Mechanical weathering is the physical breakdown and fragmentation of rocks and other geological materials into smaller pieces without any chemical changes to the material. This type of weathering occurs as a result of mechanical forces such as temperature changes, abrasion, and impacts from wind, water, or ice.

Mechanical weathering can take place through a variety of processes such as frost wedging, where water expands as it freezes in the cracks of rocks, causing them to break apart. Another process is exfoliation, where rocks expand and contract due to temperature changes, causing layers of the rock to peel off. Other examples of mechanical weathering include the action of waves on coastlines, the grinding of rocks against each other by glaciers, and the constant pounding of water on rocks in a stream or river.