Erosion and deposition are ongoing natural processes that take place all around us, taking place whenever soil is removed by fluid flow, wind, ice or gravity and moved elsewhere (deposition).
Physical erosion gradually wears away at rock surfaces, altering their shape and altering their surface texture – leading to features like the mushroom rocks in Badain Jaran, Egypt.
Water
Water erosion is a powerful force shaping our land. It begins when raindrops hit soil particles and break them apart before flowing water carries the particles downstream. Erosion tends to be more severe on steep slopes than gentle ones, and also more likely where there is vegetation cover which slows water’s flow.
Erosion by water can contaminate our drinking supply with dangerous materials like chemicals, fertilizers and pesticides that wash away with it.
Water erosion can transport rocks and sediment to other locations through water erosion, known as deposition. Deposition can happen either nearby, such as just feet from where erosion occurred, or farther away when carried downstream by rivers to form alluvial fans or deltas.
Wind
Erosion is a natural process found everywhere on Earth. It involves the wear-and-tear breakdown and transportation of rock, soil and other geological materials from one location to another. Deposition refers to when these same rocks and soils are laid down (deposited) somewhere new.
Landscape shape and topography play a large role in erosion. Earthen floodplains in river valleys are especially susceptible to erosion than rocky canyon walls. Weather also plays an influential role, as warm temperatures can cause permafrost ice sheets to disintegrate along coastlines, leading to coastal erosion.
Wind erosion is a serious global concern, resulting in the production of atmospheric dust which poses threats to ecosystems and human health. Wind erosion may occur locally – for example in dry or sandy soils – or over great distances; emissions may result from surface creep, saltation or suspension of sediments being eroded from surfaces.
Ice
Erosion occurs when pieces of Earth are worn away by forces such as wind or water. Deposition occurs when those pieces end up elsewhere – whether gradually like on beaches or suddenly like with mudslides that carry large sections downhill.
Ice is also known to play an influential role in erosion and deposition. Glaciers erode the ground as they move downhill across landscapes, transporting rocks that end up somewhere else in their wake. Erosion creates dramatic landforms like eskers and kames while it may also carry pollutants into lakes and rivers, polluting drinking water in our drinking supply.
Human Activity
Human activities have an immense effect on erosion rates, particularly when they expose dirt to wind, rain and moving water. Human-induced erosion rates tend to be between 10-20 times greater than natural ones.
Plowing is a common agricultural practice that can disturb soil structure and leave it more susceptible to erosion, while logging removes vegetation that holds the land together. Construction or recreational activities may further exacerbate erosion by disturbing or compacting it – leaving more room for displacement of its components.
Although human activity is responsible for most excessive erosion consequences, steps can be taken to mitigate its effects. Adjusting farming practices to reduce land disturbance, planting trees and other vegetation that help retain the soil in place and using sediment control during construction projects all help slow erosion down; so too can creating living shorelines with plants, rocks and materials along wet coasts designed to prevent erosion while stabilizing coastlines.