Major features of the earth- Form one
Major features of the earth surface
Earth’s surface refers to the outer most layer of Earth, including both land masses, [continents and island] and water bodies [ocean seas, lakes and rivers.
It is made up of continental landmasses which cover 29% and water bodies which cover 71%of the Earth surface
Continents and ocean of the world
In the beginning the Earth’s surface there was a single giant landmass called Pangaea that was surrounded by a single super ocean called Panthalasa. Over millions of years the geomorphic process caused the Pangea to break up into two big land masses
The Northern land mass was called Raurasia and the southern was called Gondwana.
The two landmasses were separated by Teths Sea. The two supercontinents broke into present continent where by Laurasia included the present day Northern America, Europe and Asia while Gondwana comprised of present Africa, South Africa, Antarctica and Australia.
A continent is a major land mass rising from the ocean floor
Continents are surrounded by large Mass of water bodies such as ocean and seas. Island is also part of continent.
There are seven continents on the Earth namely Asia, Africa, South America, Australia, Europe and Antarctica
Five continents are separated by ocean and seas, while Europe and Asia are separated by Ural Mountains.
Description of continents based on the size from the largest to the smallest
Interrelation between continental landmasses and water bodies.
Some continental landmasses interact with water bodies.
This interaction results in the formation of different features like
Gulf: Is a part of the ocean that penetrates as landmass e.g. Persian gulf (western Asia and the gulf of guinea.
A strait: is a narrow water path that separates land masses e.g. straits gibraltar (morocco), Luzon strait (Taiwan), straits in Indonesia.
A cape: is a pointed or narrow extension of land entering into a body of water such as ocean, sea, lake or river e.g. A cape of good hope in South Africa.
Peninsula: is a land mass that is almost surrounded by water, but still connected to the mainland. It is larger than a cape. e.g Msasani in Tanzania, Arabian, Alaskan and indo in china.
Isthmus: is a narrow land stretch that joins two major land masses. e.g Isthmus of Panama between Africa and Asia.
Major relief features of continents
The surface of any continent is not smooth. It has mountains, hills, plain and plateaus, river valleys, lakes, basins and rift valleys.
Altitude and slope give rise to different relief features as seen below.
a) Plain,
b) plateaus,
c) basins
d) mountains
e) Rift valleys
A]Plains
Plains are continuous stretches of comparatively flat land not rising much above the sea level.
Many extensive plains are a result of down warping of the earth’s crust for example, Siberia in Asia, North European plains. A great part of any continent is plain.
B]Plateaus
Is an extensive high altitude areas with more or less uniform summit levels. They are formed when forces formed within the earth uplift a plain region. Example central plateau of Africa, the Brazilian Highlands and the Arabian plateau.
C]Mountain
Is a part of the earths surface that rises abruptlly to a greater height, usually above 300m from the surrounding level.
There are four major types of Mountains: These are;
a) Fold mountains
b) Block mountain
c) Volcanic mountain
d) residual mountains.
i] Fold mount
formed by the wrinkling of the upper part of the earth’s crust due to compressional forces. e.g. himalaya in Asia, the rockiees and appalachians in north america and the andes in south america, alps in europe, the atlas in north america and the cape ranges in south africa.
ii] Block Mountains.
is an upland area with a table like structure bordered by faults on one or both sides.
They are formed when tensional or compressional forces in the crust force layers of crustal rocks to break resulting in central part being uplifted.
Example usambara, Uruguru and Ruwenzori mountains in East Africa, the Vosges and Black forest mountains in Europe and mount Sinai in Asia.
iii] Volcanic mountain
are formed from eruption,cooling and solidifaication of molten material from earths interial after volcanic eruption.
Types of volcanic mountain
a) Active volcanic mountain: are those that still experience periodic eruptions: e.g. mountain Italy, the Krakatoa in Indonesia, the Mufumbiro in Uganda, Oldonyo Lengai in Tanzania and the Cameroons in Equatorial Africa.
b) Dormant volcanic mountain: are volcanic mountains, which erupted only once in historical time and are no longer active. A good examples are the Kilimanjaro and Meru mountains.
c) Extinct (dead) volcanic mountain: are volcanic mountains which have not erupted for a very long time and have not shown any signs of erupting again. e.g. Kenya, Elgon and Rungwe Mountains.
iv]Residual mountains
Residual Mountains are formed by a prolonged denudation process. Denudation removes weaker rocks thus leaving resistant rock known as residual mountains.include e.g. Haggard Mountains of central Sahara, Sekenke hills of Singida in Tanzania, Adamawa mountains of Eastern Niger, the Highlands of Scotland.
D] Rift Valley
A long narrow deep sided depression between parallel faults on the earth surface.
It is formed through tension or compression forces when the ground between two parallel faults sinks.
The walls of rift valley form escarpment
The great East Africa Rift valley is the largest valley in the world.
It stretches from Jordan, through Red sea, Ethiopia, Kenya, and Tanzania to lower Zambez in Mozambique
E] Basins;
Basins are a natural depression or bowl –shaped hollow on the earth’s surface. It is formed when part of the land sinks due to earth movements.
[Some of the basins are found in ocean [ocean basins] or sea [sea basin] or lake [lake basins].
Basin situated above the sea level is drained by rivers and their tributaries are called river basins. River basin includes Congo River basin, and Amazon basin in South America.
Lake Victoria and kyoga in Uganda are example of basin occupied by water.]
Water Bodies on the Earth Surface
Water body is a mass of stationary or moving water which occupy the surface of the earth
Water occupies 71% of the earth surface.
Water bodies include the following
River: is a mass of fresh water flowing by gravity in a definite channel from its source to the mouth. Its source may be rainfall, natural springs, melting of glacier, marsh land or lake.
The major river in Tanzania are rufiji , Ruvuma, kagera, pangani, malagalasi, ruaha, wami and ruvu river.
The major river in Africa is Nile and Congo
Lake: is a hollow or depression in the earth surface that contain fresh or salty water. e.g Lake Tanganyika, nyasa, rukwa, manyara and lake eyas. All lakes except Lake Victoria are Rift Valley Lake.
Some lakes are so large that they are called seas e.g. Caspian Sea and Dead Sea.
Sea: is a larger body of salt water that is surrounded in whole or in part by land. e.g. Mediterranean Sea, red sea, China Sea, yellow sea etc.
Ocean: is a larger body of salty water surrounding the landmass of the earth. The major oceans of the world are pacific, Atlantic, Indian, southern and Arctic Ocean.
The salinity of sea and ocean water depends on the temperature and the amount of fresh water from rivers and melting of ice that is discharged into it
Ocean floor and its features
Ocean floor (sea bed) is a landscape found at the bottom of the ocean.
The major features of the ocean floor
Continental shelf, Continental slope, Ocean ridge, Deep sea plain, Ocean deep (trenches) Ocean plain, Oceanic Island
a) Continental shelf: is a gently sloping margin of a continent which occupies shallow water. It extends from the coastline to a depth of 200 meters towards the continental slope.
b) Continental slope: is found at the point where the continental shelf forms a steep slope toward the ocean.
c) Mid oceanic ridge: is a raised part of the ocean floor
d) Deep sea plain: are extensive undulating areas of the ocean floor. It is also known as abyssal plains.
e) Abyssal hill: are small sharp hills rising from abyssal plain surface.
f) Ocean deep (trench) is a long narrow steep sided depression plunging from the deep sea plane to the depth of 10000 meters or more.
g) Island: is a piece of land surrounded by water. A group of island is called archipelago.
Types of island
i. Continental island: is a larger unbroken landmass rising from continental shelf. e.g. mafia, pemba and unguja.
ii. Ocean Island: is the island that rises directly from the ocean floor. eg Hawaii, Cape Verde, Iceland and Seychelles.
iii. Coral island: is an island which is built up from limestone rocks made of skeletons of small marine organisms called coral polyps.eg Maldives, aldabra, Bermuda.
Vegetation
Vegetation refers to a community of plants, trees, shrubs, grasses and other green specious that grow in a particular area.
Importance of vegetation
a) It supports various animals specious
b) It maintains ecological balance
c) It contribute to the overall health of the environment through temperature regulation
d) It supports rain formation
e) It protect soil against erosion
Types of vegetations
a) Natural vegetation and
b) Artificial vegetation (planted)
a]Natural vegetation: grows without direct influence of human being e.g. woodlands, forests, grasslands, desert vegetation, and swamps vegetation
a) Woodland vegetation: are wide regions covered by open and lo density trees. e.g miombo woodland in Tabora and Ruvuma region.
b) Forest vegetation: is a large area of land covered predominantly with tall trees and other woody vegetations e.g. uluguru, usambara, selous, udzungwa.
c) Grassland: is vegetation dominated by grasses. In Grassland vegetation trees and shrubs are relatively sparse or absent.
d) Swamp vegetation: is a wet land with woody vegetation
e) Desert vegetation; is vegetation found in areas with very little rainfall.
Planted vegetation/artificial vegetation: are vegetation grown by man.
Distribution of the world vegetation
There are six main vegetation ones in different parts of the world. Namely
a) Tundra or polar vegetation
b) temperature vegetation
c) desert vegetation
d) Tropical vegetation
e) Mediterranean vegetation
f) Mountain vegetation.
g) Aquatic vegetation (area covered by water)
Factors influencing vegetation zones of the world
a) Climatic factor e.g. Temperature ,precipitation, sunshine and wind
b) Topographical factors [altitude or elevation of an area e.g. slope, Relief and Aspects
c) Edaphic factor/soil .the type and quality of soil in an area.
d) Biotic factors; human activities can develop or destroy Vegetation of an area
Importance of vegetation to human life
a) Production of oxygen through photosynthesis
b) It helps in carbon dioxide absorption-
c) source of food
d) Help to control soil erosion
e) source of medicine
f) Source of income e.g. agriculture and forest
g) Habitat and biodiversity
h) It helps in climate regulation
i) useful in Aesthetic and recreational value
j) It helps in improving soil fertility
k) It is a source of fuel
l) source of building Materials
Despite the Importance of vegetation human activities contribute in degrading environment by
a) Deforestation
b) poor agricultural practices
c) Production of charcoal and unsustainable timber harvesting.
d) inadequate alternative source of energy for cooking
Earth’s surface refers to the outer most layer of Earth, including both land masses, [continents and island] and water bodies [ocean seas, lakes and rivers.
It is made up of continental landmasses which cover 29% and water bodies which cover 71%of the Earth surface
Continents and ocean of the world
In the beginning the Earth’s surface there was a single giant landmass called Pangaea that was surrounded by a single super ocean called Panthalasa. Over millions of years the geomorphic process caused the Pangea to break up into two big land masses
The Northern land mass was called Raurasia and the southern was called Gondwana.
The two landmasses were separated by Teths Sea. The two supercontinents broke into present continent where by Laurasia included the present day Northern America, Europe and Asia while Gondwana comprised of present Africa, South Africa, Antarctica and Australia.
A continent is a major land mass rising from the ocean floor
Continents are surrounded by large Mass of water bodies such as ocean and seas. Island is also part of continent.
There are seven continents on the Earth namely Asia, Africa, South America, Australia, Europe and Antarctica
Five continents are separated by ocean and seas, while Europe and Asia are separated by Ural Mountains.
Description of continents based on the size from the largest to the smallest
1 | Asia
| Is the largest continent. It covers more than one third of the earth. Its total area is 44.6 m square km. It stretches from 10áµ’S to 78áµ’N and from 30áµ’E to about 180áµ’E. |
2 | Africa | Its area is about 30.3 million square km It extends from 35áµ’5 to 37áµ’N and from 15áµ’W TO 50áµ’E? It is the only continent crossed by 3 tropics It Crossed by Equator, tropics of cancer and the tropic of Capricorn |
3 | North America
| Its area is about 4.7 millions square km. It extends from 10áµ’N to 80áµ’N and from 60áµ’W to 160áµ’W, |
4 | South America
| It is about 17.8 million square km. It lies between 10áµ’N and 50áµ’S and 35áµ’W and 80áµ’W |
5 | Antarctica.
| It is about 14millins square km It is located around the South Pole and almost all of it lies within latitude 66áµ’S. It is surrounded by the southern ocean It’s not inhabited by human being because of the extreme low temperature below freezing point throughout the year |
6 | Europe | It has an area of 10.1million square km It lies between 40áµ’N and the Arctic and between 10áµ’W and 60áµ’E |
7 | Australia | It is about 8.5 million square km. It lies approximately between 10áµ’S and 40áµ’S and 115áµ’E and 150áµ’ E
|
Interrelation between continental landmasses and water bodies.
Some continental landmasses interact with water bodies.
This interaction results in the formation of different features like
Gulf: Is a part of the ocean that penetrates as landmass e.g. Persian gulf (western Asia and the gulf of guinea.
A strait: is a narrow water path that separates land masses e.g. straits gibraltar (morocco), Luzon strait (Taiwan), straits in Indonesia.
A cape: is a pointed or narrow extension of land entering into a body of water such as ocean, sea, lake or river e.g. A cape of good hope in South Africa.
Peninsula: is a land mass that is almost surrounded by water, but still connected to the mainland. It is larger than a cape. e.g Msasani in Tanzania, Arabian, Alaskan and indo in china.
Isthmus: is a narrow land stretch that joins two major land masses. e.g Isthmus of Panama between Africa and Asia.
Major relief features of continents
The surface of any continent is not smooth. It has mountains, hills, plain and plateaus, river valleys, lakes, basins and rift valleys.
Altitude and slope give rise to different relief features as seen below.
a) Plain,
b) plateaus,
c) basins
d) mountains
e) Rift valleys
A]Plains
Plains are continuous stretches of comparatively flat land not rising much above the sea level.
Many extensive plains are a result of down warping of the earth’s crust for example, Siberia in Asia, North European plains. A great part of any continent is plain.
B]Plateaus
Is an extensive high altitude areas with more or less uniform summit levels. They are formed when forces formed within the earth uplift a plain region. Example central plateau of Africa, the Brazilian Highlands and the Arabian plateau.
C]Mountain
Is a part of the earths surface that rises abruptlly to a greater height, usually above 300m from the surrounding level.
There are four major types of Mountains: These are;
a) Fold mountains
b) Block mountain
c) Volcanic mountain
d) residual mountains.
i] Fold mount
formed by the wrinkling of the upper part of the earth’s crust due to compressional forces. e.g. himalaya in Asia, the rockiees and appalachians in north america and the andes in south america, alps in europe, the atlas in north america and the cape ranges in south africa.
ii] Block Mountains.
is an upland area with a table like structure bordered by faults on one or both sides.
They are formed when tensional or compressional forces in the crust force layers of crustal rocks to break resulting in central part being uplifted.
Example usambara, Uruguru and Ruwenzori mountains in East Africa, the Vosges and Black forest mountains in Europe and mount Sinai in Asia.
iii] Volcanic mountain
are formed from eruption,cooling and solidifaication of molten material from earths interial after volcanic eruption.
Types of volcanic mountain
a) Active volcanic mountain: are those that still experience periodic eruptions: e.g. mountain Italy, the Krakatoa in Indonesia, the Mufumbiro in Uganda, Oldonyo Lengai in Tanzania and the Cameroons in Equatorial Africa.
b) Dormant volcanic mountain: are volcanic mountains, which erupted only once in historical time and are no longer active. A good examples are the Kilimanjaro and Meru mountains.
c) Extinct (dead) volcanic mountain: are volcanic mountains which have not erupted for a very long time and have not shown any signs of erupting again. e.g. Kenya, Elgon and Rungwe Mountains.
iv]Residual mountains
Residual Mountains are formed by a prolonged denudation process. Denudation removes weaker rocks thus leaving resistant rock known as residual mountains.include e.g. Haggard Mountains of central Sahara, Sekenke hills of Singida in Tanzania, Adamawa mountains of Eastern Niger, the Highlands of Scotland.
D] Rift Valley
A long narrow deep sided depression between parallel faults on the earth surface.
It is formed through tension or compression forces when the ground between two parallel faults sinks.
The walls of rift valley form escarpment
The great East Africa Rift valley is the largest valley in the world.
It stretches from Jordan, through Red sea, Ethiopia, Kenya, and Tanzania to lower Zambez in Mozambique
E] Basins;
Basins are a natural depression or bowl –shaped hollow on the earth’s surface. It is formed when part of the land sinks due to earth movements.
[Some of the basins are found in ocean [ocean basins] or sea [sea basin] or lake [lake basins].
Basin situated above the sea level is drained by rivers and their tributaries are called river basins. River basin includes Congo River basin, and Amazon basin in South America.
Lake Victoria and kyoga in Uganda are example of basin occupied by water.]
Water Bodies on the Earth Surface
Water body is a mass of stationary or moving water which occupy the surface of the earth
Water occupies 71% of the earth surface.
Water bodies include the following
River: is a mass of fresh water flowing by gravity in a definite channel from its source to the mouth. Its source may be rainfall, natural springs, melting of glacier, marsh land or lake.
The major river in Tanzania are rufiji , Ruvuma, kagera, pangani, malagalasi, ruaha, wami and ruvu river.
The major river in Africa is Nile and Congo
Lake: is a hollow or depression in the earth surface that contain fresh or salty water. e.g Lake Tanganyika, nyasa, rukwa, manyara and lake eyas. All lakes except Lake Victoria are Rift Valley Lake.
Some lakes are so large that they are called seas e.g. Caspian Sea and Dead Sea.
Sea: is a larger body of salt water that is surrounded in whole or in part by land. e.g. Mediterranean Sea, red sea, China Sea, yellow sea etc.
Ocean: is a larger body of salty water surrounding the landmass of the earth. The major oceans of the world are pacific, Atlantic, Indian, southern and Arctic Ocean.
The salinity of sea and ocean water depends on the temperature and the amount of fresh water from rivers and melting of ice that is discharged into it
1 | Pacific ocean |
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2 | Atlantic ocean |
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3 | Indian ocean |
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4 | Sothern ocean |
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5 | Arctic ocean |
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Ocean floor and its features
Ocean floor (sea bed) is a landscape found at the bottom of the ocean.
The major features of the ocean floor
Continental shelf, Continental slope, Ocean ridge, Deep sea plain, Ocean deep (trenches) Ocean plain, Oceanic Island
a) Continental shelf: is a gently sloping margin of a continent which occupies shallow water. It extends from the coastline to a depth of 200 meters towards the continental slope.
b) Continental slope: is found at the point where the continental shelf forms a steep slope toward the ocean.
c) Mid oceanic ridge: is a raised part of the ocean floor
d) Deep sea plain: are extensive undulating areas of the ocean floor. It is also known as abyssal plains.
e) Abyssal hill: are small sharp hills rising from abyssal plain surface.
f) Ocean deep (trench) is a long narrow steep sided depression plunging from the deep sea plane to the depth of 10000 meters or more.
g) Island: is a piece of land surrounded by water. A group of island is called archipelago.
Types of island
i. Continental island: is a larger unbroken landmass rising from continental shelf. e.g. mafia, pemba and unguja.
ii. Ocean Island: is the island that rises directly from the ocean floor. eg Hawaii, Cape Verde, Iceland and Seychelles.
iii. Coral island: is an island which is built up from limestone rocks made of skeletons of small marine organisms called coral polyps.eg Maldives, aldabra, Bermuda.
Vegetation
Vegetation refers to a community of plants, trees, shrubs, grasses and other green specious that grow in a particular area.
Importance of vegetation
a) It supports various animals specious
b) It maintains ecological balance
c) It contribute to the overall health of the environment through temperature regulation
d) It supports rain formation
e) It protect soil against erosion
Types of vegetations
a) Natural vegetation and
b) Artificial vegetation (planted)
a]Natural vegetation: grows without direct influence of human being e.g. woodlands, forests, grasslands, desert vegetation, and swamps vegetation
a) Woodland vegetation: are wide regions covered by open and lo density trees. e.g miombo woodland in Tabora and Ruvuma region.
b) Forest vegetation: is a large area of land covered predominantly with tall trees and other woody vegetations e.g. uluguru, usambara, selous, udzungwa.
c) Grassland: is vegetation dominated by grasses. In Grassland vegetation trees and shrubs are relatively sparse or absent.
d) Swamp vegetation: is a wet land with woody vegetation
e) Desert vegetation; is vegetation found in areas with very little rainfall.
Planted vegetation/artificial vegetation: are vegetation grown by man.
Distribution of the world vegetation
There are six main vegetation ones in different parts of the world. Namely
a) Tundra or polar vegetation
b) temperature vegetation
c) desert vegetation
d) Tropical vegetation
e) Mediterranean vegetation
f) Mountain vegetation.
g) Aquatic vegetation (area covered by water)
Factors influencing vegetation zones of the world
a) Climatic factor e.g. Temperature ,precipitation, sunshine and wind
b) Topographical factors [altitude or elevation of an area e.g. slope, Relief and Aspects
c) Edaphic factor/soil .the type and quality of soil in an area.
d) Biotic factors; human activities can develop or destroy Vegetation of an area
Importance of vegetation to human life
a) Production of oxygen through photosynthesis
b) It helps in carbon dioxide absorption-
c) source of food
d) Help to control soil erosion
e) source of medicine
f) Source of income e.g. agriculture and forest
g) Habitat and biodiversity
h) It helps in climate regulation
i) useful in Aesthetic and recreational value
j) It helps in improving soil fertility
k) It is a source of fuel
l) source of building Materials
Despite the Importance of vegetation human activities contribute in degrading environment by
a) Deforestation
b) poor agricultural practices
c) Production of charcoal and unsustainable timber harvesting.
d) inadequate alternative source of energy for cooking
e) Poor industrial and mining practices.
