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

Types of Plains

(i) Structural Plain (ii) Erosional Plain (iii) Depositional Plain

(1)        Structural Plains

Mode of Formation: These are 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.

(2)        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 peneplains while those formed when wind blows and reduces a highland to a flat or level but a gentle land is called pediplain. Examples of erosional plains include Canadian Shield, Reg and Hamada of Sahara desert.

Evaluaton Questions:

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

(3)        Depositional Plain

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:

(a)        Alluvial Plains                                             (b)           Flood Plains

(c)        Deltaic Plains                                              (d)           Outwash Plain

(e)        Aeolian Plains                                             (f)            Lacustrine Plains

(g)        Coastal Plains

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 are 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 serious barrier to communication, especially water either from river or after rain. It therefore increases the cost of developing such areas e.g. construction of flyovers.

Evaluaton Questions:

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

General Evaluation Questions:

1. What is a 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 effects of  earth rotation.

Reading Assignment

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

Weekend Assignment

1.         An extensive area of level or gentle undulating land which is usually a few meters above the sea level is known as (a) Plain (b) Mountain (c) Valley   (d) Plateau

2.         Which f these plain is associated with glacier (a) Deltaic Plain (b) Flood Plain (c) Outwash Plains (d) Lacustrine Plains

3.         Plains formed by agents of denudation are known as (a) Dissected Plain    (b) Residual Plain (c) Erosional Plains (d) Structural Plain

4.         Which of the following is not a depositional plain (a) Outwash Plains        (b) Pedi Plain (c) Deltaic Plain (d) Flood Plain

5.         Great plains of USA is a good example of (a) Volcanic Plains (b) Structural Plains (c) Erosional Plains (d) Depositional Plains

THEORY

1.         Explain briefly the difference between Pene Plain and Pedi Plain.

2.         State four disadvantages of plains.