The soil supports much of the life on earth. Soil is made up of rocks, gravel, sand, clay, and decaying organic materials.
Plants receive nutrients from the soil.
Many species of insects spend at least part of their life cycle in soil. Many other animals, including many mammals, either make their homes in the soil or hunt animals that do. The atmosphere is a gas envelope that rises 960 kilometres above the planet's surface and protects organisms from the harmful rays of the sun. Yet most life exists in the few kilometres nearest the earth's surface. The air contains the gases needed by organisms to live.