Lowland (Plains)

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Welcome to class! 

In today’s class, we will be talking about lowland (plains). Enjoy the class!

Lowland (Plains)

A plain is an extensive area of level or gentle undulating land, usually a few meters above the sea-level.

Types of plains

1. Structural Plain
2. Erosional Plain
3. Depositional Plain

• Structural plains:

Mode of Formation: These are the relatively undisturbed horizontal surface of the earth, formed by bedded sedimentary rocks. Examples include the Russian Platform and the Great Plains of the U.S.A.

• Erosional plains:

Mode of Formation: These plains are formed by the agents of denudation such as river, wind, rain, glacier and ocean waves which wear out irregular rock surface and smoothen them into plain known as erosional plains. Plain, resulting from the action of these agents of denudation are called pen plains while those formed when the wind blows and reduces a highland to a flat or level but a gentle land is called Pedi plain. Examples of erosional plains include Canadian Shield, Reg and Hamada of Sahara desert.

 Evaluation

1. What is plain?
2. State the types of the plain.

• Depositional plains:

Mode of formation: These are plains formed by the deposition of materials or sediments transported by the various agents of transportation such as river, wind, wave and glacier.

Depositional plains are grouped into the following categories:

1. Alluvial Plains
2.  Flood Plains
3. Deltaic Plains
4. Outwash Plain
5. Aeolian Plains
6. Lacustrine Plains
7. Coastal Plains

• Alluvial plains are formed from the deposition of sediments eroded from the upper course of a river to the lower course of that river. The deposition materials on the lower course of the river from the alluvial plains.
• Flood plains are also formed from the deposition of sediments eroded from the upper course of a river and deposited materials on the lower course, especially when the river overflows its banks. It can also be formed from the deposition of sediments carried by running water e.g. flood.
• Deltaic plains are formed from the deposition of sediments brought down by a river onto the mouth of that river. Alluvial, flood and deltaic plains are all rich and fertile soils which are very good for serious farming activities.
• Outwash plains are formed from the deposition of materials brought down by glaciers.
• Aeolian plains are formed in arid or desert and semi-arid regions where wind-blown sand is deposited to form to form an extensive plain.
• Lacustrine plains are formed for the deposition of sediments which covers beds of lakes that have become dry.
• Coastal plains are formed in the deposition of sediments brought by ocean waves on the continental shelf. Coastal plains can also be formed by the uplift of part of sea-floor bordering a continent.

Importance or uses of plains

1. Plains, especially level ones are good for human habitation. Population and settlements are usually concentrated on plains.
2. Some plains are rich sources of minerals like petroleum and coal.
3. Plains, especially depositional plains are rich fertile soils which favour intensive agriculture.
4. Plains generally favour construction of roads, railway and airport.
5. In areas of low rainfall, rearing of animals is carried out in plains as they favour the growth of pasture.
6. Rivers in plains provide water for drinking and transportation.
7. Rivers in plains provide jobs e.g. fishing.

Disadvantages of plain

1. Some plains, especially in delta areas may be flooded with water and this reduces human activities.
2. Some may pose a serious barrier to communication, especially water either from the river or after rain. It, therefore, increases the cost of developing such areas e.g. construction of flyovers.

 Evaluation 

1. Explain depositional plain.
2. State the uses of plain.

 General evaluation

1. What is plain?
2. Mention the major types of plains.
3. Mention any five types of depositional plains.
4. Differentiate between structural plain and erosional plain.
5. Explain the effects of earth rotation.

 Reading assignment

Read on plains in Essential Geography, Pgs. 35-36.

Theory

1. Explain briefly the difference between Pene Plain and Pedi Plain.
2. State four disadvantages of plains.

 

In our next class, we will be talking about the Environment.  We hope you enjoyed the class.

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