| 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 weathered rock and soil |
| abrasion | the grinding away of rock by other rock particles carried in water, ice, or wind |
| permeable | characteristic of a material that is full of tiny, connected air spaces that water can seep through |
| 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 of 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 minerals |
| decomposer | soil organism that breaks down the remains of organisms and digests them |
