Major Landforms & Water Bodies of the Earth
Geography For Middle School
Continents:
Continents are very large masses that are surrounded by vast water bodies called oceans on all sides. They are the primary divisions of land. There are seven continents in the world.
Asia is the largest continent. It occupies about one-third of the land area of our planet. It is joined to the land mass of Europe, and thus, we use the term Eurasia for this combined land mass. The Ural Mountains, the Black Sea, and the Caspian Sea separate the two continents. We find oceans on three sides of this land mass. To its north lies the Arctic Ocean, to its east is the Pacific Ocean and to its south is the Indian Ocean.
Africa is the second largest continent after Asia. It is surrounded by water bodies on all sides. In the north, the Mediterranean Sea separates it from Europe, and on its east is the Indian Ocean. The Atlantic Ocean in the west separates it from the two Americas. In Africa lies the largest desert in the world, the Sahara Desert.
North America is the third largest continent in size. It is joined to South America by a narrow stretch of land called the Isthmus of Panama. The Atlantic Ocean lies to its east and the Pacific Ocean to its west.
South America is the fourth largest continent. On its east lies the Atlantic Ocean while on the west is the Pacific Ocean. It is shaped roughly like an inverted triangle.
Antarctica, a large frozen land mass located in the extreme south, is the bleakest and most barren part of the world. It is almost circular in shape. Antarctica contains 90 per cent of the world's ice. It is even colder than the Arctic region and is surrounded by the stormiest seas. Several countries of the world have set up research stations in Antarctica to conduct research in climatology, earth sciences, human physiology, and medicine.
Europe is smaller in size in comparison to the other continents mentioned above but has some of the most developed nations in the world. To its north is the Arctic Ocean. The Atlantic Ocean separates it from North America. It has the most indented coastline among the continents, which is why it has numerous ports and some of the finest harbours in the world.
Australia is sometimes called 'the Land Down Under' as it lies to the south of the main land masses. It is also the smallest continent in size. As there is water on all sides - the Indian Ocean in the west, the South Pacific Ocean in the east, the Southern Ocean in the south, and the Arafura Sea in the north - it is an island and is therefore also called the 'island'.
Major Landforms:
Plains:
Plains or lowlands are vast, nearly flat, expanses of land which are usually less than 200 metres above sea level. They are mostly built by alluvium deposited by big rivers and their tributaries and are therefore, also called river plains. River plains are fertile and owing to the flat nature of the land, it is easy to construct roads and railways in plains.
Plains that are found along the edges of continents adjacent to seas are called coastal plains, for example, the eastern and the western coastal plains of India.
Q.1. What are plateaux? Why are they of great economic value?
Plateaux:
Plateaux are the uplifted sections of the earth's crust that are level and usually descend steeply to the surrounding lowlands. A plateau is also sometimes referred to as a plain-in-the-air or tableland. The plateau of Tibet in Asia, the East African Plateau in Africa, and the Colorado Plateau in North America are well-known examples. In India, the Deccan Plateau and the Chota Nagpur Plateau are good examples. The former covers a large area and is fertile, while the latter is a storehouse of mineral wealth.
Mountains:
Mountains are massive areas of the earth's crust that rise to great heights above their surroundings. They may have steep or gentle slopes and occur in long narrow chains called ranges. There are three main types of mountains: (a) fold mountains (b) volcanic mountains, and (c) block mountains.
Q. What are fold mountains? With the help of a neat sketch, briefly explain their formation.
Q. State two chief differences between old and young mountains. Give examples.
Fold Mountains:
Fold mountains are formed when the layers of the earth's crust are folded by compression.
The compression is caused by forces generated by movements inside the earth.
There are many examples of fold mountains which were formed over 250 million years ago such as the Urals in Russia, the Appalachians in North America, and the Aravallis in India. They are called old fold mountains and have gentle slopes and low altitudes due to weathering over time. Young fold mountains comprise the world's highest mountain ranges which were formed comparatively recently, about 25 million years ago. These mountains are rugged and lofty. The Rockies of North America, the Andes of South America, the Alps of Europe, and the Himalayas of Asia are examples of young fold mountains.
Volcanic Mountains:
Perhaps you have read or heard about the destruction caused by the volcanic eruptions of Mt Krakatoa, Mt Vesuvius, and Mt Pelee. Volcanic mountains are built when molten lava, ash, cinder, and dust from deep inside the earth come out on the surface through cracks in the earth's crust and accumulate in the shape of high cones.
The opening through which lava and other materials come to the surface is called a vent. The funnel-shaped depression at the top of a vent is called carter. Examples of volcanic mountains include Mt Fuji (Japan), Mt Mayon (the Philipines), and Mt Vesuvius and Mt Etna (Italy).
Block Mountains:
When cracks or faults occur in the earth's crust and the land between the cracks sinks, it leaves upstanding blocks or either side which are called block mountains. The edges of such mountains are steep and surfaces are almost level. The Vosges and the Black Forest of Europe are examples of block mountains.
Mountains are important for us. Most rivers originate in mountains. Mountains also support a variety of flora and fauna. They also affect the climate of an area. For example, the Himalayas cause rainfall in India by blocking the south-west monsoon winds and also protect us from the cold winds of Central Asia in winter.
Basins:
A basin is a depressed section of the earth's crust with surrounding higher land. Many basins are found alongside plateau edges and form areas of inland drainage, i.e., the rivers flowing in the basin do not reach the sea. The Tarim and Tsaidam Basin of Asia and the Chad Basin of north-central Africa are basins of inland drainage.
Valleys:
Valleys are low-lying land between hills or mountains. They may or may not have a river flowing through them. River valleys are usually V-shaped. The Rhine Valley in Europe and the Damodar Valley in India are examples of river valleys.
Q.1. How is Mount Fuji of Japan different from the Vosges of Europe?
2. What is a V-shaped valley?
3. What is a peninsula? Take the help of your atlas and name four major peninsulas of the world.
4. Which two land masses does the Isthmus of Panama connect?
Major Waterbodies:
Q. Describe the Atlantic ocean.
Oceans:
There are five major oceans in the world - the Pacific, the Atlantic, the Indian, the Arctic, and the Southern Ocean. About 71 percent of the earth's surface is covered by oceans, and they contain about 97 percent of the earth's water.
The Pacific Ocean is the largest ocean and spreads over one-third of the globe. It is almost circular in shape and is bordered on its edges by new fold mountains that have the maximum concentration of active volcanoes. Therefore, these mountain ranges have been termed the 'Fiery Ring of the Pacific'. The southern part of the Pacific merges with the Atlantic and the Indian Oceans. The deepest part of the earth's crust - the Mariana Trench - lies in this ocean near the Philippine ( Mindanao) Trench, Japan Trench, and the Kuril Trench.
The Atlantic Ocean is shaped like the letter 'S' and is much smaller in size. It is almost half the size of the Pacific Ocean but the total length of its coastline is longer than the combined coastlines of the Pacific and the Indian Oceans.
It is the busiest ocean in the world as many trades and transportation routes pass across it. On its east coast lie Europe and Africa while on its western borders, lie the two Americas.
In the middle of the Atlantic Ocean is a submerged mountain range that has some high peaks that form islands in the middle of the ocean. Some of these islands are volcanic in nature such as Iceland. This ridge is called the Mid-Atlantic Ridge.
The Indian Ocean is roughly triangular in shape and covers one-fifth of the total area under the ocean. India is located at the head of this ocean, which is why it has been named after this country. The Arabian Sea and the Bay of Bengal are two important parts of the Indian Ocean to its north. Asia lies to its north, Australia to its east and Africa forms its western shores.
The Arctic Ocean is the northernmost ocean and lies to the north of North America, Europe, and Asia. It is located mostly within the Arctic Circle and so remains frozen for most part of the year.
Apart from these oceans, there is the Southern Ocean or Antarctic Ocean, which surrounds the continents of Antarctica. This ocean is formed by the merging of the Pacific, the Atlantic, and the Indian Oceans.
Seas:
A sea is part of an ocean that is smaller and shallower. It is usually located close to the edge of the land mass or continent. A careful observation of the world map in your atlas will reveal the presence of seas along the edges of continents. You can see easily locate the Caribbean Sea, China Sea, Arabian Sea and White Sea.
Gulfs and Bays:
A gulf is an inlet of the sea of large areal proportions while a bay is an open, curving indentation made by the sea or a lake into a coastline. Gulfs are more indented than bays and also more enclosed.
Observe in your atlas the proportions of the Bay of Bengal the Hudson Bay, and the Bay of Biscay as compared to the Persian Gulf, the Gulf of Mexico and the Gulf of Carpentaria.
Straits:
A strait is a narrow stretch of water that joins two large water bodies. The Strait of Gibraltar, for example, connects the Mediterranean Sea to the North Atlantic Ocean.
Lakes:
Lakes are small bodies of water which are surrounded by land on all sides. Lake Balkhash and Lake Baikal are examples of lakes. Large lakes are also called inland seas, for example, the areal Sea, the Black Sea, and the Caspian Sea of Eurasia.
Rivers:
A river is a stream of water which flows in a channel from high ground to low ground and finally to a lake or sea. The place where a river originates is called its source, which normally lies in a hill or a mountain. The place where a river ends its journey is called its mouth. The mouth is normally the place where the river enters the sea.
Chapter-4
Representation of the Earth
The various ways of representing the earth are globes, maps, pictures, sketches and plans.
Globes:
A globe is an object representing the spherical shape of the earth with a map of the world on its surface, usually on a stand so that it can be rotated. It is a man-made model of the earth, in three dimensions.
Advantages of Globe:
1. It is the most accurate three-dimensional representation of the earth.
2. It shows the distribution of continents and oceans accurately.
3. Lines of latitude and longitude are marked on a globe.
Disadvantages of Globe:
1. Only a part of the earth can be seen on a globe, at one glance.
2. All details cannot be marked on a globe.
3. A globe is difficult to carry around.
Maps:
A map is a drawing of the whole earth or a part of it on a flat surface. It is usually a symbolic representation drawn on paper that provides information about the earth's surface in a simple and graphic manner. A collection of different types of maps bound together in the form of a book is called an atlas.
Different Types of Maps:
Political maps show the boundaries of countries, states, etc. and also the location of capital cities and important towns.
Physical maps show mountains, valleys, plains, rivers, and other surface features. These maps generally use different colours to represent land of different heights.
Thematic maps show features such as climate, agriculture, minerals etc.
Advantages of Maps:
1. They are easy to carry.
2. They show selected features and are not usually congested.
3. They use different signs, symbols, and colours to provide distinct information.
Disadvantages of Maps:
1. The curved surface of the earth cannot be represented accurately on a flat surface.
2. Maps of large areas, especially continents, have some distortion of size, shape or distance.
Aerial Photographs & Satellite Pictures:
Another tool for representing the earth or a part of it is aerial photography. Photographs of the earth are taken from a camera mounted on an aircraft or an artificial satellite. In fact, such photographs have been used widely in the preparation of accurate maps.
Sketches:
A sketch is a rough drawing showing the relative locations of a few chosen features in an area. It does not show the true shape and size of the features and it is not drawn to scale, i.e. the distance between different features shown in the sketch is not in the same proportion as it is on land.
Plans:
A plan is a drawing that shows the horizontal section of a small area or building. It is drawn to scale. It is useful because it tells us where exactly things are on the ground.
Chapter-5
Measuring Distances & Directions
Q.1. What are the cardinal directions?
Ans: Directions North, South, East and West- are also called the cardinal directions. The diagram on the left shows the cardinal directions can be divided into eight intermediate directions can be further divided to get sixteen directions as shown in the diagram here.
2. What is meant by the scale of a map?
Ans: A scale is the ratio of the distance between two places on a map to the actual distance between the same two places on the ground.
3. Which three ways are used to represent the scale of a map?
Ans: Map scales are given in three different ways:
verbal or statement scale
graphical or linear scale
representative fraction
4. Convert the statement 1 cm = 100 km into R.F. scale.
Ans: RF = Distance on the map/Distance on the ground
5. What method would you use to measure the length of a river?
Ans: Distances along curved lines are measured using either the divider method or the twine method. These methods are useful in measuring the lengths of rivers, railway lines, curved roads, cart tracks, etc.
In the divider method, a divider whose pointed ends are 1 or 2 cm apart is used. Beginning at one end of the feature to be measured, the divider is turned continuously till the other end is reached. The number of turns is counted and then using the scale of the map, the actual distance on the ground is calculated.
In the twine method, a twine is placed along the feature to be measured from one end to the other, carefully following all the curves and bends. The length of the twine is then measured in centimetres or inches using a ruler or linear scale. Thereafter, this length is converted into kilometres or miles using the scale of the given map.
6. Describe the ways of representing a map scale.
Ans: A scale is the ratio of the distance between two places on a map to the actual distance between the same two places on the ground. Map scales are represented in three different ways:
a) Verbal or statement scale: The scale is stated in words. The units are usually mentioned in this type of scale, for example, 1 cm = 5 km or 1 cm to 5 km. It means that 1 cm on the map is equal to 5 km on the ground.
b) Graphical or linear scale: This consists of a straight line which is divided into lengths that represent given distances on the earth's surface. It is usually drawn near the lower portion of the map.
In the diagram on the previous page, the linear scale line is divided into 5 equal parts, 1 cm apart. Each of these parts represents a distance of 50 km on the ground. At the extreme left-hand, one part of 1 cm has been further subdivided into two parts of 5 mm each representing 25 km.
c) Representative Fraction (RF): This is a fraction in which the numerator expresses the distance on the map and the denominator represents the actual distance on the ground. It must be noted that the numerator is always 1 and both the numerator and the denominator are expressed in the same unit.
RF = Distance on the map / Distance on the ground
= 1 / 50,000
= 1 : 50,000
This means that 1 cm on the map represents 50,000 cm on the ground. So, it will be shown on the map as 1 / 50,000.
Lesson-1
Geography of the United States
What can geography teach us about the United States?
Vocabulary:
Climate = weather elements, such as temperature, rainfall, and wind, that are measured over a period of time in an area.
Compass = a tool or instrument for finding directions
Geography =The study of our physical surroundings and how humans interact with them
Globe = a sphere that is a model of Earth and most accurately represents it
Government = the organization that makes the laws in a country, state or community and has the power to enforce them
Landform = a physical feature on Earth's surface such as a mountain or a plain
Latitude = an imaginary line called a parallel that runs west and est around Earth
Longitude = an imaginary line called a meridian that runs from the North Pole to the South Pole
Physical feature = a part of Earth's surface including landmasses and bodies of water
Vegetation = the types of plants in an area or a region
Understanding the Globe
Earth is a sphere or something that is shaped like a ball. Most maps that show Earth's surface are flat. But a globe is a type of map that is a sphere, and so it provides a more accurate picture of our planet.
Maps, like a globe, are important because they help people understand geography, or the study of the world around us and its people. People can use a globe to find places around Earth.
The most northern point on Earth is the North Pole, and the most southern point is the South Pole. No matter where you are on Earth, the north is always in the direction of the North Pole, and the south is always in the direction of the South Pole. When you face north, east is to your right, and west is to your left. These four directions are the main points on a compass. These directions are called cardinal directions.
Points in between the cardinal directions are called intermediate directions. These directions include northeast, northwest, southeast, and southwest. Many maps have a symbol that shows all or some of these directions. This symbol is called a compass rose.
An imaginary line circles Earth halfway between the North Pole and the South Pole. This line is called the equator, and it divides Earth into two half-spheres called hemispheres. The half of Earth north of the equator is the Northern Hemisphere, and the southern half is the Southern Hemisphere.
Another special imaginary line runs from the North Pole to the South Pole. It forms half of a circle that divides Earth into two equal parts. This line is called the prime meridian. On the world map, half of the world is to the east of the prime meridian. This half of Earth is called the Eastern Hemisphere. The half of Earth that is to the west of the prime meridian is called the Western Hemisphere.
Which hemisphere do you live in?
A globe also shows us that we live on a watery planet. In fact, water covers almost three-fourths of Earth's surface. Most of this water is the salt water of oceans, which are the largest bodies of water on Earth. There are five oceans on Earth, and they are all different sizes.
Which ocean is the largest?
From largest to smallest, the oceans are the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean, and the Arctic Ocean. As you can see on the world map, all five oceans are connected.
These oceans surround large masses of land called continents. There are seven continents on Earth. Like the oceans, each continent is a different size.
Can you name all the continents?
In order from largest to smallest, they are
Asia
Africa
North America
South America
Antarctica
Europe
Australia
Understanding Latitude and Longitude:
The lines that run east and west around Earth are called parallels of latitude. These imaginary lines show how far north or south a place is. The distance between parallel lines is always the same.
The starting point for measuring parallels of latitude is the equator. The equator is halfway between the North Pole and the South Pole. It is at ߀૦ latitude. All places located north of the equator are north latitude, and all places located south of the equator are south latitude. The places farthest from the equator are the poles. The North Pole is at 90૦ north latitude, and the South Pole is at 90૦ south latitude.
Other parallels of latitude have special names. The Arctic Circle is located at 66.5૦ north latitude, also written as 66.5૦ N. The Tropic of Cancer is at 23.5૦ N. The Antarctic Circle is located 66.5 ૦ S. The Tropic of Capricorn is at 23.5૦S. Find these special lines on World Map:
Latitude
Longitude
These lines also separate areas of Earth that receive different amounts of sunlight throughout the year. The closer a line of latitude is to the equator, the more sunlight a place can receive throughout the year.
The lines that run between the North Pole to the South Pole are called meridians of longitude. These imaginary lines show how far east or west a place is from the prime meridian. These lines are half-circles. They are not parallels because they are not always the same distance apart. They are farthest apart where they cross the equator.
Political Geography of the United States:
Today, the United States is made up of 50 states, which you can see on a political map. People create states to support their needs. To do this, each state has its own government. The government of each state is found in its state capital.