How Do Soils Form?
Dig down deep into any soil, and you’ll see that it is made of layers, or horizons. Put the horizons together, and they form a soil profile. Like a biography, each profile tells a story about the life of a soil.
Every soil originally formed from parent material: a deposit at the Earth’s surface. The material could have been bedrock that weathered in place or smaller materials carried by flooding rivers, moving glaciers, or blowing winds. Over time, sun, water, wind, ice, and living creatures help transform, or change, the parent material into soil.
Soil changes with age
As a soil ages, it gradually starts to look different from its parent material. That’s because soil is dynamic. Its components—minerals, water, air, organic matter, and organisms—constantly change. Some components are added. Some are lost. Some move from place to place within the soil. And some components are transformed into others.
Soils differ from one part of the world to another, and even from one part of a backyard to another. They differ because of where and how they formed. Over time, five major factors control how a soil forms. They are climate, organisms, relief (landscape), parent material, and time--or CLORPT, for short.