The earth was formed 4600 billion years ago, and throughout its history it has been transforming and undergoing modifications that are due to the various phenomena that occur as a result of the interactions between its components.
When we look around us, we see the same mountains, the same valleys of all our lives, however that does not mean that all the time they have remained like this, the face of the earth is always changing, although we cannot perceive it, since many are the are changes that occur slowly and gradually, but other times the changes are more violent and we can evidence them quickly. The forces that originate these changes in the earth's crust and shape it are known as diastrophism, and they happen as a way for the crust itself to balance itself, since the particles that wear out in one place must be deposited in another, which produces a sinking and originates a nine pressure that brings as a consequence that another place on the earth's surface rises .
Relief is the set of different shapes and geographical features that make up the land surface and the ocean floor, and includes the difference in elevation of the high and low points of any surface.
Different types of relief
The diverse forms that the earth presents are represented by the relief and this is divided into two large groups: The Continental relief and the oceanic relief.
Continental relief type
El continental relief. It is made up of the different shapes found on the continents, that is, the emerged surface of the earth's crust. The forms of the continental relief can be divided into the following groups:
- Moutains. They constitute the highest elevation areas, with very abrupt inequalities that are manifested in very steep slopes, sunken valleys and small peaks. It is commonly accepted that mountains have heights that are above 600 meters. They are presented as mountain ranges, chains and Cordilleras. Among the types of mountains we have:
- Serranias. Sierra from the Latin language serra, is a subset of Mountains that, because they are within another larger mountain system and whose line of peaks has a broken or quite pronounced serrated shape, is generally longer than wide and its central axis is called the axis. orographic.
- Chains. Also known as mountain ranges, its name comes from the Latin Catena, which means a succession of links that are united in some way. A mountain chain is a series of mountains that are linked together and whose extension is greater than the mountain range.
- mountain range A mountain range is a chain of mountains that are linked together. These mountainous successions were formed in the continental limits from the accumulation of sediments, since the compression exerted by the lateral pressure, produced folds and generated the elevations.
- Plateaus. They are highlands in tabular form, located at more than 200 meters high. They are elevated terrain with flat tops, which is why they are also known as plateaus. They have characteristics similar to those of the plains, but are found above 600 meters of altitude.
- Colinas They are elevations of the terrain that are less high and less complex than the relief of the mountains. They are located between 200 and 600 meters high. Less abrupt in nature. They tend to be transit areas between mountains and plains, often occupying large tracts of land suitable for agriculture and forest formation.
- Valleys Valleys are depressions generally occupied by a river. According to their origin they are glacial or fluvial. The river valleys originated from the erosion produced by a river, therefore they are narrow and deep and have a “V” -shaped profile. On the other hand, the glacial valleys originated from the erosion caused by the passage of a glacier, so they are wider, with a flat bottom and a “U” -shaped profile. Constant irrigation in the valleys makes them very fertile.
Types of ocean relief.
The oceanic relief. It is considered as part of this group, the mantle of the earth that is found at the bottom of the oceans. It is also known as sea relief, underwater relief or ocean floor. Within the formations of the oceanic relief we find:
- The continental shelf: It is the region of the ocean floor closest to the coast. It consists of a flat extension of greater or lesser width according to the regions and that presents a slight increase in depth as it moves away from the coastline. Its level ranges between 0 and 200 meters below the sea surface. Most of the marine plant and animal species are found in this area.
- The Continental Slope. It involves a sharp decline or descent between the continental shelf to levels between 3000 and 4000 meters deep. It is the zone of sediment precipitation, which is controlled by gravity, especially by the currents that flow in the direction of the slope of the slope, to the bottom where the sediments are deposited in the form of layers or strata and originate underwater fans. (Fan-shaped accumulations of sediments towards deeper areas of the seas. The slope, together with the continental shelf, occupies 78 million square kilometers of surface, almost a quarter of the seabed.
- Underwater basins. It is a large depression in the land surface of the ocean floor, it is logically occupied by the ocean, whose types of reliefs fundamental are the following:
- Abyssal plains. Extensive flat areas formed by sediments of continental origin.
- Ocean trenches They are long and narrow depressions, where the plates of the lithosphere are destroyed by subduction. When two plates of the Earth's crust collide, the oceanic plate, which is the densest, is placed under the continental plate, which is less dense, giving rise to trenches and areas of seismic activity.
- Oceanic ridges. Cordilleras formed on the ocean floor around a bottom of expansion, when two plates separate, a fissure opens through which the magmatic material rises and a symmetry that becomes a center is created on both sides of the center of the fissure. In these ridges there is, therefore, great volcanic and seismic activity.
- Sea Mountains. Volcanic hills and guyots: The seamounts are elevations of the seabed, of volcanic origin that reach up to 1000 meters above said bottom. The volcanic hills They are similar to the oceanic mountains, but their height averages two hundred and fifty meters. The guyots They are truncated volcanic cones (flat-topped.)
Classification according to its origin
The inequalities of the continental land relief are due, in part, to the action of endogenous forces, the most obvious manifestations of which are the diastrophism and volcanism. The set of processes that produce these forces is called tectonism. Tectonic activity gives rise to a type of relief known as structural relief.
In addition to the endogenous forces in the formation of the continental land relief, exogenous processes such as weathering, erosion and sedimentation intervene, driven by solar energy. Thanks to these processes, the Gradation relief.
The shape of the relief then depends on its genesis and its structure: ,it is the result of endogenous forces; on the contrary the erosion relief includes non-structural shapes that are products of modeling
Classification of structural relief
In the structural relief, three main categories can be distinguished:
Cratons they are relatively stable parts of the continents, they are ancient cores of the continents. They are fundamentally constituted of a shield and an underlying buried extension known as a plinth or platform.
Mountains and tectonic reliefs. These have been produced by orogenesis, which is the process of mountain formation, by folds or faults and by epirogenic movements, lifting and sinking movements of the earth's crust.
Mountains and other accidents formed by the accumulation of molten rocks (lava) that rises by eruption from the interior of the lithosphere.
Classification of non-structural relief
It is one that has its origin by the action of external or exogenous forces also called gradation that are contrary to the endogenous forces originating from tectonism. These forces tend to reduce the accidents or irregularities of the surface caused by tectonism.
The gradation forces have their origin in the hydrosphere (rivers, waves, tides, ocean currents) in the cryosphere (glaciers), in the atmosphere (winds) and in the biosphere (animals and plants) These agents take their energy from the sun and act by gravity.
The forces of gradation are manifested through three major processes:
Weathering: process through which rocks disintegrate dissolve by the action of exogenous forces.
Erosion. Set of modeling processes of the earth's surface by natural agents such as: water, ice and wind, includes the transport of materials but not weathering.
Sedimentation: deposition of rocky materials worked by erosion, fragmented and dragged by agents such as rivers, waves, wind, glaciers, as well as the accumulation of dead organisms or chemical substances.
Thank you for your collaboration in our interest to learn