- Soil is formed from parent material, which can be bedrock (residual soil) or transported materials like those moved by glaciers, rivers, or wind (transported soil).
- Soil develops in layers called horizons: the O horizon (organic matter/humus), A horizon (topsoil rich in organic material and minerals), B horizon (subsoil with leached minerals), and C horizon (partially weathered parent material over bedrock).
- Chemical weathering breaks down rocks using chemical reactions (e.g., acids from decaying organic matter), while mechanical weathering physically breaks rocks into smaller pieces.
- Plant and animal activity contributes organic matter and creates pores for air and water movement; burrowing animals like earthworms mix soil and enhance circulation.
- Soil erosion removes topsoil through water or wind action, and it takes 100 to 400 years to form just one centimeter of topsoil, highlighting its slow formation and vulnerability.
Parent Tip: Review the logic above to help your child master the concept of weathering and soil formation worksheet.
