WHAT ARE EPIROGENIC MOVEMENTS? - GEOGRAPHY - 2024

The epirogénicos movements are vertical movements up and down, which occur slowly in the earth 's crust. For years, various movements have occurred in the earth's crust, due to the pressures it receives from the inner layers of the Earth.

These movements have generated changes in the shape of the cortex, the effects of which are being felt today. Among these movements are: orogenic, epirogenic, seismic and volcanic eruptions.

Image recovered from Ciencia Geográfica.

The former are the uneven movements that led to the formation of the mountains. The epirogenic ones for their part are the slow movements of the earth's crust.

The seismic are those violent and short vibrations of the crust. Finally, volcanic eruptions represent the abrupt expulsion of molten rocks from the interior of the Earth.

Difference between epirogenic and orogenic movements

The orogenic ones are relatively fast tectonic movements and can be horizontal or vertical, their etymological meaning is genesis of mountains.

Therefore, it is understood that these movements were the ones that originated the mountains and their relief. These movements can be horizontal or by bending, and vertical or by fracture.

The epirogenic, on the other hand, are the movements of ascent and descent, much slower and less powerful than the orogenic but capable of shaping a relief without fracturing it. These movements are produced in the tectonic plates producing irregularities in the terrain slowly but progressively.

The different plates on which each continent and ocean rests are floating on top of the magma that abounds in the interior of the planet.

As these are separate plates within a liquid and unstable medium, even if it is not perceived, they are definitely in motion. From this type of mobility, volcanoes, earthquakes and other geographical features are formed.

Causes of epirogenic movements

The vertical movements of the earth's crust are called epirogenic. These occur in large or continental regions, they are very slow upheavals of ascent and descent of the largest continental masses.

Although it is true that they do not produce major disasters, they can be perceived by human beings. These are responsible for the overall balance of a platform. They do not exceed a slope of 15 °.

The upward epigenesis is mainly produced by the disappearance of a weight that exerted pressure on the continental mass, while the downward movement originates when said weight appears and acts on the mass (Jacome, 2012).

A well-known example of this phenomenon is that of the great glacial masses, where the ice from the continent exerts pressure on the rocks causing a descent of that platform. As the ice disappears, the continent progressively rises, allowing isostatic equilibrium to be maintained.

This type of movement induces the immersion of one coast and the emergence of another, as evidenced in the cliffs of Patagonia, which in turn produces a regression of the sea or marine retreat on the raised coast.

Consequences of epirogenesis

The tilting or sustained movement of the epirogenesis produces monoclinal structures that do not exceed 15 ° in elevation and in only one direction.

It can also generate larger bulges, causing unfolded structures, also known as aclinear. If it is an ascending bulge it is called anteclise, but if it is descending it is called sineclise.

In the first case, rocks of plutonic origin prevail because it functions as an eroded surface; for its part, the sineclise is equivalent to accumulation basins in which sedimentary rocks abound. It is from these structures that the tabular relief and the slope relief emerge (Bonilla, 2014).

When epriogenic movements are downward or negative, part of the continental shields are submerged, forming shallow seas and continental shelves, leaving the sedimentary layers deposited on the oldest igneous or metamorphic rocks.

When it occurs in positive or upward movement, the sedimentary layers are located above sea level, being exposed to erosion.

The effect of epirogenesis is observed in the change of coastlines and the progressive transformation of the appearance of the continents.

In geography, tectonism is the branch that studies all these movements that occur inside the earth's crust, among which is precisely the orogenic and epirogenic movement.

These movements are studied because they directly affect the crust of the Earth, causing the deformation of the rock layers, which fracture or rearrange (Velásquez, 2012).

Theory of global tectonics

To understand the movements of the earth's crust, modern geology has relied on the Global Tectonics Theory developed in the 20th century, which explains the different geological processes and phenomena to understand the characteristics and development of the outer layer of the Earth and its internal structure.

Between 1945 and 1950, a large amount of information was collected on the ocean floor, the results of these investigations generated acceptance among scientists about the mobility of the continents.

By 1968 a complete theory had already been developed on the geological processes and transformations of the earth's crust: plate tectonics (Santillana, 2013).

Much of the information obtained was thanks to sound navigation technology, also known as SONAR, which was developed during World War II (1939-1945) due to the warlike need to detect objects submerged at the bottom of the oceans. With the use of SONAR, his was able to produce detailed and descriptive maps of the ocean floor. (Santillana, 2013).

Plate tectonics is based on observation, noting that the solid crust of the Earth is divided into about twenty semi-rigid plates. According to this theory, the tectonic plates that make up the lithosphere move very slowly, dragged by the movement of the boiling mantle that is under them.

The boundary between these plates are areas with tectonic activity in which earthquakes and volcanic eruptions regularly occur, because the plates collide, separate or overlap each other, causing the appearance of new forms of relief or the destruction of a specific part of East.

References

1. Bonilla, C. (2014) E pirogénesis y Orogénesis Recovered from prezi.com.
2. Ecured. (2012) Continental Shields. Recovered from ecured.cu.
3. Fitcher, L. (2000) Plate Tectonic Theory: Plate Boundaries and Interplate Relationships Retrieved from csmres.jmu.edu.
4. Geological Survey. Continental Drift and Plate-Tectonics Theory. Recovered from infoplease.com.
5. Jacome, L. (2012) Orogenesis and Epirogenesis. Recovered from geograecología.blogsport.com.
6. Santillana. (2013) Theory of plate tectonics. General Geography 1st year, 28. Caracas.
7. Strahler, Artur. (1989) Physical Geography. Carcelona: Omega.
8. Velásquez, V. (2012) Geography and Environment Tectonism. Recovered from geografíaymedioambiente.blogspot.com.