Weathering-mechanical & chemical destruction of rocks @ Earth’s surface Importance=makes sediment (makes other rocks), makes soil, releases nutrients, removes CO 2 from atmosphere Mechanical weathering=physical disintegration of rock (Dry,High,Cold) Wedging=enlargement of fractures by pressure (ice, mineral crystals, plant roots) Chemical Weathering of apatite(mineral)=primary way of making phosphate available Soil Horizons= O rganic materials just below ground vegetation, A “topsoil” leaching by downward percolation water; organic acids from above (a lot of chemical weathering decomposes organic matter) E , B (illuviation) C fragments mechanically weathered from bedrock & some partially decomposed (saprolite) R bedrock (Mineral Soils <25% Organic Materials)(Organic Soil >25%OM) Variable that determine soil type=vegetation type, precipitation/climate, parent material, time Environmental Tracer= Tritium SMOW-standard mean ocean water (^evaporation ^salinity ^O 18 heavy)(Less evaporation ^precipitation less salinity ^0 16 light) Summer>lighter isotopes taken outta atmosphere-photosynthesis Winter>respiration-added back to atmosphere 12 C-can identity where water formed/what kind of water it is (ocean circulation) Drainage basin =1large river; all surface water flows into (Mississippi River Drainage Basin = >40%of US) D.B. are separated by divide-high elevation
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This note was uploaded on 05/02/2008 for the course ENV. SCI. 101 taught by Professor Smith during the Spring '06 term at Roger Williams.