| A | B |
|---|
| loam | silt, sand, and clay |
| Appalachian Mts | rounded shape showed they have been eroding for millions of years |
| abrasion | mechanical weathering where one rock is worn away by action of other rocks |
| humus | formed from earthworm waste |
| frost wedging | freezing and thawing of water that causes mechanical weatehring |
| B horizon | clay, minerals, and little humus |
| fast weathering | takes place in warm moist environment |
| permeable rock | contains many small airspaces |
| contour plowing | plowing along the curve of a slope |
| soil formation | begins with weatehring of bedrock |
| Dust Bowl | enhanced by removed grass and exposed soil |
| fertile soil | high in humus |
| chemical weathering | causes change in composition of minerals |
| A horizon | loam that is rich in humus |
| conservation plowing | keeps moisture in and holds soil in place |
| soil conservation | management of soil to prevent loss |
