form two notes.pdf

8/12/2019 Form Two Notes.pdf

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TABLE OF CONTENTSContents Page

Chapter one 1-22

Chapter two 23-39

Chapter three. 40-43

Chapter four 44-49

Chapter five 50-53

Ch apter six. 54-62

Chapter seven 63-76

Chapter eight. 77-80

Chapter nine... 81-91

Chapter ten.. 92-101

Chapter eleven 102-119


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CHAPTER 1: INTERNAL LAND FORMING

INTERNAL LANDFORMING PROCESSES Landforms are a result of various processes that operate inside the earth . These are the internal land forming processes, also called endogenetic or

endogenic processes.

EARTH MOVEMENTS These are adjustments of the crustal rocks caused by tectonic forces. There are two types of earth movements;

1. Horizontal earth movements.2. Vertical earth movements

HORIZONTAL EARTH MOVEMENTS Also known as Lateral or orogenic movements. Operate along a horizontal plane within the crustal rocks. They cause the earth rocks to:

1.stretch(tensional forces)2.shorten(compressional forces)3.shear(opposite forces)

TECTONIC FORCES THAT CAUSE HORIZONTAL EARTH MOVEMENT


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COMPRESSIONAL FORCE

SHEARINGBlocks moving past each other

VERTICAL EARTH MOVEMENTS Also known as Epeirogenic movements Operate along the radius of the earth .

They cause the crustal rocks to be :1. Lifted upwards(up warping)2. Pulled downwards (down warping)3. Tilted.


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CAUSES OF EARTH MOVEMENTS Movement of magma within the earth crust.

Gravitative pressure. Convectional currents within the mantle. Isocratic adjustment.

CONVECTIONAL CURRENTS IN THE MANTLE

EFFECTS OF EARTH MOVEMENTS ON THE LANDSCAPE Horizontal Earth movements are responsible for:

a) Fold mountainsb) Rift valleyc) Fault blocksd) Escarpmentse) Basins Vertical earth movements are responsible for:

a) Rift valleyb) Tilt blocksc) Escarpmentsd) Basinse) Raised clifff) Raised beachesg) Sub -merged coasts


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Fold mountain

Escarpment


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Raised beach

Sub-merged coasts

THE THEORY OF CONTINENTAL DRIFT. Its by ALFRED WEGNER. It states that the earth was one land mass called pangea. It was surrounded by a water mass called panthalassa. Pangea broke into two blocks:

a) Laurasiab) Gondwanaland

The two blocks were separated by a narrow ocean called Tethys.Laurasia broke into :

a) Laurentian shield.b) Fennoscadia

Gondwanaland broke into:a) Africab) Australia

c) The Americas


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d) Antarcticae) The Indian Sub-continent

Africa and the Indian sub-continent drifted northwards while Australia driftedeastwards. The Americas drifted westwards.

Continents


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PROOFS OF THE CONTINENTAL THEORY Jigsaw fit of the countries bordering the Atlantic Ocean. Evidence of paleoclimates is shown by ancient glaciations in some of the

continents. Presence of major coalfields in both the northern and southern hemisphere. Evidence of the mid-Atlantic ridge . The cape folds of South Africa resemble those to the south of Argentina. Evidence of the shores of the red sea having undergone lateral displacement

THE PLATE TECTONICS THEORY The earths crust is a series of semi - rigid blocks called tectonic plates. The plates are separated by distinct boundaries . The plates move along their boundaries relative to each other. There are three types of boundaries:

a) Extensional /constructive /divergent boundaryb) Compressional /destructive /convergent boundary.c) Transform plate/conservative boundary

THE TYPES OF BOUNDARIES Extensional boundary has the plates moving away from each other. Compressional boundary has the plates moving towards each other. When an oceanic plate collides with a continental plate ,the edge of the

oceanic plate slides beneath the continental one in a movement calledsubduction.

When oceanic plates collide , there is subduction to form a trench.

EXTENSIONAL AND COMPRESSIONALBOUNDARY


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Trench and oceanic ridge

Plate boundaries

Beautiful landform


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Folding Folding is the process of crustal rocks distortion whereby young sedimentary

rocks are bent upwards or downwards by compressional forces It occurs in

young rocks. The magnitude of the fold depends on the amount of force involved. The uplifted part is the anticline while the sunken part is the syncline. The

crest is the uppermost part of the anticline while the trough is the lowest partof the syncline.

Types of folds.Simple symmetrical folds.

They are caused by compressional forces of equal magnitude causing therocks to bend evenly.

Assymetrical folds They result from compressional forces of unequal magnitude causing one

slope to be steeper.

Overfold. They are asymmetrical folds caused by a very strong force pushing against a

resistant force causing the anticline to be pushed over the next fold.

Isoclinal folds.

This is a group of folds closely packed together wit all limbs almost in parallelwith each other or dipping in one direction.


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Nappe/overthrust fold. Great pressure due to compressional forces may cause a fracture to occur

hence one limb is thrust by a stronger force over the other such that the

overlying fold slides forward along the surface of the fracture also called thethrust plane.

Anticlinorium and synclinorium complex. Initially land may be subjected to minor folding resulting in formation of minor

folds. When much greater forces act on this land they form bigger folds. The up fold being the anticlinorium and the down fold being the synclinorium.

Recumbent folds.They are overfolds which are completely pushed over one side such that they almost

lie in a horizontal manner

Features from foldingRolling plains

Low lying and relatively level land can be transformed into a rolling plain . Ifcompressional forces act on a landscape forming gently sloping anticlines andwide synclines.


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Ridge and valley landscape. Where compressional forces are stronger and uneven the landscape could be

transformed into a series of assymetrical folds forming a topography of ridgesand valleys.

Fold mountains. They are formed via folding.

Theories to explain formation of fold mountains.Contraction theory:

As the earth cooled the crust cooled faster hence when the interior begancooling the crust started to wrinkle to fit in the cooling interior rocks, formingthe fold mountains.

Disadvantage of the theory Wrinkling would have resulted in very high mountains that the world could

support. Fold mountains are sedimentary rocks formed many years after the earth was

formed.

Convectional currents theory:It states that when convectional currents in the mantle move horizontally they causea frictional pull on crustal rocks, the coasts in between the land are compressedforming the folds.

CONTINENTAL DRIFT THEORY:During the drift India drifted northwards against static Eurasia. The crust and sediments were squeezed by the Indian subcontinent against

Eurasia causing folding and forming Himalayas mountains.PLATE TECTONICS THEORY:When an oceanic plate meets a continental one the edge of the oceanic plate sinksin a process called subduction.

The sediments at the bottom are compressed causing them to fold.


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Formation of foldmountains by geosyncline

An extensive depression called a geosynclines formed on the surface andwas filled with water.

The surrounding land masses were eroded and the materials were depositedin the geosynclines .

The weight caused the land to subside and as it subsided compressionalforces acted on the land and caused the sediments in the geosynclines foldinto mountains bordering a water body . Examples are the Alps and Atlas.

Inter-montane plateausThis is a level land between mountains formed when edges of rocks are folded toform mountains but the middle ground is unaffectedExample are the Bolivian plateau of S.America and Tibetan plateaus


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Inter-montane basins They are formed when inter-montane plateaus are formed and the fill with

water. Examples are the Utah in U.S.A , Great basin of Nevada etc,

Fold mountains formation periods. Orogenesis : It is the process of fold mountain formation. Orogeny : It is the fold mountain building period. They are; Charnian orogeny Caledonian orogeny Hercynian orogeny Alpine orogeny

DISTRIBUTION OF FOLD MOUNTAINSAFRICA

Atlas mountains-Morocco Drankensberg mountains-South Africa

ASIA Himalayas mountains

EUROPE Alps mountains

NORTH AMERICA Rockies mountains Appalachians mountains

SOUTH AMERICA Andes mountains

SIGNIFICANCE OF FOLDINGPOSITIVE EFFECTS

Intense pressure and heat exerted on rocks may lead to metamorphism ofrocks.

Fossil fuels are exposed. Fold mountain slopes receive rainfall hence supporting growth of vegetation The folding process enhances the beauty of the scenery,. It leads to formation of lakes.

NEGATIVE EFFECTS. Intense compressional force leads to fractures in rocks that cause vulcanicityto occur and earthquakes leading to loss of property and life.

Mountain climates are cold while their leeward side is dry hence hindersettlements.

Fold mountains result to rugged slopes that hinder transport andcommunication and make it expensive to construct their facilities.

High fold mountains cause poor visibility to aircrafts when it is foggy. Leeward sides of the fold mountains do not support vegetation and could lead

to aridity.


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Faulting

What is faulting? Its the process of crustal rocks breaking due to tectonic forces

Features resulting from faulting Fault scarps Fault steps Fault blocks Tilt blocks Rift valleys

PROCESS OF FAULTINGForces involved; Tensional forcesCompresional forces


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Fault scarps/escarpments They are the exposed parts of fault planes

Examples; Ethopian scarp(one of the highest in the world) Nyandarua scarp- Kenya

Fault blocks They are raised landblocks above the sorounding land,clearly demarcated by

faults. Its caused by tectonic vertical forces where land on 1 side is raised/lowered

along fault planes Mountains cformed this way are called BLOCK MOUNTAINS e.g danakil alps-

Ethiopia

Tilt blocks Formed when vertical tectonic forces blocks of land upwards thus some parts

raised more than others due to uneven forces thus tilted block. Examples include ;Aberdares range

Ruwenzori block

Fault StepsWhen a series of fairly parallel faults develop,and land is displaced at diferent levels;aseries of fault scarps of diferent levels is formed i.e. steps faulting

Tilt block


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Rift Valleys

Normal Faults


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RIFT VALLEYThis is valleys formed through faultingExamples; the great rift valley-E.africa- The rhine Rift valley-Europe- The benue Rift Valley-W.Africa- Baikal rift valley-.Siberia

FORMATION OF A RIFT VALLLEY It is formed due to; Tensional forces Compressional forces Anticlinal arching

Due to tensional forces Rock layers experience tension . Lines of weaknesses form leading to normal faults As side blocks are pulled away,middle sinks forming floor of rift valley

Due to anticlinal arching When vertical forces push earths crust up continuosly,a lot of stress is

created at anticline creating a huge crack that forms the rift valley Furthermore,the upward arching leads to development of several cracks at

the crest thus pushing outer blocks more than the middle one.

This results into a rift valleyDue to compressional forces

Rocks are subjected to compression Parallel reverse faults are formed on land As outer blocks are pushed towards each other, middle block may sink

forming the rift valley.


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The Great Rift Valley

THE GREAT RIFT VALLEY It is the most famous rift valley It comprises of three parts;

Western rift valley Malawi rift valley Ethiopian rift valley

Negative significance of faulting Disjointing of land thus disrupting transport lines e.g. roads Subsidence of land thus loss of lives Changing of river cause/ disappearing into ground Burying of valuable minerals underground

Positive significance of faulting Formation of depressions that may fill with water forming lakes Creates weaklines becoming passage of hot water from undeground in forms

of springs and geysers Formation of springs are a source of water thus encourage settlement Features formed e.G riftvalleys and block mountans enrich the country with

foreign exchange from tourism Block mountains receive heavy rainfall on wind ward side thus encouraging

agriculture Exposure of valuable minerals on the surface e.g. diatomite

Normal fault They are caused by tensional forces acting on a land surface These forces s stetcg the earths crust thus creation of faults Land on one side of the fault moves upward in relation to the other


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Reverse faults


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Shear faults

Reverse faults They occur due to compressional forces Acting on crustal rocks As compression occurs undue stress is created on rocks causing faults One part of the landslides downward in relation to the other

Shear faults

They are also called tear/transform faults They occur when two adjacent land blocks move/slide past each other The land is thus horizontally displaced with no vertical adjustments


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Thrust fault

Thrust faults It occurs as a result of strong compresional forces The fault develop nearly in almost a horizontal position Therefore a block of land is pushed over the other along the fault


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Anticlinal faults

Anticlinal faults A land may undergo compression forming anticlines Continued compression causes stress at the crest


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CHAPTER 2: VULCANICITY AND EARTHQUAKES

VULCANICITY AND VOLCANICITY Vulcanicity is the process by which solid gaseous and liquid materials are forced outof the earths surface or intrude into the sub -crustal layers.

Vulcanicity is the process where igneous materials reach the surface of the earththrough volcanic eruption.

TYPES OF VOLCANIC MATERIALS forced onto the surface of the

earth. s crust.

Magma and lava

Magma is a molten material in the earth s crust.


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Lava is magma extruded on the surface of the earth.

CAUSES OF VULCANICITY

Presence of high pressure in the interior of the earth. Faulting of earth s crust causing cracks and fissures through which

volcanic materials escape. High temperatures in the interior changes solid rock to molten material. Water percolating through the rocks comes into contact with the hot

material's beneath the by turning into gaseous form under pressure

Types of lava

1. Acidic lava. It is extremely viscous. It doesnt flo w very far but it is thrown by pressure of gases through heat. It has more than 65% of silica in it. It solidifies rapidly at high temperatures of about 850 degrees Celsius. It has low viscosity i.e. very fluid and mobile. It is able to flow for very long distances before solidifying. It has a silica content of between 45-55% e.g. basalt

2. INTERMEDIATE LAVA It is fairly viscous and unable to flow far before solidifying. Silica content of between 55% to 65%. Tranchyte and phonolite.

3. ULTRA-BASIC LAVA. It flows very far. Silica content of < 45%

INTRUSIVE FEATURES Formed when magma gets trapped in the earths crust as it moves up from the

interior of the earth.


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The features formed are referred to as volcanic or igneous intrusions. They include;

Sills Dykes Laccoliths or Laccolites

Batholiths or Bathyliths Lopoliths. Phacolithes or Phacolyths

It is a layer of igneous intrusion formed when a sheet of fluid magma forces its waybetween the bedding planes of rock strata where it spreads, cools and solidifies.

DYKES It is a layer of igneous intrusion when a sheet of fluid magma forces its way throughlayers of crustal rocks by cutting across the bedding planes.


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Laccoliths or laccolite. It is a mushroom or dome shaped igneous intrusion with a flat floor which liesbetween the bedding planes of the country rock.

BATHOLITH OR BATHYLITHS. It consists of a plutonic mass of magma intrusion intruded the country rock. It is sohot that it metamorphoses the country rock on its path and on its sides turningsandstone into quartzite.


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Lopolith A lopolith is a very large saucer-shaped mass of igneous intrusion. It occupies the bedding planes of the country rock

PHACCOLITHS OR PHACOLITE It is a strip of lens shaped igneous intrusion resembling a lopolith.

EXTRUSIVE FEATURES

They include;

Caleras Fumaroles , solfatara and mofettes

Hot springs


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PHACCOLITHS OR PHACOLITE It is a strip of lens shaped igneous intrusion resembling a lopolith.

ACID LAVA DOMES Formed when magma pushes its way to the surface through a vent. On

reaching the earths surface the magma is no longer explosive since the pyroclasts areabsent. Since he lava is intermediate it does not flow far before it solidifies. It accumulatesaround The vent and pushes the hardened outer layers of the dome outwards

Lava domes do not have craters and are known as tholoids. Examples are;Itasy Massif and Managasha


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PLUG DOMES It forms when a mass of very viscous acidic magma is forced out of the

ground in the shape of a rigid cylindrical column. In the initial stages eruptions are very explosive. The magma comes out amid

clouds of hot luminous ash and cinders. A column of stiff magma is forced out and as

soon as it reaches he surface it rapidly starts to cool and harden as it rises vertically. Also known as a plug volcano or a spine. Examples are; Hyrax tower at hells gate Lassen peak

COMPOSITE VOLCANOES Also known as strato-volcano or complex cone. Formed when successive vent eruptions occur. First eruptions throws out solid materials that is ash ,dust and cinder. This materials settle around the vent. A mass

of lava follows and spreads over the pyroclasts cools and solidifies forming another

layer. This process is repeated over and over forming a volcanic cone which has several compact and alternating layers of pyroclasts and lava.


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Examples are Tibesti mountains and Mt.Cameroon

ASH AND CINDER CONES As gases rises through the weak lines they break off portions of the earth's rocks. On

reaching the surface pressure is released causing a vent eruption which emitspyroclasts. They are violent and throw materials to great heights some of which goback inside while some settle on the sides of the vent .Continuous processes lead tothe formation of ash and cinder cones.

Examples are tororo rock and Rangwa hill.

VOLCANIC PLUGS Its a column of magma that cooled and solidified inside the vent. The solidified lavaforming volcano is eroded causing solidified magma column in the vent to beexposed. Rocks making up the plug have cooled slowly making them harder than thesurrounding lava. With time a plug is exposed as a resistant6 column of rock.

Examples are peaks of Mount Kenya and Tororo hill.

BASIC LAVA DOMES OR CONES It is a large low lying volcanic dome which has a broad base and gentle slopes. They are also referred to as shield volcanoes.

DIFFERENCES BETWEEN COMPOSITE VOLCANOS


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BASIC LAVA DOMES AND ASH AND CINDER CONES 1. Ash and cinder domes are smallest narrowest and shortest at the base 2. Composite volcanoes are far much higher and much wider at the base. 3. Basic lava domes are the widest at the base though they are much shorter than

the composite volcanoes.

Note: a seamount an eventually appear above the water and form a volcanic Island.

LAVA PLATEAUS

This is an extensive fairly upland area which is elevated to cover 500 m above sealava.

Lava plateaus and plains

A lava plateau is an extrusive fairly level upland area which is elevated o cover 500m above sea level.

A lava plain is like a plateau but its surface is at an altitude of less than 500 m abovesea level and is also covered in lava flows.

Crater A crater is a round funnel shaped hollow mouth of a volcanic cent. Ways in which craters are formed: 1. During the formation of a volcano.

Once the outpouring of lava stops the magma in the vent cools and contractsforming a depression.

2. Due to a volcanic explosion at ground level. Gases and water vapor that are I contact with the magma are heated and theexpand due to pressure build up. They escape through small lines of weakness

they approach the surface the pressure is released resulting in a volcanic


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explosion leaving a hole in the ground. 3. Through a non volcanic process.

It forms as the result of a meteorite falling on the earths surface.

Calderas

A caldera is also called a basal wreck. It is a large basin shaped depression surrounded by steep sides(cliffs ) and mayform in any of the following ways: 1. By violent eruption : It occurs when a volcano explodes violently, blowing off its upper part. 2. By cauldron or block subsidence .

After an eruption a void is formed. Faulting causes weak lines to develop involcanos, leading to their eventual collapse. A large depression is left o the nowmuch lower depression. It is referred to as a collapse caldera. 3. Outward collapsing.

A volcano built of ash and pyroclasts can grow to be very high and eventually


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become unstable. The materials at the base begin to spread as the top of the

Fumaroles,solfatara and moffettes A fumarole is a subsidiary vent on a volcano or a hole in the ground which mainlyemits gases or steam.

HOT SPRINGS This is a place where hot water comes out of the ground. Rain water enters the crustal rocks to THE REGION

WHERE THE HOT ROCKS ARE LOCATED. Once there it is heated by the hot rocks

and even magma itself. Some of this water collects in the sumps within the hot rocks.The steam builds up pressure causing the water in the chambers getting themsuperheated. The pressure forces the steam upwards. As steam escapes to thesurface it heats the ground water on the surrounding rocks. This ground wateralready heated and under pressure may find its way to the surface where it QUIETLY comes out as a hot spring.


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GEYSERS Rain water or surface water enters the crustal rocks through cracks and holes. Thewater percolates through the rocks to the region where hot rocks are. It is heated byhot rocks or even magma itself. Some of the water turns i9nto steam and expands.Some of the water collects in chambers or sumps within the hot rocks. Continuedpressure by the steam causes water in the chambers to become super heated. Theaccumulated pressure forces the steam upwards through the cracks and holes. Asmore steam escapes the pressure of the superheated water in the chamber isreduced. This causes the water to expand and rise to the surface. As I gets closer tothe surface the pressure is reduced suddenly causing the water to begin boiling andshooting out of the ground as a geyser.

TYPES OF VOLCANOES Active-A Volcano known to have erupted recently. Dormant-a volcano which has not erupted in recent times but shows signs of

life. Extinct-a volcano which does not show any signs of any future eruptions.

Significance of vulcanicity POSITIVE.

Formation of fertile soil Formation of valuable minerals Geysers are sources of geo-thermal electricity.

Water from hot springs is pumped into houses for heating.

Tourist attraction. It encourages settlement. Many varieties of rocks are economically valuable Fishing is carried out in some crater lakes

NEGATIVE Loss of life Destruction of property Formation of infertile soils

Create barriers in infrastructure


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Rugged nature of land discourages economic activities

EARTHQUAKES DEFINITION OF TERMS

Seismology: it is the scientific study and interpretation of earth quakes.

Seismic focus/ origin: the point of origin of an earthquake. Epicenter: it is the point where the shock waves are first Experienced on the earths surface. Seismograph: it is a pendulum based instrument for recording seismic waves. Seismogram: it is a graph like record on which impulses are recorded. Earthquake: a sudden rapid movement of the earths crust. Tsunami: earthquakes which occur in the oceans create waves called

tsunamis. Seismeter: it is a delicate instrument for receiving impulses and is attached to

a seismograph.

WAYS OF PREDICTING EARTH QUAKES

Use of pre-quake instruments The behavior of birds i.e. they stop to take water Snakes coming out of their cages or holes

DIAGRAM OF AN EARTHQUAKE

CAUSE OF EARTHQUAKES NATURAL CAUSES 1. Tectonic movements. 2. vulcanicity. 3. Gravitative pressure. 4. Isostatic adjustment.5. Energy release from the mantle


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HUMAN CAUSES 1. Underground nuclear tests. 2. Movement of trains. 3. Uses of explosives. 4. Construction of large reservoirs.

TYPES OF EARTHQUAKE WAVES

The shock waves originating from the focus are also called seismic waves. There are two main types namely: 1. Body waves 2. Surface waves. 1. BODY WAVES. These are waves that travel through the surface of the earth. (a) Primary waves. They cause each crustal rock to move back and forth along the direction of the Wavemovement. They are also the fastest waves. (b) Secondary waves. Referred to as shake or shear waves since they cause the crustal rock particles tovibrate vertically to the direction of the waves movement.

2. Surface waves. They travel on the surface of the earth and are responsible from a third set ofimpulses.

(a) Rayleigh waves They cause the surface of the earth to move in elliptical orbits therefore they causethe surface to have vertical circular movement very similar to that of water in sea.

(b) Love waves. These waves make the earths crust to move in a side to side manner and at right angles to the direction of the wave movement.


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NOTE: waves move faster in denser materials therefore the velocity of wavesincreases with increase in depth

More on waves:


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Description of waves Shallow focus earth quakes; they occur at a depth of 0-70 km below the

earths surface. Deep focus earth quakes: occur at depths if between 300-700 km. Between the two types of earthquakes are the intermediate earthquakes

MEASUREMENT OF EARTH QUAKES

The strength of an earth quake is measured by its intensity and magnitude

Intensity is the measure if how strong or hard the earthquake shakes the ground. It is measured using the Mercalli scale by noting the earth quakes effects in people,buildings etc Magnitude is the measure of amount if energy given off by an earthquake.

It is measured on the Richter scale. An earthquake of magnitude four gives ten

times as much energy as one of magnitude three. The Richter scale ranges from 0-8.9

EFFECTS OF EARTHQUAKES

On the earths crust Rocks on the crust are displaced. Earthquakes cause uplift and subsidence of the land. They cause lowering or the raising of the sea floor. They can trigger off landslides on the surface of the earths crust They can also lead to volcanic eruptions. They can expose minerals or bury them deeper in the ears crust.


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On human environment Destruction of property and loss of lives It can trigger off a tsunami resulting in flooding in coastal areas. It may cause fires associated with vulcanicity.

The vertical and lateral displacement caused by earthquakes can causedamage on transport and communication lines.

It can spark off landslides leading to loss of lives and property.

On physical environment They can trigger off faulting and vulcanicity. They can cause tsunamis which can cause submergence of coastal regions. It can lead to shearing of rocks resulting in horizontal displacement of rocks. Landslides due to earthquakes can block rivers resulting in diversion of

drainage or formation of lakes. It leads to lowering or rising of the sea floor.

NOTE: places that are prone to earthquakes are referred to as seismic zones placesthat are not prone to earthquakes are known as a seismeic zones.


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CHAPTER 3: MAPS AND MAP WORK

Map-representation of an area on a piece of paper.

DIRECTION AND BEARING

Direction-a line or course upon which something is moving to pointing or facing

Bearing-an expression of direction using degrees of an angle

Traditional methods of showing direction

Landmarks

Use of heavenly bodies

Dead reckoning-involves recording the direction of movement, time and speed

of travel from a known position.Modern methods of showing direction

Landmarks for example buildings, rivers etc

Compass direction

Bearing

The difference between direction and bearing is that, while direction is a line

or course upon which a body is pointing or moving, bearing is the expression

of this direction using degrees of an angle measured from north in a clockwise

direction.

These two, methods, compass direction and bearing can be used on

topographical maps when referring to or finding direction.

Types of bearing

The magnetic poles of the earth are not in exactly in the same position as its

geographical poles. This is partly why we have three slightly different north directions

TRUE NORTH- also called geographical bearing. It is the direction of the North Pole.

It is the position on the globe where all longitudes meet. Bearings calculated from the

true north are also called true bearings

MAGNETIC NORTH- Based on the earths magnetic field which has a north pole and

a south pole. When a needle is left to swing freely it comes to rest in a north south


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position .its north point indicates the earths magnetic north. Bearings calculated

from the magnetic north are called magnetic bearing

GRID NORTH- the lines on topographical maps which form a network of squares are

called grid lines. They meet at a point in the North Pole called grid north. The grid

north is based on the determined national grid system of a country. Bearings

calculated from the grid north are called grid bearings .

True north and grid north are fixed points. Magnetic north changes according to the

position of the earths magnetic north Topographical map showing grid lines .

Topographical map showing grid lines

Location of placesvoiUse of place names e.g. Nairobi, Kisumu or Use of direction,

bearing and distance

Use of latitudes and longitudes

Use of grid references. Grid lines drawn from north to south are called eastings and

their value increases eastwards on the map while those drawn from east to west

across the map, are called grid northings.


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Grid referencing

Four figure grid reference

Used if a feature or point is at the intersection of grid lines

Six figure grid referencing

Used to give the precise location of a feature.

Methods of representing relief on topographical maps Spot heights-are points

on a map whose positions and heights have been determined by surveyors.

Shown by a dot and a figure.

Show the actual height of a point on a map Trigonometrical stations-they show

actual heights of a place on a map.Contours and form lines-contour is a line on a map joining all points which are on the

same height above sea level. Also known as isohypes while form lines are lines

drawn on a map joining points of approximately the same height above sea level.

Contuor intervals is the difference in height between any two successive contours

also called vertical interval.

Other methods of representing relief on maps Pictorials. Pictures of landforms suchas hills and mountains are drawn on the map in the approximate positions where the

landforms are to be found.

Disadvantages of using pictorials

The symbols are viewed from an angle which is contrary to the idea that a

map is supposed to be viewed vertically from above.

The pictures may obscure the details behind them.

They do not give the heights of land above sea level

Only a limited variety of landforms may be shown

Hill shading. Used to illuminate some parts of the map while casting shadows

on others.

Difficulties associated with hill shading as a method of

Does not show accurate heights above sea level

Insertion of more details is difficult in the darkly shaded regions. Difficult to

representing relief


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determine the direction of slope as well as the types of landforms on the map.

Layer tinting or layer colouring .Involves the use of colour or some form of

shade. Land within a particular range of altitude is given a particular colour or

shade. The faintest tint or colour usually represents the lowest land and it

becomes progressively darker with increasing altitude

Hypsometric .Also called line shading can be used to depict relief in the same

manner the tints are used.

Limitations of using layer tinting

Only suitable for a region of varied relief.

It can be misleading in that one colour or shade assumes uniformity of height

and yet the land is usually steadily rising.

Difficult to identify landforms on such maps.

Difficult to estimate heights of certain places.

In regions of high altitude the tints or shades may be so dark that insertion of

additional information becomes impossible.


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CHAPTER 4: PHOTOGRAPHY

A photograph is an image or a picture of an object recorded by a camera on a lightsensitive film or paper.Photographs may be still or motion pictures.

Types of photographs

1. Ground photographsThey are taken from the ground. The object is usually directly in front of the persontaking the photograph.

a. Ground horizontalsThey are taken with the camera held at the same level as the object. Whatever is inthe foreground is shown clearly. The area that is hidden from view is known as deadground. There are two types of ground horizontal photographs:

i. Ground close-ups/ Ground particular photographs:The camera is focused on one major item and obscures the other things behind it.

Ground close-upGround general view:Objects become progressively smaller from the foreground to the background. Thecameraman is usually at the same level with the object.


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Ground general view

b. Ground oblique :The cameraman holds the camera at an angle on a raised ground

2. Aerial photographsThey are taken from the air.a. Aerial obliquesThey are taken with the camera tilted towards the ground and cover a large area e.g.the horizon.


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b. Vertical aerial photographsThey are taken with the camera directly above the object/scenery. However, they aredifficult to interpret.

Vertical ariel

Parts of a photographa) Horizontally: It is divided into the foreground, the middle ground and the

background.b) Vertically: It is divided into the left, right and centre parts.

Uses of photographs1. In learning Geography as they show objects as they appear.2. To study physical features.3. To study the various types of vegetation and their distribution.4. To study the drainage types of an area.5. To identify human economic activities e.g. transport and communication.

Limitations of using photographs1. They are expensive to produce.2. Wrong interpretation

3. Vertical aerial photographs are difficult to interpret without the use ofstereoscopes.4. Details in the photograph may be blurred if the camera is not properly focused.

Interpretation of photographsIt involves:1. Determining the title.2. Estimating the time, season and direction:

It is possible to determine the time of day if we know where it was taken. Thevegetation, clouds, skies and type of clothing can be used to determine theseason.

3. Estimating direction:4. The direction of the shadow can be used to determine the direction the


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cameraman was facing.5. Estimating size of features.6. Identifying human activities.7. Suggesting the possible location of the area in the photograph.

Prominent hills and isolated hills on the flat land are called STUDYING PHYSICALFEATURES inselbergs ON PHOTOGRAPHS1) Reliefa. Flat LandscapeOccurs in lowlands (plains) and uplands (plateaus) and is also associated withmeandering rivers. A relatively flat area with low-lying hills is referred to asundulating ground.Flat lands can be identified by the type of crops grown. E.g. rice

Prominent hills and isolated hills on the flat land are called inselbergs

b. Hilly and mountainous landscape An area of more than 2000m above the sea level is referred to as mountainous. It ischaracterized by steep slopes on an individual block of land. The crops growing in anarea can be used to deduce the altitude of an area. E.g. tea and wheat grows in highaltitude areas

c. DrainageIt is the process by which water is removed from the land to a lake or sea by asystem of streams or rivers. They may also include: swamps, waterholes, ponds andrivers. The presence of waterfalls and rapids indicate that a river is flowing in steepregion. Meanders show that a river is in its middle stage or old stage. Some

meanders may be cut off from the main river to form an oxbow lake.


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A river delta can be identified by the presence of many channels.

d. VegetationIt is the plant cover that develops under natural conditions in a particular climate,relief and soil. The vegetation on photos is commonly likely to be secondary or

derived.

Aspects to be taken into account when describing vegetation1. Identify the type of vegetation2. Describe the height and the shapes of vegetation. E.g. needle shaped leaves.3. Identify some species of trees easily identifiable e.g. baobab4. Relate vegetation types to climatic regions.5. Try to distinguish natural vegetation from planted vegetation

e. ClimateOne can tell the climate by gathering information from physical features and humanactivities e.g. presence or absence of clouds, clothes people wear, types of housesand the styles of building the houses, types of crops grown and the animals kept.

f. SoilsThey can be determined by the types of crops grown in the area e.g.Coffee trees grow in acidic and volcanic soils, rice grows in areas with clay soils andcoconut and cashew nuts grow in sandy soils, most horticultural crops grow in loamysoils.

g. Human ActivitiesFarmingIt is divided into subsistence and commercial. It can be interpreted by:Main characteristics of each type of crop. Areas where such farming is carried outBenefits and problems associated with each type of farming.Effects of each type of farming on the environmentGovernment policy on each type of farming.

SettlementsIt is a group of dwellings where people live and interact.It is divided into rural or urban dwellings.Rural dwellings can be indicated by:

1. Simple architectural design of houses2. Evidence of farming and fishing activities3. Uneven distribution of dwellings or presence of villages4. Urban settlements can be indicated by:5. Permanent buildings6. Regular street patterns7. Several storied buildings8. Industrial parts of the town with warehouses and large buildings9. High population densities10. Heavy motor vehicle traffic11. Port facilities like docks

12. Well developed communication network


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Industrial and mining activities Are indicated by the presence of:

1. Factory buildings with tall chimneys2. Nucleated settlements of workers

3. Large open pits, large excavators, lorries carrying loads of rocks4. Oil refineries with chimneys emitting flames of fire

Lumbering can be indicated by:5. People cutting trees with power saws6. People loading timber into lorries7. Rafts of logs floating down a river8. Logs piled near a sawmill9. Large forest clearings with tree stumps and piles of logs

Transport and communication1. Motor transport: roads, motor vehicles2. Rail transport: railway lines with or without trains3. Air transport: large flat tarmacked piece of ground with buildings on one side,

control tower4. Water transport: boats, ship, large water vessels5. Communication services: telephone lines, booths, satellite masts, television

and radio stations, post offices, newspapers etc.

Sketching diagrams from photographs1. Draw a rectangle or square of the same size or proportional to the size of the

photo.2. Subdivide the photo into three equal sections: foreground, middle ground and

background.3. Draw faint vertical lines to obtain left, centre and right sections.4. Starting with the background, draw the skyline as it is in the photo.5. Fill in the main features in the background.6. Complete details in the middle ground and finally put important features in the

foreground.7. Complete the sketch by drawing and labeling important features e.g.

vegetation.8. Give the sketch a suitable title.


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CHAPTER 5: STATISTICAL METHODS

Types of statistical presentation

Comparative line graph

Comparative bar graph Divided bar /rectangle

COMPARATIVE LINE GRAPHS Also known as group line graphs /multiple line graphsThey are a series of line graph drawn on the same chart to show the relationshipBetween sets of similar statistics for more itemsIt is an appropriate method of presenting data for purpose of comparing informationin two or more sets of data

COMPARATIVE LINE GRAPH

STEPS TO CONSTRUCTING A COMPARATIVE BAR GRAPH

CROP 1997 1998 1999 2000 2001TEA 24126 32971 33065 35150 34485COFFEE 16856 12817 12029 11707 7460HORTICULTURE 13752 14938 17641 21216 19846TOBACCO &

PRODUCTS

1607 1554 2167 2887

PYRETHRUMEXTRACT

716 656 704 993

SISAL 723 689 636 606 728MAIZE 56 130 488 33 18TOTAL 58609 63868 66069 71583 66417


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Decide on a suitable scale for both horizontal and vertical axis.Draw line graphs for each crop on the same frame but separate lines.Write the crop name along its line other than creating a key for easier comparison.

Write an informative title above the diagram.

NOTE : the maximum number of items to be presented in a graph should not exceedfive.

INTERPRETATION OF STATISTICAL DIAGRAMS

Examine the trend of the graphs and their detailsIdentify various lines/bars and study the trends and their interrelationshipMake meaningful conclusionsProvide explanations where reasons are known

COMPARATIVE LINE GRAPHSAdvantages

a) Simple to constructb) Comparison of items is easyc) Easy to read the exact values from each graph

Disadvantagesa) Number of items that can beb) Crossing of lines is inevitable inc) some cases causing difficulties in interpretation

COMPARATIVE BAR GRAPHS


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Also called group or multiple bar graphsDrawn for purpose of comparing quantities of different items over the same periodThey are more suitable in representing quantities which are solid and tangiblebecause of their solid appearance.

CONSTRUCTIONa) Choose a suitable scaleb) Draw bars starting with the one representing the largest single component then

the next till the smallest is drawn.NOTE: the order will remain the same in the other years even if the ranking invalues change.Others will always come last even if it has the largest values.

A gap is left after each group of bars.c) Choose different shading for each bar in the first group. adopt the same shading

in the other groups for respective barsd) Add a key

e) Add a suitable title.

Advantages Give a better impression of totality and of the individual contribution made by

each of the component part. The bars emphasize quantities well Easy to see difference in quantities. Emphasizes too much on quantities Easy to construct and read Easy to compare.

DisadvantagesDifficult to follow trendsNot easy to compare the totals in each year

DIVIDED BAR/RECTANGLES

A rectangle is divided to present statistical data. The subdivisions represent an item, a commodity, a value, a region, or a

country. This method is very versatile in representing statistics.

CONSTRUCTION Length is determined by the values and size of the paper. Choose a suitable scale for the length of the rectangle. Should have a definite

width. Draw a horizontal rectangle proportional to the scale chosen. Starting from the left mark off strips from the largest to the smallest single

component. Write the name of each component on the face of each strip. A short line scale should accompany the rectangle especially if the values are

not indicated on the drawing


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Advantages Easy to construct Easy to compare Takes less space than comparative bars Each components proportional to the total can easily be seen at a glance

Disadvantages Difficult to assess the value of the individual components because they do not

start from a common base Not appealing Only one unit of measurement can be used


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CHAPTER 6: CLIMATE 1

Introduction and Kenyas climatic regions Definition

Weather refers to the condition of the atmosphere of a place at a particulartime over a short period of time.

Climate refers to the typical average weather conditions of a place or a regionobserved over a long period of time.

1. Factors influencing climate2. Latitude3. Altitude4. Distance from the sea5. Aspect6. Ocean currents7. Winds and air masses8. Configuration of the coastline9. Inter-Tropical Convergence Zone[ITCZ]10. Forests11. Human activities

1. LatitudeLatitude influences;

1. The planetary wind system2. Rainfall3. Temperature4. sunshine

Areas nearer the equator experience higher temperatures than those far from theequator.Rainfall is influenced in that there is seasonal variation of rainfall for example, thenorthern tropical experiences a rainy season in March and July.The face of the mountain towards the sun experiences a lot of sunshine.


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5. Ocean currentsThis influence;

Temperature Rainfall Onshore winds are warmed or cooled from below as they blow over warm or

cold ocean currents causing temperature change on the adjacent land. If these winds acquire moisture from the current they bring rainfall.

6. Winds and air massesThis influence;

Rainfall Temperature If winds blow from warm regions they warm the regions they are blowing over

and vice versa in cool regions. Moisture laden winds cause rainfall in a region while dry winds cause desert

like conditions. Katabatic winds are responsible for low temperatures at night in valleys and

lowland regions while anabatic are responsible for formation of cumulusclouds and afternoon showers in highlands.

Fohn and Chinook cause dryness on the leeward side they blow across.

7. Configuration of the coastline\ alignmentThis influence:

Rainfall

Temperature If the coastline is parallel to onshore winds they bring no effect of rainfall tothe coastal regions while an irregular coastline allows the winds to penetrateto the land thus bringing rainfall and changes in temperature.

8. Inter tropical convergence zoneThis influence;

Temperature Rainfall Rain bearing winds converge in this low pressure region causing two rainy

seasons when the sun is overhead.

Areas further away experience one rainy season when the sun is overhead.


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9. ForestsThis influence; Temperature, Rainfall, Humidity Temperatures tend to be lowerbecause of shade reducing solar insolation. Trees act as windbreakers causing amicroclimate.Trees undergo evapo-transpiration causing high humidity and rainfall

10. Human activities Activities include; agriculture, development of settlement, construction has an effecton local climate.Emissions from factories like chlorofluorocarbons and other gases cause globalwarming.

How to describe climateTemperature and rainfall are the main elements used in description of climate.N/B: Limuru cannot be described as cold but cool.When describing climate of areas beyond the tropics the seasons i.e. summer,

autumn, winter, spring are used


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Mean annual range of temperature Temperature data More than 30 19-30 8-18

3-7 Less than 3

Range description Very large Large Moderate Small Negligible

Rainfall amountMore than 1500mm1000-1500mm500-999mm250-499mmLess than 250mm

Rainfall descriptionVery highHighModerateLowVery low

Climate descriptionVery wetWetFairly wetDryVery dry

Mean monthly and annual temperatureTemperature descriptionVery highHighModerateLowVery lowExtremely low

Climate descriptionVery hot

Hot


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WarmCoolColdVery cold

Temperature dataMore than 3020-3010-190-9-10-0Less than -10

Temperature descriptionMore than 125mm100-125mm50-99mmLess than 50mm

Rainfall descriptionVery highHighModeratelow

Climate descriptionVery wet WetFairly wetDry

Characteristics of lake Victoria climate1. Mean annual temperature ranges between 22 to 322. Annual range of temperature is small3. Rainfall varies between 1000mm and 1600mm annually4. The rainfall regime is a double maxima

5. Rain falls all year round6. Rainfall is of convectional type. It falls mainly in the afternoon accompanied bythunder storms

7. There is high humidity.

Modified equatorial of the coastIt is influenced by the local prevailing trade winds and the presence of the Indianocean.Some of its characteristics include;1. Experiences rain throughout the year.2. Has double maxima of rainfall, long rains come between March and May while

short rains are experienced between September and October.


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3. Receives convectional rainfall due to the presence of the Indian ocean.4. Annual rainfall ranges between 1000 mm and 1250 mm which reduces inland.5. Temperatures are generally high throughout the year, ranging between 22 to 30.6. Experiences high relative humidity throughout the year7. Low mean annual temperature range.

Modified tropical climateTemperature ranges between 17 and 24.

Annual range of temperature is small, Between 3 and 5Days are generally warm while nights are cool and sometimes chilly.The coolest months are June to August while the rest of the year is generally warm.The region receives rainfall of between 1000mm and 1500mm on average.It rains throughout the year.The rainfall regime is a double maxima in highlands east of the rift valley and asingle maxima in the highlands west of Rift Valley.Long rains are received between March and May and short rains betweenSeptember and December in the east of the rift valley while in the west of Rift Valleythe peak is between May and August.Rainfall is mainly the orographic rainfall causedby the South East trade winds.Rainfall is high on the windward slops than on the lee ward slope.Tropical continental or semi desert climate

Also called the SavannaExperienced in large areas in Kenya especially the plateau and the low lands of

Nyika and Rift valleySome of its characteristics include;

1. Experiences two dry seasons and two rainy seasons.2. Rain falls between March and May and between September and October after

the overhead sun.3. Rainfall is moderate averaging between 750 mm and 1000mm4. in a year.5. Rainfall is mainly convectional.6. Temperature throughout is high averaging at 277. During the dry month the temperatures are relatively low.


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Tropical climate1. Temperatures are high as those of tropical continental climate but in areas

with high relief its modified e.g. Loita hills2. Influence of relief makes it more habitable than semi-desert3. Rainfalls in one season and it is generally low4. The amounts are higher than semi desert5. Rainfall received is more than 250 mm

Tropical northern climateExperienced in the North West part of Kenya and Uganda

1. Average temperature is high and slightly modified.2. Mean annual rainfall is 850 mm and falls between June and September.3. Long dry season lasting six month.


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Kalori desert


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CHAPTER 7: CLIMATE 2WORLD CLIMATIC REGIONS

1. Hot climates

a) Equatorial Climate Along the west coast of Africa from Guinea. ThroughCote dIvoireSouth-western and central GhanaSouthern NigeriaCameroonCentral AfricanRepublicGabonCongoDemocratic Republic of Congo


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Characteristics High temperature all year (24-27 degrees centigrade) with a small annual

range of 3 degrees centigrade. Diurnal mean temperature of about 26 degrees centigrade all year with a

diurnal range of below 8 degrees centigrade.

Mean annual rainfall exceeds 1500mm and is evenly distributed throughoutthe year.

Rainfall regime is a double maxima after the equinox. Very high relative humidity throughout the year. Plenty of sunshine and low atmospheric pressure of about 1014 millibars.

b) Equatorial Monsoon InSouth-East Asian, it is experienced in theMalaysian and Indonesian islands of:a) Sumatrab) iJavac) Borneod) Salawesie) Mindanaof) New Guineag) The whole Malaya peninsula

Characteristics.

High temperature of between 24 and 27 degrees Celsius throughout the year with a small annual range of between 3-5degrees Celsius.

Diurnal mean of about 36 degrees Celsius with a diurnal range that is smallabout 6 degrees Celsius.

Mean annual rainfall exceeds 1800 mm and is evenly distributed during theyear.

Relative humidity of over 80% throughout the year and plenty of sunshine.


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C) Tropical monsoon Southern China Northern Australia Southern Senegal

Guinea Bissau Guinea Sierra Leone Liberia South East Asia

Characteristics High mean annual temperature of about 28 degrees Celsius with the annual range being about 7 degrees Celsius although not uniform for all places. Seasonal reversal rains with onshore winds causing heavy rainfall. Rainfall amount varies between 600 and 1300 mm with a distinct dry season

The coast of Eastern

d) Africa from Kenya,a) Tropical marine through Tanzania to Mozambiqueb) The Eastern coast of Madagascarc) The Philippines Islandsd) The East Coast of Queensland, Australiae) South America along the east coast of Brazil.f) Central America from Guatemala through Panama.g) Along the northern coast of South America from Colombia to Surinamh) The Caribbean Island of Cuba, Jamaica, Haiti and Puerto Rico


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Characteristics

High mean annual temperature of about 25 degrees Celsius with the annual range being about 8 degrees Celsius. Mean annual rainfall of between 1100 and 2000mm experienced all year

round. Humidity is high throughout the year. Prevailing winds are trade winds. Tropical cyclones occur towards the end of the hot season.

e) South America onTropical the Braziliancontinental. Plateau of Mato Grosso, The lower lands of Colombia and Venezuela, and someparts of Guyana Highlands Australia where it forms a broad belt in the AustralianDesert and the tropical monsoon coast. Central and Southern Mexico


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Characteristics Temperatures are high throughout the year varying between 26 and 32

degrees Celsius with an annual range of about 11 degrees Celsius. Rainfall varies between 750 and 1000 mm and is convectional. It falls during

the hot season.

Rainfall increases towards the equatorial regions and decreases away fromthe equator.

Prevailing winds are trade winds.

Sahara, Kalahari and Namib deserts off) Tropical desert Africaa) Jordan, Syria, Iran, Iraq, Saudi Arabia, Afghanistan and Israel in the middle east.b) The desert of India.c) Mohave, Colorado and Mexican deserts of North and Central Americad) Atacama Desert of South America.e) The Great Australian desert.

Characteristics High mean annual temperature of 27 degrees Celsius with an annual range of

about 26 to 28 degrees Celsius. Large diurnal range of temperature Very low annual rainfall less than 250mm which is erratic and unreliable. Humidity is low and strong winds are frequent. Atmospheric pressure is low during the hot season and high during the cold

season.

2. Warm Climate

I. The lands borderinga) Warm temperate the Mediterranean western margin


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sea that is Southern Europe and Northern Africa South West tip of Africaaround Cape Town Central Coast of California in North America Central Chilein South America. South West Australia around Perth and the southern partaround Adelaide.

Characteristics Hot summers with temperatures of about 21 degrees Celsius and mild winters

with temperatures of about 10 degrees Celsius. Annual range of temperature is moderate about 11 degrees Celsius. Mean annual rainfall varies between 500 and 900 mm with most of it falling in

winter. Cyclonic rainfall caused by depressions falls in showers. Trade winds are offshore in summer while onshore westerlies dominate in

winter. Hot and cold local winds are common.

b) Warm Temperate Continental Climate The high Veld of South Africa Western Oklahoma extending into some parts

of Texas in North America Central parts of Argentina and Paraguay in South America The Murray-Darling lowlands of Australia


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Characteristics Hot summers with temperatures of about 26 degrees Celsius and mild to cool

winters with temperatures of about 10 degrees or less. Moderate annual range of temperature of about 16 degrees Celsius. Low moderate rainfall of about 380-700 mm which mainly falls in summer.

Rainfall is mainly convectional because of the south east trade winds.

c) Warm Temperate Desert Climate Nevada and Utah states of North America Patagonia in South America In The interiors of Eurasia which extends from Turkey, Northern Syria, Northern Iran, Across the Caspian and Aral seas into former

USSR and into Mongolia Gobi Desert

Characteristics Very large diurnal and annual ranges of temperature. Hot to very hot summers with temperatures of about 25-37 degrees Celsius and cold winters of below 7 degrees Celsius. Low and unreliable rainfall about 250 mm yearly. Most rain falls in late winter or early spring.

Coastal belt of Natal ond) Warm Temperate the South Eastern Part Eastern Margin of Africa The South and the South Eastern states of the USA. Southern Brazil, Uruguay, Eastern Paraguay and the coast of Argentina to the

east of the Pampas. South East China around Hong Kong and Southern Japan. South Eastern Australia including the northern island of New Zealand


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Characteristics Hot summers with temperature of about 26 degrees Celsius and mild to cool winters with temperature of about 13 degrees

Celsius. Mean annual rainfall of about 1000mm with most rain falling in summer

(summer maximum). Trade winds are onshore in summer while westerlies are offshore in winter. Monsoon winds develop in some coastal regions and islands. Tropical cyclones are common is south east USA and China.

3. Cool Climate.The British Isles, Southerna) Cool Temperate Scandinavia, Central Western Margin and Western EuropeThe Coastal par of British Columbia in Canada, extending southwards through thecoastal parts of Washington and Oregon states of the USAThe coastal part of ChileTasmania and the south island of New Zealand


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Characteristics

Warm summers with temperature of between 13 and 15 degrees Celsius andcool winters of between 2 and 7 degrees Celsius.

A moderate mean annual range of temperature.

Onshore westerlies prevail throughout the year. Rainfall is moderate to very high about 760-2000mm and is well distributedthroughout the year with the peak in winter.

Depressions and anticyclones are common. Humidity is high especially in winter.

b) Cool TemperateContinental ClimateCentral and EasternEurope and the western part of former USSR around MoscowIn the Midwest and north-central USAThe provinces of Alberta, Saskatchewan and Manitoba in Canada

Characteristics Warm summers with temperatures of about 18 degrees Celsius and very cold

winters where temperatures go below -19 degrees Celsius. The annual range of temperature is very large upto 37 degrees Celsius and

the mean annual rainfall is low about 400-500 mm. Rainfall is mainly convectional and falls throughout the year. Depressions occur occasionally causing rainfall.

c) Cool Temperate Eastern Margin.The maritime provinces of Canada and North EasternUSA in New EnglandNorthern China, Korea, Central and Northern Japan


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Characteristics.Warm summers with temperatures of between 12-18 degrees

Celsius in America. In Asia they are hot about 16-24 degrees Celsius. Winters are cool and cold about 4-15 degrees Celsius. Large annual range of temperature of between 28-39 degrees Celsius. Precipitation is a mixture of rain and snow. Precipitation of more than 1000mm in North America and northern Japan

occurs throughout the year. In Asia it is about 700mm. Westerlies are dominant in North America and are also experienced in Asia

where rainfall is heavy in summer when the winds are onshore.

4. Cold Climate.a) Cold Temperate Western Margin ClimateInterior of the state of Alaska in North AmericaCentral and Northern Norway and Sweden up to the ArcticCoast


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Characteristics. Westerlies are dominant and are onshore. Depressions are common. Mean annual rainfall is about 750mm. Precipitation is in the form of rain which falls in most months but in winter it

falls as snow. Cool short summers with a mean of 12 degrees Celsius and cool and coldlong winters with temperatures of between -2 degrees Celsius and 4 degreesCelsius.

b) Cold Temperate Continental ClimateIn the interior part of North America from the Alaskan border in the west to Labradorin the EastIn Europe it extends from Finland in the west through Siberia in Russia toVerkhoyansk range in the east

Characteristics Warm short summers with temperature not exceeding 21 degrees Celsius and

very cold long winters with temperature going below -45 degrees Celsius. Annual precipitation is about 380 mm and most of it falls in summer with snow

falling in winter.

Rainfall is convectional.


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c) Cold TemperateEastern Margin.North east Pacific coast of Russia

Characteristics Short but hot summers with mean temperature of 21degrees Celsius and long

severe winters with average temperature of -20 degrees Celsius. Very large annual range of temperature. South easterly moist winds blow in summer and the strong dry north

westerlies blow in winter. Mean annual rainfall is between 500 and 1000 mm with rainfall mainly in

summer.

5. Arctic climate.a) Tundra Climate Coast of Northern America that borders the Arctic ocean,including the Baffin Island and the south coast of Greenland In Eurasia, it occursalong the Arctic coast from the Northern coast of Scandinavia to the north east ofRussia


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Characteristics Cool summers with temperature of about 10 degrees Celsius and very cold

long winters with temperaturesranging between -29 degrees

Celsius and -40 degrees Celsius. Avery large annual range of temperature. Low mean annual precipitation of about 250mm in the form of rain and snow.

b) Polar Climate

Interior of Iceland, Greenland and Antarctica

Characteristics Temperature below 0 degrees Celsius throughout the year. Blizzzards are frequent.

6. Mountain Climate. Highlands Ethiopian Highlands The Drakensberg Mountains Mount Cameroon Atlas Mountains The Rockies of North America The Andes of South America The Alps and the Balkans of Europe The Himalayas in Asia

I.East African


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Characteristics

Temperature decreases with increase in altitude. In temperate regions slopes facing the equator are warmer than those facingthe poles.

Rainfall increases with height upto 3000m then it starts to decrease. Windward slopes are generally wetter than leeward slopes. Atmospheric pressure decreases with increasing altitude. Local winds are common and they blow up the slope during the day and down

the slope at night.

WORLD CLIMATIC REGIONS


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CHAPTER 8: ARIDITY ANDDESERTIFICATION AND CLIMATE CHANGE

Definition;IntroductionThe state of land being deficient in moisture leading to scanty or lack of vegetation.Desertification-slow but steady process of encroachment of desert like conditionsonto potentially or formerly productive agricultural land.

Causes of aridity and desertification1. Natural physical causes

Rainfall

Temperature Cold ocean currents Relief barriers Continentality or nearness to a large Water body Wind systems Pressure systems

Effects of aridity and desertification has led to the development of infertile soils whichsupport little or no vegetation cover.

Excessive high temperature and little unreliable rainfall in arid areas do notallow agricultural practices to be carried out.

Land is exposed to severe soil erosion. People tend to move to more productive areas during drought. Arid areas are open and experience strong dry wind.


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A desert that has been caused by natural causes

Climate change

2. Human causes of vegetation Reclamation of swamp land and irrigation schemes Poor irrigation practices Poor agricultural practices

Industrialization

Possible solutions to aridity andDesertification and reafforestationControlling soil erosion and adopting

conservation measures


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Controlling grazing. Introduction of suitable farming methods. Irrigation of the dry land. Stabilizing sand dunes. Introduction of other sources of energy. E.g biogas and energy saving stoves. Controlling industrallization.

Climate change in atmospheric conditions of a given place after a long period oftime. The sun has an effect on climate; It emits energy in form of light and solar radiation.(not all of it reaches earth as it

is reflected, absorbed or scattered by clouds, gases , dust particles and water vapour)

Causes of climate change1. Natural causes in the earths orbital characteristics. Orbit gradually changes frombeing elliptical to nearly circular then back to elliptical.

2. It causes perihelion and aphelion. The smaller the angle of tilt the less theclimatic variation between summer and winter.

3. Variation in atmospheric carbon(iv)oxide. High concentrations of carbon(iv)oxidewould result in higher temperatures.

4. Volcanic eruptions. Large quantities of volcanic ash and dust when thrown andspread in the atmosphere they block and reflect solar insolation. Temperaturesbelow the cloud formed will be lower.

5. Variation in solar output. Change in solar output of 1% per century will lower

global average temperature by 0.5C -1C.

A diagram showing the aphelion and the perihelion


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2. Human causes of fossil fuels . For industries, transportation e.t.c Forest and grassland fires. Burning vegetation adds carbon(iv)oxide to the

atmosphere. Deforestation and land use changes. Clearing of large tracts of vegetation for

agriculture, industries and settlement leads to build up of excess carbon (iv)

oxide. Chloroflouro carbons. When released into the atmosphere they destroy the

ozone layer thus increasing amount of solar radiation received. Industrial and agricultural developments.

Greenhouse effect Involves solar radiation being absorbed and received by the earthand transformed to terrestrial radiation. It is retained in the earth due to high levels ofcarbon (iv) oxide and reflection from clouds.

Consequences of climate change or decreased rainfall received. Effect on agriculture. Shifting of crop growing areas. Disruption of natural ecosystems. City environments become warmer. Water use and long term planning. Drier areas will have to find new sources

of water. Wetter areas dont need dams or such. Abnormal fast growth of plants. Flooding from rising sea (water) levels. Increased ultra-violet radiation.Effects include: snow blindness, increased sun

burn, skin cancer e.t.c

Save the earth, reduce climate change!!!


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CHAPTER 9: VEGETATION 1

DefinitionThis is the collective plant cover growing in a particular area. It consists of trees,grasses, bushes, thickets, shrubs, herbs, mosses, among other

Types of vegetation Natural vegetation Secondary vegetation Planted vegetation

The plants grow and spread through natural means of seed dispersal .it may befound in the thick forests of the Amazon and Congo. In Kenya it is found in Malava,kaimosi, sokoke-Arabuko forests


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Secondary vegetation

It is also known as semi-natural vegetation or derived vegetation because theconditions of its growth are not purely natural. It is common in areas where shiftingcultivation and bush-fallowing are practiced. It does not grow as luxuriously as thenatural vegetation

Planted vegetation


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This is the vegetation that is deliberately grown by humans. It is either done throughafforestation or re-afforestation

Characteristics of planted vegetation

Similar species Same height Appear in rows

Places where planted vegetation are found: Turbo Timboroa Maji Mazuri Limuru

Factors influencing distribution of vegetation: Topographical factors Climatic factors Edaphic factors Biological(biotic) factors

Topographical factors Relief Aspect Drainage


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a) Relief Altitude has a major influence on temperature and rainfall. Highlands have cooler temperatures. Plants thrive in warm areas while others

can only survive under cool temperatures. The windward sides of mountains receive heavy rainfall which supports

luxuriant growth Mountain tops receive very little rain and there temperatures are also low.

This inhibits plant growth

b) Aspect In the northern mid latitudes the south facing slopes receive more sunlight

which leads to higher temperatures and support a dense vegetation. It ismainly experienced in the lower latitudes on the windward sides that benefitfrom moisture from prevailing winds. Forests are therefore abundant on thesouthward facing slopes

c) Drainage A large variety of plants grow on well drained slopes. Swamp plants can

survive in water logged conditions as there roots have special adaptations tooxygen free soil conditions. Prolonged flooding leads to many plants dying

Climatic factors Temperature Precipitation Sunlight Wind

a) Temperature Trees growing in tropical regions develop broad leaves to enable them to

transpire adequately when the rainfall is heavy. Where rainfall is moderate,the trees have small needle like leaves to reduce the water lost through

transpiration.


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In cold regions trees have a conical shape and needle like leaves to allow thesnow to slide off easily

b) Precipitation Various forms of precipitations provide moisture for plants the amount of

rainfall received in an area determines the kind of plants that dominate thearea

c) Sunlight Places which experience long hours of sunlight have large varieties of plants

unlike those which receive less amount of sunlight and for short periods.

d) Wind Hot dry winds cause drought conditions to set in whereas moist winds are

responsible for increased precipitation where they blow. Warm dry winds areresponsible for increased rates of transpiration where strong are dominant tallplant species are usually non existent and those present become stunted. Itfacilitates the spread of seeds to aid in pollination

Edaphic factorsPedology

This is the scientific study of soils with respect to their origin, characteristicsand how they are utilized.

It is mainly concerned with the soil forming processes such as leaching and isinfluenced by processes such as; parent rock material, climate and livingorganisms.

Soils with well balanced nutrients support a large variety of plants and gigantictrees. Some plants like conifers do well in moderate to highly acidic soils whileothers like grasses do well with lower acidity. That is why grasses aredominant in dry regions where soils are more alkaline

Biotic factors Human activities Competition Effect of insect animals

Human activities (anthropogenic)

Human activities such as mining, urbanization, industrialization, roadconstruction, deforestation upset the development of vegetation growing.Large tracts of forests have been cleared to provide fuel and furniture. Bushfires have caused some plant species to be destroyed completely whileovergrazing has turned some grassland into pure deserts

Competition Plants compete with each other for light and water. The most dominant

species kill off the weaker species through natural selection. In the rainforestswhere tall plants form a canopy, they prevent sunlight from reaching theground thereby resisting growth of small shrubs.


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Effect of insect animals Some insects attack plants resulting to their death and deformation. Aphids,

ants, and termites attack tree trunks and roots making the trees to wither.Burrowing animals affect the growth of trees. Such trees become weak andeasily fall down.

VEGETATION DISTRIBUTION IN KENYA

Factors influencing vegetation distribution in Kenya Variation in rainfall Variation in temperature Variation in soil types Human activities

Factors influencing vegetation distribution in Kenya Variation in rainfall Variation in temperature Variation in soil types Human activities

Forests Lowland and plateau forests Montane forests


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Lowland and plateau forests Found between the sea level and 1800m Influenced by high temperatures and high humidity at the coast, coupled with

deep porous sandy soils

Distribution Tanzania; the northern part of the coast Kenya; the south coast upwards to lamu The plateau forest; Gwasi hills of Suba district, Kenya.

Montane forest

DistributionTo the east of the rift valley;

Nairobi Kijabe Nyandarua (aberdare) range

Mount Kenya forest To the west of the rift valley; Nguruman escarpment

DistributionTo the west of the rift valley;

Nguruman escarpment Loita hills Mau escarpment Kaptagat hills Cherangani hills

Elgon hills


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Savanna Wooded grassland Bush land and thicket Highland grassland

Wooded grassland It is composed of grass which varies in height. The grass is mixed with trees especially the thorny acacias As rainfall decreases and becomes more seasonal, the forest vegetation

gives way to the wooded grassland

Distribution Along coastal strips Plateaus bordering the highlands east of the rift valley Lake Victoria basin

Bush land and thicket It comprises a mixture of thorny acacias which are tall and umbrella shaped Shrubs grow in between these trees forming thickets of thorn bush The plants are adapted to long dry seasons thus have thin leaves, hard

cuticles, long tap roots. For example, the baobab tree


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Swamp vegetation They are found in wet areas The mangrove belt along the coast The vegetation is adapted to waterlogged conditions There is a wide variety of plants with the papyrus variety being the most

dominant It includes the mashes, grasses with smooth surfaces and long blades Trees are not common under water logged conditions


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CHAPTER 10: VEGETATION 2:MAJOR VEGETATION ZONES OF THE WORLD

The worlds vegetations can be classified according to Climatic regions:

TropicalTemperate

ArcticMontane

The worlds vegetation is thereby grouped in to:ForestsGrasslands

Mediterranean

Desert (hot desert and cold desert _tundra)Mountain

1. forests A forest is a continuous growth of trees covering a large tract of land.Types of forests

forests (boreal/taiga)

TROPICAL RAINFORESTSCharacteristics of tropical rainforests

Have closely set canopy Trees are smooth with no branches Have broad leaves to protect them from collapsing during intense midday

insolation

Have a variety of species


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Uses1. The hardwoods are a source of timber2. used for decorations3. Cinchona trees have medicinal value

4. Habitats to animals5. Fibres obtained from animals used to make panama huts mats6. Balata juices are available for making machinery belting7. Chicle used for making chewing gum

LOCATION1. Mozambique2. Madagascar3. Guinea4. Gambia5. Sierra Leone6. South American coast near Amazon River7. South East Asia

Characteristics of tropical monsoonSome trees have roots that grow horizontally to provide the plant with growingmechanismHave special roots which are partly aerial for

USEStannin which is used in tanning

leather.sed in building and construction.

LOCATION MONSOONFORESTSouthern EuropeNorth AfricaCape TownCalifornia

Central ChileSouth west Australia

Characteristics of Mediterranean forest1. They have long taproots in order to reach for water down below the surface2. Some are evergreen others are deciduous3. Are thick and bushy4. Many of the plants are sweet smelling e.g. lavender

Uses1. The bark of the cork oak provides cork for bottling wine

2. Fruits of olive tree are used for cooking


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3. Timber is obtained from trees like pine chestnut4. The shrubs and grasses are used as pastureTEMPERATE EVERGREEN FORESTS

Characteristics of temperate evergreen vegetation Forests are evergreen due to the high rainfall Most trees have broad leaves Common trees are the tulips camphor magnolia palm Most of the trees are hardwoods

Uses of temperate evergreen forests The hardwoods are very valuable in making furniture and as building

materials. Wattle trunks are useful in coal mines of Natal. Bamboo is used in making furniture and also building. Softwoods like pines are used in manufacture of paper. Some trees like walnut produce nuts used in making chocolate. Ivory nuts are used in making buttons. The young shoots of bamboo plants are eaten as vegetables.

Temperate evergreen forestSouth Africa along coast of natal

Southern ChinaSouthern JapanNewzealandBrazil

TEMPERATE DECIDUOUS FORESTS Have broad leaves Trees are hardwoods Trees shed leaves in autumn in preparation of winter Species of trees may be mixed E.g. oak, beech, chestnut


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Central Sweden Southern Hokkaido islands of Japan

GRASSLANDSThis type of vegetation grows in areas experiencing one rainfall season with a longdryperiod.Can be categorized into:

Tropical (Savanna) Temperate grasslands(Prairies of Canada and U.S.A/Steppes of Eurasia /Pampas of Argentina/Veldt of south Africa /Downs of Australia new Zealand) Mountain grasslands

USES Grazing Commercial ranching is practiced They increase the humus in the soil Reduce soil erosion Home to wild animals Habitats for bees which provide honey Wild fruits and berries found are consumed as food Trees provide fuel


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Tropical and temperate savanna Widely spread trees Umbrella shaped crowns Drought-resistant trees Deciduous trees

Rainfall is between 1000-1800 Have deep roots and thick barks

1. Tropical grasslands

Location1. Venezuela2. Brazil3. Mexico4. Northern Australia5. Deccan in India

2. Temperate grasslandsLocation1. . Canada2. U.S.A3. Eurasia4. Argentina5. Australia6. New Zealand7. South Africa

Uses Large scale grain cultivation Livestock farming


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3. DESERT VEGETATIONGrows in areas in areas where rainfall is extremely unreliableBelow 250mm

Can be classified into:Tropical desert and cold deserts

A) Tropical Desert

Location1. Sahara2. Arabian3. Kalahari4. Atacama5. Thar in India6. Mohave and Colorado7. California

Adaptation Succulent perennials Evergreen hard leaved plants Drought resistant deciduous shrubs Salt tolerant plants Short leaved plants

B) Temperate and Arctic desert vegetation

Nevada and Utah in America Patagonian desert in Argentina Turkey China Northern Iran

Location


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Adaptations Deciduous Mainly succulents Small waxy and thorny leaves Rough tree trunks and twisted thick bark to

reduce water lose Some are pyrophitic (resistant to local fires) Flat topped crowns to withstand strong winds

Uses of desert vegetation1. The small trees are a source of fuel for2. Eskimos who leave in arctic regions3. It is food for desert animals4. Plants like bilberries bear edible fruits

4. MOUNTAIN VEGETATION/ALPINEFound in mountain summits in the tropics where the temperatures have beenlowered by elevation hence the areas become too cold.Vegetation is not uniform all over the mountain due to:

Altitude Aspect Slope Moisture availability Temperature

Uses Uses of mountain vegetation Large scale grain cultivation Livestock farming Summer pastures for animals

Grazing carried out on the grasslands


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Provide timber and building materials Habitats for wild animals Mountainous areas act as water catchment areas Forests help in balancing ecosystem Vegetation in the mountain is used in scientific research

Significance of vegetation Add beauty to the landscape Prevent soil erosion Plants decay to become humus Act as a habitat for wildlife Purify air Some plants have medicinal value Some trees are used in pulp and paper industry Forests modify the climate Some plants are consumed as food Fibrous plants are used for making robes Latex extracted from rubber trees is used in manufacture of rubber


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CHAPTER 11: FORESTRY

DEFINITION OF TERMS:

A FOREST is a continuous growth of trees and undergrowth covering a large tract ofland.

FORESTRYis the science of

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