Land, sometimes referred to as dry land, is the solid surface of the Earth that is not permanently covered by water. The vast majority of human activity occurs in land areas that support agriculture, habitat, and various natural resources. Some life forms have developed from predecessor species that lived in bodies of water. Areas where land meets large bodies of water are called coastal zones.
The division between land and water is a fundamental concept to humans. The demarcation between land and water can vary by local jurisdiction and other factors. A maritime boundary is one example of a political demarcation. A variety of natural boundaries exist to help clearly define where water meets land. Solid rock land forms are easier to demarcate than marshy or swampy boundaries, where there is no clear point at which the land ends and a body of water has begun. Demarcation can further vary due to tides and weather.
The word ‘land’ is derived from Middle English land, lond and Old English land, lond (“earth, land, soil, ground; defined piece of land, territory, realm, province, district; landed property; country (not town); ridge in a ploughed field”), from Proto-Germanic *landą (“land”), and from Proto-Indo-European *lendʰ- (“land, heath”). Cognate with Scots land (“land”), West Frisian lân (“land”), Dutch land (“land”), German Land (“land, country, state”), Swedish land (“land, country, shore, territory”), Icelandic land (“land”). Non-Germanic cognates include Old Irish lann (“heath”), Welsh llan (“enclosure”), Breton lann (“heath”), Old Church Slavonic lędо from Proto-Slavic *lenda (“heath, wasteland”) and Albanian lëndinë (“heath, grassland”) from lëndë (“matter, substance”).
No man ever steps in the same river twice, for it’s not the same river and he’s not the same man. – Heraclitus
A continuous area of land surrounded by ocean is called a “landmass”. Although it may be most often written as one word to distinguish it from the usage “land mass”—the measure of land area—it is also used as two words. Landmasses include supercontinents, continents, and islands.
There are four major continuous landmasses of the Earth: Afro-Eurasia, Americas, Australia and Antarctica. Land, capable of being ploughed and used to grow crops, is called arable land.
A country or region may be referred to as the motherland, fatherland, or homeland of its people. Many countries and other places have names incorporating -land (e.g. Iceland).
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. By 4.54±0.04 bya, the primordial Earth had formed. The formation and evolution of 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 disk, which the planets then grow out of in tandem with the star. A nebula contains gas, ice grains and dust (including primordial nuclides). In nebular theory, planetesimals commence forming as particulate matter accrues by cohesive clumping and then by gravity. The assembly of the primordial Earth proceeded for 10–20 myr.
Earth’s atmosphere and oceans were formed by volcanic activity and outgassing that included water vapor. The origin of the world’s oceans was condensation augmented by water and ice delivered by asteroids, proto-planets, and comets. In this model, atmospheric “greenhouse gases” kept the oceans from freezing while the newly forming Sun was only at 70% luminosity. By 3.5 bya, 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.
The crust, which currently forms the Earth’s land, was created when the molten outer layer of the planet Earth cooled to form a solid mass as the accumulated water vapor began to act in the atmosphere. Once land became capable of supporting life, biodiversity evolved over hundreds of million years, expanding continually except when punctuated by mass extinctions.
The two models that explain land mass propose either 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 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 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.