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Weathering and Soil
Term | Definition |
---|---|
sediment | small pieces of broken rock; usually clay, silt and sand |
mechanical weathering | physical process that breaks apart rock |
causes of mechanical weathering | plant roots and burrowing animals; ice; large surface area; cold climates |
chemical weathering | chemicals reactions dissolve minerals |
causes of chemical weathering | carbonic acid; oxidation; warm climates |
climate | patterns of weather that occur over time |
soil formation | mixture of weathered rock, decayed organic matter, mineral fragments, and air; influenced by climate, vegetation, time; can take thousands of years |
soil composition | sediment, humus, air and water pockets |
humus | decaying, dark-colored plant and animal material |
soil profile | different layers of soil; Horizon A, litter, fertile layer |
Horizon A | top soil layer |
litter | organic matter that can turn into humus |
fertile layer | more humus and less rock/minerals |
Horizon B | middle layer; less humus, lighter color than Horizon A; minerals from leaching |
leaching | how minerals travel through different rock layers |
Horizon C | bottom layer of soil; very little organic matter; no leaching; has rock (parent material for soil); deposited by glaciers |
parent material rock | where soil comes from |
soil types | sand, silt, or clay; formed different climates, parent rock, time, and slopes |
soil erosion | when soil is removed; plants can't grow |
causes of erosion | Agriculture (farming); forest harvesting; overgrazing; urban construction |
erosion prevention | manage crops; plants shelter trees; cover soil with compost; graze animals on vegetation; no-till farming |
prevent erosion on slopes | contour farming; terracing |
contour farming | plant along the curves of slopes |
terrace farming | plant steep-sided flat areas (look like steps) on the sides of hills and mountains |
prevention erosion in construction | use mulch, mats, or plastic; spray water; replace topsoil; plant trees; net and straw; retaining wall |
mulch | ground up wood and plant matter |
retaining wall | wall that holds back soil |