Soil that is blown or washed away from its parent rock is called eroded soil. Erosion can occur rapidly due to heavy rainfall or winds, or it can occur gradually over thousands of years due to natural weathering processes. Soil erosion is a severe environmental problem because it can result in decreased soil fertility, reduced crop yields, water pollution, and increased flooding. In order to slow down soil erosion, a number of conservation practices can be implemented, such as terracing, contour plowing, and planting cover crops.