The answer is: weathering; erosion
Weathering is the breaking down of soil, rocks, or woods that is caused by a contact with water, air, or the atmosphere. Water, air , and atmosphere could create pressures that resulted in a force that strong enough to destroy the structure/composition of the soil, rocks, or woods.
Erosion on the other hand, is the removal of earth's material from one place to another. Erosion could be influenced by water flow that came from river's current, waves, or heavy rain.