5 Agents of Mechanical Weathring

Animal Actions

• Animals that burrow in the ground break apart rocks in the soil.
• The animals include moles, gophers, prairie dogs, Earthworms 

Freezing & Thawing

• When water freezes in a crack in a rock, and the crack gets bigger.
• This process is called frost wedging.

Plant Growth

• Plant roots enter cracks in a rock.  
• The roots grow and force the cracks to apart.
• Eventually small plants can pry apart cracked rocks. 

Release of Pressure

• When erosion removes material from a rock's surface, the pressure reduces.
• When the pressure is released the outside of the rock will crack and flake.

Abrasion

• Sand and other erosion can wear away a rock's surface.
• The erosion can be carried by wind, water, or ice.