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GEO3: AFRICA

Geography Senior Three, Unit One

Introduction

Africa is the second-largest continent of the world after Eurasia (combines Europe and Asia) it is about three times as large as Europe and has a total area of 30,300,000 km2.

Africa generally has a smooth coastline which makes it have a compact shape. It has several countries that are far away from the sea which makes it a disadvantage because goods from far inland have to go through long distances before reaching the sea and then to the world market.

POSITION OF AFRICA

Africa is caused by the Equator extended from 370N to 33 /340 about 2/3 of the total area lies between the two tropics more than half of the continent lies in the Northern hemisphere because of the extensive land occupied by West Africa and from the North to the South in a straight line is 7200km.

Africa is crossed by three major latitudes.

  1. The Equator (00)
  2. Tropic of cancer (2320N
  3. Tropic of copricam (2320S)

Africa is also surrounded by several islands, the largest being Madagascar then Zanzibar, Pemba, Canary island.

Africa as a continent is covered/ characterized by several rivers and this include: River Nile, R. Ruvuma, Blue Nile, R. Tana, R. Orange, R. Rufigi.

There are also great lakes and this includes L. Victoria and L. Tanganyika of East Africa being the largest and deepest respectively in Africa, the others include L. Chad, L. Kyoga, L. Turkana, L. Albert etc.

A MAP OF AFRICA SHOWING COUNTRIES, MAJOR LAKES, RIVERS, OCEANS AND ISLANDS

 

africa

Redraw this map and fill everything on it

Africa is characterized by ocean currents. Ocean currents can be defined as drifts or mass of water moving in a specified direction. There are 2 types of ocean currents namely:-

Cold ocean current and warn the ocean current.

Cold ocean currents

The means water which moves away from the polar region towards the Equator. Examples include The canary and Benguela currents.

Characteristics  

  • They are cold in nature
  • Cold ocean currents originate from the polar region to the Equator.
  • They are located on the western side of the continent
  • The lower the temperature of the surrounding areas.
  • They are responsible for the formation of desert conditions like the Namib Desert in S. West Africa and the Sahara desert in N. West Africa.
  • They are responsible for the formation of tog which is responsible for the poor visibility

EFFECTS

  • The lower temperature of the surrounding area
  • Cause poor visibility
  • They cause desert conditions
  • They promote fishing activities.

Warm ocean current

These are ocean currents that originate from the Equator towards the polar region.

Examples include- Mozambique’s current Guinea currents.

Characteristics

  1. They are warm in nature
  2. Always on the on Eastern side of the continent
  3. They rise temperatures of the surrounding area.
  4. Responsible for heavy rainfall in surrounding areas.
  5. They move clockwise.

EFFECTS

  1. They Rise temperature of the surrounding area
  2. Promote Agriculture activities.
  3. They lead the surrounding area

A MAP OF AFRICA SHOWING THE DIFFERENT OCEAN CURRENTS.

africa1

KEY

Ocean current

Cold Ocean current

Warm ocean current

Ocean

RELIEF FEATURES OF AFRICA

The text box below describes the Relief features of Africa. Mark all words that are examples of relief features

An illustration of a volcano.

volcano

 

THE PLATEAU

This is a large flat area that is high above sea level almost ¾’s of Africa is made up of a plateau. The high plateau lies between 900_1300m above sea level.

It is mainly found in the south and eastern parts of the continent. The plateau is higher in the east and lower in the west. It is interrupted by rivers, lakes, mountains and the rift valley.

Plateau
The plateau

THE HIGHLANDS (200M ash)

These include land which is over 200m above sea level.

The cards below show the 3 types of Mountains.  Click on the button above the description for the audio, turn card to see the answer and click on the lower right-side button to go to the next card.

Highlands receive high rainfall and low temperature due to the high altitude.

Highlands such as Ethiopia highlands, Cameroon mountains, Mt. Kilimanjaro and the Longonot Mt. of Kenya, Tibesti, Haggar of the Sahara desert are a result of volcanicity.

Volcanicity is a process through which rocks and gases are forced onto the earth’s surface/ crust due to heat and pressure underground.

When cracks develop in the earth’s crust, larva escapes at times instead of following for a long distance. Larva which is thick and more solid builds up a volcano when it reaches the surface.

On top of a volcano, a crater is formed and sometimes a lake can be formed.

Formation of a crater

Craters can be formed by mass explosion. This occurs when acidic larva blocks the pipe and pressure builds up until it can no longer be contained and a huge explosion takes place which flows off the top of the volcano.

crater

 

Alternatively, a crater can be formed by subsiding. There is space left beneath a volcano after a violent eruption and nothing is left to support the weight of the volcano and then the top of the volcano just collapses on itself

crater1

 

The cone material sinks into the magma, living a huge often circular depression that may fill to form a lake. The larva in the central pipe is usually much harder than the outside slope which may easily be eroded and the hard central cone which is left out sliding. This is called a volcanic plug.

Examples; – Tororo Rock and

  • Fisheries tower in Kenya.
  • Peaks of mountain Kenya.
  • Kilimanjaro

Folding;

Folding of acient segmentary rocks took place in North West Africa and Northern tip of Africa. Examples of fold mountains; Atlas and Cape ranges.

Fold mountains are formed when huge water-filled depression within the earth’s surface known as Geosyndines gradually fills with waterborne deposits of eroded Rock material.

Gradually the increased weight in the deposits deepens the geocydines towards the central.

Pressure on the segmentary Rock is increased and slowly they are folded up and uplifted out of the water high in the atmosphere.

The formation of the Northern Fold Mountain of Africa.

block

block2

 

 

 

BLOCK MOUNTAINS (HOST MOUNTAIN)

A host is araised fault block. It is found in areas of normal faulting. The formation begins with the division of earth’s crust into individual fault blocks.

After which the block move at different rates (directions)ie 3 blocks may be forced to move but the middle one rises faster than the outer tabs. The faster moving block will form the peak of the horst.

Three blocks may ie downwards but the outer 2 slip faster than the one in the middle. The block which remains on the upper elevation it becomes the peak of the horst.

blocks

The 2 outer blocks remain while the middle one alone is forced to rise alone.

stable

 

A MAP SHOWING THE RELIEF OF AFRICA.

africa2

 

IMPORTANCE OF HIGHLANDS (uses)

  1. We are able to grow certain crops that need a relatively higher altitude and fertile soils in that way promote cultivation.
  2. For tourist attraction.
  3. Source of water from crater lakes for domestic use and fishing.
  4. For mineral resource ie some highlands are deposited with minerals, thus promoting mining.
  5. Forestry and lumbering on highlands.
  6. For settlement.
  7. Employment for people who carry luggage for mountain climbers (tourist).
  8. Development of rural areas through tourism and mining.
  9. Foreign exchange from tourists.
  10. Source of income from Revenue and tax to the government.
  11. Sources of river which can be used for transport.
  12. Hot springs used in generation of geothermal power and medicinal purposes.
  13. Act as boundaries for regions.

Negative effects of highlands (problems.)

  1. Transport and communication are made difficult.
  2. Natural hazards like landslides, eruption which may lead to death of people.
  3. Barriers to easy settlement because of each wild animals and natural hazards.
  4. Dry conditions on the leeward side that doesn’t favour farming.
  5. High mountains have cold conditions which don’t favour settlement.
  6. Act as hiding places for rebels.
  7. Steep mountains faced with a problem of soil erosion which is growing to lead to low yields.

 

Attachments14

ASSIGNMENT : AFRICA -S.3 assignment MARKS : 10  DURATION : 1 week, 3 days