GEOGRAPHY FULL NOTES ORDINARY LEVEL – (FORM 1 – 4)
GEOGRAPHY FULL NOTES: Geography is the study of distribution and interrelationship of phenomena in relation to the earth’s surface.
Geography is a science that deals with the earth and its life, the description of land sea ,air, plants and animal life including human being and their activities.
It is the science of distributions and is concerned with spatial variations in any physical or cultural.
General Subject Competences
General competences are expressions that describe what a secondary school student does as a result of teaching and learning this subject. It is therefore expected that a Geography student
demonstrates the ability to:-
(a) Understand this country and value it as his/her heritage.
(b) Use natural resources sustainable to raise the standard of living.
(c) Use different ways to overcome day to day social and economic constraints.
(d) Show an understating of interactions between their country and other countries and draw
lessons to solve existing problems.
(e) Observe, record, analyze, interpret geographical phenomena and conducts research.
BRANCHES OF GEOGRAPHY
There are three main branches of geography namely: –
(a) Physical geography
(b) Human and economic geography
(c) Practical geography
A. PHYSICAL GEOGRAPHY
Is concerned with Land formation processes, weather and climate. Also it is the branch of geography that studies all physical features e.g .Mountain, rift valley
The areas covered include:
a) The earth and the solar system.
b) The internal land forming processes.
c) The external land forming processes
d) weather and climate
B. HUMAN AND ECONOMIC GEOGRAPHY OR REGIONAL GEOGRAPHY.
It deals with all activities of human on the earth’s surface, which includes mining, agriculture, transportation, settlement, tourism etc.
The areas covered include:
e) Wildlife and tourism
g) Energy etc.
C. PRACTICAL GEOGRAPHY
Is concerned with field study of photograph interpretation, map work , statistics and research.
The areas under practical geography includes:
a) Statistical methods
b) Map work
c) Field work
d) Photograph work
Importance of studying Geography
a) To gain skills of observing, measuring, recording and interpreting phenomena
b) To understand interaction between our country and other countries and share ideas of solving problems.
c) To acquire skills for combating environment problems in order to conserve and manage the environment in a sustainable way.
d) To develop awareness and knowledge about natural resources(Land forests, mineral deposits, water etc) wild animals climatic regions and other natural resources.
e) It provides base for specialization career for example cartographer, climatology, geologist etc
f) It helps to learn on how other countries in the world solve different problems like fire outbreak disease, environment problems etc.
g) It helps us to understand aspect of weather and climate and how it influence the environment
h) To gain the knowledge of employment opportunities
1. LITHOSPHERE / CRUST
Is the outermost and thinnest zone of the earth which found between 8 – 50km or 5 – 30 miles.
– It is largely composed of igneous rocks.
– Other types of rocks also exist as a result of changes on the earth’s surface. When subjected to forces
or any stress.
– Igneous rocks are hard and brittle.
– The crust also consist of two layers are sial and sima layers.
THE SIAL LAYER
Is the outer layer of the crust which rich in silica and Aluminium minerals.
– The sial layer consist of granites rocks with density of about 2.65.
– The sial for the basis of the continent.
– The presence of silica and aluminium minerals collectively form SIAL layer.
– Is the layer which found beneath the sial.
– Is the inner layer of the crust which separated from sial layer by the zone called Conrad discontinuity
– The sima layer is composed by silica and magnesium.
– It has the density of about
– It forms the basis of ocean floor.
Note: – Sial and sima layer together forms the crust.
2. MESOSPHERE / MANTLE
Mesosphere or mantle which found between the crust and core.
– It lies beneath the crust
– It separated from the crust by the zone of separation called Mohorovic discontinuity line has
temperature which may reaches to.
– It consists of denser rock to about 3.03 –
– It consists of pale green minerals called Olivine (Ferromagnesium silicate) in form of ultra basic rock
– It consists of lower and upper mantle.
– The upper mantle is rigid and crust to form a large layer called lithosphere.
– The lower mantle is less rigid and forms the moltern layer within the earth’s interior called
– Asthenosphere is the molten layer layer which responsible for the balancing movement of the earth’s
material called isostatic readjustment.
– Asthenosphere has been investigated is found between 100 to 200km below the upper surface.
3. THE BARYSHERE / CORE
The core is the innermost zone of the internal structure of the earth.
– It has diameter of about 69000km (4300 miles) density of about.
– The core is also classified into two parts i.e. the outer and inner core.
– It separated from the mantle by zone of separation called Gutenberg discontinuity
– The outer core is liquid in nature because of temperature of up to
– The outer core is consisting of nickel and Iron (NIFE)
– It estimated to be 2100km
– Its density is about.
– The inner core is solid in nature because of high pressure exerted from different parts toward the center
– It composed mainly by iron
– Its density is about 16 – 17
– It has diameter of about 2600 – 2700km. (1600 – 1700 miles)
– The temperature at the center is about
The average density of the whole earth is about 5.17gm/cm
ii) The total mass of the earth is about 5.976 x 1021 tons.
STRUCTURE OF ATMOSPHERE
According to the temperature changes, atmosphere divided into two zones. These are
Homosphere is the layer which found between 0 – 80km above the sea level.
– This is the lowest part of the atmosphere which composed of uniform composition gas of uniform composition of gases and temperature
– Homosphere consist of three layers. These are
– This layer extends by 0 – 15km above the sea level.
– Troposphere is the first layer of homosphere located nearest to the earth
– It contains water vapor, gases and dust particles
– It is the layer of atmosphere which support life on the earth due to the presence of plenty oxygen gas.
– All processes of rainfall formation take place in this layer and the temperature decreases as the altitude increases at the rate of per every 100 meters or per every 1000 meters.
Note: – This situation where by temperature decreases as altitude increases is called lapse rate and because it occurs near to the ground is called environmental Lapse rate.
The upper limit of Troposphere which separates it to the next later is called Tropopause.
Tropopause makes the upper limit of troposphere to the next layer called stratosphere.
Stratosphere exists between 15 – 48 km above the sea level.
– This is the second layer of homosphere which lies above the tropopause.
– It is also composed of water vapor, dust particles and various gases
– It is the layer of atmosphere which characterized by high concentration of Ozonic gases. This gases form Ozone layer which found particularly at 20 – 35 km in the stratosphere
– The Ozonosphere or ozone layer is the layer which form a shield or cover that prevent the earth’s surface from destroying by the sun rays.
– It prevents the direct incoming of harmful rays from the sun to fall direct on the earth’s surface.
– The temperature remains unchanged about between 20 – 35 km from the earth’s surface. Then temperature increases with height to about at the upper limit of stratosphere called stratopause.
– The increase in temperature with height is referred to as temperature invasion.
– This layer extends between 48- 80 kilometers above the sea level.
– Mesosphere is the third part of the homosphere where temperature decreases as the altitude increases.
– It separated from the stratosphere by the zone of separation called stratopause.
– The upper limit of mesosphere is called mesopause.
– Mesopause record minimum temperature of this zone that may fall to making this zone to be coldest.
– It is at this zone where strong upper air streams of wind like jet streams are experienced.
– Is the second layer of atmosphere which extends from 80km towards the interplanetary space
– Heterosphere divided into two layers which include.
– Is the lower part of heterosphere where temperature increases as the altitude increases from – i.e. temperature invasion. This is because; there is no water vapor or dust particle in this zone.
– Is the part of heterosphere which found above the thermosphere.
– It has high temperature through it has little significance as it has not been greatly researched.
Note: – Within the heterosphere, there is also a scientific significant layer called ionosphere.
-Ionosphere consists of some ions which influence radio waves. This is because, ionosphere is electrically charged with free electrons that allow the passage of radio waves, television waves and telephone or mobile phone waves.
– Is the layer of water bodies of the earth including all oceans, rivers, precipitation and underground water.
– It is estimated that 75% of the Earth’s surface is covered by water bodies.
THE LITHOSPHERE / LAND MASS
– Is the whole solid body of the earth with various landforms such as mountains, valleys and plateaus.
– The lithosphere is also known as the crust.
– It includes all land masses. The major land mass is called continent and the minor land mass is called islands.
– Biosphere is the complex zone which comprises all living things.
– It includes a lower level of atmosphere and the upper level of lithosphere and hydrosphere.
– Biosphere receives substantial supply of energy from the sun which gives it condition necessary for life and does not occur in any part of the solar system.
– The living organisms that inhibit biosphere interact with each other and their environment.
– The sum of all these interaction components is called the ecological system or ecosystem.
– Biosphere comprises all living organism both macro and microorganisms living in water bodies, soils and on air.
FUNCTION OF ATMOSPHERE