Erosion and deposition work together to reshape Earth’s surface over time. Erosion wears down rocks, transports them away and deposits it in new locations; while deposition deposits it somewhere new.
Deposition occurs when erosion reaches its limit; for instance, when a river no longer has enough energy to transport sediment downstream, it deposits it on the banks instead.
Wind
Wind erosion is a prevalent problem in arid regions. When wind blows over dry soil, small particles such as silt and clay are picked up by the breeze and carried along on their journey by the breeze – eventually wearing away at rocks’ surfaces and creating gullies and pits in them over time.
Erosion also forms land near rivers, constantly shaping riverbanks and beds by the force of running water carrying away sediment bits that eventually end up back downstream as deposition – creating sandy beaches, estuaries, sand bars, deltas and lagoons in its wake.
Erosion and deposition can also be reduced or prevented through the formation of clods of soil that act to slow or stop its flow of sediment, known as erosion-resisting structures (ERC). CLODS protect soil from further erosion until they break down due to weathering, tillage or other forces; once this happens they can return as part of the erosion cycle and start contributing again.
Water
The water cycle plays an essential role in erosion and deposition processes. Water can transport soil particles and rock fragments too large for wind or gravity to carry, as well as erosion steep slopes based on speed and force of its flow. Water’s action affects how rapidly its wears away the surface of Earth.
Water erosion can be a significant threat to people, as it can lead to flooding and wash away vital soil materials. Human activity often speeds up erosion rates by clearing trees or pulling up grasses that hold onto soil particles; faster erosion increases the likelihood of floods or landslides occuring on affected land areas.
Once erosion has worn away a steep slope, its remaining material is dropped back onto it by deposition, leaving a deposit of sediment that creates flood plains and rich delta soils. River water does the same thing when carrying away rocks that have worn away over time from riverbanks and beds along its route – eventually carving the Grand Canyon!
Ice
Modern glaciers often rest, at least partially, on bedrock which exerts an immense influence over their behavior. A commonly held assumption is that no sliding motion between the glacier sole and rock or sediment surfaces occurs unless heated to melting point temperature (Goldthwait, 1960), yet this fundamental assumption has resulted in many contradictory geomorphological contrasts.
As glacier velocity declines down-glacier, deformation rates decrease and erosional zones shrink; however, when glacier velocity increases over a long distance, deformation rates accelerate and erosional zones expand, leading to the creation of stacked till units with interspersed erosion surfaces such as boulder pavements (Reference ClarkClark, 1991). Furthermore, as indicated in Figure 10, sediment packages moving along time-distance trajectory B A may undergo composition changes along their journey as indicated by different colors indicating various lithologies deposited at successive sites along trajectory B A as illustrated in Figure 10.
Sun
The Sun is a vast ball of hot plasma fueled by nuclear fusion reactions in its core, providing energy and light that help support life on our planet.
The center of our Sun, known as its core, is home to hydrogen’s conversion into helium and its subsequent combination with heavier elements such as oxygen, neon and carbon from dead stars that exploded in past explosions (see Chapter 10, Mass Wasting).
As hydrogen burns within the Sun’s core, its loose electrons will eventually run out, prompting it to fuse together into a denser type of star called a white dwarf that no longer emits energy. Before reaching this state however, first its outer layers must shed in what’s known as its red giant phase – a process which could take trillions of years before reaching this state.