A plain is a countryside or ground no highs or lows . It is, therefore, a surface dilated that is characterized by its equality.
It is known as plain or plain at flat geographical area or whose undulation is less than 150 meters high above sea level. If it presented a higher elevation, we would be facing a plateau .
The plains account for about 55% of the continental surface and 40% of the bottom of the land that makes up the ocean floor.
The one at the bottom of the ocean is called abyssal plain or platform and it has a depth that goes from 2,200 to 5,500 m. In the case of the plains of the earth's surface, its origin comes from the ancient rocks that were part of the stable interiors of the continents. They are the result of millions of years of erosion.
There are different types of plains, such as pedillanuras , the bullshit , the corrosion plains , the panllanuras , the coastal platforms and the cryoplane surfaces .
The pedillanuras they are surfaces that arise from the retreat of escarpments and pedimentation (the formation of concave platforms with gentle slopes at the foot of steep slopes). The bullshit , on the other hand, they are surfaces that have almost no topographic accidents.
The corrosion plains they derive from other pre-existing plains, arising after chemical weathering processes and the dismantling of eroded material. The panllanuras they cover the flat surfaces that appear as a result of the union of alluvial plains, while the coastal platforms they are created by the erosive action of the waves.
Finally, the cryoplane surfaces they are developed with the deposition of the weathered material in depressions.
With all this it is evident that the quality of the land in a plain varies according to the type of soil that forms it, being some of immense qualities of fertility and others of low fertility. Some most famous plains of the planet they are "Valle del Po" (Italy), "Coastal plain of the gulf" (Mexico), "Llanura Pampeana" (Argentina), "Sabana Made" (Venezuela) and "Plain of La Mancha" (Spain).
Differences between the plain and the valley
Just as a plain resembles in some things the plateauIt also has similarities with the valleys, although they are clearly two different geographical features.
In a flat terrain there may be certain elevations but between the height of these and that of the rest of the territory there can be no difference. These elevations within a flat terrain receive different names according to their characteristics, they can be hills, oteros or hills.
In turn, as we have already said, they can be presented plateaus (they have a certain height and have an abundance of grassland and little tree vegetation) and depressions (They are perceived as small uneven terrain that is surrounded by the mountain; they have extensive vegetation and tend to be very fertile).
Within the various depressions there is a very particular classification that is that of the valleys. These are characterized by being low and flat parts of land enclosed between the mountains at a lower height than the rest of the surrounding land and of elongated diameters. In turn they are isolated from the rest of the territories and the only way to access them is the so-called mountain ports, which are trails marked by the thaw that are used for transit.
Anyway, surely one of the fundamental characteristics of the valleys is its great fertility, possibly fed by that difficult access and by the feeding of rivers and streams that descend from the mountain providing the necessary water for the proliferation of all kinds of vegetation.