weathering and erosion. weathering breakdown of rock at or near the earth’s surface 2 types of...
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Weathering and ErosionWeathering and Erosion
Weathering • Breakdown of rock at or near the
earth’s surface
• 2 types of weathering– Mechanical– Chemical
Mechanical WeatheringMechanical Weathering: no change : no change in chemical composition--just in chemical composition--just disintegration into smaller piecesdisintegration into smaller pieces
Mechanical WeatheringMechanical Weathering
• Types of Mechanical weatheringTypes of Mechanical weathering– Frost heaving and Frost wedgingFrost heaving and Frost wedging– Plant rootsPlant roots
Frost WedgingFrost Wedging: water freezes in a : water freezes in a crack and breaks it apart (MOST crack and breaks it apart (MOST COMMON TYPES OF MECHANICAL)COMMON TYPES OF MECHANICAL)
Frost HeavingFrost Heaving
Plant RootsPlant Roots
Chemical WeatheringChemical Weathering: changes or : changes or alters as a result of chemical reactionsalters as a result of chemical reactions
CaCO3+CO2+H2O ---> Ca2+ + 2HCO3-
Chemical WeatheringChemical Weathering
• The agents of chemical weatheringThe agents of chemical weathering– WaterWater– Acid RainAcid Rain
WaterWater
Acid RainAcid Rain• Compounds from burning coal, oil Compounds from burning coal, oil
and gas react with water forming and gas react with water forming acids.acids.
1908 1969
Acid rain has eaten away this limestone statue.
ErosionErosionThe movement of weathered materials by
water, wind, or glaciers
Water Erosion forms the Water Erosion forms the largest canyons and the largest canyons and the
deepest valleysdeepest valleys
Wind ErosionWind Erosion
•Picks up small particles.
•Usually in areas of little water or little vegetation
Wind ErosionWind Erosion
Erosion by Glaciers that were Erosion by Glaciers that were formed over many years as ice and formed over many years as ice and
snow are compressedsnow are compressed
Glaciers can create lakes as they melt