Almost everyone knows what plains are and how they look, because most people live on them. And human economic activity is also mainly associated with these landforms. At first glance, they all seem the same and monotonous, because there are no sharp changes in elevation, as in mountainous countries, terrible earthquakes do not occur here, there are no snow avalanches and terrible mudflows.
Flat or slightly hilly land areas are called plains. They, unlike mountains, are usually located on ancient stable sections of the earth's crust, called platforms. Therefore, they are stable and inactive, and the history of their development is usually ancient and much more complicated than in the mountain zones of our planet.
To answer the question of what the plains are, you need to know about their great diversity. They can have not only different origins, but also different heights above sea level. Depending on this, emit:
- lowlands;
- elevations;
- plateaus.
Lowlands include land with a height of up to 200 meters. In some interior regions of the continents, they may even be lower than the level of the World Ocean, for example, the Caspian lowland, whose height is minus 28 meters. They occupy significant areas along the coasts of the seas and oceans. Everyone knows what plains stretch along the Gulf of Mexico - these are swampy and often flooded areas. In some cases, coastal lowlands are located in areas of the earth's crust, which are gradually descending. On one of these is the famous Italian city of Venice, slowly going under the water. The inhabitants of the Netherlands recaptured almost a third of the territory of their country from the advancing sea, which is constantly under the threat of flooding.
Some lowlands are located in platform troughs, for example, the East Siberian Plain, and represent vast swampy spaces along which one or more large rivers flow.
Large areas are occupied by lowlands in the valleys of large rivers. The Amazonian lowlands in South America and the West Siberian in the Asian part of Eurasia are considered one of the largest plains of the planet. Mesopotamian - is the place of origin and prosperity of one of the most ancient civilizations.
What are the highlands plains can be judged by the Great American and desert central parts of Australia. Sometimes on hilly elevated areas there are remains of ancient mountain ranges in the form of single elevations.
The plateaus by all indications belong to the plains, only raised above them to considerable heights. Often they are divided by deep canyons into separate parts. In their geological history, these land areas were first leveled and then elevated by new tectonic movements. A striking example of this is the Colorado Plateau, located in North America.
An even relief, a favorable climate, good fertile soils contribute to the intensive development of these relief forms, many of which are the most densely populated areas of the Earth. In this regard, the Great Plain of China stands out, with such large cities as Beijing and Tianjin.
