Erosion occurs when soil, rocks and mountains are worn away over time by natural forces such as wind and rain. This gradual process has left many fascinating landforms across Earth in its wake.
Erosion is caused by several different forces, but water is by far the dominant one. Other culprits include wind, ice and living organisms. As erosion progresses it can create landforms such as cliffs, canyons and beaches as well as dunes and deltas.
Water
Rain and snow can dislodge soil particles, leading to water erosion. This phenomenon is more likely to happen where there is significant wind, such as in arid or semi-arid regions.
Erosion caused by flowing streams and rivers is another source of erosion seen frequently in canyons and river valleys.
Glaciers can contribute to erosion. This active process involves breaking apart and wearing away rocks as they slowly move across the ground surface.
Other natural factors that influence erosion include tectonic activity, topography, vegetation and weather. Plant growth on a site can have an effect on its rate of erosion as plants help stabilize the soil; overgrazing reduces this amount, increasing exposure to rainwater erosion. Erosion increases when improperly designed tile outlets or splash pads let water wash away soil particles into waterways.
Wind
Wind can erode soil by blowing loose particles away (deflation), or by sandblasting rocks and soil against each other (abrasion). Wind erosion may also wear down rock surfaces over time. Although wind erosion occurs less frequently than water erosion, it still occurs frequently in dry environments with little vegetation protecting soil layers.
Different types of soil vary in their susceptibility to wind erosion. Loamy sand or silty clay soils tend to be least vulnerable, while coarse sands, gravelly or rocky surfaces, and coarse particles make up coarse sands the most prone (Bagnold 1937). Particle size also matters greatly: particles larger than several microns often stick together more effectively and are thus harder to be transported by wind erosion (Bagnold 1937).
Activities that reduce ground cover, remove trees and shrubs, expose sloping land to wind erosion are key contributors. Farmers use windbreaks to slow erosion while creating terraces on sloped land to catch rainwater before it runs downstream.
Glaciers
Glaciers differ significantly from streams in terms of both their erosional and deposition processes, and how they shape the landscape. A glacier traveling downhill causes erosion by scraping against bedrock on its bottom surface causing scratches known as striations. They may also pick up rocks fragments from bedrock surfaces by plucking, transporting them down the glacier using this process before depositing them at their feet to form moraines or moraines.
Many residents living in arid climates rely on glacier meltwater for part of their water supply, yet as glaciers retreat and their number diminishes, so does quality of drinking water. People can help reduce glacier losses by decreasing greenhouse gas emissions from vehicles and homes.
Human activity
Erosion caused by human activity occurs when people alter the natural environment. Clear-cutting forests or plowing up grasslands exposes soil to rain and wind erosion, leaving sediment behind to wash away into rivers, clog them up, harm plants and animals and poison drinking water supplies.
Waves cause erosion on beaches as sand is worn away and carried further from shore, creating sand dunes as another type of erosion created by waves. Wind erosion occurs frequently in arid regions where wind blows sand particles around; wind can also wear away rock through an process known as abrasion.
Grow trees and other vegetation to slow erosion. Their roots anchor soil while their branches anchor rocks as their growth cracks and chips the terrain – this type of erosion known as bioerosion. Glacier movement can also cause significant erosion along mountaintops and valleys, but such events can be mitigated using ice dams and other structures such as walls.