Land

Land, also called dry land, ground, or earth, is the solid surface of our planet that is not covered by oceans or other bodies of water. It makes up about 29.2% of Earth's surface and includes all continents and islands. This surface is covered with a layer of rock, soil, and minerals, and it plays a big role in Earth's climate, helping with the carbon cycle, nitrogen cycle, and water cycle.

One-third of land is filled with trees, another third is used for growing food, and some parts are covered with snow and glaciers. The rest includes deserts, savannahs, and prairies. Land has many different shapes, like mountains, deserts, plains, and plateaus, formed over millions of years by movements in Earth's crust and the action of streams and rivers.

Land is also home to many natural resources, such as rivers, lakes, and all the plants and animals that live there. Most human history has happened on land that can support farming and provide natural resources. Today, it is very important to take care of our land by restoring damaged soil, protecting plants and animals, and helping to fight climate change.

Definition

Land is the solid, dry surface of Earth. The word land can also mean all of Earth's natural resources, like its land cover, rivers, small lakes, plants and animals, the lowest part of the sky called the troposphere, water under the ground called groundwater, and things people build such as buildings and farms. The place where land meets the sea is called the shoreline.

Etymology

The word land comes from old languages. In Old English, it meant ground that had not been farmed. Similar ideas appear in other old languages, like Old Irish and Old East Slavic.

Some countries are called the motherland, fatherland, or homeland of their people. Many place names end in -land, like England, Greenland, and New Zealand. Other names end in -stan, such as Pakistan and Afghanistan.

Physical science

The study of land and its history is called geography. Mineralogy looks at minerals, and petrology studies rocks. Soil science examines soils, including how they form and how they support life.

Earth formed around 4.5 billion years ago from dust and gas in space. Its atmosphere and oceans came from volcanic activity and materials from space. Over time, Earth's surface cooled and formed solid land. Land has changed through processes like wind, water, and movement of Earth's plates. These changes happen very slowly, but humans have sped up some of these processes.

Land includes big areas like continents and islands. These landmasses are shaped by their height, slopes, and features like mountains and valleys. The way land is shaped affects weather, water flow, and where people can live. Studying these shapes helps us understand how Earth changes over time.

Features

A landform is a natural or human-made feature on the land. Together, landforms make up the shape of the land, called the landscape. Landforms include hills, mountains, canyons, valleys, and shoreline features such as bays, capes, and peninsulas.

The shoreline is where the land meets the ocean. It changes daily with tides and over long periods as sea levels change. Coasts are important for nature, providing homes for many plants and animals, such as wetlands, saltmarshes, mangroves, seagrasses, and coral reefs. Many people live near coasts, and these areas are important for fishing, tourism, and protecting against big waves and rising sea levels.

Islands are pieces of land surrounded by water. They can form in different ways, such as from volcanic activity or from sinking land that leaves a ring of reefs. Mountains are tall landforms that rise high above the surrounding area, formed by the movement of Earth's plates. Plateaus are wide, flat areas of high land, often formed by volcanic activity or erosion. Plains are large, flat areas of land that are important for farming. Caves are natural spaces in the ground that people can enter, while craters are lower areas that do not provide shelter.

Layers

The pedosphere is the top layer of Earth's land, made of soil and shaped by natural processes. Below it lies the lithosphere, which includes the Earth's crust and the top part of the mantle. The lithosphere "floats" on the mantle thanks to isostasy.^: 463  Above the ground, we have the troposphere and the ways humans use the land.

Land cover

Land cover is what sits on the Earth's surface, like crops, grass, deserts, and shrubs. Human-made surfaces, such as cities, cover a very small part of the land. Land use is how people choose to use the land, for farming, raising animals, or enjoying nature like in national parks. There is a lot of land used for growing food and raising animals around the world.

Soil

Main article: Soil

Soil is a mix of different things like organic material, minerals, air, water, and tiny living things that help support life. It has solid parts and spaces that hold air and water. Soil forms from many influences over time and is always changing. It is very important because it helps plants grow, supports many living things, and plays a big role in the Earth's systems.

Continental crust

Main articles: Continental crust and Continental shelf

See also: Abundance of elements in Earth's crust

The continental crust is the thick layer of rock that makes up the land and the shallow areas under the ocean near continents, called continental shelves. It is made of different types of rocks and has a lower density than the ocean floor. The land's rocks are thicker and more varied than those under the oceans, and a lot of the land is actually covered by sedimentary rocks formed from accumulated sediments.

Life science

Land helps us in many ways, like keeping our climate stable, managing water, and growing food. Because there is only a limited amount of land, rules and good practices have been created to protect these important services.

Land biomes

Main article: Biome

A biome is a big area with plants, soil, weather, and animals that are all similar. There are five main types of land biomes: grasslands, forests, deserts, tundras, and freshwater areas. Other types include shrublands, wetlands, and polar ice caps. An ecosystem is all the living things in one place and how they interact with each other. A habitat is where a particular animal or plant lives. Biomes can cover more than one continent and have many different ecosystems and habitats.

• Deserts have very little rain, usually less than 25 centimetres (9.8 in) a year. They are found on every continent and can be very hot or very cold. Deserts are home to special plants and animals that can survive with little water. Deserts can grow bigger because of deforestation and too many animals eating the plants.
• Tundra is a cold area where trees cannot grow because it is too freezing and the growing season is too short. There are different kinds of tundra in different places.
• A forest is land covered mostly with trees. Forests can look different depending on where they are, but they all have lots of trees. Types of forests include rainforests, deciduous forests, and boreal forests.
• Grasslands are areas where grasses are the main plants. They can also have other plants like shrubs and small flowers. Grasslands are found on every continent except Antarctica and are very important for the world. Types include natural grasslands, ones partly made by people, and ones used for farming. Savannas are grasslands with a few scattered trees.

Fauna and flora

Land plants came from water plants and include trees, shrubs, ferns, grass, moss, and flowers. Most plants can move water and minerals through their tissues. They make their food from sunlight and water, taking in carbon dioxide and giving out oxygen. Land plants make between 20 and 50% of the world’s oxygen.

Animals that live on land are not all closely related. Some animals, like whales, started life on land but moved back into the water. Many large animals from the past, like non-avian dinosaurs, are no longer alive because of events that changed the world.

Humans and land

Land is very important for people. It helps us survive and gives us food, shelter, and space to live. Many cultures and religions see land as something special, full of meaning and beauty. It often connects people to their ancestors and history.

People have always traveled over land for many reasons, like business, adventure, or to find new places. With cars, trains, planes, and ships, traveling has become much easier. Trade on land has existed for thousands of years, with famous routes like the Silk Road helping connect different parts of the world.

Land is also where we grow our food. Most of our food comes from farming on land. As more people live in cities, there is growing demand for food, which puts pressure on land use. People also use land for mining minerals like iron and coal, which are important for many things we use every day.

Environmental issues

Land degradation means the loss of the usefulness or productivity of land because of human actions. Many activities cause this, such as farming, building cities, making energy, and mining. Humans have changed most of the land that isn’t covered in ice, which has greatly changed natural habitats. Scientists who study the environment look at how land, plants, animals, and air are affected by human actions. Their work has helped create international plans to protect nature and use land in ways that are better for the Earth. These plans are part of the United Nations' Sustainable Development Goals.

Soil degradation

Main article: Soil retrogression and degradation

When we use land, we can sometimes damage the soil, making it worse for growing plants or other uses. Things like using too many chemicals on farms, building structures, and mining can hurt the soil. Soil can break down in different ways. For example, rain can wash away the top layer of soil, or chemicals can change the soil in harmful ways. One big problem is when soil becomes too salty, which makes it hard to grow food. Sometimes, people plow the land too much, which can also damage the soil.

Pollution

Main article: Pollution

Pollution on land happens when harmful things get into the soil or water. This can be caused by improper waste disposal, using too many chemicals on farms, or not taking good care of places where waste is buried. Some of these waste places can be very large. Water pollution happens when harmful substances get into lakes, rivers, or underground water. This can be caused by toxic materials like oil, metals, plastics, and chemicals used in farming.

Biodiversity loss

Main articles: Biodiversity loss and Habitat destruction

Earth’s many plants and animals are facing big problems because of climate change, human actions, and invasive species. As more animals and plants disappear, the loss of biodiversity grows. Farming takes up a lot of land, which can destroy habitats. Using pesticides and herbicides can also harm local wildlife. Building things like roads and buildings outside cities can also break up habitats. Sometimes, damaged areas can recover, but other times the loss is permanent. The loss of biodiversity can affect our food and the balance of nature. Earth is currently in a major loss of species because of human actions.

Resource depletion

Main articles: Overexploitation and Conflict resource

Humans have always used land for its resources like wood, minerals, and energy. But since the Industrial Revolution, the need for these resources has grown very fast because there are more people. When we use a resource so much that it can’t be used anymore, we call this overexploitation. Some resources, like wood, can grow back if we use them carefully. But others, like coal, take millions of years to form and won’t come back in our lifetime. The way we use resources today often harms the Earth, unlike how people used them before the Industrial Revolution.