Mechanical and chemical weathering shape the Earth's surface by breaking down rocks. Mechanical weathering is the breakdown of rocks into smaller pieces through physical processes like ice wedging, abrasion by wind and water, and plant and animal activity. Chemical weathering breaks rocks down through chemical reactions, such as those involving water, acids, and oxygen. The rate of weathering depends on factors like the rock type, surface area exposed, climate, elevation, and slope of terrain. Over long periods of time, differential weathering leaves more resistant rock formations behind.