| A | B |
|---|
| weathering | breaking down of rocks into smaller and smaller fragments |
| mechanical weathering | breaks rocks apart without changing their chemical composition |
| plant roots grow and wedge rocks apart | example of mechanical weathering |
| ice wedging | mechanical weathering resulting from water in cracks freezing, expanding, and thawing |
| chemical weathering | occurs when water, air, and other substances react with the minerals in rocks |
| water | important agent of chemical weathering |
| acids | form naturally in some plants and cause chemical weathering |
| oxidation | occurs when a material is exposed to oxygen and water |
| climate | the pattern of weather that occurs in a particular area over many years |
| soil | a mixture of weathered rock, organic matter, mineral fragments, water, and air |
| humus | dark-colored organic matter found in soil |
| horizon | layer of soil |
| soil profile | made up of the A, B, and C horizons |
| A horizon | topsoil |
| B horizon | middle layer of soil |
| C horizon | bottom layer of soil |
| solid rock | below the C horizon |
| leaching | removal of soil materials dissolved in water |
