Weathering and Erosion

Weathering and Erosion

1. Weathering is the breaking apart of rock due to exposure to atmosphere.

   • Chemical weathering
     • It is the breakdown of rocks by chemical reactions that change the rocks makeup or composition.
     • dissolution (soluble rocks and minerals dissolve in acidic waters)
     • Hydrolysis is the chemical weathering that refers to a chemical change to a substance when it interacts with water.
       • Acid rain causes rocks to weather much faster than they would naturally.
     • oxidation (rusting of iron)
       • Why is the dirt red on Mars? The dirt on Mars is red because of rust / oxidation. This is an example of chemical weathering.
   • Mechanical Weathering
     • Mechanical weathering, or disintegration, involves physically breaking rocks into fragments without changing the chemical make-up of the minerals within them.
     • Ice wedging occurs when water fills a crack or pore, expands because it freezes and splits the rock apart when ice melts.
     • Exfoliation – Layers of rock that breaks because of pressure from below.
     • organisms - Animals and plants in action
   • Things like flash floods, mud slides, landslides, and other forms of mass wasting can cause weathering.

2. Erosion is defined as removal and transport of rocks.

   • Wind can play a role by carrying material (especially sand and clay) from one place to another.
   • When water flows over land, erosion occurs. Runoff picks up pieces of rock and "runs" downhill cutting tiny grooves (called rills) into the land.
   • Glaciers wear down the landscape; by picking up and carrying debris that moves across the land along with the ice.
   • Gravity Erosion is better known as Mass Movement and is defined as the transfer of rock and soil down slope by direct action of gravity without a flowing medium (such as water or ice).

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