weathering
Weather makes life interesting. Weather also causes weathering. Weathering is the slow wearing down of rocks on Earths surface. Wind-blown sand scours rocks like sandpaper. Glaciers of ice scrape across rock surfaces like a file. Even gentle rain may seep into rocks and slowly dissolve them. If the water freezes, it expands. This eventually causes the rocks to crack. Without the atmosphere, none of this weathering would happen. Rocks at the surface would be pristine and unaltered.