Soil formation worksheet Interactive Worksheet - Edform - Free Printable

- Soil is a mixture of weathered rock and organic matter that covers bedrock.
- Chemical weathering turns hard minerals into soft ones, while mechanical weathering breaks solid rock into smaller pieces.
- Plants and animals contribute organic materials through waste and dead organisms; decay of this organic matter produces acids that speed up chemical weathering.
- Burrowing animals like earthworms, insects, and rodents help circulate air and water and mix mineral and organic remains in the soil.
- The material from which soil forms is called parent material. Soil formed directly from underlying bedrock is residual soil; soil not matching its underlying bedrock is transported soil, deposited by erosion agents like wind, rivers, or glaciers.
- A cross section of soil is called a soil profile, composed of layers known as soil horizons: A-horizon (topsoil rich in humus), B-horizon (subsoil with washed-down minerals and clay), and C-horizon (partially weathered bedrock over solid bedrock).
- Soil erosion is the removal of topsoil by water or wind; it takes 100–400 years to form one centimeter of topsoil.
- Loss of topsoil occurs when plant roots are absent to hold soil; salting roads, overgrazing, winds, construction, and mining can all damage plant cover and accelerate erosion.