| A | B |
|---|
| weathering | The breakdown of rock into smaller and smaller pieces by mechanical or chemical means. |
| mechanical weathering | The breakdown of rock into smaller pieces by physical means. |
| abrasion | The grinding and wearing down of rock surfaces by other rock or sand particles. |
| chemical weathering | The chemical breakdown of rocks and minerals into new substances. |
| acid precipitation | Precipitation that contains acids due to air pollution. |
| oxidation | A chemical reaction in which an element combines with oxygen to form an oxide. |
| differential weathering | The process by which softer, less weather-resistant rocks wear away, leaving harder, more weather-resistant rocks behind. |
| soil | A loose mixture of small mineral fragments and organic material. |
| bedrock | The layer of rock beneath the soil. |
| parent rock | Rock that is the source of soil. |
| humus | Very small particles of decayed plant and animal material in soil. |
| topsoil | The top layer of soil that generally contains humus. |
| leaching | The process by which rainwater dissolves and carries away the minerals and nutrients in topsoil. |
| soil conservation | The various methods by which humans take care of the soil. |
| erosion | The removal and transport of material by wind, water, or ice. |
