| A | B |
|---|
| topsoil | another name for A horizon |
| terracing | farming method used on steep slopes |
| O Horizon | organic matter covering the ground that eventually becomes humus |
| soil | a mixture of weathered rock, air, water, minerals, and decaying organic matter |
| humus | a dark colored material found above and in the A horizon of a soil profile |
| no till farming | farming method of growing crops from year to year without disturbing the soil through plowing |
| contour farming | farming method of planting across the slope following the shape of the land |
| C horizon | consists partially of weathered rocks, coarse sediment, the start of soil formation |
| parent material/ weathered rock | another name for C horizon |
| chemical weathering | weathering that changes the mineral makeup of a rock |
| mechanical weathering | weathering often caused by tree roots, freezing and thawing, abrasion |
| mechanical weathering | weathering that changes the rock physically without changing the chemical makeup |
| examples of chemical weathering | acid rain, lichens, oxygen and water |
| O horizon | horizon known as surface litter; humus |
| R horizon | horizon known as bedrock; solid layer of rock |
| clay | smallest soil particle; sticky when wet; difficult for water to get through |
| loam | mixture of all three soil particle types; best for gardening |
| silt | finer than sand; excellent for farm land but erodes easily |
| sand | big spaces between the particles; doesn't hold water or nutrients |
| metamorphic rock | rock formed from heat and pressure |
| sedimentary rock | rock formed when rocks weather and erode into sediment and then compact and cement |
| igneous rock | rock that forms when lava or magma cools |
| metamorphic rock | rock has ribbon-like layers; Gneiss is an example |
| igneous rock | rock can form above or below ground; Obsidian is an example |
| sedimentary rock | rock is only type that usually contains fossils |
| melting | first process a rock has to go through to become igneous |
| weathering and erosion | the process that causes rocks to turn into sediment |
| heat and pressure | the process a rock goes through to change into a metamorphic rock |
| intrusive | igneous rocks that form when MAGMA cools |
| extrusive | igneous rocks that form when LAVA cools |
