EXO

• Exogenic processes take place at or near the earth's surface and cause the surface to wear away
• Different types of exogenic processes include weathering, erosion, and mass movement (mass wasting)
• Weathering is the mechanical and chemical breakdown of rocks
• Types of weathering:

  • Physical weathering: breakdown of rocks without a change in composition, also known as mechanical weathering
  • Chemical weathering: decomposition of rocks due to chemical reactions between minerals in rocks and the environment
• Processes that can cause physical weathering:

  • Thermal and pressure change
  • Wind and waves
  • Freeze and thaw
  • Organic activity
• Processes that can cause chemical weathering:

  • Hydration/hydrolysis
  • Carbonation
  • Oxidation
• Erosion involves the movement of weathered rock from their site of weathering by agents such as wind, moving water, ice, and gravity
• Weathering does not always occur before erosion, but erosion always follows after weathering
• Transport completes the movement of eroded materials and sediments, and weathering can continue during transport
• Transport by water:

  • Rainwater and gravity
  • Physical weathering dominates at higher elevations, while chemical weathering is more active at lower elevations
  • Water can carry rocks of almost any size, with greater volume of water and steeper slopes transporting bigger rocks
• Transport by wind:

  • Wind continuously moves loose particles of rocks and soil from place to place
  • Wind can create sandstorms that deposit dust particles in wide areas
• Mass movement (mass wasting) involves slope movement and bulk movements of soil, sand, and rock debris downslopes in response to gravity
• Sinking mass movement that occurs rapidly is known as subsidence, while gradual movement is called settlement
• Talus refers to pieces of rock at the bottom of a rock fall