Relief Modeling Agents (continued)

Relief Modeling Agents (continued)

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Erosion It is the displacement of weathered material from one area to another, different from its place of formation.

- Transport (by water, in the form of rivers, floods, or even in the oceans, by waves, tides and currents, wind or glaciers);

- Sedimentation, which occurs when the transport agent no longer has the energy to continue loading the material.

Erosion - Natural Bridge, Bryce Canyon - Once the rock is broken because of degradation, the small pieces can be moved by water, ice, wind, or gravity.

Over the long geological time - 4 billion and 600 million years, the age of the earth - natural processes have been going on and leaving marks on rocks and other geological formations.

We have in Brazil some large sedimentary basins, which received eroded sediments from higher areas. This is the case of the Paraná Basin, Parnaíba Basin, Amazon Basin and other smaller basins.

Sedimentary Basins in Brazil

Since sedimentation in these basins took place for a long time, the lower layers were sufficiently buried to become hard rock: the sedimentary rocks.

Man contributes a lot to actions that accelerate the erosion process, such as:

  • Deforestation, unprotecting the soil from rain;
  • Construction of hillside dwellings / slums, in addition to clearing, causing acceleration of erosion due to the slope of the terrain;
  • Inadequate agricultural techniques, when extensive deforestation is promoted to give way to planted areas;
  • Land occupation, preventing large areas of land from fulfilling their role as water absorber, thus increasing the potential of material transport due to surface runoff.

Slope constructions

Erosion in rural road

Deforestation and forest destruction

Erosion Types

The types of erosion can be determined based on their forming agents and the processes of soil formation and wear. We can highlight:

Rain erosion: caused by the action of rainwater. In general, any soil wear caused by precipitation can be classified as rainfall erosion, but in areas where the terrain is less protected by vegetation and other elements, the effects of water action can be most intensely felt.

Rain erosion in agricultural area

Wind erosion: caused by the action of winds, which slowly carve rocks and transport soil particles.

Rock formation sculpted by wind action

Marine erosion: happens when rocks or coastal soil are worn out by water from the sea waves. It is a natural process that becomes a problem when housing or roads are erected in areas occasionally occupied by waves.

Marine erosion

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Erosion glacial: is the type of erosion driven by the action of ice, both snow and glaciers. Most often, it occurs because temperature variations freeze and thaw water, which expands and compresses, affecting rocks and soils. Other forms of ice movement, such as avalanches, also act in this process.

Glacial erosion

River erosion: It is the erosion caused by the riverbed, both when they exceed and advance on the banks, as when the riparian vegetation is removed and unprotects the relief around the watercourses.

Erosion caused by removal of riparian forest on the banks of a river

Geological erosion: is also known as natural erosion or that has not suffered from human interference. It acts by modeling the landscapes, with a combination of several other types of erosive actions.

Geological erosion - modeling a valley or canyon by water and wind

The human being can generate what is commonly called anthropic action. In addition, the other living beings also collaborate in some way to shape the terrestrial relief. Plants, for example, play a major role in soil protection: they provide organic matter and prevent their destruction.