Weathering Erosion Soils Weathering is the the breakdown of solid rock at or near the Earth s surface Weathering may be mechanical or chemical Mechanical weathering is the physical abrasion due to the action of Water Streams Rivers and Surf Ice Frost Snow Glaciers Wind Chemical weathering is the chemical reaction of minerals with the water and oxygen of our atmosphere Chemical Weathering Increases with Temperature Increases with Moisture Rainfall Increases with Acidity Decreases with Silica Polymerization Bowen s Reaction Series Chemical Weathering of Igneous Rock Minerals Oxides Ferromags Feldspar Mica Quartz Hydroxides Mg Fe Clay Al Clay Na K Ca Al Fe Clay Na K Ca Quartz Sand Erosion and Transport Erosion is the reduction of exposed landforms Transport is the movement of eroded material downslope Transport by water sorts the particles by size Because different minerals dominate different size fractions the deposited material differs from the parent rock in mineralogy and chemistry Weathering Products Are Sorted by Size Coarse particles require moving water or wind Rock grains Quartz Pebbles Cobbles Boulders Pebbles and Sand Fine particles require standing water Clays Very fine 10 m Dissolved ions require evaporation Na K Ca Dissolved Soils A regolith is any accumulation of fine rock material on a planetary surface A soil is the accumulation of weathered rock material together with organic matter A pedocal is a dry climate soil containing soluble calcium minerals calcite A pedalfer is a humid climate soil rich in Al and Fe A laterite is an extreme pedalfer in tropical climates Acid Rain Results from burning of sulfur rich fossil fuels Is mainly a problem in humid temperate climates NE US Europe Acid Mine Drainage Results from oxidation of sulfide minerals pyrite in unsaturated rock 2FeS2 7H2O 2O2 2Fe OH 3 4H2SO4 Pyrite water oxygen limonite sulfuric acid Big Problem in CO
View Full Document
Unlocking...