5. Earth’s magnetic field • Earth “feels” effects of two fields; magnetic and gravity
Earth Interior 07:20 o 4. Another viable mechanism to produce a magnetic field is with electric currents; a dynamo- a magnetic field created by electric current How did this happen?
Weathering, Erosion, and Mass Wasting 07:20 About Weathering, etc. • Weathering produces all the soils, clays, sediments, and dissolved substances • Erosion is the removal of sediments by natural processes such as wind and rivers • Mass wasting is the downslope movement of masses of Earth materials. 1. Weathering, Erosion, Mass Wasting, and the Rock Cycle • Weathering is the process of converting rock into sediment and forming soils, a main process in the rock cycle. • Erosion and mass wasting are the processes that loosen and transport soil and rock downhill. • Properties of the parent rock o Various minerals weather at different rates o A rock’s structure affects its susceptibility to cracking and fragmentation. 2. Controls on Weathering 3. Chemical Weathering • Carbon Dioxide o 1. When rock weathers, the climate system and the lithosphere interact. o 2. Variability in atmospheric CO2 leads to corresponding variability in the rate of weathering. o 3. Weathering of silicates such as feldspar removes CO2 from the atmosphere. o 4. CO2 is added to the atmosphere during volcanic eruptions. • Chemical stability : a speed control for weathering o Solubility o Rate of dissolution o Relative stability of common rock-forming minerals.
Weathering, Erosion, and Mass Wasting 07:20 • Role of oxygen in weathering : from iron silicates to iron oxides o Ferric and ferrous iron o Hematite, a common mineral o Red and brown-the colors of oxidized iron Red means iron • What determines how rock breaks? o Natural zones of weakness o Activity of organisms o Frost wedging o Exfoliation 4. Physical weathering: joints in rocks
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