| 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. |
| Mechanical weathering breaks rock into pieces by | freezing and thawing, release of pressure, growth of plants, actions of animals, and abrasion. |
| 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. |
| The agents of chemical weathering include | water, oxygen, carbon dioxide, living organisms, and acid rain. |
| The most important factors that determine the rate at which weathering occurs are | type of rock and climate. |
| 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. |
| Soil is a mixture of | rock particles, minerals, decayed organic material, air, and water. |
| humus | Dark-colored organic material in soil |
| loam | Rich, fertile soil that is made up of about equal parts of clay, sand, and silt. |
| soil horizon | A layer of soil that differs in color and texture from the layers above or below it. |
| top soil | 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 minerals. |
| litter | The loose layer of dead plant leaves and stems on the surface of the soil. |
| Fertile soil is | rich in nutrients that plants need, such as nitrogen and phosphorus. |
| decomposer | An organism that breaks down wastes and dead organisms. |
| Three uses that change the land are | agriculture, development, and mining. |
| development | The construction of buildings, roads, dams, and other structures. |
| Soil is one of Earth’s most valuable resources | because everything that lives on land depends directly or indirectly on soil. |
| 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. |
| Ways that soil can be conserved include | contour plowing, conservation plowing, leaving the soil to lie fallow, and crop rotation |
| 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. |
| Three methods of handling solid waste are | to bury it, to burn it, or to recycle it. |
| 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. |
| Most recycling involves four major categories of products: | metal, glass, paper, and plastic. |
| to help control the solid waste problem. These actions are sometimes called the “three R’s” | reduce, reuse, and recycle. |
| hazardous waste | A material that can be harmful if it is not properly disposed of. |
| There are four categories of hazardous waste: | toxic, explosive, flammable, and corrosive. |
| Long-term exposure to hazardous wastes may cause | diseases such as cancer, and may damage body organs, including the brain, liver, kidneys, and lungs. |
