5 Agents of Mechanical Weathering

Animal Actions

• Animals that burrow into the ground break apart rocks in the soil
• moles, gophers, prairie dogs, and some insects are animals that burrow

Freezing and Thawing

• when water freezes in a crack inside a rock, it expands and makes the crack
• The process of frost wedging also widens cracks in sidewalks
• Frost wedging also creates potholes in streets

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.

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

Abrasion

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