5 Agents of Mechanical Weathering

Animal Actions

• These are animals that burrow into the ground.
• Moles, gophers, prairie dogs, and some insects burrow into the ground.
• These animals loosen and break apart rocks in the soil.

Freezing and Thawing

• When water freezes in a crack in a rock, it expands making the crack bigger
• The process of frost wedging also widens cracks in sidewalks and causes 
• potholes in streets.

Abrasion

• Sand and other rock particles that are carried by wind, water, or ice can 
• away.  Exposed rock surfaces like sandpaper on wood.

Release of Pressure

• As erosion removes material from the surface of a mass of rock, pressure on
• the rock is reduced.  This release of pressure causes the outside of the 
• rock to crack and flake off like the layers of an onion.

Plant Growth

• Plant roots enter cracks in rocks.  As roots grow, they force the cracks 
• apart.  Over time, the roots of even small plants can pry apart cracked 
• rocks.

Those are the 5 Agents of Mechanical Weathering