Mechanical Weathering

5 Agents

• abrasion
• release of pressure
• plant growth 
• freezing and thawing
• animal actions

Abrasion: Rock particles carried away by wind, water, or ice. Abrasion scrapes away the outer edges of the rock. It's like sandpaper on wood, the sandpaper takes it away.

Release of Pressure: Erosion removes material from the surface of a rock, pressure on the rock decreases. The decrease of pressure causes the outside layer of the rock flake off.

Plant Growth: Plant roots enter cracks in rocks, as they get bigger they pry the rocks apart. The roots of either small or big plants can pry the rocks apart.

Freezing and Thawing: When water gets in a crack of a rock and freezes, it makes the crack much bigger. Even a small sidewalk crack can turn into a hazard.

Animal Actions: Animals that burrow in the ground for a change in seasons, like moles, insects, and prairie dogs. They loosen and break apart the soil.