Meaning of Plains

Detailed Explanation of Plains

A plain is an extensive area of relatively flat or gently rolling land. Unlike mountains that rise steeply or plateaus that stand high above surroundings, plains have very little variation in height. When you stand on a plain, you can see far into the distance because there are no hills or mountains blocking your view.

Plains rarely rise more than a few hundred meters above sea level. Most are found below 200 meters elevation. The land may be completely flat like a table top, or it may have gentle rolling hills. The key feature is that slopes are gradual, not steep. You can walk or drive across a plain easily without climbing up and down.

In Nigeria, plains are found in many regions. The Chad Basin in the northeast is a large plain surrounding Lake Chad. The Niger Delta region in the south is a coastal plain formed by sediment deposits from the Niger River. The Sokoto Plains in the northwest and parts of the Middle Belt also contain extensive plain areas.

How Plains Are Formed

Plains develop through different natural processes over millions of years. Understanding how they form helps explain why they have different characteristics.

Erosional Plains

These plains form when rivers, wind, and rain wear down high land over long periods. Mountains and hills are slowly eroded away, and the material is carried off. What remains is a flat or gently sloping surface. The process takes millions of years. Most old land surfaces have been eroded into plains. Parts of the Nigerian basement complex have been worn down to create erosional plains.

Depositional Plains

These form when rivers, glaciers, or ocean waves deposit sediment in an area. As material builds up over time, it creates flat land. The Niger Delta is an excellent example. The Niger and Benue rivers carry silt and sand from inland areas and deposit it where they meet the Atlantic Ocean. Over thousands of years, these deposits have built up a large coastal plain.

Floodplains along rivers like the Niger and Benue are also depositional plains. During floods, rivers overflow their banks and spread sediment across the surrounding land. This happens year after year, building up flat, fertile areas alongside the river.

Structural Plains

These plains form from horizontal layers of rock that have not been folded or tilted. They are often created when ancient seabeds are exposed as sea levels drop or land rises. The rock layers remain flat, creating a plain surface. Some parts of the Sokoto Basin are structural plains formed this way.

Volcanic Plains

These rare plains form when lava flows spread over large areas and cool into flat surfaces. The lava is so fluid that it creates level ground rather than building up into volcanic mountains. Volcanic plains are not common in Nigeria, but they exist in places like parts of eastern Africa.

Characteristics of Plains

Plains share several important features that make them valuable for human use.

Flat or Gently Sloping Terrain

The defining feature of all plains is their level surface. Slopes are so gentle that water does not run off quickly. This allows rain to soak into the ground, which is good for farming. The flat terrain also makes construction easy and cheap.

Fertile Soils

Many plains, especially depositional plains near rivers, have very fertile soil. Rivers deposit nutrient-rich sediment during floods. This sediment contains organic matter and minerals that plants need to grow well. The Niger Delta and Benue floodplains are extremely fertile because of regular sediment deposits.

Even erosional plains can have good soil if the underlying rock contains valuable minerals. The lack of steep slopes means soil stays in place rather than washing away. Farmers can use the same fields year after year without serious soil loss.

Good Drainage or Poor Drainage

Plains can have different drainage characteristics. Some plains have rivers and streams that carry water away efficiently. Others may have poor drainage, creating swamps and marshes. The Chad Basin plains sometimes flood during the rainy season because water cannot drain away quickly on such flat land.

Easy Access and Transportation

The flat terrain of plains makes them ideal for roads, railways, and airports. Construction is cheaper because you do not need to cut through mountains or build bridges over deep valleys. Roads can be straight, which reduces travel time and costs. Nigeria’s major highways run across plains whenever possible.

Why Plains Are Important

Plains are the most valuable land in any country for human activities. They offer advantages that mountains and plateaus cannot match.

Agricultural Productivity

Plains provide the best land for farming. The flat terrain allows farmers to use tractors, combine harvesters, and other modern equipment. Large farms can operate efficiently. The fertile soil produces high crop yields. Nigeria grows most of its rice, cassava, yams, and maize on plains.

The Middle Belt plains are major food-producing areas. The Benue valley plains support rice farming. The coastal plains in the south grow cassava, plantains, and vegetables. Without plains, Nigeria would struggle to feed its large population.

Dense Settlement and Cities

Most people live on plains because life is easier there. Building houses and towns is simple on flat land. Water and electricity systems are cheaper to install. Roads connect communities easily. Nigeria’s largest cities including Lagos, Kano, Ibadan, and Port Harcourt are all located on plains or coastal lowlands.

Plains allow cities to expand in all directions as populations grow. There are no mountains to block expansion. This is why plain areas tend to be densely populated compared to mountainous regions.

Industrial Development

Factories and industries prefer plains for several reasons. Flat land is cheap and easy to build on. Transportation of raw materials and finished products is efficient. Workers can commute easily from nearby towns. Industrial estates in Nigeria are almost always located on plains.

Transportation Networks

Railways, highways, and airports are built on plains whenever possible. The flat terrain reduces construction costs dramatically. Trains can travel faster on level ground than on slopes. Airports need long, flat runways that only plains can provide easily. Nigeria’s rail network connecting Lagos to Kano runs across plains for most of its route.

Types of Plains in Nigeria

Coastal Plains

These are found along the Atlantic coast in southern Nigeria. The Niger Delta is the largest coastal plain. These areas are very flat, often barely above sea level. They are formed by sediment deposits from rivers meeting the ocean. Coastal plains are fertile but may flood easily.

River Floodplains

Found along the Niger and Benue rivers and their tributaries. During annual floods, rivers deposit fresh sediment, making these plains extremely fertile. Farmers grow rice, vegetables, and other crops on floodplains. Towns like Lokoja sit on floodplains where rivers meet.

Interior Plains

These plains are found away from coasts and major rivers. The Sokoto Plains and parts of the Chad Basin are interior plains. They may be formed by erosion or from horizontal rock layers. Interior plains are important for agriculture and grazing livestock.

Comparison: Plains vs. Other Landforms

Challenges of Plains

While plains offer many advantages, they also have some disadvantages that students should know for WAEC exams.

Flooding Risk

Low-lying plains near rivers or coasts can flood during heavy rains or high tides. The flat terrain means water spreads over wide areas rather than running off quickly. The 2012 floods in Nigeria affected many plain areas along the Niger and Benue rivers, destroying farms and homes.

Poor Drainage in Some Areas

Very flat plains sometimes have poor drainage, creating swamps and marshes. These areas may be unsuitable for farming or settlement without expensive drainage systems. Parts of the Niger Delta remain swampy because water cannot drain away naturally.

Soil Erosion from Wind

Plains with little vegetation can suffer from wind erosion. Strong winds blow away dry topsoil, especially during the dry season. The Sokoto Plains experience some wind erosion when the Harmattan wind blows from the Sahara Desert.

Limited Minerals

Sedimentary plains may lack mineral resources like metals and precious stones, which are more common in mountainous areas. However, some plains contain oil and natural gas, like the Niger Delta.

Common Exam Mistakes

Mistake 1: Confusing plains with plateaus. Remember that plateaus are high flat areas, while plains are low flat areas. A plateau is like a table standing on legs; a plain is like a table lying on the floor.

Mistake 2: Writing that all plains are formed the same way. WAEC examiners want you to know that plains form through different processes: erosion, deposition, volcanic activity, or structural geology. Explain the specific process when asked.

Mistake 3: Listing features without explaining why they matter. Instead of just writing “plains have fertile soil,” explain that fertile soil makes plains ideal for agriculture, which feeds large populations and supports the economy.

Mistake 4: Forgetting to give Nigerian examples. Examiners prefer answers that reference local examples like the Niger Delta, Sokoto Plains, or Chad Basin rather than foreign examples.

Mistake 5: Writing “plains are completely flat” when they can be gently rolling. Use accurate language: “flat or gently undulating” is better than “completely flat.”

Practice Questions

Multiple Choice Questions

1. A plain is best described as:
a) A high flat area with steep sides
b) A broad, flat or gently rolling expanse of land at low elevation ✓
c) A pointed peak rising high above surroundings
d) A deep valley between two mountains

2. Which of these is an example of a plain in Nigeria?
a) Jos Plateau
b) Obudu Mountains
c) Niger Delta ✓
d) Mambilla Plateau

3. Depositional plains are formed by:
a) Volcanic lava cooling into flat surfaces
b) Rivers and waves depositing sediment over time ✓
c) Tectonic plates pushing land upward
d) Ice glaciers carving out valleys

4. Why are plains ideal for agriculture?
a) They have steep slopes for water drainage
b) They are too high for pests to survive
c) Flat terrain allows mechanized farming and soil is often fertile ✓
d) They receive less rainfall than other areas

Essay/Theory Questions

1. Define a plain and explain three ways in which plains are formed. (10 marks)

Examiner’s tip: Start with a clear definition (flat/gently rolling lowland). Then explain three formation processes in detail: erosional (wearing down of high land), depositional (rivers/ocean depositing sediment), and structural (horizontal rock layers exposed). Use Nigerian examples like the Niger Delta for depositional plains.

2. State five characteristics of plains. (5 marks)

Examiner’s tip: “State” means list without long explanations. Simply write: (i) Flat or gently sloping terrain (ii) Low elevation, usually below 200 meters (iii) Fertile soils, especially depositional plains (iv) Easy access and transportation (v) Dense settlement and cities.

3. Explain four reasons why plains are important for human activities. (8 marks)

Examiner’s tip: “Explain” requires details. For each reason, say what it is and why it matters. Example: “Plains provide excellent agricultural land because the flat terrain allows use of tractors and combines, while fertile soils produce high crop yields to feed large populations.” Give four such detailed explanations.

4. Compare and contrast plains and plateaus with reference to examples from Nigeria. (12 marks)

Examiner’s tip: Comparison means showing similarities and differences. Similarities: both can have flat surfaces, support farming and settlement. Differences: elevation (plains are low, plateaus high), formation processes, climate. Use Nigerian examples: Niger Delta plains vs Jos Plateau. Structure your answer clearly with paragraphs for similarities and differences.

Memory Aids

Remember FLATS for plain characteristics:

• Flat or gently rolling terrain
• Low elevation (below 200 meters typically)
• Agricultural productivity (fertile soils)
• Transportation ease (roads, rail, airports)
• Settlement density (cities and towns)

Plain formation: Remember DEVS

• Depositional plains (rivers deposit sediment)
• Erosional plains (wearing down of high land)
• Volcanic plains (lava flows create flat surfaces)
• Structural plains (horizontal rock layers)

Nigerian plains: Think “NCS”

• Niger Delta (coastal plain)
• Chad Basin (interior plain)
• Sokoto Plains (interior plain)

Related Topics

To deepen your understanding of landforms, explore these related geography topics:

• Types of Plateaus and Their Formation
• Negative Effects of Mountains (contrast with plain advantages)
• River Landforms and Depositional Features
• Coastal Landforms in Nigeria
• Soil Types and Fertility in Different Landforms