FIRST TERM E-LEARNING NOTE
SUBJECT: GEOGRAPHY CLASS: SS2
SCHEME OF WORK
1&2 REVISION/ACTION OF RUNNING WATER
3 ACTION OF WIND
4 ACTION OF GLACIER
5 ACTION OF WAVE
7 CLASSIFICATION OF CLIMATE
8 ENVIRONMENTAL RESOURCES
9 RENEWABLE AND NON-RENEWABLE RESOURCES
10 ENVIRONMENTAL PROBLEMS
- Essential Geography for Senior Secondary Schools, O.A. Iwena.
WEEK ONE AND TWO
ACTION OF RUNNING WATER (RIVER)
Running water is one of the most important agents of denudation. Rivers are involved in erosion transportation and deposition of materials.
TERMS ASSOCIATED WITH RIVERS
(1) Source of a river: The source a river refers to where a river starts or begins, usually around highlands.
(2) Course of a river: This refers to the path or channel through which the river flows.
(3) Mouth of a river: This is where the river ends or where it enters into the sea, ocean or lake.
(4) River basin or catchment area: It refers to all the areas drained by a river and its tributaries.
(5) Water shed or water divide: It is the highland area which separatestwo or more rivers or two river basins. It is from the watershed that rivers take their sources.
(6) River regime: This refers to the seasonal changes in the volume of water in a river in a year. It could be single regime where there is one period of high volume and one period of low volume and double regime where there are two distinct periods of high volume of water in a year. Knowledge of a river regime is important to man in controlling floods, storing up water for irrigation and human consumption and also for planning H.E.P production.
(7) Confluence of a river: This refers to the meeting point of two rivers.
(8) Tributaries: These are smaller rivers or streams that join together to form a larger river.
(9) Distributaries: These are channels formed by the division of a river as it flows into the sea. They are usually found in the delta region of a river.
(10) River energy: It refers to the velocity of a river. The efficiency of a river to erode and transport the eroded materials depends very much on its velocity.
FACTORS AFFECTING THE VELOCITY OF A RIVER
(a) The volume of water released. (b) Slope of the river valley.
(c) Shape of the river valley. (d) Amount and size of materials.
STAGES OF A RIVER
The entire length, valley or course of a river is divided into three main stages.
(1) The upper course or mountain course (Youthful stage).
(2) The middle course or valley course (Mature stage).
(3) The lower course or plain course (Old stage).
UPPER COURSE OF A RIVER
CHARACTERISTICS OF UPPER COURSE OF A RIVER:
(a) It marks thebeginning or source of a River.
(b) It is found around highland areas.
(c) It has steep sides.
(d) The river flows swiftly down the steep slope.
(e) The dominant work of the river is vertical corrosion or erosion.
PROCESSES OF RIVER EROSION
The load or materials carried by a river are the main agents of erosion, but the erosive work of a river consist of four processes. These are:
(a) Hydraulic action: In this process, fast flowing water forces itself into cracks and joints within the valley under pressure and enlarges the cracks.
(b) Corrosion: Corrosion is the wearing away of the sides and floor of the river with the aid of sand, pebbles, silts and boulders which are being transported. These materials eventually widen and deepen the river valley.
(c) Attrition: This is the wearing down of the load as they collide with one another and with the floor and side of the valley. Large boulders are broken down into small pieces like pebbles.
(d) Solution: This refers to chemical action of water on materials it comes in contact with while flowing. Here, rock salt is dissolved and carried away in solution.
FEATURES OF UPPER COURSE OF A RIVER
(a) V-Shaped Valley
(c) River Capture
(d) Rapid and Cataracts
MIDDLE COURSE OF A RIVER
Characteristics of Middle Course of a River
(a) Lateral erosion is dominant over vertical erosion, resulting in widening of the river valley.
(b) There is increase in the volume of water due to addition of more water from tributaries.
(c) There is increase in the load of the river.
(d) The work of the river is mainly transportation with little deposition.
- Mention the stages of a river and a feature in each stage.
- Mention three characteristics of a river in its middle course.
PROCESSES OF RIVER TRANSPORTATION
The load of a river is carried or transported along the course of a river through four main processes. These are:
(a) Solution (b) Suspension
(c) Saltation (d) Traction
FEATURES OF MIDDLE COURSE OF A RIVER
(a) Wide V- shaped Valley
(c) River Cliff and Slip – off Slopes
(d) Interlocking Spur
LOWER COURSE OF A RIVER
CHARACTERISTICS OF THE LOWER COURSE OF A RIVER
- The main work of the river is deposition of materials.
- There is active lateral erosion.
- There is lowering of the gradient of the valley floor.
- There is drastic reduction in the speed of the river.
FEATURES OF LOWER COURSE OF A RIVER:
(a) Flood plain
(c) Ox-bow lake
(d) Braided river
A river system which includes the main river and its tributaries may develop certain patterns from their basin and the types of drainage patterns include:
- Dendritic drainage pattern: In this type, the tributaries called the subsequent rivers join the main river called the consequent river at oblique angle. It is a tree like structure i.e. like branches of a tree which develop on homogenous rocks of bed.
- Trellised drainage pattern: This is formed due to the alternate layers of hard and soft rocks, resulting in the tributaries following the pattern of the rock structure and at right- angle to the main river in form of rectangular shape.
- Radial drainage pattern: The streams or tributaries flow outward and down the hill thus given rise to a radial drainage pattern like the shape of a bicycle wheel.
- Centripetal drainage pattern: In this type, many rivers or streams flow from different directions into a lake.
- Annular drainage pattern: The main stream or river almost form a concentric ring around a highland i.e it almost flows round or encircles a hill.
IMPORTANCE OF RIVERS
- Medium of transportation.
- Generation of hydro-electric power (H.E.P) where rapids and waterfalls exist.
- It Provides water for irrigation purposes.
- Provision of water for domestic and industrial purposes.
- Formation of flood plain by rivers also provides fertile soil for agricultural activities.
- Rivers provide food e.g. fish, prawns, crabs, etc.
- It provides employment to many people e.g. fishermen and canoe builders.
(8) Some rivers act as political boundaries between states, regions and nations.
(9) Some rivers are centers of tourist attraction and may generate foreign exchange.
- Mention two features of a river in the lower stage.
- Mention four ways a river can transport its load.
- What is running water?
- State the stages of a river.
- Explain the processes of river erosion.
- State the processes of river transportation.
- Mention the features of a river in its lower course.
Essential Geography, O.A. Iwena, Pages 51-58.
- The point where a river enters into the sea, ocean or lake is known as (a) Course of a river (b) mouth of a river (c) source of a river (d) end of a river
- Which of these is not a feature of the middle course of a river? (a) gorge (b) meander (c) river cliff (d) interlocking spurs
- The following conditions are favourable for the formation of delta except (a) Strong current running at right angle to the river mouth (b) active vertical erosion in the upper course of the river (c) sheltered and almost tireless coast (d) absence of large lakes in the course
- The processes of river transportation include the following except (a) saltation (b) hydration (c) solution (d) traction
- Which of these is not a feature of the lower course of a river? (a) ox-bow lakes (b) delta (c) rapids and cataract (d) leaves
- With the aid of a diagram, describe river piracy.
- With the aid of a diagram, describe ox-bow lake.
ACTION OF WIND IN THE DESERT
The action of wind is dominant in desert and other semi arid regions of the world. Deserts are places with little or no vegetation. Deserts which are associated with aridity (dryness) are caused by low rainfall, high temperature, cold currents and high evaporation rate. Examples of Deserts are:
(i) Sahara desert (West Africa).
(ii) Kalahari and Namib deserts (South Africa).
(iii) Arabian, Iranian and Thar deserts (Middle East).
(iv) Australian desert (Australia).
(v) Atacama desert (South America).
(vi) Mohave desert (U.S.A).
CHARACTERISTICS OF DESERTS
(i) Extreme of Temperature. (ii) Low rainfall.
(iii) Absence of vegetation cover. (iv) High evaporation rate.
(v) Wind action is dominant. (vi) Presence of cold currents.
TYPES OF DESERTS
There are five distinct kinds of deserts
- Erg or Sandy desert 2. Hamada or rocky deserts
- Reg or stony deserts 4. Badlands
- Mountain deserts
ACTION OF WIND EROSION
Wind erosion is carried out in the following ways:-
- Deflation: This is the lifting and blowing of loose sand and pebbles by wind. Deflation results in the lowering of the land surface to form large depression called Deflation hollows.
- Abrasion: This is the process whereby sand particles carried by wind are used to blast or wear away rock surfaces.
- Attrition: This is the process whereby materials carried by wind collide with one another thereby wearing away each other.
DIFFERENCES BETWEEN DEFLATION AND ABRASION
- Deflation involves blowing while abrasion involves hauling rock against rock surface by wind.
- Deflation involves rolling of loose materials along the ground whereas in abrasion, rock surface are polished, scratched and worn away.
- Deflation usually results in lowering of land surface while abrasion is most effective at the base of rocks.
- Deflation is associated with wind while abrasion can be caused by wind, water and wave.
- What are the causes of desert?
- Mention the five types of desert.
FEATURES OF WIND EROSION IN THE DESERT
- Rock Pedestals
Characteristics: Rock pedestals are irregular in shape e.g. mushroom shape with alternate horizontal layers of hard and soft rocks. They are like pillars in structure. They are desert land forms which range from 10 – 15 meters in height.
Mode of formation: Rock pedestals are formed by wind abrasion on alternate horizontal layers of hard and soft rocks. Abrasion is greater at ground level, resulting in serious under cutting, to produce irregular shaped feature called rock pedestals in deserts.
Characteristics: These are tabular masses with a layer of soft rocks lying beneath a surface layer of hard rock. It has a long ridge and furrow landscape. They are also formed by wind abrasion in deserts.
PRIMARY 4 THIRD TERM LESSON NOTE BASIC SCIENCE
Mode of formation: Zeugen is formed when a tabular mass of rock which has a layer of soft rocks lying under a layer of a more resistance hard rock islying horizontally to the direction of wind. The mass of rock is then attacked by wind abrasion and then wears the mass into a ridge and furrow landscape, leading to the formation of Zeugen. Mechanical weathering starts the formation by opening up joints of the surface of hard rocks.
Characteristics: Yardages have vertical bands of hard and soft rocks, ridge and furrow of landscape of about 10 – 15 meters long.
Mode of formation: Yardangs are formed when hard and soft rocks in vertical bands are aligned in the direction of prevailing wind. Wind abrasion wears off the softer rocks into long narrow corridors which separate the steep-sided ridges of the hard rocks. These hard rocks are called Yardangs.
- Mesas and Buttes
Characteristics: Mesa is a flat, table-like landmass. It has a resistant horizontal top layer with steep sides and is made up of soft and hard layers.
Mode of formation: As a result of the action of denudation, the hard top layer of rock resists agents of denudation and protects the softer layers of rocks below from being eroded. At times, mesas may be formed in canyon regions. Canyon develops in the space between mesas and butte. Denudation, sometimes, may reduce mesas in areas to become isolated flat topped hills called buttes.
Characteristics: Inselberg is an arid land form. It is an isolated rocky out crop having steep sides, round top and composed of granite. It may rise up to a height of over 500metres and may occur singly or in group. Examples are found in Northern Nigeria, Kalahari desert, and Western Australia.
Mode of formation:Inselbergis formed from the existence of extensive old plateau. It is caused as a result of weathering and removal of weathered materials by water and wind. It is an exposure of rock out-crop.
- Ventifacts and Dreikanters: These are pebbles sharpened or faceted by sand blasting. Wind abrasion shapes and polishes the pebbles and new facets develop when wind direction changes. Ventifacts with three wind faceted surfaces are called dreikanters.
- Deflation Hollows or Depression:
Characteristics: They are formed by wind deflation. It is a desert landform with varying depths. There may be presence of sand dunes on the leeward side. It has a basin and a saucer shape. It is very extensive and can form oasis in deserts.
Mode of formation: As a result of wind deflation, large depression or hollows are produced by the scooping away of loose sand materials by wind, Sometimes below the water table. When this happens, water seeps out and oasis or swamps are formed.
FEATURES OF WIND DEPOSITION IN DESERTS
(1) Dunes: Dunes are hills or ridges of sand formed by the piling up of sand into hill shape by the action of wind. They are initiated when an obstacle of some kind prevents free movement of the wind. Thus, creating certain shape against the obstacle until it covers the latter and falls over to the other side. There are two main types of dunes, These are:
Characteristics: A barchan is a cresentic or moon shaped structure. They may occur in groups or singly. A barchan has a convex shape on windward side and a concave shape on the leeward side with horns of 15-30 metre long. It is formed by wind deposition in deserts.
Mode of Formation: A barchan is formed when an obstacle like rock impedes or prevents the movement of wind, resulting in the accumulation of sand materials. Later the sand begins to accumulate on the other side of the obstacle, leading to a crescent or moon shaped structure with horns called Barchan. The windward side of a barchan is convex and gentle, while the leeward side, being sheltered is concave and steep.
(b) Seifs or Longitudinal Dunes
Characteristics: Seifs are sword-shape. They have long and narrow ridges of sand usually of hundreds of kilometers. They are formed by wind deposition in the desert e.g. Sahara desert.
Mode of formation:Seifs are formed during wind deposition. They lie parallel to the prevailing wind which clear the corridors between dunes of sand. Eddies blow towards the side of the corridor and build up seif dunes.
(2) Loess: These are fine soil particles carried by wind. They are deposited outside the desert as loess. Loess is a fine loam, very fertile and porous.
- Mention two features of wind erosion.
- State two differences between Zeugen and Yardang.
- What is a desert?
- State three causes of a desert.
- Mention four types of desert.
- Explain action of wind erosion in desert regions.
- Describe a rock pedestal.
Essential Geography, O.A. Iwena, Pages 58-62.
- The largest desert is (a) Kalahari desert (b) Sahara desert (c) Atacama desert (d) Namib desert
- Which of these deserts is sandy (a) Erg (b) Reg (c) Hamada (d) Mountain desert
- The process of wind erosion which involves the lifting and blowing away of loose sand is (a) Abrasion (b) Deflation (c) Attrition (d) Saltation
- Which of these is formed by the deposition action of wind? (a) Dunes (b) Yardang (c) Zeugen (d) Rock pedestals
- An Isolated rocky outcrop of granite is (a) Dunes (b) Inselberg (c) Seifs (d) Yardang
- With the aid of a diagram, describe the mode of formation of yardeng.
- List two differences between yardeng and zeugen.
ACTION OF GLACIER
The action of glacier is an important agent of erosion, transportation and deposition in temperate regions or mountainous regions.
TERMS ASSOCIATED WITH GLACIER
- Ice: This is solid form of water which results from freezing when the temperature is below 00C.
- Snow: This refers to frozen water vapour that falls in form of crystals from the atmosphere.
- Snow-Line: It is the lower limit of snow cover on a mountain.
- Glacier: This means moving ice i.e large accumulation of ice in motion.
- Glaciation: It is the wearing away of the earth surface by glacier.
- Snow Field: This is the region or area that is permanently covered by snow
- What is glacier?
- Which parts of the world are mostly affected by glacier?
ACTION OF GLACIER EROSION
- Sapping: This is the braking up of rock by alternate freezing and thawing of water at the bottom of cracks.
- Plucking: It is the tearing away of rocks which have become frozen on the side or bottom of a glacier.
- Abrasion: This is the wearing away of rocks beneath a glacier by the scouring action of the rocks embedded in the glacier.
SS 3 FIRST TERM LESSON NOTE GEOGRAPHY
FEATURES OF GLACIER DEPOSITION IN LOWLAND AREAS
- Boulder Clay: This consist of stones of various sizes in a mass of sand and clay.
- Erratics: These are transported rock fragments which are composed of materials entirely different from the bedrock of the region where they are deposited. They are deposited when the ice carrying them melt into water.
- Drumlins: It is composed mainly of boulder clay.
- Eskers: These are long narrow ridges of sand and gravel deposited by melting water. They are usually porous.
- Terminal Moraines: They are made up of boulders which are deposited at the edge of the ice-sheet.
- Outwash Plain: This is a large area consisting of sand and gravel that are washed down the mountainous zone and deposited to form outwash plain which lies beyond the terminal moraines.
- State the processes of glacier erosion.
- Describe plucking.
- Explain abrasion.
- Explain at least three features of glacier deposition in lowland areas.
- What is Time Zone?
Essential Geography, O.A. Iwena, Pages 63-65.
- The action of glacier is more dominant in (a) humid region (b) tropical region (c) temperate region (d) desert region
- All are processes of glacier erosion except (a) Plucking (b) Hydration (c) Sapping (d) Abrasion
- The breaking down of rocks through the collision of the different rock fragments is called (a) Attrition (b) Abrasion (c) Traction (d) Sapping
- All are features of glacier erosion in highland areas except (a) Arete (b) Striations (c) Corries (d) Bay
- Which of the following is a feature of glacier deposition? (a) Beach (b) Seifs (c) Boulder clay (d) Delta
- State two features of glacier erosion in lowlands.
- Explain abrasion.
ACTION OF WAVE
The action of wave as an important agent of erosion, transportation and deposition of material is confined to the coast of seas and oceans. The rate of marine erosion depends on the nature of the rocks, the amount of rock exposed to the sea, the effects of tides and currents and human interference in coast protection.
TERMS ASSOCIATED WITH WAVE
(i) Wave: Wave means turbulent movement of water as a result of wind moving over the water.
(ii) Tide: Tide is the alternate rise and fall of the surface of the sea approximately two times a day.
(iii) Current: Ocean current is the movement of water in the ocean in a particular direction.
(iv) Coast: This refers to the meeting point between the land and the sea.
(v) Shore: This is the part of the land that lies between high water and low water.
(vi) Beach: This refers to the material deposited on the shore by the action of wave.
(vii) Swash: This refers to water thrown up the beach by breaking waves.
(viii) Back wash: This is the water that sucks back and retreats after wash.
(ix) Undertow: This is water which flows near the bottom away from the shore.
PROCESSES OF WAVE EROSION
(1) Corrosion: This is the wearing down of the base of the cliff by wave action.
(2) Attrition: This is breaking down of materials like pebbles, boulders, etc. against cliff faces and against each other, as the wave continues its activities.
(3) Hydraulic action: In this process, fast moving waves force itself into cracks within the base of the cliff under pressure and enlarge the cracks.
(4) Solvent action: This involves the disintegration of rock materials such as limestone in the coast by chemical action of the sea.
- Differentiate between swash and backwash.
- Describe how a beach is formed.
FEATURES PRODUCED BY WAVE EROSION
(1) Capes and Bays: They are features of marine erosion in coastline which can be made of hard rock (cape) or soft rock (bays). A bay usually contains water and could be used as harbour.
(2) Cliff: These are steep rock faces adjoining the coast. They are formed due to the action of waves on the base of headland which cut backward as the wave action intensifies.
(3) Coastal Cave: A cave is a feature of marine erosion.It is an arch-shaped feature found in steep coast or cliff coast.It may contain blow-holes or geo.
(4) Arch: When two caves approach each other from either side of a headland, they meet to form an arch.
(5) Stack: Continuous action of waves makes an arch to collapse. The seaward portion of the highland that remains is called a stack.
(6) Stump: When the stack is seriously eroded to a point that a small portion is just visible above the sea level, a stump is said to be formed.
(7) Geo: Geo develops when a wave cuts into a cliff, resulting into a narrow hole called a geo. It is formed when a cave collapses.
(8) Gloup or Blowhole: Owing to hydraulic action of wave, a hole might develop at the roof of a cave. Continued erosion will result in the hole piercing through to the surface of the cave and water at times may force itself through these holes to form a gloup or blow-holes.
Features of Coastal Deposition
(1) Beaches: Beaches are made up of sand and gravel. They are depositional features on the coast. Beaches are formed when sand and gravel loosened from the land are moved by wavesand deposited along the shore. These deposits of sand and gravel on the shore are called beaches.
(2) Spits: These are ridges of sand and gravel formed by long shore drift across the entrance to coastal inlet by lying on one side to the land and the other side into the ocean.
(3) Bar: Bar is a ridge, usually of sand or rock debris formed by deposition across the mouth of a river or across the entrance of a bay.
(4) Marine dunes and dune belt: Dunes are on shore wind with large force which makes a large amount of coastal sand to move to form marine dunes. Marine dunes will later stretch into dune belts.
- Mention any three features produced by wave erosion.
- What is an arch?
- Describe a wave.
- Describe a beach.
- What is ocean current?
- Explain attrition as a process of wave erosion.
- What is a bay?
Essential Geography, O.A. Iwena, Pages 65-68.
- The water thrown up the beach by wave is known as (a) Swash (b) Backwash (c) Current (d) Tide
- Which of these is not a mechanism of wave erosion? (a) Solvent action (b) Attrition
(c) Traction (d) Corrasion
- Steep rocks adjoining the coast are_____ (a) Capes (b) Cliffs (c) Bays (d) Stack
- When two caves meet and unite, they form (a) Stack (b) Stump (c) Arch (d) Bays
- Which of these is not a feature of coastal deposition? (a) Beaches (b) Dunes (c) Spits
- State two differences between Ria coast and Fiord Coast.
- List any three features of coastal deposition.
Climate is the average weather condition of the atmosphere over a long period of time usually about 30-35years.
FACTORS THAT CAN AFFECT OR DETEMINE CLIMATE
- Latitude 6. Cloud cover
- Altitude 7. Vegetation
- Distance from the sea 8. Planetary wind
- Ocean currents
Elements of climate
- Relative humidity
- Cloud cover
- What is climate?
- Differentiate between weather and climate.
TYPES OF CLIMATE
- HOT CLIMATE
Location: This is located within 50 North and South of the equator.
Areas: Amazon Basin of South America, Zaire Basin of Central Africa, The Coast of West Africa.
(b)Tropical Continental (Sudan) Climate
Location: It is located between 50-200 North and South of the equator
Areas: Central America, North Western part of South America, Interior upland of Brazil and Bolivia, West Africa, part of East Africa, parts of India and South East Asia, Northern Australia.
Location: It is found around 900 North and South of the Equator, especially around the poles.
Areas: Greenland, Iceland and Antarctica.
Location: It is located around 600-900 North and South of the equator especially around the Arctic and Antarctic circles.
Areas: Coastal strip of Greenland, Northern Canada and Alaska, parts of Eurasia and Antarctica.
(a)Hot Desert Climate
Location: Within latitude 150 and 300North and South of the equator.
Areas: Sahara desert, Arabian desert, Iranian desert, Thar desert, Namib desert, Kalahari desert, Great Australian desert and Atacama desert.
(b)Cold Desert Climate
Location: Within 450-600 North and South of the equator.
Areas: Eurasia, North America and South America.
Other types of climate are:
WARM TEMPERATE CLIMATE WESTERN MARGIN (MEDITERRANEAN TYPE)
Location: 300-450 North and south of the equator.
Areas: North Africa, South West of South Africa, Central Chile, California, Southern Australia, France, Spain and Italy.
JSS 1 THIRD TERM LESSON NOTE CIVIC EDUCATION
WARM TEMPERATE CLIMATE EASTERN MARGIN (CHINA TYPE)
Location: 200-400 North and south of the equator.
Areas: China, U.S.A, Mexico, Natal in South Africa and Australia.
COOL TEMPERATE CLIMATE WESTERN MARGIN (BRITISH TYPE)
Location: 450-600 North and south of the equator.
Areas: Britain, France, Belgium, Netherland, Denmark, Norway and British Columbia.
COOL TEMPERATE CLIMATE EASTERN MARGIN (LAURENTIAN TYPE)
Location: 400 and 500 North of the equator.
Areas: North Eastern part of North America, North East Canada and Northern Asia.
- Mention any four elements of weather and climate.
- State any three importance of weather and climate to man.
- What is weather and climate?
- Explain the importance of weather and climate.
- Mention the instrument used for measuring rainfall.
- Explain equatorial climate.
- Mention the areas that experience Mediterranean climate.
Essential Geography, O.A. Iwena, Pages 93-101.
- The height of a place above the sea level is known as (a) Latitude (b) Altitude (c) Lapse rate (d) Spot height
- Which of these factors does not affect weather and climate (a) Cloud cover (b) Humidity (c) Latitude (d) Natural Vegetation
- The instrument used for measuring wind direction is (a) Wind vane (b) Thermometer
(c) Anemometer (d) Rain guage
- Wet and dry bulb thermometer could be used for measuring (a) Rainfall (b) Relative humidity (c) Temperature (d) Wind speed
- Which of the following weather elements is paired with the wrong instrument? (a) Wind direction and wind vane (b) Humidity and anemometer (c) Rainfall and rain guage (d) Atmospheric pressure and barometer
- What is weather?
- Highlight five importance of weather and climate to man.
CLASSIFICATION OF CLIMATE
Climate varies from place to place and the following are the common classification of climate:
- Greek system of classification and
- Koppen system of classification
GREEK SYSTEM OF CLASSIFICATION OF CLIMATE
This is one of the earliest climatic classification which was made by the Greeks. The basis for the Greek classification is temperature. This system of classification divides the world into three climatic zones. These zones are:
- Torrid zone: This zone is found within the tropics. It is very hot and has high
temperature throughout the year.
- Temperate zone: It is found between the torrid and frigid zone and has moderate
- Frigid zone: It is found around the polar regions and It is very cold with low temperature
all year round. It has lot of ice-caps in most part of the year.
KOPPEN SYSTEM CLASSIFICATION OF CLIMATE
Thebasis for Koppen’s classification of climate aretemperature and rainfall. He identified five major climatic groups which correspond with the five principal vegetationgroups. These climatic groups are represented with capital letters as follows:
A-Tropical Rainy Climate
Environment is defined as the total surrounding or medium of any organism in a given area. This include the physical surroundings, climatic factors and other living organisms in that surrounding.
SPHERES OF THE ENVIRONMENT
The earth as an environment is grouped into four spheres:
- Lithosphere: The solid portion of the environment which contains rocks, sand, soil, minerals etc.
- Hydrosphere: This is the liquid portion of the environment like rivers, lakes and oceans.
iii. Atmosphere: This is the gaseous portion of the environment where gases like oxygen, nitrogen, carbon-dioxide, ozone are found.
- Biosphere: This is the portion of the environment where plants and animals are found. These four spheres of the environment are interrelated and interdependent on each other.
Ecosystem: An ecosystem is defined as the community of plants and animals living together in harmony and interacting with their physical environment.
In other word; ecosystem can be defined as the relationship that exists between living thing and their non-living environment.
Components of Ecosystem
The ecosystem is made up of two main components. These are:
(a) Abiotic (non-living) component: These are the components like soil, water, gases, sunlight etc in the environment.
(b) Biotic component: This is the living component of the ecosystem. It includes plants and animals.
Biotic component can be grouped into three (3)
(1) Autotrophs: This are also called the producers. They include the green plants which manufacture their own food through a process known as photosynthesis.
(2) Heterotrophs: These are called primary and secondary consumers. These organisms cannot manufacture their own food but depend directly or indirectly on plants for their own food e.g. man, parasites, saprophytes.
(3) Decomposers: These are micro – organisms that decompose dead organic matter in order to release nutrients required by producers to prepare their food e.g. Fungi and bacteria wholistically, the components of an ecosystem can be grouped into the following:
(1) Land (soil) (2) Water (Lake, Oceans) (3) plants (4) Animals
(5) Drainage (river) (6)Climate (Atmosphere)
INTERDEPENDENCE WITHIN THE ECOSYSTEM
Interdependence is the word used to describe the relationship between the components of the ecosystem. This is because, components in an ecostystem depend on one another and they cannot exist in isolation. A state of inter-dependence within the ecosystem is best achieved where the components are undisturbed.
Inter-dependence in an ecosystem exists in three ways:
(1) Interdependence within Abiotic components e.g. The weathering of rock to form soil or the evaporation of water to form cloud etc.
(2) Interdependence within Abiotic components e.g. Animals depend on plants for food or the exchange of oxygen and carbondioxide by plants and animals.
(3) Interdependence between the biotic and abiotic components e.g. plants depend on soil for support and nutrients, Autotrophs conver sunlight, energy. Water and carbon dioxide during photosynthesis to produce food etc.
Environmental balance refers to the ways of recycling matter and the flow of energy withing an ecosystem in order to ensure continuous supply or availability.
Environmental balance is achieved through the following processes:
(i) Hydrological (water) cycle
(ii) Carbon cycle
(iii) Nitrogen cycle
(iv) Mineral nutrient cycle
(v) Food chain and food web. (for details, see pages 115 – 118 of Essential Geography)
- What is the Word ‘Interdependence’ mean?
- What is Environmental balance and how is it achieved?
- The liquid portion of the earth is called ________
(a) Hydrosphere (b) Biosphere (c) Atmosphere
- Animals, man and parasites are grouped as ______
(a) Decomposers (b) Heterotrophs (c) Autotrophs
- The relationship between organisms and its physical environment is called __________
(a) Environment (b) Ecosystem (c) Community
- The best example of autorophsare ________
(a) Animals (b) Man (c) plants
- One of these is not a way an environmental balance is achieved:
(a) Food chain (b) Water cycle (c) Sand cycle
- What is an Ecosystem?
- Mention the components of Ecocystem and briefly explain each of them.
INTERVENTIONS WITHIN THE NATURAL ENVIRONMENT
MEANING: Environmental intervention refers to the forces of nature and the activities of man that change the natural existence of the components of the eco-system.
TYPES OF ENVIRONMENTAL INTERVENTION
There are two types of interventions in our environmental. There are man-made and natural intervention.
- Natural Intervention includes Desert Encroachment, volcanism, sea – level changes, Earthquakes, climatic changes, Drought, flooding, Hurricane etc.
- Human Interventions deal with man’s interference with the ecosystem through his activities. Human intervention include:Deforestation, pollution, land reclamation, farming activities, construction urbanization, grazing, industrialization etc.
- What is Environmental Intervention.
- Name the two types of Environmental intervention and give two examples of each.