Erosion refers to the gradual wear-and-tear process by natural forces such as water, wind, or glacial ice that wear away and shape Earth’s surface materials such as rocks. Erosion often transports material from one location (e.g. a mountaintop to valley).
Water erosion is the predominant force shaping most landscapes, yet its speed varies drastically from place to place.
Water
An active river can be an extremely powerful force of erosion. Over time, its flow erodes rock and soil from its path, gradually shaping canyons, carving streams and depositing sediment in rivers, lakes and oceans. Erosion also occurs through glacier movement sculpting Earth as they melt away.
Water can erode land in two ways: splash erosion and flowing water erosion. Splash erosion occurs when raindrops hit the ground and break apart soil aggregates before washing away particles of soil over short distances. Meanwhile, flowing water carries these particles further afield and forms stream beds or river deltas as a result.
Erosion occurs when topsoil washes into rivers with all its nutrients, depleted through wind or human activities like farming, road building or urban sprawl; as it brings with it oxygen-depleting compounds which lower oxygen levels in the water, thus decreasing quality for aquatic life and making it unhealthy for living things to use as their natural habitat. Wind-driven erosion increases erosion rate while planting trees or other forms of vegetation may help slow erosion down or stop it altogether.
Ice
Glaciers, in particular, can be powerful tools of erosion. Glaciers use both abrasion and plucking processes to erode land through glacial motions – the former involves rock being scraped against other rocks, while polishing and gouging through bedrock, while plucking occurs when melting water seeps through cracks in glaciers before freezing to form pieces of rock which then break off and become transported along by them.
Glacial erosion creates distinct landforms such as drumlins, U-shaped valleys, and cirques. This form of erosion is essential in transporting soil and rock materials from one location to the next, creating material for new land formations.
Human activities can hasten erosion by stripping away ground-covering plants that protect soil. Activities such as tilling and overgrazing expose dirt; clearing land for cultivation or development expose it further; mining exposes it even more; while unexpected weather changes exacerbate erosion even further.
Wind
These small particles, including silt and clay, are susceptible to wind erosion. When transported over distance or left where they were initially found, this form of erosion becomes less frequent than its counterpart caused by water or ice.
Windborne particles vary based on soil size, how tightly its particles cling together, and wind velocity. Furthermore, erosion depends on whether there is enough vegetation acting as a windbreak and land use practices that reduce vegetation coverage such as land clearing or excessive cropping practices that reduce or limit vegetation presence.
Other factors that contribute to physical erosion include rock size and distribution on a landscape, the steepness of any slopes involved and availability of natural resources like water or shade from sunlight. Sometimes erosion caused by water or wind wears away soil gradually leading to sudden collapse or mass waste of rocks and earth into rivers or oceans, creating avalanches or mass wastage of landmasses.
Vegetation
Vegetation helps combat erosion by binding soil with its roots and restricting water flow. Plants also intercept raindrops to mitigate their energy release as raindroplets fall, thus decreasing droplet impact energy and helping prevent splash erosion.
Bioerosion occurs when living plants break apart rock fragments and dissolve materials that contribute to physical erosion, contributing to physical loss of soil as well as changes in landform shape.
Steep slopes tend to erode quickly. Erosion may be further hastened by glaciers, ocean waves and movement of ice (glaciers). When mass of rock and soil suddenly descend a slope it forms landslides which often result in catastrophic events like earthquakes.
Erosion can be caused by intensive agriculture, deforestation, roads and human-caused climate change; but there are several prevention and remediation practices that can combat erosion. Living shorelines – made of native plants, stone, sand or even living organisms placed along wetland coastlines to anchor soil and prevent erosion while creating habitat and providing protection from powerful storm surges – are one such solution.