1. Frost action: Water seeps into cracks in rocks, freezes and expands, causing the rocks to break.

2. Thermal stress: Rocks expand when heated and contract when cooled, which can cause them to crack.

3. Exfoliation: The outer layers of rocks peel off due to changes in temperature and humidity.

4. Abrasion: Rocks are worn down by the friction of other rocks, sand, and water.

5. Impact: Rocks are broken by the impact of falling objects, such as rocks, trees, and ice.