Moving water in rivers and streams shapes and reshapes Earth’s surface by moving rocks and soil from higher elevations and depositing them at lower elevations. Erosion is the process by which weathered earth materials, such as rock fragments, sand, and soil, are removed from one place on Earth’s surface and transported by wind and/or water. As the kinetic energy of the wind or water decreases, the earth materials are deposited, building up new land. Deltas form at the end of rivers when this new land builds up over time.
