L1.1: Mechanical Weathering

• Mechanical Weathering

  - Physical weathering does not change the chemical composition of the rock.
• ● Agents of Mechanical Weathering

  ○ Water

  ○ Wind

  ○ Biological activity
• ○ Water – Moving water tumbles rocks against each other, breaking them into pieces in this way moving streams and rivers weather away land and produce canyons.

  ■ Ice: When water is collected in the rock crack and the temperature drops, the water freezes and expands, forcing the crack to widen. Frost Wedging.
• ○ Wind – is another agent of weathering. Strong, steady wind-carrying sand can grind hard desert rock.
• ○ Biological activity – plants and animals (including humans) as agents of mechanical weathering. Plant roots wedge into rocks or when burrowing animals bring fresh earth material to the surface where it will be more quickly weathered.