Erosion is the natural process of breaking down and moving materials such as rocks, soil or other substances using elements like water, wind or glaciers. Erosion differs from weathering in that it involves movement.
Trees and plants help mitigate erosion by holding soil in place, but without these measures erosion could occur more rapidly.
Water
As water moves through a stream, it can carry away particles of soil, sand and rock – this process is known as erosion. Rivers play an especially destructive role as they travel down from mountains into the sea.
Wind and glaciers can also contribute to erosion. When used alone, wind can rapidly dislodge surface materials from dry areas while glaciers slowly melt, carving out valleys and shaping mountains as they gradually carve valleys and mountains into valleys and mountains. Erosion caused by these natural forces is known as mass wasting while human activities may hasten this process – for example when people remove trees and plants from an area leaving exposed soil exposed to rainstorms which wash it away, often leading to floods.
Erosion and weathering are often confused; however, they are two separate processes. Weathering involves breaking rocks apart into smaller pieces while erosion moves these fragments from their original locations. Raindrops hitting the ground with force can cause splash erosion while collecting on top of soil surface can create rill erosion or even create gullies in its wake.
Wind
Wind erosion occurs when loose soil particles are carried by moving air currents away from their source of origin and eventually deposited elsewhere. It is much faster than weathering which involves no movement of rock or soil particles; smaller than sand-sized particles tend to travel further while clay and silt particles tend to remain closer to their place of origin.
Erosion rates depend on several factors, such as rainfall or snowfall rates and intensity, soil compaction, living organisms that break up or hold together soil layers, climate conditions (particularly arid regions) and surface gradient (whether steep or shallow).
Human activities, including plowing (tilling) fields and grazing livestock, can expose soil to erosion by water and wind. Erosion rates can also be further increased during droughts and floods; all this leads to the loss of valuable topsoil resources essential to life on Earth.
Gravity
Gravity forces water, ice and rock to flow downhill, which contributes to erosion both directly and indirectly. Directly, erosion moves rock and soil down slopes causing landslides and mudflows; indirectly it moves glaciers sculpting valleys and shaping mountains.
Water erosion includes splash erosion caused by raindrop impact and flowing water transporting detached soil particles downhill, wearing away rocks while carrying sediment to rivers, lakes and oceans.
Wind erosion can be extremely swift. It spreads dust, sand and smaller dirt particles from one location to the next quickly – creating desert dunes of incredible height in Arches National Park by moving it from one side of their landscape to the other; soft rock streams in mountain streams may erode while “desert varnish” covers certain rocks along Yellow River of China. Living organisms also assist erosion by breaking up rocks, soil or ice so it’s easier for water or wind to carry it away.
Ice
Glaciers are massive ice masses that move rocks and debris over land surfaces, shaping the environment around them and leaving behind evidence. Glaciers cause erosion through two main methods: plucking and abrasion. Plucking occurs when glacier ice scrapes across rocks’ surfaces, picking up chunks from underneath that it deposits elsewhere; while abrasion occurs when glaciers grind their way through rocks they carry, wearing away at their surface to weaken it further and reduce its strength.
Mechanical erosion, also known as abrasion erosion, occurs at much faster rates than water or wind erosion. Mechanical erosion often results from human activities like plowing (tilling) the soil before or after planting crops or clearing forests for logging purposes; while natural processes like wind, rain, temperature fluctuations also play a part. Learning about different forms of erosion helps students connect these natural processes with their actions and understand how Earth materials change through time – something which is crucial to maintain healthy environments which sustain agriculture, habitats and manmade structures.