mechanical weathering
The weathering of rocks and minerals can be mechanical or chemical. Mechanical weathering changes the size of a mineral or rock. Mechanical weathering does not change the chemical composition of that material. Chemical weathering changes the composition of a mineral or rock. Different types of weathering can alter the same material. Soil forms on top of rock. The type of soil that forms depends on the environment of the region. For example, warm and wet climates form different soils than cold and dry climates. A profile through the soil shows different horizons. Topsoil is the most important layer for crops. Water, ice, wind, and gravity create or modify landforms on Earth's surface. These agents can erode or deposit features that indicate their presence. Erosion by water and ice lowered and rounded the Appalachians. These old mountains no longer look like the Himalaya. Someday the Himalaya may look like the Appalachians do now.