Plains are certainly the most important and populous landforms because the world population lives on them. Some plains have fertile soils and they are extensively cultivated for agricultural purposes. One of the disadvantages of plains is that they are extensively vulnerable to flooding especially when they are located close to the sea or to a large river.
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What is a plain
A plain is an extensive high land above the sea level with a gentle slope. A plain landform shows a land that is less rugged usually with low altitude from sea level. These type of plains have been formed by the erosional and depositional work of different landforming activities like river, glacier, and wind. A gently undulating land with less rugged relief is most suitable for agricultural activity, settlement and road construction. however, concentrated settlements have been developed on plain lands.
Types of Plains
There are three major types of plains based on the mode of formation which include:
- Erosional plains
- Depositional plains
- Structural plains
These are plains that have been levelled by various agents of denudation such as running water, rivers, wind and glacier which gradually wears out the rugged surface and smoothens them as well. In this case, the upper rocks are eroded gradually and the lands with steep slope are transformed to plains. The type of plains formed due to agents of denudation are referred to as Peneplains while those that are formed as a result of wind action are called Pediplain. An example of Peneplain is the Great lakes plain of the Hudson Bay area of North America. An example of Pediplain are Reg and Hamad of Sahara Desert.
Depositional plains are formed by the deposition of materials that have been carried over a long distance by various agents transportation such as winds, water (rivers), waves and glacier. The Formation of this kind of plains can be seen anywhere ranging from mountainous regions to the sea coast. When this action is effected, the following feature are then formed:
- Flood plains: these features are formed as a result of the deposition of sediments moved from the upper course of the river and deposited at the lower course. During this process, the river overflows it banks due to the sluggish movement of sediments in great masses, this slow transportation result to floods and the sediments are then deposited gradually on both sides of the river forming a plain land. Some good examples of these are the flood plains of the Dhaleswari and the lower Niger River in Nigeria where the river overflows its banks.
- Alluvial plains: these plains are formed from the deposition of sediments eroded from the upper course of the a river on the lower course.
- Coastal plains: these plains are formed from the deposition of materials by ocean waves and currents in the continental shelf. An example of this type of plain is the coastal plains of Chittagong which stretches from the mouth of the Feni river up to Teknaf.
- Deltaic plains: these are plains formed from the deposition of sediments brought down by a river on the mouth of that river. A good example of this is the Ganges Delta in the south western part of Bangladesh.
- Outwash plains: these are plains formed from the deposition of sediments brought by glaciers. These type of plains are normally seen in cold areas for example the Prairie of Canada.
- Loess plains: Loess plains are usually found in Arid and semi-arid regions (desert) where fine particles are deposited not only within the desert but in the neighbouring lands. This type of plains are very fertile and intensively cultivated by farmers. An example of this type of plain is the Loess soil of North China and the Sokoto plains in northern Nigeria.
These are plains that have not been altered by earth-movement. The plains are structurally depressed areas of the world that make up some of the most extensive natural lowlands on the Earth surface. Examples of these type of plains are the Great plains of United States of America and central lowland of Australia.
Importance of plains
- Plains support grasslands which in turn provide good pastures for rearing of animals.
- Plains provide rich fertile soils which favours intensive cultivation of crops such as coffee, apples, tea, etc.
- Alluvial terraces have always attracted good settlements and population concentration because of their advantage over valley-bottom flood plains, which are subjected to annual flooding and the hillslopes beyond which may be too steep and rocky to cultivate.
- Towns are easily laid out on flat ground of a terrace.
- Plains provide a levelled ground for sporting activities.
- The provide mineral resources such as coal, petroleum and tin.
- Plains provide good communication route ways such as roads, railways, airports along the terrace surface parallel with the river.
Disadvantages of Plains
- Plains are extensively liable for flooding where they are located close sea or to a large river body.
- Plains may be subjected to a harsh climate depending on its location. A good example is the Sahara desert.
- Plains are not good areas for protection during war as they are easy for an invading enemy to overrun.