Chemical and Physical weathering

• What is weathering?

  Decomposition and disintegration of rocks
• What are the two main types of weathering?

  Decomposition and disintegration
• What is decomposition in weathering?

  Chemical breakdown of rocks
• What is disintegration in weathering?

  Mechanical or physical breakdown of rocks
• What is the combination of weathering processes?

  • Biological weathering by plants and animals
• What is freeze-thaw weathering?

  Ice crystal growth causing rock disintegration

  
• How does freeze-thaw weathering occur?

  Water enters cracks, freezes, and expands

  
• What happens to water at or below 0 degrees Celsius?

  It freezes and turns to ice
• How much greater is the volume of ice compared to water?

  10% greater volume
• What effect does ice expansion have on rocks?

  It exerts pressure causing cracks to widen

  
• What types of rocks are affected by freeze-thaw weathering?

  Marble, granite, limestone, sandstone
• In which regions does freeze-thaw weathering commonly occur?

  Alpine and periglavial regions
• What is salt crystal growth weathering?

  Pressure from expanding salt crystals in rocks

  
• What temperature range is associated with Type 1 salt crystal growth?

  26-28 degrees Celsius
• What happens to sodium sulfate and sodium carbonate during salt crystal growth?

  They increase volume by 3 times
• What is the result of salt crystal growth on rocks?

  It creates pressure on joints and cracks

  
• What types of rocks are affected by Type 1 salt crystal growth?

  Chalk, limestone, sandstone, shale
• In which regions does Type 2 salt crystal growth occur?

  Hot desert regions with little rainfall
• What is heating and cooling disintegration also known as?

  Onion skin weathering
• What causes onion skin weathering?

  Large diurnal temperature fluctuations
• What happens to rocks during the day in hot deserts?

  Rocks expand and heat up significantly
• What occurs to rocks at night in hot deserts?

  Rocks contract due to freezing temperatures
• What is the result of heating and cooling disintegration?

  Peeling of outer rock layers
• What is pressure release weathering also known as?

  Dilatation
• What types of rocks are affected by onion skin weathering?

  Granite, sandstone, limestone, shale, basalt
• What causes pressure release weathering?

  Removal of overlying rocks by erosion
• What happens when overlying pressure is removed?

  Cracks or joints form at right angles
• What are lines of weakness in rocks called?

  Cracks
• What happens if horizontal pressure is released on a cliff face?

  Vertical joints will develop
• What types of rocks are affected by pressure release weathering?

  Metamorphic rocks, marble, granite, basalt
• What is root pry in vegetation weathering?

  Plant roots push rocks and break them
• What happens when a plant dies or is knocked over?

  It can yank the rock out (root throw)
• Why is root throw debated as erosion?

  It involves small movement of rock
• Where must vegetation be abundant for root weathering?

  In areas with more moderate temperatures
• What types of rocks are affected by vegetation weathering?

  Sandstone, slate, granite, limestone
• What is necessary for chemical weathering to occur?

  Water must be present
• Where is chemical weathering most effective?

  Sub-surface with percolating water
• Why is the amount of water important in chemical weathering?

  It removes weathered products by solution
• What are the three types of chemical weathering?

  Carbonation, hydration, hydrolysis
• What is carbonation in chemical weathering?

  CO2 dissolved in water breaks down rocks