Plateaux are elevated uplands. They have extensive flat or level surfaces which usually descend sharply to the surrounding lowland. It has gentle slope. They are often referred to as table lands because of their flat or level surfaces. Plateaus are tabular in shape, steep-sided with rough and irregular surface. They have narrow valleys and sometimes used for hydrological centers. Mesas and buttes may be present.
Most Plateaux are relics of ancient mountain ranges.
Types of Plateau
(i) Tectonic Plateau (ii) Volcanic Plateau (iii) Dissected Plateau
(a) Tectonic Plateaux
Mode of Formation: These plateaux are formed as a result of earth movement which causes the uplift of some areas and the depression of others. Uplifted areas of level or undulating land form tectonic plateau and the depressed area form basins.
Tectonic plateau are two types (i) Table Land and Intermont. Examples of Tectonic Plateau include Decan plateau (India), Harz (Germany), and Mesetal (Liberia). Intermont is formed when the uplifted areas are enclosed by fold mountains e.g. Tibetan plateau between Himalayas and Kunlun, and Bolivia plateau.
(b) Volcanic or Lava Plateau
Mode of Formation: These plateaus are formed when molten lava comes out of the earth’s crust through a vent and spreads out in successive layers. The lava cools solidifies to form volcanic or lava plateau. Examples include Antrim plateau of Northern Ireland and Columbia Snake Plateau.
Evaluation Questions:
1. What is a plateau?
2. How is tectonic plateau formed?
3. Mention the two types of tectonic plateau.
(c) Dissected Plateau
Mode of Formation: These plateaux are formed due to weathering and agents of denudation such as running water, wind, ice etc which wear down large and extensive plateau into remnant structures of irregular surface called dissected plateau. They may also be formed as a result of uplift. Examples include Jos Plateau (Nigeria), edges of Fouta Djallon Plateau (Guinea) and Kumasi Plateau (Ghana).
Importance or Uses of Plateau
(1) Some plateaux are sources of valuable mineral like tin, gold, diamond, etc. which are useful to man.
(2) Some plateaux are centers of tourist attraction.
(3) Some plateaux are sources of rivers.
(4) Some plateaux like Jos plateau, have cold climate which encourages settlement of people.
(5) Most plateaux, due to their cold climate and fertility, promote some specialization farming which gives rise to the cultivation of specific crops.
(6) Plateaux also support the growth of pasture grasses and legumes which support the rearing of animals e.g. cattle, sheep and goat.
Disadvantages of Plateaux
- Some plateaux are barriers to communication as they prevent road, railway and airport construction.
(2) Some plateaux are associated with erosion which tends to reduce or prevent serious farming activities.
Evaluation Questions:
1. When will a plateau be regarded as dissected?
2. Give two examples of a dissected plateau.
General Evaluation
- Mention two advantages and two disadvantages of a plateau.
- Explain the mode of formation of a dissected plateau.
- Explain tectonic plateau.
- What is solar system?
- List the nine planets.
READING ASSIGNMENT
Read on plateau in Essential Geography. Pgs 34-35.
Weekend Assignment
1. The uplifted area of the level land which is enclosed by fold mountain is known as (a) table land (b) plateau (c) intermont (d) horst
2. The type of plateau which is formed by agents of denudation is (a) volcanic plateau (b) tectonic plateau (c) residual plateau (d) dissected plateau
3. Jos Plateau in Nigeria is a good example of (a) Volcanic plateau (b) tectonic plateau (c) Dissected plateau (d) Residual plateau
4. Which of these plateaux is known as Lava plateau? (a) Volcanic plateau (b) Tectonic plateau (c) Dissected plateau (d) Residual Plateau
5. Columbia snake plateau is an example of (a) Dissected plateau (b) Volcanic plateau (c) Tectonic plateau (d) Block plateau
THEORY
1. What is intermont?
2. State four uses of plateau.
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