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WEATHERING, EROSION & SOIL FORMATION. WEATHERING, EROSION, TRANSPORTATION. Weathering - Physical disintegration and chemical decomposition of rocks Erosion - Physical removal Transportation - Movement of eroded particles Chemical vs. Physical Weathering Effects of weathering
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WEATHERING, EROSION, TRANSPORTATION • Weathering- Physical disintegration and chemical decomposition of rocks • Erosion- Physical removal • Transportation- Movement of eroded particles • Chemical vs. Physical Weathering • Effects of weathering • Surface alteration of outcrops • Spheroidal weathering • Differential weathering
WEATHERING, EROSION, TRANSPORTATION • Weathering- Physical disintegration and chemical decomposition of rocks • Erosion- Physical removal • Transportation- Movement of eroded particles • Chemical vs. Physical Weathering • Effects of weathering • Surface alteration of outcrops • Spheroidal weathering • Differential weathering
MECHANICAL WEATHERING • Disintegration of rocks • Frost Action • Frost wedging - rock pried apart along joints • water expands upon freezing (ice wedge) • Frost heaving
MECHANICAL WEATHERING • Pressure Release • sheet joint • exfoliation • exfoliation domes • Other • Plant growth; Burrowing animals • Pressure of salt crystals • Extreme temperature changes • Mechanical weathering increases surface area facilitating chemical weathering
Mechanical Weathering Growth of salt crystal in arid/semi-arid regions can split rocks Heat and cold extremes can also cause rock breakage
CHEMICAL WEATHERING • Decomposition of rock to form new substances • Equilibrium • Role of Oxygen • Fe in ferromagnesian minerals becomes oxidized • Hematite • Limonite
Chemical Weathering • Role of Acid • Hydrogen ions in water • pH=-Log[H+] Acid/Base • Carbonic Acid H2CO3 • CO2 + H2O -> H2CO3 • H2CO3 -> H+ + HCO3- (in water) • Solution weathering- Karstic Features • Calcite (in limestone) dissolves in acidic water • fluted (channeled) rock surface • caves
Chemical Weathering • Role of Acid • Hydrogen ions in water • pH=-Log[H+] Acid/Base • Carbonic Acid H2CO3 • CO2 + H2O -> H2CO3 • H2CO3 -> H+ + HCO3- (in water) • Solution weathering- Karstic Features • Calcite (in limestone) dissolves in acidic water • fluted (channeled) rock surface • caves
Chemical Weathering • Chemical weathering of feldspar • H+ + feldspar -> clay mineral • Chemical weathering of other minerals • Weathering and climate • Weathering Products
Chemical Weathering • Chemical weathering of feldspar • H+ + feldspar -> clay mineral • Chemical weathering of other minerals • Weathering and climate • Weathering Products