Erosion, transport and deposition are three processes that change the surface of Earth. Without these processes taking place, rock would accumulate wherever it formed and ruin our landscapes.
Water, wind, ice and gravity all play their parts in transporting and depositing sediments that build layers of sedimentary rocks. These processes of weathering, erosion and deposition comprise what’s known as the Rock Cycle.
Water Erosion
Erosion by water is a widespread environmental issue that poses several threats, such as the loss of nutrients, soil deposition and mudflows, while also having serious repercussions for those living near rivers, streams or lakes. Erosion is accelerated by steep slopes, rain, wind, glaciers moving and sea level changes which accelerate its progress.
Precipitation is one of the primary climatic factors impacting erosion. Rainfall impacts soil surface erosion by dislodging particles from their original locations and transporting them downslope. Particle size also plays an integral part in how far erosion spreads: fine clay particles may travel far while larger gravel and sand-sized particles remain suspended for shorter durations.
River erosion creates features such as waterfalls, flood plains, meanders and deltas. Erosion typically occurs on the longest least sharp side of river bends where slow moving water deposits sediment. Through chemical weathering processes that allow carbonic acid in groundwater to seep into cracks in rocks and create caves underground.
Soil Erosion
Soil erosion occurs when natural forces like wind wear away at surface materials, often rapidly. Erosion reduces a soil’s ability to retain moisture, nutrients and plants as well as transport these materials into water bodies where they could negatively impact fish and aquatic life.
Soil erosion that deposit organic matter into water bodies can increase turbidity, interfering with photosynthesis and clogging the gills of fish and aquatic organisms. Furthermore, soil erosion carries sediments contaminated with agricultural chemicals or pesticides into water bodies which could harm or kill wildlife while polluting drinking water sources.
Unchecked erosion can result in land degradation, reduced crop production and loss of land value; as well as an increased risk of floods, droughts and other environmental catastrophes. Therefore, it’s vitally important that individuals gain knowledge about erosion’s causes, effects and prevention methods. Weathering, erosion and deposition have been ongoing processes for billions of years in nature’s Geologic Cycle.
Glacier Erosion
Glaciers can erode rock and soil from their original location and move it far from where it began, creating some interesting landforms in their wake. Two key forms of glacial erosion processes include plucking and abrasion.
Plucking occurs when loose or partially dissolving rock beneath a glacier breaks off and is carried along by its motion downward. For optimal results, this process should occur when moving downward rather than uphill or sideways.
Abrasion occurs when ice scrapes the surface of bedrock and creates grooves known as striations in its path, leaving grooves along its route.
When several glaciers erode a piece of bedrock at once, they can create pyramidal mountain peaks called horns. Other features of glacial erosion are U-shaped valleys, hanging valleys, ribbon lakes, roche moutonnee and crag and tail formations. Glaciers also deposit material at their termini including moraine deposits (Koppes 2015). Though glacier erosion rates vary widely depending on temperature, location and formation factors; basal sliding rates often drive most erosion rates (Koppes 2015); although their relationship to friction remains complicated (Koppes 2015).
Wind Erosion
Wind erosion occurs when there is no rain to wash away soil particles from their source and transports them over great distances, transporting fine soil particles away from their original locations and transporting them over vast distances. At large scales, wind erosion produces yardangs (Figure 5(a)), systems of ridges and swales aligned with the wind current, smoothed bedrock surfaces as well as erosional changes such as smoothing, polishing, faceting, fluting or grooving in bedrock surfaces resulting from wind erosional processes.
Wind erosion depends on a number of variables. Surface roughness, soil cloddiness, soil moisture levels, field size and vegetative cover all play an integral part in its severity. Rough or ridged surfaces trap and hold soil particles more securely and are therefore less vulnerable to wind erosion than smooth or flat surfaces; while those containing low silt, clay and organic-matter content tend to experience greater levels of wind erosion.
As with water erosion, wind erosion is caused by activities that remove protective vegetation, including intensive agriculture, deforestation, road construction and acid rain – contributing significantly to erosion worldwide. Long distance transport of dust ejected from denuded landscapes contributes to air pollution both locally and in surrounding countries.