The wearing away of the land surface by wind, water, ice or other geological agents. Erosion occurs naturally from weather or runoff but is often intensified by human land use practices. Water is the most primary instrument causing erosion on the planet earth. Water from not just runoff, but seawater, rivers, floods, and rainfall work in washing away solids and sediments and breaking them down after a period of time. Oceans provide such a massive force of erosion that the seawater is capable of even altering entire coastlines, including dissolving sand, rocks and the ground on the beach. As the coastlines and surrounding areas of the ocean are changed by erosion, human settlement and the ecosystem will be greatly impacted. Valleys are made larger by the erosion process in which rushing rivers and streams wear away the banks and bedrocks, and even forming deep canyons.