Erosion/ɪˈrəʊʒn/ Definition 1 of 3Pro Tip 1/3Natural Causes Erosion in this context is always caused by natural forces, not human activities. Years of river flow resulted in the erosion of its banks. Pro Tip 2/3Gradual Change Erosion refers to a slow process; it doesn't happen overnight. Rain erosion shapes the mountain's structure over millennia. Pro Tip 3/3Negative Impact Erosion often implies harmful effects on the environment. Soil erosion can destroy habitats and alter landscapes.