Examples of physical weathering are ice wedging, plant activities and rapidly moving water. The process results from environmental effects or movements of the Earth.
Physical, or mechanical, weathering is a geological process of breaking rocks apart without changing their chemical composition, according to the American Geosciences Institute. Ice wedging, plant activities and rapid moving water physically weather rocks as a result of extreme pressure or impact.
- Ice wedging As small crevices of rock fill with water and the temperature dips below freezing, the fluid expands as it freezes, exerting substantial pressure on the rock. The ice behaves like a wedge, widening the crack. As the temperature rises, the water melts and the rock contracts. The repeated expansion and contraction can cause the rock to break apart.
- Plant activities The pressure of the confined roots of plants growing in cracks in rocks can be tremendous. As the plant grows, the pressure can become great enough to expand the crack, ultimately breaking the rock apart. An everyday example is weeds growing in cracks in the sidewalk.
- Rapid moving water Rocks on the bottom of a stream can lift for brief periods of time as water moves swiftly. Their impact with other rocks causes physical weathering as small pieces break off.