimately derived from theProto-Indo-Iranian*sthāna-,[10] is also present in many country and location names, such asPakistan,Afghanistan, and others throughoutCentral Asia.[11] The suffix is also used more generally, as inPersianrigestân (ریگستان) "place of sand, desert",golestân (گلستان) "place of flowers, garden",gurestân (گورستان) "graveyard, cemetery",[12] andHindustân (هندوستان) "land of theIndo people".[13]
The study of land and its history in general is calledgeography.Mineralogy is the study of minerals, andpetrology is the study of rocks.Soil science is the study of soils, encompassing the sub-disciplines ofpedology, which focuses on soil formation, andedaphology, which focuses on the relationship between soil and life.
The earliest material found in the Solar System is dated to4.5672±0.0006 bya (billion years ago);[14] therefore, Earth itself must have been formed byaccretion around this time. Theformation and evolution of the Solar System bodies occurred in tandem with the Sun. In theory, asolar nebula partitions a volume out of amolecular cloud by gravitational collapse, which begins to spin and flatten into acircumstellar disc, out of which the planets then grow (in tandem with the star). A nebula contains gas, ice grains anddust (includingprimordial nuclides). In thenebular hypothesis,planetesimals begin to form asparticulate matter accumulates bycohesive clumping and then by gravity. The primordial Earth's assembly took 10–20 myr.[15] By4.54±0.04 bya, the primordial Earth had formed.[16][17]
Earth's atmosphere and oceans were formed byvolcanic activity andoutgassing that includedwater vapour. Theorigin of the world's oceans was condensation augmented by water and ice delivered byasteroids,protoplanets, andcomets.[18] Inthis model, atmospheric "greenhouse gases" kept the oceans from freezing while the newly formed Sun was only at 70%luminosity.[19] By3.5 bya, theEarth's magnetic field was established, which helped prevent the atmosphere from being stripped away by thesolar wind.[20] The atmosphere and oceans of the Earth continuously shape the land by eroding and transporting solids on the surface.[21]
Earth's crust formed when the molten outer layer of Planet Earth cooled toform a solid mass[22] 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.[23]
The two models[24] that explain land mass propose either a steady growth to the present-day forms[25] or, more likely, a rapid growth[26] early in Earth history[27] followed by a long-term steady continental area.[28][29][30]Continents are formed byplate tectonics, a process ultimately driven by the continuous loss of heat from the Earth's interior. Ontime scales lasting hundreds of millions of years, thesupercontinents have formed and broken apart three times. Roughly750 mya (million years ago), one of the earliest known supercontinents,Rodinia, began to break apart.[31] The continents later recombined to formPannotia, 600–540 mya, then finallyPangaea, which also broke apart180 mya.[32]
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.[33] There are four major continuous landmasses on Earth:Africa–Eurasia,America (landmass),Antarctica, andAustralia (landmass), which are subdivided intocontinents.[34] Up to seven geographical regions are commonly regarded as continents. Ordered from greatest to least land area, these continents areAsia,Africa,North America,South America,Antarctica,Europe, andAustralia.[35]
Terrain refers to an area of land and its features.[36] Terrain affects travel, mapmaking, ecosystems, and surfacewater flow and distribution. Over a large area, it can influence climate and weather patterns. The terrain of a region largely determines its suitability for human settlement: flatteralluvial plains tend to have better farming soils than steeper, rockier uplands.[37]
Elevation is defined as the vertical distance between an object and sea level, whilealtitude is defined as the vertical distance from an object to Earth's surface.[38] The elevation of Earth's land surface varies from the low point of −418 metres (−1,371 feet) at theDead Sea, to a maximum altitude of 8,848 metres (29,029 feet) at the top of Mount Everest. The mean height of land above sea level is about 797 metres (2,615 feet),[39] with 98.9% of dry land situated above sea level.[40]
Relief refers to the difference in elevation within a landscape; for example, flat terrain would have "low relief", while terrain with a large elevation difference between the highest and lowest points would be deemed "high relief". Most land has relatively low relief.[41] The change in elevation between two points of the terrain is called a slope or gradient. Atopographic map is a form ofterrain cartography which depicts terrain in terms of its elevation, slope, and the orientation of its landforms. It has prominentcontour lines, which connect points of similar elevation, while perpendicular slope lines point in the direction of the steepest slope.[42]Hypsometric tints are colors placed between contour lines to indicate elevation relative tosea level.[43]
A difference between uplands, orhighlands, and lowlands is drawn in severalearth 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 ofmacrophytes to grow there.[44] The term "upland" is also used in wetland ecology, where "upland" plants indicate an area that is not a wetland.[45] In addition, the termmoorland refers to uplandshrubland biomes with acidic soils, whileheathlands are lowland shrublands with acidic soils.[46]
Geomorphology refers to the study of the natural processes that shape land's surface, creating landforms.[47]: 3 Erosion and tectonics,volcanic eruptions,flooding,weathering,glaciation, the growth ofcoral reefs, and meteorite impacts are among the processes that constantly reshape Earth's surface overgeological time.[48][49]
Erosion transports one part of land to another via natural processes, such aswind, water,ice, andgravity. In contrast, weathering wears away rock and other solid land without transporting the land somewhere else.[4]: 210–211 Natural erosional processes usually take a long time to cause noticeable changes in the landscape—for example, theGrand Canyon was created over the past 70 million years by theColorado River,[50][51] which scientists estimate continues to erode the canyon at a rate of 0.3 meters (0.98 feet) every 200 years.[52] However, humans have caused erosion to be 10–40 times faster than normal,[53] causing half thetopsoil of the surface of Earth's land to be lost within the past 150 years.[54]
Plate tectonics refers to the theory that Earth's lithosphere is divided into "tectonic plates" that move over the mantle.[4]: 66 This results incontinental drift, with continents moving relative to each other.[55] The scientistAlfred Wegener first hypothesized the theory of continental drift in 1912.[56] More researchers developed his idea throughout the 20th century into the now widely accepted theory of plate tectonics.
Several key characteristics define the modern understanding of plate tectonics. The place where two tectonic plates meet is called aplate boundary,[57] with different geological phenomena occurring across different kinds of boundaries. For example, atdivergent plate boundaries,seafloor spreading is usually seen,[4]: 74–75 in contrast with thesubduction zones ofconvergent ortransform plate boundaries.[4]: 78–80
Earthquakes andvolcanic activity are common in all types of boundaries. Volcanic activity refers to any rupture in Earth's surface wheremagma escapes, therefore becominglava.[4]: 170–172 TheRing of Fire, containing two-thirds of the world's volcanos, and over 70% of Earth'sseismological activity, comprises plate boundaries surrounding thePacific Ocean.[58][59]: 68 [60]: 409–452 [a]
Earth's land interacts with and influences itsclimate heavily, since the land's surface heats up and cools down faster than air or water.[61]Latitude,elevation,topography,reflectivity, andland use all have varying effects on climate. The latitude of the land will influence how muchsolar radiation reaches its surface. High latitudes receive less solar radiation than low latitudes.[61] The land's topography is important in creating and transforming airflow andprecipitation. Large landforms, such as mountain ranges, can divert wind energy and makeair parcels less dense and therefore able to hold less heat.[61] As air rises, this cooling effect causescondensation and precipitation.
Different types of land cover will influence the land'salbedo, a measure of the solar radiation that is reflected, rather than absorbed and transferred to Earth.[62]Vegetation has a relatively low albedo, meaning that vegetated surfaces are good absorbers of the sun's energy.Forests have an albedo of 10–15 percent whilegrasslands have an albedo of 15–20 percent. In comparison, sandydeserts have an albedo of 25–40 percent.[62]
Land use by humans also plays a role in the regional and global climate. Densely populated cities are warmer and createurban heat islands that have effects on the precipitation,cloud cover, and temperature of the region.[61]
A landform is a natural or manmade[63] land feature. Landforms together make up a given terrain, and their arrangement in thelandscape is known astopography. Landforms includehills,mountains,canyons, andvalleys, as well asshoreline features such asbays,capes, andpeninsulas.
Theshoreline is the interface between the land and theocean. It migrates each day astides rise and fall and moves over long periods of time assea levels change. The shore extends from the low tide line to the highest elevation that can be reached by storm waves, and thecoast stretches out inland until the point where ocean-related features are no longer found.[4]: 625–626
When land is in contact with bodies of water, it can be eroded. The weathering of a coastline may be impacted by thetides, caused by changes in gravitational forces on larger bodies of water.[47]: 352–353 [64] Coasts are important zones in natural ecosystems, often home to a wide range ofbiodiversity.[65] On land, they harbour important ecosystems such as freshwater or estuarinewetlands, which are important for bird populations and other terrestrial animals. In wave-protected areas they harborsaltmarshes,mangroves orseagrasses, all of which can providenursery habitat for finfish,shellfish, and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for a wide range ofsessile animals (e.g.mussels,starfish,barnacles) and various kinds ofseaweeds. Alongtropical coasts with clear, nutrient-poor water,coral reefs can often be found between depths of 1–50 meters (3.3–164.0 ft).[66]
According to aUnited Nations atlas, 44% of all people live within 150 km (93 mi) of the sea.[67] Because of their importance in society and high concentration of population, the coast is important for major parts of the global food and economic system, and they provide manyecosystem services to humankind. For example, important human activities happen inport cities. Coastalfisheries for commercial, recreational, and subsistence purposes, andaquaculture are major economic activities and provide jobs, livelihoods, andprotein for the majority of coastal human populations. Other coastal spaces likebeaches andseaside resorts generate economic activity throughtourism.Marine coastal ecosystems can also provide protection againstsea level rise andtsunamis. In many countries, the coastalmangrove is the primary source of wood for fuel (e.g. charcoal) and building materials. Coastal ecosystems have a much higher capacity forcarbon sequestration than manyterrestrial ecosystems, and as such can play a critical role in the near future to helpmitigate climate change effects by uptake ofatmospheric anthropogenic carbon dioxide.[68]
A subcontinental area of land surrounded by water is anisland,[69]: xxxi and a chain of islands is anarchipelago. 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.[70] Islands can be formed by a variety of processes. TheHawaiian islands, for example, even though they are not near a plate boundary, formed fromisolated volcanic activity.[69]: 406 Atolls are ring-shaped islands made ofcoral, created whensubsidence causes an island to sink beneath the ocean surface and leaves a ring of reefs around it.[69]: 69 [71]
Mountains are features that usually rise at least 300 metres (980 ft) higher than the surrounding terrain.[72] Theformation of mountain belts is called orogenesis, and results fromplate tectonics.[4]: 448–449 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 is pushed upwards,[4]: 454–460 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.[4]: 449–453
Aplateau, 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 steepcliffs orescarpments.[47]: 99 Both volcanic activity such as theupwelling of magma andextrusion of lava, or erosion of mountains caused from water, glaciers, or aeolian processes, can create plateaus. Plateaus are classified according to their surrounding environment asintermontane,piedmont, orcontinental.[73] 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 the widest, andmesas are a general-sized plateau with horizontalbedrockstrata.[74][75][76]
Wide, flat areas of land are calledplains, which cover more than one-third of Earth's land area.[77] When they occur as lowered areas between mountains, they can createvalleys,canyons or gorges, andravines.[78] 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 the harvest of crops.[79]Floodplains provided agricultural land for some of theearliest civilizations.[80] Erosion is often a main driver for the creation of plains and valleys, withrift valleys being a noticeable exception.Fjords are glacial valleys that can be thousands of meters deep, opening out to the sea.[81]
Any natural void in the ground which can be entered by a human can be considered acave.[82][83] They have been important to humans as a place ofshelter since the dawn of humanity.[84]
Craters are depressions in the ground, but unlike caves, they do not provide shelter or extendunderground. There are many kinds of craters, such asimpact craters, volcaniccalderas, andisostatic depressions.Karst processes can create bothsolution caves, the most frequent cave type, and craters, as seen in karstsinkholes.[85]
Thepedosphere is the outermost layer of Earth's continental surface and is composed of soil and subject tosoil formation processes. Below it, thelithosphere encompasses both Earth's crust and the uppermost layer of themantle.[86] The lithosphere rests, or "floats", on top of the mantle below it viaisostasy.[4]: 463 Above the solid ground, thetroposphere and humans' use of land can be considered layers of the land.[3]
Land cover refers to 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.[87]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 km2 (6.4 million sq mi) of cropland, and 33.5 million km2 (12.9 million sq mi) of pastureland.[88]
Land cover change detection usingremote sensing and geospatial data provides baseline information for assessing 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 interdisciplinaryland change science, which uses it to determine the consequences of land change on climate.[89]Land change modeling is used to predict and analyze changes in land cover and use.[90]
Soil is amixture oforganic matter,minerals,gases,liquids, andorganisms that together supportlife. Soil consists of a solid phase of minerals and organic matter (the soil matrix),[4]: 222 as well as aporous phase that holdsgases (the soil atmosphere) andwater (the soil solution).[91] Accordingly, soil is a three-state system of solids, liquids, and gases.[92] Soil is a product of several factors: the influence ofclimate,relief (elevation, orientation, and slope of terrain), organisms, and the soil'sparent materials (original minerals) interacting over time.[93] It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering anderosion.[47]: 148–150
Given its complexity and strong internalconnectedness,soil ecologists regard soil as anecosystem.[94] Soil acts as an engineering medium, a habitat forsoil organisms, a recycling system fornutrients andorganic wastes, a regulator ofwater quality, a modifier ofatmospheric composition, and a medium forplant growth, making it a critically important provider ofecosystem services.[95] Since soil has a tremendous range of availableniches andhabitats, it contains a prominent part of the Earth'sgenetic diversity. A gram of soil can contain billions of organisms, belonging to thousands of species, mostly microbial and largely still unexplored.[96]
Soil 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 fromozone depletion andglobal warming torainforest destruction andwater pollution. With respect to Earth'scarbon cycle, soil acts as an importantcarbon reservoir,[97] and it is potentially one of the most reactive to human disturbance[98] and climate change.[99] As the planet warms, it has been predicted that soils will add carbon dioxide to the atmosphere due to increasedbiological activity at higher temperatures, apositive feedback (amplification).[100] This prediction has, however, been questioned on consideration of more recent knowledge onsoil carbon turnover.[101]
Continental crust is the layer ofigneous,sedimentary, andmetamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known ascontinental shelves. This layer is sometimes calledsial because its bulk composition is richer inaluminium silicate and has a lower density compared to theoceanic crust,[102] calledsima which is richer inmagnesium silicate. Changes inseismic wave velocities have shown that at a certain depth (theConrad discontinuity), there is a reasonably sharp contrast between the morefelsic upper continental crust and the lower continental crust, which is moremafic in character.[103]
The composition of land is not uniform across the Earth, varying between locations and betweenstrata within the same location. The most prominent components of upper continental crust includesilicon dioxide,aluminium oxide, andmagnesium.[104] Thecontinental crust consists of lower density material such as the igneous rocksgranite[105] andandesite. Less common isbasalt, a denser volcanic rock that is the primary constituent of theocean floors.[106] Sedimentary rock is formed from the accumulation of sediment that becomes buried andcompacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form about 5% of the crust.[107]
The most abundantsilicate minerals on Earth's surface includequartz,feldspars,amphibole,mica,pyroxene andolivine.[108] Commoncarbonate minerals includecalcite (found inlimestone) anddolomite.[109] The rock that makes up land is thicker thanoceanic 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.[104]
Land provides manyecosystem 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 a set of practices calledsustainable land management.[3]
A biome is an area "characterized by its vegetation, soil, climate, andwildlife."[110][111] There are five major types of biomes on land: grasslands, forests, deserts, tundras, and freshwater.[110] Other types of biomes include shrublands,[b] wetlands,[c] andpolar ice caps.[113] Anecosystem refers to the interaction between organisms within a particular environment, and ahabitat 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.[114]
Land plants evolved fromgreen algae, and are calledembryophytes. They includetrees,shrubs,ferns,grass,moss, andflowers. Most plants arevascular plants, meaning that their tissues distribute water and minerals throughout the plant.[121] Throughphotosynthesis, 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.[122]
Unlike plants,terrestrial animals are not amonophyletic group—that is, a group including all terrestrial animals does not encompass all lineages from acommon ancestor. This is because there are organisms, such as thewhale, thatevolved from terrestrial mammals back to an aquatic lifestyle.[123] Manymegafauna of the past, such as non-aviandinosaurs, have become extinct due to extinction events, e.g. theQuaternary extinction event.[124]
Land is "deeply intertwined with human development."[3]: 21 It is a crucial resource for human survival,[125] 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 the world's philosophies and religions recognize a human duty ofstewardship towards land and nature.[3]
Many humans see land as a source of "spirituality, inspiration, and beauty." Many also derive a sense of belonging from land, especially if it also belonged to their ancestors.[3] Variousreligions teach about a connection between humans and the land (such as veneration ofBhumi, a personification of the Earth inHinduism,[127] and the obligation to protect land ashima inIslam), and in almost everyIndigenous group there areetiological stories about the land they live on.[3] For Indigenous peoples, connection to the land is an important part of their identity and culture,[128] and some religious groups consider a particular area of land to besacred, such as theHoly Land in theAbrahamic religions.[129]
Creation myths in many religions involve stories of the creation of the world by a supernaturaldeity or deities, including accounts wherein the land is separated from the oceans and the air. The Earth itself has often been personified as adeity, in particular agoddess. In many cultures, themother goddess is also portrayed as afertility deity. To theAztecs, Earth was calledTonantzin—"our mother"; to theIncas, Earth was calledPachamama—"mother earth". InNorse mythology, the Earth giantessJörð was the mother ofThor and the daughter ofAnnar.[130]Ancient Egyptian mythology is different from that of other cultures because Earth (Geb) is male and the sky (Nut) is female.[131]
Ancient Near Eastern cultures conceived of the world as a flat disk of land surrounded by ocean. ThePyramid Texts andCoffin Texts reveal that the ancient Egyptians believedNun (the ocean) was a circular body surroundingnbwt (a term meaning "dry lands" or "islands").[132] TheHebrew Bible, drawing on other Near Eastern ideas,depicts the Earth as a flat disc floating on water, with another expanse of water above it.[133] A similar model is found in theHomeric account of the 8th century BC in which "Okeanos, the personified body of water surrounding the circular surface of the Earth, is the begetter of all life and possibly of all gods."[134]
The spherical form of the Earth was suggested by earlyGreek philosophers, a belief espoused byPythagoras. Contrary to popular belief, most educated people in theMiddle Ages did not believe the Earth was flat: this misconception is often called the "Myth of the Flat Earth". As evidenced by thinkers such asThomas Aquinas, the European belief in aspherical Earth was widespread by this point in time.[135] Prior tocircumnavigation of the planet and the introduction ofspace flight, belief in a spherical Earth was based on observations of the secondary effects of the Earth's shape and parallels drawn with the shape of other planets.[136]
Humans have commonlytraveled for business, pleasure, discovery, and adventure, all made easier in recent human history as a result of technologies likecars,trains,planes, andships.Land navigation is an aspect of travel and refers to progressing through unfamiliar terrain using navigational tools like maps with references to terrain, acompass, orsatellite navigation.[139] Navigation on land is often facilitated by reference tolandmarks – enduring and recognizable natural or artificial features that stand out from their nearby environment and are often visible from long distances.[140] Natural landmarks can be characteristic features, such as mountains or plateaus, with examples includingTable Mountain in South Africa,Mount Ararat in Turkey, theGrand Canyon in the United States,Uluru in Australia, andMount Fuji in Japan.[141]
Two major eras of exploration occurred in human history: one of divergence, and one of convergence. The former saw humans moving out of Africa, settling in new lands, and developing distinct cultures in relative isolation.[142] Early explorers settled in Europe and Asia; 14,000 years ago, some crossed theIce Age land bridge from Siberia to Alaska and moved southbound to settle in the Americas.[143] For the most part, these cultures were ignorant of each other's existence.[142] The second period, occurring over roughly the last 10,000 years, saw increased cross-cultural exchange through trade and exploration, marking a new era of cultural intermingling.[142]
Human trade has occurred since the prehistoric era.Peter Watson dates thehistory of long-distance commerce fromc. 150,000 years ago.[144] Majortrade routes throughout history have existed on land, such as theSilk Road which linkedEast Asia withEurope[145] and theAmber Road which was used to transferamber fromNorthern Europe to theMediterranean Sea.[146] TheDark Ages led trade to collapse in the West, but it continued to flourish among the kingdoms of Africa, the Middle East, India, China, and Southeast Asia. During the Middle Ages, Central Asia was the economic centre of the world, and luxury goods were commonly traded in Europe. Physical money (either barter or precious metals) was dangerous to carry over a long distance. To address this, a burgeoning banking industry enabled the shift to movable wealth or capital, making it far easier and safer to trade across long distances. After theAge of Sail, international trade mostly occurred along sea routes, notably to prevent intermediary countries from being able to control trade routes and the flow of goods.[citation needed]
In economics,land refers to afactor of production. It can be leased in exchange forrent, and use of its variousraw material resources (trees, oil, metals).[147]
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For more than 10,000 years, humans have engaged in activities on land such ashunting,foraging,controlled burning,land clearing, andagriculture. Beginning with theNeolithic Revolution and the spread of agriculture around the world, human land use has significantly alteredterrestrial ecosystems, with an essentially global transformation of Earth's landscape by 3000 years ago.[148]: 30 [149][150] From around 1750, human land use has increased at an accelerating rate due to theIndustrial Revolution, which created a greater demand for natural resources and caused rapid population growth.[148]: 34
Agriculture includes bothcrop farming andanimal husbandry.[151] A third of Earth's land surface is used for agriculture,[152][153]: 126 with estimated 16.7 million km2 (6.4 million sq mi) of cropland and 33.5 million km2 (12.9 million sq mi) of pastureland.[88] This has had significant impacts on Earth's ecosystems. When land is cleared to make way for agriculture, native flora and fauna are replaced with newly introduced crops and livestock.[148]: 31 Excessively high agricultural land use is driven by poor management practices (which lead to lower food yields, necessitating more land use), food demand,food waste, anddiets high in meat.[153]: 126
Urbanization has led to greater population growth inurban areas in the last century. Although urban areas make up less than 3 percent of Earth's land area, the global population shifted from a majority living inrural areas to a majority living in urban areas in 2007.[148]: 35 People living in urban areas depend on food produced in rural areas outside of their cities, which creates greater demand for agriculture and drivesland use change well beyond city boundaries.[148]: 35 Urbanization also displaces agricultural land because it mainly takes place on the most fertile land. Urban expansion inperi-urban areas fragments agricultural and natural lands, forcing agriculture to move to less fertile land elsewhere. Because this land is less fertile, more land is needed for the same output, which increases the total agricultural land use.[154]: 119
Another form of land use ismining, wherebyminerals are extracted from the ground using a variety of methods. Evidence of mining activity dates back to around 3000 BCE inAncient Egypt.[148]: 34 Important minerals includeiron ore, mined for use as araw material;coal, mined forenergy production; andgemstones, mined for use injewellery andcurrency.[148]: 34
The phrase "the law of the land" first appeared in 1215 inMagna Carta, inspiring its later usage in theUnited States Constitution.[155] The idea ofcommon land also originated with medievalEnglish law, and refers collective ownership of land, treating it as acommon good.[3] In environmental science, economics, and game theory, thetragedy of the commons refers to individuals' use of common spaces for their own gain, deteriorating the land overall by taking more than their fair share and not cooperating with others.[156] The idea of common land suggests public ownership; but there is still some land that can be privatized asproperty for an individual, such as alandlord orking. In the developed world, land is expected to be privately owned by an individual with legaltitle, but in the developing world the right to use land is often divided, with the rights to land resources being given to different people at different times for the same area of land.[3] Beginning in the late 20th century, the international community has begun to recogniseIndigenous land rights in law, for example, theTreaty of Waitangi forMāori people, theAct on Greenland Self-Government forInuit, and the Indigenous Peoples Rights Act in thePhilippines.[128]
Borders are geographical boundaries imposed either by geographic features (oceans,mountain ranges,rivers) or bypolitical entities (governments, states, or subnational entities). Political borders can be established throughwarfare,colonization, or mutual agreements between the political entities that reside in those areas;[157] the creation of these agreements is calledboundary delimitation.[158]
Manywars and other conflicts have occurred in efforts by participants to expand the land under their control, or to assert control of a specific area of considered to hold strategic, historical, or cultural significance. TheMongol Empire of the 13th and 14th centuries became thelargest contiguous land empire inhistory through war and conquest.[159]
In the19th-century United States, a concept ofmanifest destiny was developed by various groups, asserting that American settlers were destined to expand acrossNorth America. This concept was used to justify military action against theindigenous peoples of North America andof Mexico.[160][161][162][163]
The aggression ofNazi Germany inWorld War II was motivated in part by the concept ofLebensraum ("living space"), which had first became a geopolitical goal ofImperial Germany inWorld War I (1914–1918) originally, as the core element of theSeptemberprogramm of territorial expansion.[164] The most extreme form of this ideology was supported by theNazi Party (NSDAP). Lebensraum was one of the leading motivations Nazi Germany had in initiatingWorld War II, and it would continue this policy until the end of World War II.[165]
Land degradation is "the reduction or loss of the biological or economic productivity and complexity" of land as a result of human activity.[166]: 42 Land degradation is driven by many different activities, including agriculture, urbanization, energy production, and mining.[166]: 43 Humans have altered more than three-quarters of ice-free land through habitation and other use, fundamentally changing ecosystems.[167] Human activity is a major factor in theHolocene extinction,[168] and human-caused climate change is causingrising sea levels and ecosystem loss. Environmental scientists study land's ecosystems, natural resources,biosphere (fauna andflora),troposphere, and the impact of human activity on these.[3] Their recommendations have led to international action to preventbiodiversity loss anddesertification, and encourage sustainableforest andwaste management.[169] Theconservation movement lobbies for the protection ofendangered species and the protection of natural areas, such asparks.[170]: 253 International frameworks have focused on analyzing how humans can meet their needs while using land more efficiently and preserving its natural resources, notably under the United Nations'Sustainable Development Goals framework.[169]
Human land use can cause soil to degrade, both in quality and in quantity.[166]: 44 Soil degradation can be caused byagrochemicals (such asfertilizers,pesticides, andherbicides),infrastructure development, andmining among other activities.[166]: 43–47 There are several different processes that lead to soil degradation. Physical processes, such aserosion,sealing, andcrusting, lead to the structural breakdown of the soil. This means water cannot penetrate the soil surface, causingsurface runoff.[166]: 44 Chemical processes, such assalinization,acidification, andtoxication, lead to chemical imbalances in the soil.[166]: 44 Salinization in particular is detrimental, as it makes land less productive for agriculture and affects at least 20% of all irrigated lands.[153]: 137 Deliberate disruption of soil in the form oftillage can also alter biological processes in the soil, which leads to excessivemineralization and the loss of nutrients.[166]: 44
Desertification is a type of land degradation indrylands in which fertile areas become increasingly arid as a result of natural processes or human activities, resulting in loss of biological productivity.[171] This spread of arid areas can be influenced by a variety of human factors, such asdeforestation, improperland management,overgrazing,[172] anthropogenicclimate change,[173] andoverexploitation ofsoil.[174] Throughout geological history, desertification has occurred naturally, though in recent times it is greatly accelerated by human activity.[172][175][176]
Ground pollution issoil contamination viapollutants, such ashazardous waste orlitter. Ground pollution can be prevented by properly monitoring and disposing of waste, along with reducing unnecessary chemical and plastic use. Unfortunately, proper disposal of waste often is not economically beneficial or technologically viable, leading to short-term solutions of waste disposal that pollute the earth. Examples include dumping harmful industrial byproducts, overusing agricultural fertilizers and other chemicals, and poorly maintaininglandfills. Some landfills can be thousands of acres in size, such as theApex Regional landfill in Las Vegas.[177]
Water pollution on land is the contamination of non-oceanic hydrological surface and underground water features such aslakes,ponds,rivers,streams,wetlands,aquifers,reservoirs, andgroundwater as a result of human activities.[178]: 6 It may be caused by toxic substances (e.g., oil, metals, plastics,pesticides,persistent organic pollutants, industrial waste products),[179] stressful conditions (e.g., changes of pH,hypoxia or anoxia, increased temperatures, excessive turbidity, unpleasant taste or odor, and changes ofsalinity),[180] orpathogenic organisms.[181]
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Thebiodiversity of Earth—the variety and variability of life—is threatened by climate change, human activities, and invasive species. Due to an increase in the rate ofextinction, biodiversity loss is increasing.[182] Agriculture can cause biodiversity loss as land is converted for agricultural use at a very high rate, particularly in the tropics, which directly causes habitat loss. The use of pesticides and herbicides can also negatively impact the health of local species.[166]: 43 Ecosystems can also be divided and degraded byinfrastructure development outside of urban areas.[166]: 46
Biodiversity loss can sometimes be reversed throughecological restoration orecological resilience, such as through the restoration of abandoned agricultural areas;[166]: 45 however, it may also be permanent (e.g. throughland loss). The planet's ecosystem is quite sensitive: occasionally, minor changes from a healthyequilibrium can have dramatic influence on afood web orfood chain, up to and including thecoextinction of that entire food chain. Biodiversity loss leads to reducedecosystem services, and can eventually threatenfood security.[183] Earth is currently undergoing itssixth mass extinction (theHolocene extinction) as a result of human activities which push beyond theplanetary boundaries. So far, this extinction has proven irreversible.[184][185][186]
Although humans have used land for itsnatural resources since ancient times, demand for resources such astimber,minerals, andenergy has grown exponentially since theIndustrial Revolution due to population growth.[148]: 34 When a natural resource is depleted to the point ofdiminishing returns, it is considered the overexploitation of that resource.[187] Some natural resources, such as timber, are considered renewable, because with sustainable practices they replenish to their previous levels.[188]: 90 Fossil fuels such ascoal are not considered renewable, as they take millions of years to form, with the current supply of coal expected to peak in the middle of the 21st century.[188]: 90 Economic materialism, orconsumerism, has influenced destructive patterns of modern resource usage, in contrast with pre-industrial usage.[189]
Different varieties of landscapes:
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... on January 6, 1912, Wegener... proposed instead a grand vision of drifting continents and widening seas to explain the evolution of Earth's geography.
Our analysis of pedon data from several disturbed soil profiles suggests that physical disturbances and anthropogenic inputs of various materials (direct effects) can greatly alter the amount of C stored in these human "made" soils.
Earth (भूमि,bhūmi) is one of the five primary elements (pañcabhūta)
defined agriculture as 'all forms of activities connected with growing, harvesting and primary processing of all types of crops, with the breeding, raising and caring for animals, and with tending gardens and nurseries'.
{{cite book}}:ISBN / Date incompatibility (help)...at the firstEarth Summit, the vast majority of the world's nations declared that human actions were dismantling the Earth's ecosystems, eliminating genes, species and biological traits at an alarming rate. This observation led to the question of how such loss of biological diversity will alter the functioning of ecosystems and their ability to provide society with the goods and services needed to prosper.
Moreover, we have unleashed a mass extinction event, the sixth in roughly 540 million years, wherein many current life forms could be annihilated or at least committed to extinction by the end of this century.
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