Introduction
IN THIS LESSON
What is soil and how is it formed?
Soil is the upper layer of the earth in which plants grow. It typically comprises a mixture of organic material, clay, rock particles, gases, and liquids. It contains minerals, organisms such as earthworms, nematodes, algae and microorganisms, and organic matter (decomposing plants and animals.
Soil is formed through physical, chemical, and biological processes. As mountains, rocks and cliffs are eroded by wind, rain, ice and wave action, they become broken down into particles that lie on the earth’s surface. Over time, different soil layers are formed, namely topsoil, subsoil, parent material and bedrock. The rock type that becomes part of the soil as it erodes determines what type of soil it will become.
