Spearman's Rank Correlation
* Spearman's Rank Correlation is a technique used to test the direction and strength of the relationship between two variables. In other words, its a device to show whether any one set of numbers has an effect on another set of numbers.
* It uses the statistic Rs which falls between -1 and +1.
Procedure for using Spearman's Rank Correlation
1. State the null hypothesis i.e. "There is no relationship between the two sets of data."
2. Rank both sets of data from the highest to the lowest. Make sure to check for tied ranks.
3. Subtract the two sets of ranks to get the difference d.
4. Square the values of d.
5. Add the squared values of d to get Sigma d2.
6. Use the formula Rs = 1-(6Sigma d2/n3-n) where n is the number of ranks you have.
7. If the Rs value...
... is -1, there is a perfect negative correlation.
...falls between -1 and -0.5, there is a strong negative correlation.
...falls between -0.5 and 0, there is a weak negative correlation.
... is 0, there is no correlation
...falls between 0 and 0.5, there is a weak positive correlation.
...falls between 0.5 and 1, there is a strong positive correlation
...is 1, there is a perfect positive correlation
between the 2 sets of data.
8. If the Rs value is 0, state that null hypothesis is accepted. Otherwise, say it is rejected.
Practical Example of Spearman's Rank Correlation
Question: Use the Spearman's Rank Correlation to establish whether there is any relationship between the distance away from school students live and the IB Geography grades they attain.
* Red type indicates what you have been given. Black type indicates the working done.
#. Null Hypothesis: There is no relationship between the two sets of data.
# Rs = 1-(6 Sigma d2 / n3-n).
* Sigma d2 = 22 therefore 6 Sigma d2= 132
* n = 5 therefore n3-n = 120
# Rs = 1-(132/120)
# Rs = 1- 0.91
# Rs = 0.09
# There is a weak positive correlation between the two sets of data. The null hypothesis is rejected.
Sex Structure
Sex Structure
* The sex structure refers to the proportions of the 2 sexes in a defined population.
* It is expressed as the number of males to every 100 females.
* Male births usually exceed female births, but males die off more quickly in infancy, so by the time children are 1 yr old, there are more females than males.
* The sex structure may be affected by the following
o Where women are considered subordinate beings, they suffer a higher mortality rate and a lower life expectancy.
o Migration. There is usually a dominance of males in populations dominated by immigrants.
o In difficult environments, there is usually an imbalance in favor of males.
o Select populations such as military towns may have an imbalance for either of the sexes.
o Urban areas in developing regions have more males.
* The sex structure refers to the proportions of the 2 sexes in a defined population.
* It is expressed as the number of males to every 100 females.
* Male births usually exceed female births, but males die off more quickly in infancy, so by the time children are 1 yr old, there are more females than males.
* The sex structure may be affected by the following
o Where women are considered subordinate beings, they suffer a higher mortality rate and a lower life expectancy.
o Migration. There is usually a dominance of males in populations dominated by immigrants.
o In difficult environments, there is usually an imbalance in favor of males.
o Select populations such as military towns may have an imbalance for either of the sexes.
o Urban areas in developing regions have more males.
Population Geography and Demography
Population Geography and Demography
* Population Geography is the study of spatial variations in distribution, density, composition and growth of human numbers on earth.
* It is important because it links all other aspects of geography together.
Demography
* Demography is the study of population characteristics.
* It is significant because
1. There are more people living today than any other time in history.
2. There's been a population explosion since World War 2.
3. There is an inverse relationship between population growth and resources i.e. there are too many people in places without enough resources to support them and too few people in areas with over abundant resources
* Population Geography is the study of spatial variations in distribution, density, composition and growth of human numbers on earth.
* It is important because it links all other aspects of geography together.
Demography
* Demography is the study of population characteristics.
* It is significant because
1. There are more people living today than any other time in history.
2. There's been a population explosion since World War 2.
3. There is an inverse relationship between population growth and resources i.e. there are too many people in places without enough resources to support them and too few people in areas with over abundant resources
Migration
Migration
Migration
* Migration is the movement of people
* It is classified by such indices as
o Distance travelled
o Reason for travel
o Period of time of travel
o Volume of migrants
* Cosequences of migration include
o Increased understanding between people of different cultures
o Increased animosity between people of different cultures
o Changes in numbers of people at the destination and origin
o Creation of ghettoes in urban areas
o Inter-marriages
Ravenstein's Laws of Migration
* Ravenstein came up with his "laws" of migration in the 1880s based on studies carried out in the UK.
* The laws are as follows
1. The greatest body of migrants travel short distances.
2. This produces currents directed towards great commercial centers.
3. Each current has a compensating counter-current in the opposite direction.
4. Both currents dispaly similiar characteristics
5. Long distance movements are directed towards great commercial centers.
6. People in urban areas migrate less than people in urban areas.
7. Males migrate more over long distances and females migrate more over short distances.
Additions to These Laws
8. Most migrants are between 20-34 years of age.
9. People mainly move for economic reasons.
10. Urban housing development is inadequate for the influx of migrants so ghettoes/shanties are formed.
Zipf's Inverse Distance Law
* The volume of migrants decreases with distance from the origin.
Stouffer's Law of Intervening Distances
* The number of migrants moving from one town (i) to another (j) is directly related to the opportunities available at j but inversely proportional to the number of intervening opportunities between i and j.
Push-Pull Theory
* Any migration is as a result of push forces at the origin and pull forces at the destination. Examples of push forces are famine, war and poverty. Examples of pull forces are availability of food, peace and wealth.
Gravity Model
* This theory states that larger towns are more attractive to immigrants than smaller towns
Consequences of Migration
* These can be subdivided into 3 categories:
1. Demographic Consequences:
* Changes in the numbers and distribution of people within a region are changed.
* Intermarriages are created, leading to a new group of people.
2. Social Consequences:
* Migration brings different people together leading to conflicts.
* Migration however also creates understanding between different groups of people.
* Rural-Urban migration creates ghettoes in cities.
3. Economic Consequnces:
* This depends on the "quality" of the migrants and the economic needs of the origin and destination. Quality refers to skills, age, educational attainment, health etc.
* In overpopulated areas, emigration is beneficial because it reduces the pressure on the land.
* In underpopulated areas, emigration may slow down development.
Migration
* Migration is the movement of people
* It is classified by such indices as
o Distance travelled
o Reason for travel
o Period of time of travel
o Volume of migrants
* Cosequences of migration include
o Increased understanding between people of different cultures
o Increased animosity between people of different cultures
o Changes in numbers of people at the destination and origin
o Creation of ghettoes in urban areas
o Inter-marriages
Ravenstein's Laws of Migration
* Ravenstein came up with his "laws" of migration in the 1880s based on studies carried out in the UK.
* The laws are as follows
1. The greatest body of migrants travel short distances.
2. This produces currents directed towards great commercial centers.
3. Each current has a compensating counter-current in the opposite direction.
4. Both currents dispaly similiar characteristics
5. Long distance movements are directed towards great commercial centers.
6. People in urban areas migrate less than people in urban areas.
7. Males migrate more over long distances and females migrate more over short distances.
Additions to These Laws
8. Most migrants are between 20-34 years of age.
9. People mainly move for economic reasons.
10. Urban housing development is inadequate for the influx of migrants so ghettoes/shanties are formed.
Zipf's Inverse Distance Law
* The volume of migrants decreases with distance from the origin.
Stouffer's Law of Intervening Distances
* The number of migrants moving from one town (i) to another (j) is directly related to the opportunities available at j but inversely proportional to the number of intervening opportunities between i and j.
Push-Pull Theory
* Any migration is as a result of push forces at the origin and pull forces at the destination. Examples of push forces are famine, war and poverty. Examples of pull forces are availability of food, peace and wealth.
Gravity Model
* This theory states that larger towns are more attractive to immigrants than smaller towns
Consequences of Migration
* These can be subdivided into 3 categories:
1. Demographic Consequences:
* Changes in the numbers and distribution of people within a region are changed.
* Intermarriages are created, leading to a new group of people.
2. Social Consequences:
* Migration brings different people together leading to conflicts.
* Migration however also creates understanding between different groups of people.
* Rural-Urban migration creates ghettoes in cities.
3. Economic Consequnces:
* This depends on the "quality" of the migrants and the economic needs of the origin and destination. Quality refers to skills, age, educational attainment, health etc.
* In overpopulated areas, emigration is beneficial because it reduces the pressure on the land.
* In underpopulated areas, emigration may slow down development.
Malthus
Malthus
* Thomas Malthus, was a British Clergyman/economist.
* He came up with the Malthusian Theory of Population Growth. The salient points of his theory were
1. Food production increased at an arithmetic ratio (1, 2, 3...) while population increased at an exponential ratio (1, 2, 4, 8...).
2. Population growth would outstrip food supply, and mass starvation would follow.
3. Man is incapable of controlling his own numbers, so natural calamities such as floods and epidemics serve to control/reduce his numbers.
* His theory was wrong in a number of ways:
1. He failed to foresee the agrarian revolution that would greatly increase food production.
2. Man has proven he is capable of controlling his numbers, such as in China withe the one-child per family policy.
3. The population has not grown as rapidly as he predicted.
* Thomas Malthus, was a British Clergyman/economist.
* He came up with the Malthusian Theory of Population Growth. The salient points of his theory were
1. Food production increased at an arithmetic ratio (1, 2, 3...) while population increased at an exponential ratio (1, 2, 4, 8...).
2. Population growth would outstrip food supply, and mass starvation would follow.
3. Man is incapable of controlling his own numbers, so natural calamities such as floods and epidemics serve to control/reduce his numbers.
* His theory was wrong in a number of ways:
1. He failed to foresee the agrarian revolution that would greatly increase food production.
2. Man has proven he is capable of controlling his numbers, such as in China withe the one-child per family policy.
3. The population has not grown as rapidly as he predicted.
Factors affecting mortality
Factors affecting mortality
1. Endogenetic processes. These refer to internal/bodily factors, such as disease.
2. Exogenetic processes. These refer to external factors such as the environment.
* Other indices to gauge components of poulation change are
o Life Expectancy. This is the the number of years a child can expect to live under current conditions. It is also the average length of life of a defined population.
o The Natural Increase. It is calculated by the formula CBR - CDR / Total Population x 100
1. Endogenetic processes. These refer to internal/bodily factors, such as disease.
2. Exogenetic processes. These refer to external factors such as the environment.
* Other indices to gauge components of poulation change are
o Life Expectancy. This is the the number of years a child can expect to live under current conditions. It is also the average length of life of a defined population.
o The Natural Increase. It is calculated by the formula CBR - CDR / Total Population x 100
Age Structure
Age Structure
* There are 3 basic age structures:
1. Progressive (Brazilian) Type
2. Stationery (American) Type
3. Regressive (European) Type
Progressive Type
* It has a wide base that quickly narrows upwards to a point.
* It indicates a large birth rate, but poor conditions mean people rapidly die off, hence the triangular shape of the structure. The population is increasing.
Stationery Type
* The shape of this structure is more "square." All age roups are well represented.
* It indicates that the birth rate is moderate, and few people die off as they get older. The population is stagnant.
Regressive Type
* The structure has a fairly wide top with a bulging middle and narrow base.
* The birth rate is low, hence the low base, and there are more adults than children. The population is decreasing.
The Dependency Ratio
* This is the ratio between the non-working population (children and aged) and the workers (adults).
* It is lowest in regressive populations and highest in progressive populations.
* It is calculated using the formula (children + aged)/Adults) * 100
* In developed countries, the DRs range from 50-70. In most developing countries the DRs are over 100
The Old Age Index
* This is the proportion of aged to adults.
* It is calculated using the formula: (aged)/(adults) * 100
* There are 3 basic age structures:
1. Progressive (Brazilian) Type
2. Stationery (American) Type
3. Regressive (European) Type
Progressive Type
* It has a wide base that quickly narrows upwards to a point.
* It indicates a large birth rate, but poor conditions mean people rapidly die off, hence the triangular shape of the structure. The population is increasing.
Stationery Type
* The shape of this structure is more "square." All age roups are well represented.
* It indicates that the birth rate is moderate, and few people die off as they get older. The population is stagnant.
Regressive Type
* The structure has a fairly wide top with a bulging middle and narrow base.
* The birth rate is low, hence the low base, and there are more adults than children. The population is decreasing.
The Dependency Ratio
* This is the ratio between the non-working population (children and aged) and the workers (adults).
* It is lowest in regressive populations and highest in progressive populations.
* It is calculated using the formula (children + aged)/Adults) * 100
* In developed countries, the DRs range from 50-70. In most developing countries the DRs are over 100
The Old Age Index
* This is the proportion of aged to adults.
* It is calculated using the formula: (aged)/(adults) * 100
Weathering
Weathering
Weathering is the breaking and decomposition of rocks at/near the earth's surface by physical & chemical processes.
# There are two main types of weathering:
1. Chemical Weathering: This involves the decomposition of rocks due to chemical reactions between rock minerals, water and some atmospheric gases such as oxygen and carbon dioxide. The main types of chemical reactions are:
1. Hydration: This is the absorption of water by rock minerals.
2. Oxidation: This is when oxygen is taken up by a mineral compound.
3. Carbonation: this is when hydrogen carbonate ions combine with a mineral to give a soluble compound which can then be carried away in solution.
4. Solution: The solution of soluble minerals e.g. limestone in rocks.
5. Hydrolisis: The reaction between the hydrogen ions in water and some metal ions.
2. Mechanical Weathering:
1. Temperature changes causing expansion and contraction of rocks.
2. Freezing of water--frost action.
3. Wetting and Drying
Factors Influencing the Character and Rate of Weathering
These factors include:
* Climate
o The greater the amount of rainfall the higher the rate of chemical weathering.
o Temperature changes accelerate the rate of mechanical weathering.
* The nature of the parent rock.
* Vegetation cover
* The gradient of the slope
* Time
* Man's activities
Mass Wasting
# Mass wasting is the movement of rock materials under the influence of gravity.
Factors Affecting the Speed of Mass Wasting
These factors include:
* The nature of the material
* The angle of the slope
* Vegetation cover
* Earthquakes
* Mans activities
Main Types of Mass Wasting
1. Soil Creep: This is the downward movement of soil
2. Mudflow: When continued heavy rainfall turns the soil into a semi-liquid state.
3. Landslide: When large quantities of loosened surface rocks slide down a steep slope.
4. Rockfall: When rocks fall off a steep cliff
Weathering is the breaking and decomposition of rocks at/near the earth's surface by physical & chemical processes.
# There are two main types of weathering:
1. Chemical Weathering: This involves the decomposition of rocks due to chemical reactions between rock minerals, water and some atmospheric gases such as oxygen and carbon dioxide. The main types of chemical reactions are:
1. Hydration: This is the absorption of water by rock minerals.
2. Oxidation: This is when oxygen is taken up by a mineral compound.
3. Carbonation: this is when hydrogen carbonate ions combine with a mineral to give a soluble compound which can then be carried away in solution.
4. Solution: The solution of soluble minerals e.g. limestone in rocks.
5. Hydrolisis: The reaction between the hydrogen ions in water and some metal ions.
2. Mechanical Weathering:
1. Temperature changes causing expansion and contraction of rocks.
2. Freezing of water--frost action.
3. Wetting and Drying
Factors Influencing the Character and Rate of Weathering
These factors include:
* Climate
o The greater the amount of rainfall the higher the rate of chemical weathering.
o Temperature changes accelerate the rate of mechanical weathering.
* The nature of the parent rock.
* Vegetation cover
* The gradient of the slope
* Time
* Man's activities
Mass Wasting
# Mass wasting is the movement of rock materials under the influence of gravity.
Factors Affecting the Speed of Mass Wasting
These factors include:
* The nature of the material
* The angle of the slope
* Vegetation cover
* Earthquakes
* Mans activities
Main Types of Mass Wasting
1. Soil Creep: This is the downward movement of soil
2. Mudflow: When continued heavy rainfall turns the soil into a semi-liquid state.
3. Landslide: When large quantities of loosened surface rocks slide down a steep slope.
4. Rockfall: When rocks fall off a steep cliff
Vulcanicity and Landforms
Vulcanicity and Landforms
# Vulcanicity is the process through which gases and molten rock are either extruded on the earth's surface or intruded into the earth's crust.
# Magma is the molten rock originating from the upper plastic layer of the mantle. When it gets to the surface and loses its gases, it is known as lava.
# Pyrocrasts are the ashes, cinders and small particles of magma during an explosive volcanic eruption.
Intrusive Igneous Landforms
1. Batholiths: Largest mass of magma crumbling in the crust. An example is the Stone Mountain of Georgia.
2. Sills: Sheets of magma intruded onto bedding planes of sedimentary rocks.
3. Dykes: Wall like features formed when magma cuts across several bedding planes.
4. Pipes: The stems of volcanoes.
5. Laccoliths: Dome shaped layers of magma formed when magma encounters rock more resistant at its sides than its center.
6. Lopoliths: Bowl shaped layers of magma formed when magma encounters rock more resistant at its center than its sides.
Extrusive Igneous Landforms
1. Composite Volcano: A cone shaped feature formed by alternating layers of lava and ash. Sometimes, a volcano erupts so violently, its crater is blown off enlarging the top depression. This is then known as a caldera. If filled with water, it is known as a Caldera Lake.
2. Lava Plateau: This is an upland with a generally level summit made up off successive layers of lava and ash.
Types of Volcanoes
1. Active: This is a volcano that has erupted within the last 500 years and still shows signs of activity.
2. Dormant: This is a volcano that has not erupted within the last 500 years but still shows signs of activity such as hot springs. An example is Mt. Kilimanjaro.
3. Extinct: This is a volcano that has not erupted within the last 500 years and shows no signs of activity. An example is Mt. Kenya.
Exogenetic Processes
* These are processes that take place on the earth's surface.
* They are subdivided in two categories:
1. Processes of degradation
2. Processes of aggradation
* Processes of aggradation are those that build up material. Processes of degradation are those that destroy what has been built up by endogenetic/aggradation processes.
* The destruction of the landscape is known as denudation. There are three processes involved:
1. Weathering
2. Erosion
3. Transportation
* The exogenetic processes require the use of agents such as running water, ice and wind.
# Vulcanicity is the process through which gases and molten rock are either extruded on the earth's surface or intruded into the earth's crust.
# Magma is the molten rock originating from the upper plastic layer of the mantle. When it gets to the surface and loses its gases, it is known as lava.
# Pyrocrasts are the ashes, cinders and small particles of magma during an explosive volcanic eruption.
Intrusive Igneous Landforms
1. Batholiths: Largest mass of magma crumbling in the crust. An example is the Stone Mountain of Georgia.
2. Sills: Sheets of magma intruded onto bedding planes of sedimentary rocks.
3. Dykes: Wall like features formed when magma cuts across several bedding planes.
4. Pipes: The stems of volcanoes.
5. Laccoliths: Dome shaped layers of magma formed when magma encounters rock more resistant at its sides than its center.
6. Lopoliths: Bowl shaped layers of magma formed when magma encounters rock more resistant at its center than its sides.
Extrusive Igneous Landforms
1. Composite Volcano: A cone shaped feature formed by alternating layers of lava and ash. Sometimes, a volcano erupts so violently, its crater is blown off enlarging the top depression. This is then known as a caldera. If filled with water, it is known as a Caldera Lake.
2. Lava Plateau: This is an upland with a generally level summit made up off successive layers of lava and ash.
Types of Volcanoes
1. Active: This is a volcano that has erupted within the last 500 years and still shows signs of activity.
2. Dormant: This is a volcano that has not erupted within the last 500 years but still shows signs of activity such as hot springs. An example is Mt. Kilimanjaro.
3. Extinct: This is a volcano that has not erupted within the last 500 years and shows no signs of activity. An example is Mt. Kenya.
Exogenetic Processes
* These are processes that take place on the earth's surface.
* They are subdivided in two categories:
1. Processes of degradation
2. Processes of aggradation
* Processes of aggradation are those that build up material. Processes of degradation are those that destroy what has been built up by endogenetic/aggradation processes.
* The destruction of the landscape is known as denudation. There are three processes involved:
1. Weathering
2. Erosion
3. Transportation
* The exogenetic processes require the use of agents such as running water, ice and wind.
The action of rivers
The action of rivers
* Rivers are the most widespread agents of denudation and deposition.
* The amount of erosion, transportation and deposition of the river is dependent on the energy of the river which in turn is dependent on:
o The gradient of the slope
o The volume of water
o The shape of the channel
* Generally, the volume of the river increases from the source to the mouth. Exceptions may be such as when the river passes through a hot desert.
River Erosion
* River erosion involves 4 processes:
1. Abrasion/Corrasion: The wearing away of the sides and the bed of a river by the impact of the load.
2. Hydraulic Action: Erosion by the force of moving water.
3. Atrrition: The breaking down of the load by particles hitting against each other.
4. Solution/Corrossion: When minerals dissolve in water.
River Transport
* The material a river carries is referred to as its load.
* A river transports its load in 4 main ways:
1. Traction: The rolling of huge particles along the bed.
2. Saltation: The bouncing of particles on the bed of the river
3. Suspension: The movement of particles held up by river turbulence.
4. Solution: The movement of particles dissolved in water.
River Deposition
* Deposition takes place when a river has insufficient energy to transport its load. It takes place at all stages of a river.
* Larger particles are deposited first.
* Deposition is greatest in the lower course of a river. It is also greater during floods.
* Deposition will occur when the speed of a river is reduced. This may happen in:
o areas with a sudden increase in gradient
o the inside of meanders
o places where the river enters a sea/lake.
The Development of a River Transport System
* Surface run-off forms small streams.
* These streams join together to form larger streams.
* These largers streams join to form a river.
* The junction of 2 streams is called the confluence. When a smaller flow joins a larger flow it's called a tributa
* Rivers are the most widespread agents of denudation and deposition.
* The amount of erosion, transportation and deposition of the river is dependent on the energy of the river which in turn is dependent on:
o The gradient of the slope
o The volume of water
o The shape of the channel
* Generally, the volume of the river increases from the source to the mouth. Exceptions may be such as when the river passes through a hot desert.
River Erosion
* River erosion involves 4 processes:
1. Abrasion/Corrasion: The wearing away of the sides and the bed of a river by the impact of the load.
2. Hydraulic Action: Erosion by the force of moving water.
3. Atrrition: The breaking down of the load by particles hitting against each other.
4. Solution/Corrossion: When minerals dissolve in water.
River Transport
* The material a river carries is referred to as its load.
* A river transports its load in 4 main ways:
1. Traction: The rolling of huge particles along the bed.
2. Saltation: The bouncing of particles on the bed of the river
3. Suspension: The movement of particles held up by river turbulence.
4. Solution: The movement of particles dissolved in water.
River Deposition
* Deposition takes place when a river has insufficient energy to transport its load. It takes place at all stages of a river.
* Larger particles are deposited first.
* Deposition is greatest in the lower course of a river. It is also greater during floods.
* Deposition will occur when the speed of a river is reduced. This may happen in:
o areas with a sudden increase in gradient
o the inside of meanders
o places where the river enters a sea/lake.
The Development of a River Transport System
* Surface run-off forms small streams.
* These streams join together to form larger streams.
* These largers streams join to form a river.
* The junction of 2 streams is called the confluence. When a smaller flow joins a larger flow it's called a tributa
Plate Tectonics and Continental Drift
Plate Tectonics and Continental Drift
The Plate Tectonic Theory
* The earth's crust is divided into separate parts called tectonic plates.
* These plates float on the partially molten rocks of the upper mantle.
* The plates move due to convection cells in the mantle.
* Margins are the areas between the tectonic plates. Margins of converging plates are called constructive margins while margins of diverging plates are called constructive margins. Margins where the plates slide against each other are called conservative margins.
* Plates can be oceanic or continental. When an oceanic plate meets a continental plate, it's drawn beneath the margin of the continental plate and the rocks of the oceanic plate go into the mantle. When a continental plate meets another continental plate, folding may occur and fold mountains created.
The History of Continental Drift
* Continents drift due to the movement of the tectonic plates.
* Originally, there was one large continent called Pangea surrounded by a sea called Panthalassa. It is believed Pangea was centered around present day Africa.
* Pangea split into two other continents. The northern continent was Laurasia and the southern continent Gondwanaland. Between the two wad a sea called Tethys.
* Gondwanaland then split into the present continents.
The Plate Tectonic Theory
* The earth's crust is divided into separate parts called tectonic plates.
* These plates float on the partially molten rocks of the upper mantle.
* The plates move due to convection cells in the mantle.
* Margins are the areas between the tectonic plates. Margins of converging plates are called constructive margins while margins of diverging plates are called constructive margins. Margins where the plates slide against each other are called conservative margins.
* Plates can be oceanic or continental. When an oceanic plate meets a continental plate, it's drawn beneath the margin of the continental plate and the rocks of the oceanic plate go into the mantle. When a continental plate meets another continental plate, folding may occur and fold mountains created.
The History of Continental Drift
* Continents drift due to the movement of the tectonic plates.
* Originally, there was one large continent called Pangea surrounded by a sea called Panthalassa. It is believed Pangea was centered around present day Africa.
* Pangea split into two other continents. The northern continent was Laurasia and the southern continent Gondwanaland. Between the two wad a sea called Tethys.
* Gondwanaland then split into the present continents.
Folding
Folding
# Folding is the process through which crustal rocks are bent.
# It produces anticlines (upfolds) and synclines (downfolds).
# Folding can produce very large mountains such as the Himalayas and the Rockies.
# Orogenesis is the process through which mountains are created. There are 3 periods of recent mountain building:
1. Caledonian Period:310 million years ago. Most mountains created during this period have been destroyed through denudation. Remnants are the Scottish Highlands and the mountains of Scandinavia.
2. Hercynian Period:240 million years ago. Examples include the Cape Ranges of South Africa, the Appalachians of the United States and Welsh mountains of the UK.
3. Alpine Period:30 million years ago. Examples include the Alps and the Andes. Mountains created during this period are the highest because the have not yet been reduced by denudation.
# Folding takes place in three main stages:
1. Initial bending of rocks as plates come together
2. Simple Anticlines and Synclines are created.
3. Formation of fold mountains-asymmetrical folds.
4. Breaking of the folding results in faults/depressions.
# Peneplaination is the reduction of fold mountains to a level plain called a peneplain.
# Folding is the process through which crustal rocks are bent.
# It produces anticlines (upfolds) and synclines (downfolds).
# Folding can produce very large mountains such as the Himalayas and the Rockies.
# Orogenesis is the process through which mountains are created. There are 3 periods of recent mountain building:
1. Caledonian Period:310 million years ago. Most mountains created during this period have been destroyed through denudation. Remnants are the Scottish Highlands and the mountains of Scandinavia.
2. Hercynian Period:240 million years ago. Examples include the Cape Ranges of South Africa, the Appalachians of the United States and Welsh mountains of the UK.
3. Alpine Period:30 million years ago. Examples include the Alps and the Andes. Mountains created during this period are the highest because the have not yet been reduced by denudation.
# Folding takes place in three main stages:
1. Initial bending of rocks as plates come together
2. Simple Anticlines and Synclines are created.
3. Formation of fold mountains-asymmetrical folds.
4. Breaking of the folding results in faults/depressions.
# Peneplaination is the reduction of fold mountains to a level plain called a peneplain.
Deserts
Deserts
* Definition: An area with little/no vegetation
* Characterised by aridity (low rainfall and high evaporation usually <250mm p.a.)
* 1/3 of the world surface is desert
Location of Deserts
Location Reason
On the Western sides of continents Cold ocean currents exist off the Western sides of continents. Winds blowing over these currents lose their moisture over the sea and are dry by the time they get to sea.
In the interior of continents Winds blowing over continents are dry by the time they get to the interior of continents.
The leeward side of tall mountains Moisture carrying winds are blocked by the side (windward side) of tall mountains. The other side (leeward side) is consequently dry, and deserts may be formed there.
Depressions/basins in the interior of continents The surrounding highlands around depressions/basins cause a rainshadow effect leaving the depression dry.
Agents of Earth Sculpture in Deserts
* The main agents are wind and water.
The Action of Wind in Deserts
* Wind is the most important agent of denudation and deposition in deserts.
* The actions of wind in deserts are known as Aeolian processes.
Wind Transport
* Involves the following processes:
1. Suspension: The movement of particles held up by river turbulence.
2. Saltation: The bouncing of particles on the bed of the river
3. Surface Creep: When particles carried through saltation dislodge and push others forward.
Wind Erosion
* Involves the following processes:
1. Abrasion/Corrasion: The wearing away of the sides and the bed of a river by the impact of the load.
2. Deflation: When wind blows away rock waste leaving a depression in deserts. An example is the Qattara depression in Egypt.
3. Atrrition: The breaking down of the load by particles hitting against each other.
Features Produced by Wind Erosion
1. Rock Pedestals:
* A tower-like mass of rock made up of alternating layers of resistant and less resistant rock.
* The less resistant layers are eroded away faster than the more resistant layers leaving a mass of rock with projections protruding from it.
2. Zeugens:
* Occur in areas with resistant and less resistant rocks occurring in layers perpendicular to the prevailing wind.
* The less resistant rock is more eroded than the less resistant rock producing a ridge and furrow landscape.
3. Yardangs:
* Occur in areas with resistant and less resistant rocks occurring in layers parallel to the prevailing wind.
* The less resistant rock is more eroded than the less resistant rock producing a ridge and furrow landscape.
* An example is near Komombo in Egypt and near InSalah in Egypt
4. Deflation Hollows:
* These are depressions produced by the deflation in weak rocks.
* When the water table is reached, a swamp/oasis may be formed in these depressions.
* The largest is the Qattara depression in Egypt.
* Flat floored depressions are called pans.
Features Produced by Wind Deposition
* Dunes: deposits of sand by wind in deserts.
1. Barchans: Crescent shaped deposits made when sand being blown by wind encounters an obstruction such as a rock or a dead camel.
2. Seifs: Ridge-shaped deposits od sand with steep sides lying parallel to the prevailing winds.
Wind Blown Deposits in Deserts
* Wind blows fine particles out of deserts each year.
* Some are deposited in the sea.
* Others accumulated on land to form fertile land known as loess.
Features Produced by Water in Deserts
* Rain in deserts is infrequent and unpredictable. When it does occur, it does so in torrents.
* Torrential run-off occurs in small narrow valleys called rills.
* These rills may enlarge to form gullies.
* The gullies may further enlarge to form deep steep-sided valleys with wide flat floors and rocky walls called wadis.
* Torrential rains carries large quantities of materials which may turn into mudflows.
* The deposited material is called alluvial flans.
* This may be deposited into wadises. If irrigated, they form very fertile alluvial plains.
* Some valleys form good drainage basins. They may form temporary lakes known as playas or sebkhas.
* These soon dry up forming the playas into salt-flats.
* Some basins may be rimmed by uplands. The basins may join together to form a continous feature called a bajada.
* Between the playa and bajada is a gently sloping platform called a pediment.
* Definition: An area with little/no vegetation
* Characterised by aridity (low rainfall and high evaporation usually <250mm p.a.)
* 1/3 of the world surface is desert
Location of Deserts
Location Reason
On the Western sides of continents Cold ocean currents exist off the Western sides of continents. Winds blowing over these currents lose their moisture over the sea and are dry by the time they get to sea.
In the interior of continents Winds blowing over continents are dry by the time they get to the interior of continents.
The leeward side of tall mountains Moisture carrying winds are blocked by the side (windward side) of tall mountains. The other side (leeward side) is consequently dry, and deserts may be formed there.
Depressions/basins in the interior of continents The surrounding highlands around depressions/basins cause a rainshadow effect leaving the depression dry.
Agents of Earth Sculpture in Deserts
* The main agents are wind and water.
The Action of Wind in Deserts
* Wind is the most important agent of denudation and deposition in deserts.
* The actions of wind in deserts are known as Aeolian processes.
Wind Transport
* Involves the following processes:
1. Suspension: The movement of particles held up by river turbulence.
2. Saltation: The bouncing of particles on the bed of the river
3. Surface Creep: When particles carried through saltation dislodge and push others forward.
Wind Erosion
* Involves the following processes:
1. Abrasion/Corrasion: The wearing away of the sides and the bed of a river by the impact of the load.
2. Deflation: When wind blows away rock waste leaving a depression in deserts. An example is the Qattara depression in Egypt.
3. Atrrition: The breaking down of the load by particles hitting against each other.
Features Produced by Wind Erosion
1. Rock Pedestals:
* A tower-like mass of rock made up of alternating layers of resistant and less resistant rock.
* The less resistant layers are eroded away faster than the more resistant layers leaving a mass of rock with projections protruding from it.
2. Zeugens:
* Occur in areas with resistant and less resistant rocks occurring in layers perpendicular to the prevailing wind.
* The less resistant rock is more eroded than the less resistant rock producing a ridge and furrow landscape.
3. Yardangs:
* Occur in areas with resistant and less resistant rocks occurring in layers parallel to the prevailing wind.
* The less resistant rock is more eroded than the less resistant rock producing a ridge and furrow landscape.
* An example is near Komombo in Egypt and near InSalah in Egypt
4. Deflation Hollows:
* These are depressions produced by the deflation in weak rocks.
* When the water table is reached, a swamp/oasis may be formed in these depressions.
* The largest is the Qattara depression in Egypt.
* Flat floored depressions are called pans.
Features Produced by Wind Deposition
* Dunes: deposits of sand by wind in deserts.
1. Barchans: Crescent shaped deposits made when sand being blown by wind encounters an obstruction such as a rock or a dead camel.
2. Seifs: Ridge-shaped deposits od sand with steep sides lying parallel to the prevailing winds.
Wind Blown Deposits in Deserts
* Wind blows fine particles out of deserts each year.
* Some are deposited in the sea.
* Others accumulated on land to form fertile land known as loess.
Features Produced by Water in Deserts
* Rain in deserts is infrequent and unpredictable. When it does occur, it does so in torrents.
* Torrential run-off occurs in small narrow valleys called rills.
* These rills may enlarge to form gullies.
* The gullies may further enlarge to form deep steep-sided valleys with wide flat floors and rocky walls called wadis.
* Torrential rains carries large quantities of materials which may turn into mudflows.
* The deposited material is called alluvial flans.
* This may be deposited into wadises. If irrigated, they form very fertile alluvial plains.
* Some valleys form good drainage basins. They may form temporary lakes known as playas or sebkhas.
* These soon dry up forming the playas into salt-flats.
* Some basins may be rimmed by uplands. The basins may join together to form a continous feature called a bajada.
* Between the playa and bajada is a gently sloping platform called a pediment.
Components of Population
Components of Population
* Components of population change are births and deaths, immigrants and emigrants.
Fertility and Mortality
* Fertility is the number of live births in a defined population. It is calculated using two main indices:
o Crude Birth rate (CBR): the total number of live births / the total population x 100
o Total Fertility Rate (TFR): the total number of live births / women of childbearing age(15-49) x 100
* Mortality is the number of deaths in a defined population. It is calculated using two main indices:
o Crude Death Rate (CDR): the total number of deaths / the total population x 100
o Infant Mortality Rate (IMR): the number of infant eaths / the number of live births x 1000
Factors affecting fertility
1. Religion: most major religions favour family development so very religious populations have a high fertility.
2. Social customs and taboos, eg as regards contraception
3. Education. There is an inverse relationship between education level and the number of children .
* Components of population change are births and deaths, immigrants and emigrants.
Fertility and Mortality
* Fertility is the number of live births in a defined population. It is calculated using two main indices:
o Crude Birth rate (CBR): the total number of live births / the total population x 100
o Total Fertility Rate (TFR): the total number of live births / women of childbearing age(15-49) x 100
* Mortality is the number of deaths in a defined population. It is calculated using two main indices:
o Crude Death Rate (CDR): the total number of deaths / the total population x 100
o Infant Mortality Rate (IMR): the number of infant eaths / the number of live births x 1000
Factors affecting fertility
1. Religion: most major religions favour family development so very religious populations have a high fertility.
2. Social customs and taboos, eg as regards contraception
3. Education. There is an inverse relationship between education level and the number of children .
Action of Ice
Action of Ice
Definitions
* Coast: The strip of land where it meets the sea
* Coastline: The margin of land. The limit to which wave action takes place.
* Shore: The strip of land lying between the high and low water levels.
* Shoreline: The limit of the shore. The line where the shore and the water meet.
* Beach: A shore covered by a deposit of sand and/or pebbles.
Factors Determining the Nature of Coasts
1. Wave action
2. Tidal currents
3. Nature of the rocks forming the coast
4. Height of the coast
5. Nature of the climate
6. Work of man
Formation of Waves
1. Wind blows over the sea surface.
2. The surface of the sea exerts frictional drag on the lower layer of the wind.
3. The top layer (with the least drag) moves faster than the lower layer and hence tumbles over it.
4. This causes a circular motion of wind energy that acts on the sea to create waves.
Wave Erosion
* Wave erosion like river erosion involves 4 processes:
1. Abrasion/Corrasion: The wearing away of the sides and the bed of a river by the impact of the load.
2. Hydraulic Action: Erosion by the force of moving water.
3. Atrrition: The breaking down of the load by particles hitting against each other.
4. Solution/Corrossion: When minerals dissolve in water.
Features Produced by Wave Erosion
Cliffs, Wave Cut Platforms and Offshore Terraces
* A notch is cut by waves at high tide level and developed further.
* As this notch is developed, a cliff is formed.
* The cliff steepens as weathering attacks the base further.
* As the cliff retreats, the rock debris is swept by the backwash creating a wave-cut platform.
* Some of the debris collects along the seaward edge of the wave-cut platform forming and off-shore terrace.
Caves, Geos, Arches and Stacks
* Holes in the cliff face are enlarged by wave action
* A tunnel like opening called a cave is formed.
* The cave may develop further forming a long narrow inlet known as a geo.
* An arch is created when a cave in a headland is eroded right through i.e. the inlet has two openings
* When the arch collapses, the end of a headland stands up as a stack.
Headlands and Bays
* These are formed in areas of alternating resistant and less resistant rocks.
* Erosion/wave action acts less on the more resistant rock creating headlands and more on the less resistant rock creating bays.
Factors Affecting the Rate of Wave Erosion
1. Breaking point of the wave.
2. Wave steepness
3. Configuration of the coastline
4. Depth of the sea
5. Supply of beach material
6. Beach width
7. Nature of the rock
Wave Transport
* Sources of the load include:
o Rivers entering the sea
o Landslide on cliffs
o Wave erosion
* Types of material transported include:
o Sand
o Shingles
o Mud
* Process: Swash (forward moving waves) and backwash push and drag material up and down the shore resulting in longshore drift.
Wave Depositional Features
1. Beach: Formed by deposition of mud, sand or pebbles along the coast.
2. Barrier Beach: A long ridge of sand parallel to but separated from the coast ridge by a lagoon.
3. Spit: A narrow ridge of sand joined to the mainland with the other end terminating in the sea
4. Bar: A ridge of material (usually sand) lying parallel to the coast
5. Tombolo: A ridge joining an island to the mainland
6. Offshore Bar: Developed on the gently sloping seabed. Occurs when sand is thrown up by waves breaking close to the coast.
7. Mudflat: Developed when tides/waves deposit fine sand along gently sloping coasts particularly in bars and estuaries.
Definitions
* Coast: The strip of land where it meets the sea
* Coastline: The margin of land. The limit to which wave action takes place.
* Shore: The strip of land lying between the high and low water levels.
* Shoreline: The limit of the shore. The line where the shore and the water meet.
* Beach: A shore covered by a deposit of sand and/or pebbles.
Factors Determining the Nature of Coasts
1. Wave action
2. Tidal currents
3. Nature of the rocks forming the coast
4. Height of the coast
5. Nature of the climate
6. Work of man
Formation of Waves
1. Wind blows over the sea surface.
2. The surface of the sea exerts frictional drag on the lower layer of the wind.
3. The top layer (with the least drag) moves faster than the lower layer and hence tumbles over it.
4. This causes a circular motion of wind energy that acts on the sea to create waves.
Wave Erosion
* Wave erosion like river erosion involves 4 processes:
1. Abrasion/Corrasion: The wearing away of the sides and the bed of a river by the impact of the load.
2. Hydraulic Action: Erosion by the force of moving water.
3. Atrrition: The breaking down of the load by particles hitting against each other.
4. Solution/Corrossion: When minerals dissolve in water.
Features Produced by Wave Erosion
Cliffs, Wave Cut Platforms and Offshore Terraces
* A notch is cut by waves at high tide level and developed further.
* As this notch is developed, a cliff is formed.
* The cliff steepens as weathering attacks the base further.
* As the cliff retreats, the rock debris is swept by the backwash creating a wave-cut platform.
* Some of the debris collects along the seaward edge of the wave-cut platform forming and off-shore terrace.
Caves, Geos, Arches and Stacks
* Holes in the cliff face are enlarged by wave action
* A tunnel like opening called a cave is formed.
* The cave may develop further forming a long narrow inlet known as a geo.
* An arch is created when a cave in a headland is eroded right through i.e. the inlet has two openings
* When the arch collapses, the end of a headland stands up as a stack.
Headlands and Bays
* These are formed in areas of alternating resistant and less resistant rocks.
* Erosion/wave action acts less on the more resistant rock creating headlands and more on the less resistant rock creating bays.
Factors Affecting the Rate of Wave Erosion
1. Breaking point of the wave.
2. Wave steepness
3. Configuration of the coastline
4. Depth of the sea
5. Supply of beach material
6. Beach width
7. Nature of the rock
Wave Transport
* Sources of the load include:
o Rivers entering the sea
o Landslide on cliffs
o Wave erosion
* Types of material transported include:
o Sand
o Shingles
o Mud
* Process: Swash (forward moving waves) and backwash push and drag material up and down the shore resulting in longshore drift.
Wave Depositional Features
1. Beach: Formed by deposition of mud, sand or pebbles along the coast.
2. Barrier Beach: A long ridge of sand parallel to but separated from the coast ridge by a lagoon.
3. Spit: A narrow ridge of sand joined to the mainland with the other end terminating in the sea
4. Bar: A ridge of material (usually sand) lying parallel to the coast
5. Tombolo: A ridge joining an island to the mainland
6. Offshore Bar: Developed on the gently sloping seabed. Occurs when sand is thrown up by waves breaking close to the coast.
7. Mudflat: Developed when tides/waves deposit fine sand along gently sloping coasts particularly in bars and estuaries.
Top 10 Countries - Highways
Top 10 Countries - Highways
1 United States
2 India
3 Brazil
4 China
5 Japan
6 Russia
7 Australia
8 Canada
9 France
10 Germany
1 United States
2 India
3 Brazil
4 China
5 Japan
6 Russia
7 Australia
8 Canada
9 France
10 Germany
Top 10 Countries
Top 10 Countries - Poorest (GDP per capita)
1 Ethiopia
2 Dem. Rep. of Congo
3 Burundi
4 Sierra Leone
5 Guinea-Bissau
6 Niger
7 Eritrea
8 Malawi
9 Mozambique
10 Nepal
11 Tanzania
Top 10 Countries - Richest (GDP per capita)
1 Liechtenstein
2 Luxembourg
3 Switzerland
4 Norway
5 Denmark
6 Japan
7 Singapore
8 US
9 Iceland
10 Austria
1 Ethiopia
2 Dem. Rep. of Congo
3 Burundi
4 Sierra Leone
5 Guinea-Bissau
6 Niger
7 Eritrea
8 Malawi
9 Mozambique
10 Nepal
11 Tanzania
Top 10 Countries - Richest (GDP per capita)
1 Liechtenstein
2 Luxembourg
3 Switzerland
4 Norway
5 Denmark
6 Japan
7 Singapore
8 US
9 Iceland
10 Austria
Top 10 Countries - Population Density (Lowest)
Top 10 Countries - Population Density (Lowest)
Information from US Census Bureau.
1 Mongolia
2 Namibia
3 Australia
4 Botswana
5 Surinam
6 Mauritania
7 Iceland
8 Libya
9 Canada
10 Guyana
Information from US Census Bureau.
1 Mongolia
2 Namibia
3 Australia
4 Botswana
5 Surinam
6 Mauritania
7 Iceland
8 Libya
9 Canada
10 Guyana
Top 10 Countries - Urbanization (Least)
Top 10 Countries - Urbanization (Least)
Information from United Nations.
1 Rwanda
2 Bhutan
3 Burundi
4 Nepal
5 Uganda
6 Malawi
7 Ethiopia
8 Papua New Guinea
9 Burkino Faso
10 Eritrea
Information from United Nations.
1 Rwanda
2 Bhutan
3 Burundi
4 Nepal
5 Uganda
6 Malawi
7 Ethiopia
8 Papua New Guinea
9 Burkino Faso
10 Eritrea
Top 10 - Rail Networks (Longest)
Top 10 - Rail Networks (Longest)
Information from "The Top 10 of Everything - 2002" by Russell Ash.
1 US
2 Russia
3 China
4 India
5 Germany
6 Argentina
7 Canada
8 Australia
9 France
10 Mexico
Information from "The Top 10 of Everything - 2002" by Russell Ash.
1 US
2 Russia
3 China
4 India
5 Germany
6 Argentina
7 Canada
8 Australia
9 France
10 Mexico
Top 10 - Rivers (Longest)
Top 10 - Rivers (Longest)
Information taken from "The Top 10 of Everything - 2002" by Russell Ash.
1 Nile
2 Amazon
3 Yangtze-Kiang
4 Mississippi-Missouri-Red Rock
5 Yenisey-Angara-Selenga
6 Huang Ho
7 Ob'-Irtysh
8 Congo
9 Lena-Kirenga
10 Mekong
Information taken from "The Top 10 of Everything - 2002" by Russell Ash.
1 Nile
2 Amazon
3 Yangtze-Kiang
4 Mississippi-Missouri-Red Rock
5 Yenisey-Angara-Selenga
6 Huang Ho
7 Ob'-Irtysh
8 Congo
9 Lena-Kirenga
10 Mekong
Top 10 - Elements in the Earth's Crust
Top 10 - Elements in the Earth's Crust
Information taken from "The Top 10 of Everything - 2002" by Russell Ash.
1 Oxygen
2 Silicon
3 Aluminum
4 Iron
5 Calcium
6 Magnesium
7 Sodium
8 Potassium
9 Titanium
10 Hydrogen
Information taken from "The Top 10 of Everything - 2002" by Russell Ash.
1 Oxygen
2 Silicon
3 Aluminum
4 Iron
5 Calcium
6 Magnesium
7 Sodium
8 Potassium
9 Titanium
10 Hydrogen
Top 10 - Disasters (Most Costly Types)
Top 10 - Disasters (Most Costly Types)
Information from International Federation of Red Cross and Red Cross Societies.
1 Floods
2 Earthquakes
3 Wind storms
4 Forest / scrub fires
5 Non-natural disasters
6 Droughts
7 Extreme temperatures
8 Avalanches / landslides
9 Volcanoes
10 Other natural disasters
Information from International Federation of Red Cross and Red Cross Societies.
1 Floods
2 Earthquakes
3 Wind storms
4 Forest / scrub fires
5 Non-natural disasters
6 Droughts
7 Extreme temperatures
8 Avalanches / landslides
9 Volcanoes
10 Other natural disasters
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