| A | B |
|---|
| A Horizon | composed of topsoil, a crumbly, dark brown soil that is a mixture of humus, clay, and other materials |
| B Horizon | composed of subsoil, a heavy, reddish-brown soil made mostly of clay and other minerals but little humus |
| C Horizon | contains only partly weathered rock |
| humus | decayed plant and animal remains |
| subsoil | a heavy, reddish-brown soil made mostly of clay and other minerals but little humus |
| decomposers | organisms that break down plant and animal remains and waste |
| bedrock | the solid layer of rock beneath the soil |
| topsoil | a crumbly, dark brown soil that is a mixture of humus, clay, and other materials |
| loam | soil made up of equal parts clay, sand, and silt |
| soil horizon | a layer of soil that differs from the layers above and below it |
| soil | the loose, weathered material on Earth's surface in which plants can grow |
| litter | a loose layer of leaves and other plant material |
| erosion | movement of rock particles by wind, water or ice |
| permeable | a material has spaces which allow water to seep through it |
| weathering | process that breaks down rock and other materials on the Earth's surface |
| abrasion | grinding away of rock by other rock particles |
| ice wedging | process by which ice widens and deepens cracks in rocks |
| sod | thick mass of tough roots at the surface of the soil |
