1. Temperature changes can cause physical weathering. The rock expands during the day when it is hot and contracts when it is cold at night.
2. Plant roots can cause physical weathering. The plant roots grow into small cracks in the rocks, and push the sides of the cracks apart when they grow bigger.
3. Freeze-thaw action can cause physical weathering. Water in in the rock expands when it freezes and makes the crack bigger.
4. Rain can cause chemical weathering. The acid in the rain dissolves parts of the rock. This process is speeded up if the rain contains a lot of acid. Rain like this is called acid rain and can be caused by burning fossil fuels.
Parent Tip: Review the logic above to help your child master the concept of rocks and weathering worksheet.