| A | B |
|---|
| chemical weathering | occurs when chemical reations dissolve the minerals in rocks or change them into different minerals |
| weathering | mechanical or chemical surface processes that break rock into smaller and smaller pieces |
| contour farming | planting along the natural contours of the land to reduce soil erosion |
| horizon | each layer in a soil profile |
| humus | dark-colored, decayed organic matter that supplies nutrients to plants and is found mainly in topsoil |
| ice wedging | mechanical weathering process that occurs when water freezes in cracks of rocks and explands, causing the rock to break apart |
| leaching | removal of minerals that have been dissolved in water |
| litter | twigs, leaves, and other organic matter that help prevent erosion and hold water and may eventually be changed into humus by decomposing organisms |
| mechanical weathering | physical processes that break rock apart without changing its chemical makeup |
| no-till farming | method for reducing soil erosion |
| oxidation | chemical weathering process that occurs when some minerals are exposed to oxygen and water over time |
| soil | mixture of weathered rock and minerals fragments, decayed organic matter, mineral fragments, water and air that can take thousands of years to develop |
| soil profile | vertical sections of soil layers, ech of which is a horizon |
| terracing | farming method used to reduce erosion on steep slopes |
| climate | average weather patternin an area over a long period of time |
