How Do Rocks Break?

Lesson Plan - Get It!

Audio:

Rocks of any size can be broken down into smaller pieces through geologic processes.

• What do you think is the result of rocks being weathered and broken down?

Weathering and breaking causes rocks to change into another type of rock through the rock cycle.

Rocks are broken into smaller pieces during the process of weathering. Weathering can occur because of physical, organic, or chemical causes.

Take a sheet of paper and tear it in half. You just physically or mechanically weathered the piece of paper. You changed the appearance of the paper without changing its overall makeup.

Mechanical or physical, weathering often involves water acting as an agent of change.

• Did you know that water expands when it freezes?

Water moves into small rock cracks and expands when it freezes. That pushes the rock apart, slowly breaking it down into smaller pieces.

Water can also wear down the rock's surface, pulling small pieces off over time.

Organisms can organically break down rocks by pushing roots downward through the soil. Roots go rocks apart and release chemicals that slowly dissolve the rock material.

This is called organic weathering because it involves living organisms.

Chemical weathering involves materials changing the makeup of the rock.

Take a spoonful of sugar and dissolve it into warm water. You combine sugar and water into a solution. Water and other substances can dissolve chemicals from rocks, causing them to break down into smaller pieces.

Once the rock is broken down into smaller pieces, it can be moved to a new location.

Rocks can be broken down through physical, organic, and chemical weathering processes. Physical weathering changes the appearance of stones, while organic and chemical weathering can change the composition of the rock.

Write a short paragraph about the three types of weathering to summarize what you learned.

Then, move to the Got It? section, where you will learn how weathering and erosion differ.