1. Water: Rain, rivers, and ocean waves are powerful forces of erosion. Water can dissolve some minerals in rocks, and the force of flowing water can wear away rock surfaces.

2. Wind: Wind can carry sand and other abrasive particles, which can grind away at weathered rock surfaces. This is particularly effective in deserts and coastal areas.

3. Ice: The freezing and thawing of water in cracks within rocks can cause them to break apart. This process is called frost wedging.

4. Biological Agents: Plants can grow in cracks in rocks, and their roots can pry them apart. Animals, like burrowing creatures, can also loosen and move weathered rock fragments.

Let me know if you'd like more detail on any of these!