| A | B |
|---|
| abrasion | the grinding away of rock by other rock particles carried in water,ice or wind |
| bedrock | the solid layer of rock beneath the soil |
| conservation plowing | soil conservation method in which the dead stalks from the previous year's crop are left in the ground to hold the soil in place |
| contour plowing | plowing fields along the curve of the slope to prevent soil loss |
| decomposer | an organism that breaks down large chemicals from dead organisms into small chemicals and returns important materials to the soil and water |
| Dust Bowl | the area of the Great Plains where wind erosion caused soil loss during the 1930's |
| erosion | the process by which water,ice,wind,or gravity moves fragments rock or soil |
| humus | dark-colored organic material in soil |
| ice wedging | process that splits rock when water seeps into cracks,then freezes and expands |
| litter | the loose layer of dead plant leaves and styems on the surface of the soil |
| loam | rich,fertile soil that is made up of about equal parts of clay,sand,and silt |
| mechanical weathering | the type of weathering in which rock is physically broken into smaller pieces |
| permeable | characteristic of materials such as sand and gravel which allow to pass easily |
| renewable resource | a natural resource that can be replaced in nature at a rate close to the rate at which its being used |
| soil | the loose,weathered material on Earth's surface in which plants can grow |
| soil conservation | the management of soil to prevent its destruction |
| soil horizon | a layer of soil that differs in color and texture from the layers above or below it |
| sod | a thick mass of grass roots and soil |
| subsoil | the layer of soil beneath the topsoil that contains mostly clay and other minerals |
| topsoil | mixture of humus,clay,and other minerals that forms the crumbly,topmost layer of soil |
| chemical weathering | the process that breaks down rock through chemical changes |
| weathering | the chemical and physical processes that break down rock at Earth's surface |
