Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement.
 
Erosion is the opposite of deposition, the geological process in which earthen materials are deposited, or built up, on a landform.
 
Most erosion is performed by liquid water, wind, or ice (usually in the form of a glacier). If the wind is dusty, or water or glacial ice is muddy, erosion is taking place. The brown color indicates that bits of rock and soil are suspended in the fluid (air or water) and being transported from one place to another. This transported material is called sediment.
 
Physical Erosion
 
Physical erosion describes the process of rocks changing their physical properties without changing their basic chemical composition. Physical erosion often causes rocks to get smaller or smoother. Rocks eroded through physical erosion often form clastic sediments. Clastic sediments are composed of fragments of older rocks that have been transported from their place of origin.
 
Landslides and other forms of mass wasting are associated with physical weathering. These processes cause rocks to dislodge from hillsides and crumble as they tumble down a slope. 
 
Plant growth can also contribute to physical erosion in a process called bioerosion. Plants break up earthen materials as they take root, and can create cracks and crevices in rocks they encounter.
 
Ice and liquid water can also contribute to physical erosion as their movement forces rocks to crash together or crack apart. Some rocks shatter and crumble, while others are worn away. River rocks are often much smoother than rocks found elsewhere, for instance, because they have been eroded by constant contact with other river rocks.
 
 
Erosion by Water
 
Liquid water is the major agent of erosion on Earth. Rain, rivers, floods, lakes, and the ocean carry away bits of soil and sand and slowly wash away the sediment.
 
Rainfall produces four types of soil erosion: splash erosion, sheet erosion, rill erosion, and gully erosion. 
Splash erosion describes the impact of a falling raindrop, which can scatter tiny soil particles as far as .6 meters (2 feet). 
Sheet erosion describes erosion caused by runoff
Rill erosion describes erosion that takes place as runoff develops into discrete streams (rills). 
• Finally, gully erosion is the stage in which soil particles are transported through large channels. Gullies carry water for brief periods of time during rainfall or snowmelt but appear as small valleys or crevasses during dry seasons.
 
Valley erosion is the process in which rushing streams and rivers wear away their banks, creating larger and larger valleys. The Fish River Canyon, in southern Namibia, is the largest canyon in Africa and a product of valley erosion. Over millions of years, the Fish River wore away at the hard gneiss bedrock, carving a canyon about 160 kilometers (99 miles) in length, 27 kilometers (17 miles) wide, and 550 meters (1,084 feet) deep. 
 
The ocean is a huge force of erosion. Coastal erosion—the wearing away of rocks, earth, or sand on the beach—can change the shape of entire coastlines. During the process of coastal erosion, waves pound rocks into pebbles and pebbles into sand. Waves and currents sometimes transport sand away from beaches, moving the coastline farther inland. 
 
Coastal erosion can have a huge impact on human settlement as well as coastal ecosystems. The Cape Hatteras Lighthouse, for example, was nearly destroyed by coastal erosion. The Cape Hatteras Lighthouse was built on the Outer Banks, a series of barrier islands off the coast of the U.S. state of North Carolina, in 1870. At the time, the lighthouse was nearly 457 meters (1,500 feet) from the ocean. Over time, the ocean eroded most of the beach near the lighthouse. By 1970, the pounding surf was just 37 meters (120 feet) away and endangered the structure. Many people thought the lighthouse would collapse during a strong storm. Instead, it was moved 880 meters (2,900 feet) inland. 
 
The battering force of ocean waves also erodes seaside cliffs. The action of erosion can create an array of coastal landscape features. For example, erosion can bore holes that form caves. When water breaks through the back of the cave, it can create an arch. The continual pounding of waves can cause the top of the arch to fall, leaving nothing but rock columns called sea stacks. The seven remaining sea stacks of Twelve Apostles Marine National Park, in Victoria, Australia, are among the most dramatic and well-known of these features of coastal erosion.
 
Erosion by Wind
 
Wind is a powerful agent of erosion. Aeolian (wind-driven) processes constantly transport dust, sand, and ash from one place to another. Wind can sometimes blow sand into towering dunes. Some sand dunes in the Badain Jaran section of the Gobi Desert in China, for example, reach more than 400 meters (1,300 feet) high. 
 
In dry areas, windblown sand can blast against a rock with tremendous force, slowly wearing away the soft rock. It polishes rocks and cliffs until they are smooth—giving the stone a so-called “desert varnish.” Wind is responsible for the eroded features that give Arches National Park, in the U.S. state of Utah, its name. 
 
Wind can also erode material until little remains at all. Ventifacts are rocks that have been sculpted by wind erosion. The enormous chalk formations in the White Desert of Egypt are ventifacts carved by thousands of years of wind roaring through the flat landscape.
 
Some of the most destructive examples of wind erosion are the dust storms that characterized the “Dust Bowl” of the 1930s in North America. Made brittle by years of drought and agricultural mismanagement, millions of tons of valuable topsoil were eroded away by strong winds in what came to be known as “black blizzards.” These dust storms devastated local economies, forcing thousands of people who depended on agriculture for their livelihoods to migrate.
 
Erosion by Ice
 
Ice, usually in the form of glaciers, can erode the earth and create dramatic landforms. In frigid areas and on some mountaintops, glaciers move slowly downhill and across the land. As they move, they transport everything in their path, from tiny grains of sand to huge boulders. 
 
Rocks carried by glaciers scrape against the ground below, eroding both the ground and the rocks. In this way, glaciers grind up rocks and scrape away the soil. Moving glaciers gouge out basins and form steep-sided mountain valleys. Eroded sediment called moraine is often visible on and around glaciers.
 
Several times in Earth’s history, vast glaciers covered parts of the Northern Hemisphere. These glacial periods are known as ice ages. Ice Age glaciers carved much of the modern northern North American and European landscape. 
 
Ice Age glaciers scoured the ground to form what are now the Finger Lakes in the U.S. state of New York, for example. They carved fjords, deep inlets along the coast of Scandinavia. The snout of a glacier eroded Cape Cod Bay, Massachusetts, and formed the recognizable fishhook shape of Cape Cod itself.
 
Today, in places such as Greenland and Antarctica, glaciers continue to erode the earth. Ice sheets there can be more than a mile thick, making it difficult for scientists to measure the speed and patterns of erosion. However, ice sheets do erode remarkably quickly—as much as half a centimeter (.2 inch) every year. 
 
Other Forces of Erosion
 
Thermal erosion describes the erosion of permafrost along a river or coastline. Warm temperatures can cause ice-rich permafrost to break off coastlines in huge chunks, often carrying valuable topsoil and vegetation with them. These eroded “floating islands” can disintegrate into the ocean, or even crash into another piece of land—helping spread new life to different landscapes.
 
Mass wasting describes the downward movement of rocks, soil, and vegetation. Mass wasting incidents include landslides, rockslides, and avalanches. Mass wasting can erode and transport millions of tons of earth, reshaping hills and mountains and, often, devastating communities in its path.
 
Factors Impacting Erosion
 
Some of the natural factors impacting erosion in a landscape include climate, topography, vegetation, and tectonic activity.
 
Climate is perhaps the most influential force impacting the effect of erosion on a landscape. Climate includes precipitation and wind. Climate also includes seasonal variability, which influences the likelihood of weathered sediments being transported during a weather event such as a snowmelt, breeze, or hurricane.
 
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, shrubs, 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.S. state of Arizona. It eventually formed the Grand Canyon, which is more than 1,600 meters (1 mile) deep and as much as 29 kilometers (18 miles) wide in some places.
 
Erosion and People
 
Deposition, Soils, and Sediments
Eroded sediments have profoundly influenced the development of civilizations 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 deltas 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. The fertile lands around the Yellow River have been among China’s most productive for thousands of years.
 
Erosion Control
Erosion is a natural process, but human activity can make it happen more quickly. 
 
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 surges following hurricanes and typhoons 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. Farmers and engineers must regularly practice erosion control. 
 
Sometimes, engineers simply install structures to physically prevent soil from being transported. Gabions 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 windbreaks and riparian buffers to protect valuable agricultural land. Windbreaks, also called hedgerows or shelterbelts, 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 shorelines 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. They protect coastlines from powerful storm surges as well as erosion.
erosion
The beach beneath this beach house has eroded away

Far-Flung Dust
Wind is a powerful force. It can carry huge amounts of dust over long distances. In the winter and spring of 2004, winds eroded 45 million tons of dust from a spot called the Bodele Depression in the desert of northern Chad all the way across the Atlantic Ocean to Brazil.

Eroding Animals
Burrowing animals, such as beetles and worms, contribute to erosion by displacing soil.

Solar Erosion
The sun itself is actually an instrument of erosion! As rocks heat up, they expand. Expanding rocks can sometimes crack and crumble away.

accumulation
Noun

a buildup of something.

adhere
Verb

to stick to or support.

aeolian landform
Noun

geographic feature created by wind.

agricultural development
Noun

modern farming methods that include mechanical, chemical, engineering and technological methods. Also called industrial agriculture.

Noun

the art and science of cultivating land for growing crops (farming) or raising livestock (ranching).

array
Noun

large group.

Noun

layers of gases surrounding a planet or other celestial body.

Noun

large mass of snow and other material suddenly and quickly tumbling down a mountain.

bank
Noun

a slope of land adjoining a body of water, or a large elevated area of the sea floor.

barrier island
Noun

long, narrow strip of sandy land built up by waves and tides that protects the mainland shore from erosion.

Noun

a dip or depression in the surface of the land or ocean floor.

batter
Verb

to beat and cause damage.

Noun

narrow strip of land that lies along a body of water.

Noun

solid rock beneath the Earth's soil and sand.

bioerosion
Noun

the process in which a living organism wears away at rock or another hard substance.

Noun

deep, narrow valley with steep sides.

carbonation
Noun

absorption of, or reaction with, carbon dioxide.

carbonic acid
Noun

chemical produced as carbon dioxide dissolves in water.

cave
Noun

underground chamber that opens to the surface. Cave entrances can be on land or in water.

chalk
Noun

a soft mineral. Also called limestone and calcium carbonate.

Noun

waterway between two relatively close land masses.

chemical bond
Noun

attraction between atoms, ions or molecules that enables the formation of chemical compounds.

chemical erosion
Noun

process of rocks changing their chemical composition as they erode.

chemical reaction
Noun

process that involves a change in atoms, ions, or molecules of the substances (reagents) involved.

Noun

complex way of life that developed as humans began to develop urban settlements.

clastic sediment
Noun

rock composed of fragments of older rocks that have been transported from their place of origin.

Noun

steep wall of rock, earth, or ice.

Noun

all weather conditions for a given location over a period of time.

Noun

gradual changes in all the interconnected weather elements on our planet.

coastal erosion
Noun

wearing away of earth or sand on the beach by natural or man-made methods.

coastline
Noun

outer boundary of a shore.

Noun

deep crack, especially in a glacier.

crevice
Noun

crack in a rock.

Noun

agricultural produce.

cumulative
Adjective

growing in quantity or strength.

Noun

steady, predictable flow of fluid within a larger body of that fluid.

Noun

the flat, low-lying plain that sometimes forms at the mouth of a river from deposits of sediments.

deposition
Noun

process of silt and sediment building up in an area.

Noun

area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

desert varnish
Noun

dark, hard layer of yellowish or blackish oxides formed on exposed rock surfaces in windblown, arid regions.

discrete
Adjective

individual or distinct.

disintegrate
Verb

to fall apart and disappear.

dissolve
Verb

to break up or disintegrate.

dissolve
Verb

to break up or disintegrate.

Noun

period of greatly reduced precipitation.

dry season
Noun

time of year with little precipitation.

Noun

a mound or ridge of loose sand that has been deposited by wind.

Noun

tiny, dry particles of material solid enough for wind to carry.

Dust Bowl
Noun

(1930-1940) term for the Great Plains of the U.S. and Canada when severe dust storms forced thousands of people off their farms.

dust storm
Noun

weather pattern of wind blowing dust over large regions of land.

earth
Noun

soil or dirt.

economic
Adjective

having to do with money.

Noun

community and interactions of living and nonliving things in an area.

endanger
Verb

to put at risk.

engineer
Noun

person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).

erode
Verb

to wear away.

Noun

act in which earth is worn away, often by water, wind, or ice.

erosion control
Noun

process of preventing or reducing erosion by wind and water.

farmer
Noun

person who cultivates land and raises crops.

fertile
Adjective

able to produce crops or sustain agriculture.

fishery
Noun

industry or occupation of harvesting fish, either in the wild or through aquaculture.

Noun

long, narrow ocean inlet between steep slopes.

floating island
Noun

a mass of soil and plants torn from a coast.

Noun

overflow of a body of water onto land.

Noun

flat area alongside a stream or river that is subject to flooding.

fluid
Noun

material that is able to flow and change shape.

forest
Noun

ecosystem filled with trees and underbrush.

frequent
Adjective

often.

frigid
Adjective

very cold.

gabion
Noun

wire frame filled with rock.

geological process
Noun

method by which the Earth changes.

glacial period
Noun

time of long-term lowering of temperatures on Earth. Also known as an ice age.

Noun

mass of ice that moves slowly over land.

Noun

increase in the average temperature of the Earth's air and oceans.

gouge
Noun

hand tool with a partly curved blade, used for carving.

Noun

water found in an aquifer.

gully erosion
Noun

removal of soil along drainage lines by surface water runoff.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

hedgerow
Noun

line of bushes and trees forming a boundary.

hurricane
Noun

tropical storm with wind speeds of at least 119 kilometers (74 miles) per hour. Hurricanes are the same thing as typhoons, but usually located in the Atlantic Ocean region.

hydration
Noun

process of a substance or solution chemically combining with water.

hydrolysis
Noun

process in which a compound is split into other compounds by reacting with water.

Noun

water in its solid form.

ice age
Noun

long period of cold climate where glaciers cover large parts of the Earth. The last ice age peaked about 20,000 years ago. Also called glacial age.

Noun

thick layer of glacial ice that covers a large area of land.

indicate
Verb

to display or show.

inlet
Noun

small indentation in a shoreline.

Noun

body of land surrounded by water.

Noun

specific natural feature on the Earth's surface.

Noun

the geographic features of a region.

Noun

the fall of rocks, soil, and other materials from a mountain, hill, or slope.

lighthouse
Noun

structure displaying large, bright lights to warn and help ships navigate coastal waters.

Noun

method of creating coastal land by using stones and marine grasses to trap soil, sand, and mud.

Noun

windblown soil or silt.

mass wasting
Noun

downward movement of rock, soil, and other material.

mineral
Noun

inorganic material that has a characteristic chemical composition and specific crystal structure.

Noun

material, such as earth, sand, and gravel, transported by a glacier.

natural hazard
Noun

event in the physical environment that is destructive to human activity.

Northern Hemisphere
Noun

half of the Earth between the North Pole and the Equator.

Noun

substance an organism needs for energy, growth, and life.

oxidation
Noun

chemical process of a substance combining with oxygen to change the substance's physical and molecular structure.

Noun

permanently frozen layer of the Earth's surface.

physical erosion
Noun

process of rocks and earthen materials breaking apart and being transported without changing their chemical composition.

plow
noun, verb

tool used for cutting, lifting, and turning the soil in preparation for planting.

polish
Verb

to make smooth and shiny by rubbing.

Noun

all forms in which water falls to Earth from the atmosphere.

prone
Adjective

vulnerable or tending to act in a certain way.

rill
Noun

very small stream.

rill erosion
Noun

process of soil removal by water running through little streamlets, or headcuts.

riparian buffer
Noun

area of grass, trees, or shrubs near a river bank.

rock
Noun

natural substance composed of solid mineral matter.

Noun

overflow of fluid from a farm or industrial factory.

rust
Noun

red or orange coating that forms on the surface of iron when it is exposed to oxygen and moisture. Also called iron oxide or ferric oxide.

sand
Noun

small, loose grains of disintegrated rocks.

sand dune
Noun

mound of sand created by the wind.

Scandinavia
Noun

region and name for some countries in Northern Europe: Iceland, Norway, Sweden, Finland, and Denmark.

scour
Verb

to rub harshly, often to polish.

Noun

increase in the average reach of the ocean. The current sea level rise is 1.8 millimeters (.07 inch) per year.

sea stack
Noun

column-shaped rock formation created by waves eroding parts of coastal cliffs.

Noun

solid material transported and deposited by water, ice, and wind.

sedimentation
Noun

process of accumulating small solid deposits.

sheet erosion
Noun

removal of soil in thin layers by the forces of rain and stream flow.

shelterbelt
Noun

line of bushes and trees forming a boundary.

shrub
Noun

type of plant, smaller than a tree but having woody branches.

snout
Noun

end of a glacier.

soil
Noun

top layer of the Earth's surface where plants can grow.

solution
Noun

substance in which a gas, liquid, or solid is evenly distributed in another medium.

splash erosion
Noun

soil displacement by the impact of a falling raindrop.

storm
Noun

severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.

Noun

abnormal rise in sea level accompanying a hurricane or other intense storm. Also called a storm tide.

stream
Noun

body of flowing fluid.

surf
Noun

waves as they break on the shore or reef.

suspend
Verb

to temporarily stop an activity.

tectonic activity
Noun

movement of tectonic plates resulting in geologic activity such as volcanic eruptions and earthquakes.

tectonic uplift
Noun

movement of plates beneath the Earth's surface that causes one part of the landscape to rise higher than the surrounding area.

Noun

degree of hotness or coldness measured by a thermometer with a numerical scale.

thermal erosion
Noun

erosion of permafrost by the combined thermal and mechanical action of moving water.

topography
Noun

study of the shape of the surface features of an area.

topsoil
Noun

the most valuable, upper layer of soil, where most nutrients are found.

typhoon
Noun

tropical storm with wind speeds of at least 74 miles (119 kilometers) per hour. Typhoons are the same thing as hurricanes, but usually located in the Pacific or Indian Ocean region.

valley
Noun

depression in the Earth between hills.

valley erosion
Noun

process in which rushing streams and rivers wear away their banks, creating larger and larger valleys.

vegetation
Noun

all the plant life of a specific place.

velocity
Noun

measurement of the rate and direction of change in the position of an object.

ventifact
Noun

rock that has been shaped by wind-driven sand, dust, or ice particles.

water
Noun

chemical compound that is necessary for all forms of life.

wave
Noun

moving swell on the surface of water.

Noun

the breaking down or dissolving of the Earth's surface rocks and minerals.

Noun

area of land covered by shallow water or saturated by water.

wind
Noun

movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.

windbreak
Noun

structure that serves to interrupt an air current or flow of wind.