Accidents and shapes that modify a flat surface make up your relief . It can be depressions or elevations that alter the physiognomy. The mountains, the canyons, the mountains and the valleys, in this sense, form the relief of our planet.
He Land relief , therefore, includes those changes that can be noticed on the surface of the planet, either at the surface level or on the underwater bed. You can differentiate between the emerged relief (which develops above sea level) and the oceanic relief (which is submerged).
The notion of continental relief it is linked to the forms that exist in the continents (that is, to the surface emerged) and in the submerged area closest to them (known as Continental platform ). This definition shows us that continental relief can also be classified as emerged relief and that is part of what we understand as Land relief .
Because the continents occupy near the 30% of the land , the continental relief develops in this percentage of the planet. It includes all the mountains, plateaus, valleys, depressions and plains found in the Antarctica , America , Europe , Africa and Asia .
You can understand the continental relief as the areas of the lithosphere which is not covered by the ocean. From the Pampas plain until the Andes mountains going through the Alps and the Sahara desert , the continental relief stands out in all points of the planet.
If we analyze the continental relief taking into account its magnitude, we can distinguish between two large groups: macro forms and the minors . Let's see the corresponding ones to the first:
* old shields and massifs : they formed in the period Precambrian, the most extensive stage in the history of our planet. These are the oldest forms of relief, and on them they have acted with great intensity and for a long time both the erosion and internal forces that gave them "new life" gave them youth back;
* sedimentary plains and basins : These landforms are terrain that do not usually exceed 200 meters and have few geographical features. In Latin America, sediments are predominant, that is, those plains that have been born above large basins on which sediments have been deposited for several hundred years;
* mountain ranges that formed recently : these are mountain alignments that have risen in the last million years, a period that can be considered "recent" for the Earth. Some examples of this type of continental relief macroform are the Mountain range of the Andes, the alpine and the Himalayas. Since they have not suffered erosion for as long as other forms, the mountain ranges formed at this time are the highest in the world.
Among the minor forms of relief are the following:
* alluvial (or river) terraces : they are tables or sedimentary platforms of little extension that were built in a Valley river because of the sediments of the river that remain on the sides of the riverbed, where its slope (and, therefore, its ability to drag) decreases;
* ejection cones : they are also known by the name of alluvial fans, and these are formations that resemble terraces formed at the point where a torrent connects with a plain. The sediments that drag the first are deposited as a kind of fan and do not usually form a single channel, but several, and open in floods of greater intensity ;
* overlapping cones : In the Death Valley, in North America, there is a clear example of dejection cones that have been overlapping. There converge various torrents, which open when they reach the bottom of the valley, a phenomenon called "river coalescence."