When it is in water or just still when the water moves or when the wind blows sand or dirt will rub on it and start to break it down into little pieces. Weathering from mechanical and chemical means...
Here is a breakdown of the cycle. Water finds a way into a crack. It then freezes, thus expanding a small bit. This process repeats over and over again until the rocks are cracked completely.
Weathering is a process by which rocks and minerals are gradually broken down into smaller and smaller particles. Weathering of rocks is caused by chemical and mechanical means. Slightly acidic...