O relief should be understood as the forms acquired by earth crustrand. These forms are mountains, plateaus, plains and depressions, classified by their structures (shapes) and by their altitudes, that is, their heights in relation to sea level.
These shapes are in constant transformations due to the modeling agents, that is, to the forces that act directly in the design of shapes, reconfiguring them at all times. Agents like the wind, the Water, tectonism, volcanism and biological beings are responsible for these transformations.
In Brazil there are only three forms of relief: Planaltos, plains and depressions. There are no mountain formations here, as they are linked to plate tectonic activity, and as the Brazil is at the center of the South American Plate, it does not have strong dynamics capable of forming mountains.
Read too: Why do tectonic plates move?
Types of relief
The Earth's surface, also known as the Earth's crust, is very dynamic and has four types of relief: mountains, plateaus, plains and depressions. Each of these structures has different shapes, capable of being classified by its design in nature and its altitude. The relief forms are:
mountains
They are ways of higher altitude relief (over 3000 meters) resulting from the activities of the tectonic plates. O tectonic plate shock causes the relief to rise, giving rise to mountains. A mountain range is called mountain ranges, as an example we have the Andes Mountains, in South America. They exist mountains young (formed by tectonism) and old (formed in more remote areas), which have more modest altitudes.
ExamplesAttractions: Andes, Himalayas and Swiss Alps.
plateaus
They are older land formations and with more moderate altitude, have their formation linked to erosive processes and external agents of the Earth, like rain, wind and water. Examples are mountain ranges, hills and plateaus.
- At stoned they have table-like structures, known as escarpments, which are steep drops in their relief and whose tops are flat. Their altitude is usually over 600 meters.
- You hills they are formations with a rounded top, with an altitude between 300 and 900 meters.
- At saws they are formed by chains of hills and are sharp, with an altitude between 600 thousand and 3000 thousand meters.
plains
The plain areas have less rugged structures, that is, with flatter relief. They can appear in nature in three ways: coastal, lacustrine and fluvial.
- coastal plains: they are coastal areas, beaches, formed by the action of the sea and the decomposition of marine sediments.
- Lake plains: are flat surfaces close to lakes, formed by the decomposition of their sediments.
- River Plains: are flat areas near the rivers, formed by the decomposition of their sediments.
Depression
Depressions are landforms at a lower altitude than the surrounding terrain. They can be classified in two ways: relatives and absolutes.
- Relative depressions: are areas that have lower terrain than their surroundings, being above sea level. As an example we have the river valleys.
- Absolute depressions: are terrains lower than their surroundings, in this case, lying below sea level. The greatest example of an absolute depression is the Dead Sea.
relief agents
Relief agents are so called because they are forces acting in the modification process of the shapes of these structures, they can be classified in two ways: internal or external.
You internal or endogenous agents they are forms that work from the Earth's interior to the outside. Examples of endogenous forces are tectonic plates, which, when moving, cause earthquakes or volcanic activity, the two processes are capable of acting on the relief structures, changing or modifying them.
already the external agents orexogenous they are processes that act on the outside of the Earth, from without, modifying the relief. They cause what we call weathering, that is, the erosion of the form, modifying it or changing its structure. Examples of these forces are: wind, sun, water and biological agents.
At climate conditions of place provoke the action of one agent more than another. For example, in a desert climate, temperature and wind tend to be more active than water, whereas in more humid climates, The action of water can promote greater chemical weathering, which can cause a rock to break or promote the emergence of erosion in a River.
See too: Why do volcanoes erupt?
Brazilian relief
Brazil is a country that has three major relief units: plateaus, plains and depressions. Because it is in the center of a tectonic plate (South American Plate), our territory does not show trainingmountains.
You plateaus cover most of our territory, adding up to 11 relief units. These structures suffer a lot of wear from external agents. The most extensive Brazilian plateaus are the plateaus and plateaus of the Paraná Basin, plateaus and plateaus of the Parnaíba Basin, and plateaus and mountains of the East-Southeast Atlantic.
All Brazilian depressions are relative, that is, they are above sea level, we have a total of 11 plains units. Formed by the erosion of plateau areas, the main depressions in Brazil are the Amazon, sertaneja and the peripheral depressions of the southern region of Rio Grande do Sul. These terrains do not exceed 200 meters in altitude. Only the peripheral depression on the eastern edge of the Paraná Basin reaches the highest altitude.
already the plains, flatter and less rugged terrains, are the result of sediment deposition of rain, lacustrine or marine origin. Brazil has six units of plains, the plain and coastal plains and the plain of the Amazon River being the two largest in terms of territorial extension.
Also access: Why is it so difficult for a hurricane to hit Brazil?
solved exercises
Question 1 - The relief consists of four forms: mountains, plateaus, plains and depressions. Several Brazilian scholars have classified the relief structures and consider, in consensus, that in Brazil there is no such form. Which form of relief does the statement refer to?
a) Plateaus
b) Mountains
c) Plains
d) depressions
Resolution
Alternative B. According to the Classification of Brazilian Relief, by Ross, Ab’Saber and Azevedo, Brazil does not have Mountains in its macrostructure.
question 2 - Among the following alternatives, exogenous agents are considered, except:
a) wind
b) water
c) Tetonism
d) Temperature
Resolution
Alternative C. External or exogenous agents are forces that act from the outside to the inside in the transformation of the relief: wind, water, sun (temperature), biological agents. Only alternative C refers to an internal Earth force, so it is wrong.
