Wind erosion deposits Sand dunes are the most visible product of deposition by wind. With their shape and orientation governed by the prevailing winds. Wind erosion is capable of carrying fine dust for thousands of kilometres, before depositing it again when the winds die down. For example, dust originating from Southern Australia, and carried by a dust storm in early , was found in New Zealand!
Much of this precious topsoil actually landed in the Tasman sea, lost for perhaps millions of years, maybe until tectonic movement of the Earth's crust raises this part of the ocean to form dry land again. Wave erosion deposits The material eroded from cliffs and shorelines is usually deposited nearby as a beach or sand on the sea floor.
The cycle of erosion and deposition is an ongoing one with beach sand building up, only to be washed away in a storm and deposited on another beach. Deposition Erosion and deposition Gravity Water erosion deposits Ice erosion deposits Wind erosion deposits Wave erosion deposits.
Erosion by sea. In sedimentary rocks, bonds are weaker and are mainly caused by the cementing effect of compounds such as iron oxides, silica, or calcium. The particles found in soils are held together by even weaker bonds which result from the cohesion effects of water and the electro-chemical bonds found in clay and particles of organic matter.
Physical , chemical , and biological weathering act to weaken the particle bonds found in rock materials. As a result, weathered materials are normally more susceptible than unaltered rock to the forces of detachment. The agents of erosion can also exert their own forces of detachment upon the surface rocks and soil through the following mechanisms:. Cavitation : intense erosion due to the surface collapse of air bubbles found in rapid flows of water.
In the implosion of the bubble, a micro-jet of water is created that travels with high speeds and great pressure producing extreme stress on a very small area of a surface.
Cavitation only occurs when water has a very high velocity, and therefore its effects in nature are limited to phenomenon like high waterfalls. Raindrop impact : the force of a raindrop falling onto a soil or weathered rock surface is often sufficient to break weaker particle bonds.
The amount of force exerted by a raindrop is a function of the terminal velocity and mass of the raindrop. Abrasion : the excavation of surface particles by material carried by the erosion agent. The effectiveness of this process is related to the velocity of the moving particles, their mass, and their concentration at the eroding surface.
Abrasion is very active in glaciers where the particles are firmly held by ice. Abrasion can also occur from the particles held in the erosional mediums of wind and water.
Entrainment is the process of particle lifting by the agent of erosion. In many circumstances, it is hard to distinguish between entrainment and detachment. There are several forces that provide particles with a resistance to this process. The most important force is frictional resistance. Frictional resistance develops from the interaction between the particle to its surroundings. A number of factors increase frictional resistance, including: gravity , particle slope angle relative to the flow direction of eroding medium, particle mass , and surface roughness.
Entrainment also has to overcome the resistance that occurs because of particle cohesive bonds. These bonds are weakened by weathering or forces created by the erosion agent abrasion , plucking , raindrop impact , and cavitation.
The main force reponsible for entrainment is fluid drag. The strength of fluid drag varies with the mass of the eroding medium water is times more dense than air and its velocity. Fluid drag causes the particle to move because of horizontal force and vertical lift. Within a medium of erosion, both of these forces are controlled by velocity.
Horizontal force occurs from the push of the agent against the particle. If this push is sufficient to overcome friction and the resistance of cohesive bonds, the particle moves horizontally.
The vertical lift is produced by turbulence or eddies within the flow that push the particle upward. Topography , the shape of surface features of an area, can contribute to how erosion impacts that area. The earthen floodplains of river valleys are much more prone to erosion than rocky flood channels, which may take centuries to erode. Soft rock like chalk will erode more quickly than hard rocks like granite.
Vegetation can slow the impact of erosion. Plant roots adhere to soil and rock particles, preventing their transport during rainfall or wind events. Trees, shrub s, and other plants can even limit the impact of mass wasting events such as landslides and other natural hazards such as hurricanes.
Deserts, which generally lack thick vegetation, are often the most eroded landscapes on the planet. Finally, tectonic activity shapes the landscape itself, and thus influences the way erosion impacts an area.
Tectonic uplift , for example, causes one part of the landscape to rise higher than others. In a span of about 5 million years, tectonic uplift caused the Colorado River to cut deeper and deeper into the Colorado Plateau, land in what is now the U. It eventually formed the Grand Canyon, which is more than 1, meters 1 mile deep and as much as 29 kilometers 18 miles wide in some places. Eroded sediments have profoundly influenced the development of civilization s around the world. Agricultural development is often reliant on the nutrient -rich soils created by the accumulation of eroded earth.
When the velocity of wind or water slows, eroded sediment is deposited in a new location. The sediment builds up in a process called sedimentation and creates fertile land. River delta s are made almost entirely of sediment that has eroded from the banks and bed of a river. The rich delta soils of the San Joaquin and Sacramento rivers in northern California, for example, have created one of the most agriculturally productive areas in the world.
Loess is an agriculturally rich sediment made almost entirely of wind-blown, eroded sediment. The Yellow River in central China gets its name from the yellow loess blown into and suspended in its water. Human activity altering the vegetation of an area is perhaps the biggest human factor contributing to erosion. Trees and plants hold soil in place. When people cut down forests or plow up grasses for agriculture and development, the soil is more vulnerable to washing or blowing away.
Landslides become more common. Water rushes over exposed soil rather than soaking into it, causing flooding. Global warming , the current period of climate change , is speeding erosion. The change in climate has been linked to more frequent and severe storms.
Storm surge s following hurricanes and typhoon s can erode kilometers of coastline and coastal habitat. These coastal areas are home to residences, businesses, and economically important industries, such as fisheries. The rise in temperature is also quickly melting glaciers. The slower, more massive form of glacial erosion is being supplanted by the cumulative impact of rill, gully, and valley erosion. In areas downstream from glacial snouts, rapidly melting glaciers are contributing to sea level rise.
The rising sea erodes beaches more quickly. Erosion control is the process of reducing erosion by wind and water. Farmer s and engineer s must regularly practice erosion control. Sometimes, engineers simply install structures to physically prevent soil from being transported. Gabion s are huge wireframes that hold boulders in place, for instance. Gabions are often placed near cliffs. These cliffs, often near the coast, have homes, businesses, and highways near them. When erosion by water or wind threatens to tumble the boulders toward buildings and cars, gabions protect landowners and drivers by holding the rocks in place.
Erosion control also includes physically changing the landscape. Communities often invest in windbreak s and riparian buffer s to protect valuable agricultural land. Windbreaks, also called hedgerow s or shelterbelt s, are lines of trees and shrubs planted to protect cropland from wind erosion. Riparian buffers describe plants such as trees, shrubs, grasses, and sedges that line the banks of a river.
Riparian buffers help contain the river in times of increased stream flow and flooding. Living shoreline s are another form of erosion control in wetland areas. Living shorelines are constructed by placing native plants, stone, sand, and even living organisms such as oysters along wetland coasts.
These plants help anchor the soil to the area, preventing erosion. By securing the land, living shorelines establish a natural habitat. Erosion by ice — Glaciers erode the surface of the Earth in two ways: Plucking and Abrasion Erosion by water — Sediment, picked up by flowing water, is moved along in one of four ways: Traction, Saltation, Suspension and Solution.
Erosion by gravity — Soil creep, mudflows, landslips and Rockfalls What is Deposition? Difference between Erosion and Deposition 1. Definition Erosion Erosion is defined as wearing away of rock along the coastline. Deposition Deposition is a process in which sediments, knocked rock pieces, and soil are carried by wind, gravity and water and deposited in a new location to a landform or land mass.
Types Erosion The 4 main types of erosion are Abrasion — When pebbles grind along the river bank and bed in a sand-papering effect. Hydraulic action — This is the sheer power of the water as it smashes against the river banks. Air becomes trapped in the cracks of the river bank and bed, and causes the rock to break apart.
Solution — happens when sea water dissolves certain rock types. Attrition — takes place when sea carries the rocks and these rocks knock against each other. As a result, they break apart to become more rounded and smaller. Pollution and Poor Water Quality Deforestation and Flooding Soil Degradation Mudslides and Structural Problems Deposition Rivers and streams fill with melting snow in the springtime Water vapor changes directly to ice without first becoming a liquid Sediment deposition destroys fish spawning beds Reduces the useful storage volume in reservoirs, clogs streams Carry toxic chemicals 4.
Occurrence Erosion Erosion occurs when: There is a loss of plant cover, which increases the amount of soil lost to wind and water erosion Delta is formed at the mouth of the river Plant roots crack a parking lot Ice freezes and cracks rocks.
They break into smaller pieces Deposition Deposition occurs when: Water carrying the sediment slows down The glacier carrying the sediment melts The wind carries the sediment dies down Beach gets washed away by a hurricane Sand dunes are blown away by a wind Rocks are broken down into soil 5. Creation of Landforms Erosion Landforms created by erosion — Headlands, bays and cliffs Deposition Landforms created by deposition — Spits, salt marshes and beaches.
Summary The points of difference between Erosion and Deposition have been summarized as below: Erosion Vs.
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