| A | B |
|---|
| weathering | the chemical and physical processes that break down rock at Earth's surface |
| erosion | the process by which water, ice, wind or gravity moves fragments of rock and soil |
| mechanical weathering | the type of weathering in which rock is physically broken into smaller pieces |
| abrasion | the grinding away of rock by other rock particles carried in water, ice, or wind |
| ice wedging | process that splits rock when water seeps into cracks, then freezes and expands |
| chemical weathering | the process that breaks down rock through chemical changes |
| permeable | characteristic of materials such as sand and gravel that allow water to pass easily through them |
| soil | the loose, weathered material on Earth's surface in which plants can grow |
| bedrock | the solid layer of rock beneath the soil |
| humus | dark-colored organic material in soil |
| loam | rich, fertile soil that is made up of about equal parts clay, sand and silt |
| soil horizon | a layer of soil that differs in color and texture from the layers above or below it |
| topsoil | mixture of humus, clay and other minerals that forms the crumbly, topmost layer of soil |
| subsoil | the layer of soil beneath the topsoil that contains mostly clay and other materials |
| litter | the loose layer of dead plant leaves and stems on the surface of the soil |
| decomposer | an organism that breaks down wastes and dead organisms |
| development | the construction of buildings, roads, dams, and other structures |
| desertification | the advance of desertlike conditions into areas that previously were fertile |
| sod | a thick mass of grass roots and soil |
| Dust Bowl | the area of the Great Plains where wind erosion caused soil loss during the 1930s |
| soil conservation | the management of soil to prevent its destruction |
| contour plowing | plowing fields along the curves of a slope to prevent soil loss |
| conservation plowing | soil conservation method in which the dead stalks are left in the ground to hold the soil in place |
| fallow | left unplanted with crops |
| crop rotation | the planting of different crops in a field each year |
| land reclamation | the process of restoring land to a more natural state |
| municipal solid waste | waste produced in homes, businesses and schools |
| leachate | water that has passed through buried wastes in a landfill |
| sanitary landfill | a landfill that holds nonhazardous waste such as municipal solid waste and construction debris |
| incineration | the burning of solid waste |
| recycling | the process of reclaiming and reusing raw materials |
| hazardous waste | a material that can be harmful if it is not properly disposed of |
