Lesson Notes By Weeks and Term - Senior Secondary School 1
MOUNTAINS
MOUNTAINS
SUBJECT: GEOGRAPHY
CLASS: SS1
DATE:
TERM: 2ND TERM
REFERENCE MATERIAL
WEEK ONE
SCHEME OF WORK FOR THE TERM
1 REVISION / MOUNTAINS
2 PLATEAUX
3 - 4 LOWLAND (PLAINS)
5 THE ENVIRONMENT
6 - 7 WEATHER AND CLIMATE
8 COMPONENTS OF GEOGRAPHIC INFORMATION SYSTEM (GIS)
9 INTRODUCTION TO MAP READING: DEFINITION, TYPES OF MAP, AND SCALE
10 MAP DISTANCES (CONVERSION, DIRECTION AND BEARING)
11 REVISION
REFERENCE MATERIAL
Essential Geography for Senior Secondary Schools, O.A. Iwena.
TOPIC: MOUNTAINS
Mountains are great elevated land surfaces resulting from intense action of internal forces. They have steep slopes and show distinct peaks. Mountains are classified according to their mode of formation, resulting in four major types of mountains. These are (i) Fold mountain (ii) Block Mountain (iii) Volcanic Mountain (iv) Residual mountain
(a) Fold Mountains
Characteristics: They contain old hard rocks with steep sides. They have wrinkling or folding appearance and show distinct peaks of great heights. Fold Mountains exist in layered form. They are soft, and have anticlines and synclines.
Folding shortens the earth’s crust. They form most wide spread type of Mountains and are noted for active volcanoes. They form the highest Mountain ranges. Examples of Fold Mountains include Himalayas, Rockies, Andes, Alps and Atlas Mountains.
Mode of formation: They are formed by large-scale horizontal earth movement as a result of stress and compressional forces which cause expansion or contraction of some parts of the earth. Such stresses therefore subject the rocks to compressional forces.
The compressional forces produce wrinkling or folding of the earth. The up folds of the wrinkles are anticlines while the down folds are called syncline.
A fold may be simple, but where the compressional forces are complex, it results in asymmetrical folding. When pushed further, it forms an over-fold. An over-fold later forms a recumbent fold. In some cases, faults or cracks result in extreme folding to form over thrust fold.
Evaluation Questions
(b) Block Mountains
Characteristics: Block Mountains are made up of old hard rocks with flat or slightly sloping surfaces. They have steep sides. They are associated with rift valleys. Examples of Block Mountains include Hunsruck Mountain, Voges Mountain and the Black Forest of the Rhine land. Example of rift valley is the East African rift valley system which is about 4.800km.
Mode of formation: Block Mountains are formed when the earth cracks due to faulting. Faulting may result from tensional forces or compressional forces. Tensional forces are those that tend to pull the earth’s crust apart and they result in a normal fault while the Compressional forces are those that shorten the crust to produce a reverse or thrust fault. Therefore, if a block of rock between two normal faults rises or the land on either sides of the block subsides, a Block mountain or Horst is formed. At times, a block in between two faults may subside so that rift valley or graben is formed. The slopes and height of Block Mountains are modified by agents of denudation.
Evaluation Questions:
(c) Volcanic Mountain
Characteristics: Volcanic Mountains are made up of lava. They have irregular sides with conical shape. Materials that make up volcanic mountains include ash, volcanic bombs, and cinders which are arranged in layers. Examples include Mt. Fuji (Japan), Mt. Mayon (Philippines), Mt Kilimanjaro, Kenya, Elgon, Ruwenzori and Cameroon (all in Africa).
Mode of formation: Volcanic Mountains are formed from volcanoes which are built from materials (molten magma) ejected through fissures or vents in the earth’s crust. The materials also include molten lava, volcanic bombs, cinders, ash, dust and liquid mud. They fall around the vent in successive layers, building up an extensive volcanic cone. Volcanic mountains are also called mountain of accumulation.
(d) Residual Mountain
Characteristic: Residual Mountains are formed from the remains of already existing mountains. They have irregular surfaces with steep sides. They occur in varying heights and sizes and are caused by agents of denudation. Examples include Mt Manodnock (U.S.A), Highlands of Scotland, Highlands of Scandinavia and Decon Plateau.
Mode of formation: Residual Mountains are formed from already existing mountains which are lowered or reduced by agents of denudation such as running water, ice and wind. Residual mountains are therefore, the remains of the existing mountains. Some hard and very resistant parts of the existing mountains remain after the lowering of the upper part. This remaining part is called residual mountain which is also called mountain of denudation.
Importance or uses of mountains
Disadvantages of Mountains
Evaluation Questions:
General Evaluation Questions
Reading Assignment
Read on mountains in Essential Geography, Pgs. 31-33
WEEKEND ASSIGNMENT
(a) synclines (b) anticlines (c) push ups (d) push downs
(c) Mt. Kenya (d) Alps
THEORY
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.
(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:
(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).
(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.
(2) Some plateaux are associated with erosion which tends to reduce or prevent serious farming activities.
Evaluation Questions:
General Evaluation
READING ASSIGNMENT
Read on plateau in Essential Geography. Pgs 34-35.
Weekend Assignment
THEORY
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