Weathering is the chemical and physical changes that a rock has on the Earth. It’s also called erosion. If weathering is going to occur, the rock has to be unprotected by air and water. Chemical weathering is when a chemical reaction makes the rocks break down to even smaller rocks. Physical weathering is when the rocks are scratched with harder rocks. Biological weathering when physical or chemical weathering is caused by living organisms. Deposition is when after the rocks are broken; the pieces are transported to another spot on Earth.