Geography- Globe and Map

 

Map and Globe

 

2.1 SHAPE OF THE EARTH

Today all of us are aware that the shape of the earth is spherical. Do you know that it was thought to be flat like a disk or square in ancient times? People feared venturing out far into the sea lest they might fall off the edge of the earth. This idea about the earth's shape was accepted until Aristotle made the following observations to prove that the shape of the earth was spherical.

 

The earth's shadow during lunar eclipse is curved and

The ships disappear hull first when they sail over the horizon.

 

Today it is scientifically established that the earth is an oblate spheroid. It is slightly flattened at the poles and bulging at the equator due to its rotation, We now know that the planet's equatorial diameter is larger than its polar diameter, contributing to its shape.

 

2.2 GLOBE

A globe is a three-dimensional model of the Earth. It is usually mounted on a stand at an angle to represent the Earth's tilted axis. It is also not fixed. It can be spun from west to east, just like the Earth rotates on its axis. That is why a globe is called a true model of the Earth. It not only represents the exact shape of the Earth, but also the relative sizes, shapes, distances, and directions of all the continents and oceans.

 

 

Globes are of two types - political globes which represent political divisions of the Earth and physical globes which represent physical features of the Earth. A major drawback of using globes is that they do not allow us to see the entire Earth at a single glance. Another drawback is that the physical features of the Earth or a particular region cannot be studied in detail. Globes are also difficult to carry.

 

MAP 2.3

A map is a two-dimensional representation of the entire or a part of the Earth's surface drawn according to a scale on a flat surface. Maps are drawn from aerial photographs of the Earth. But unlike aerial photographs, maps only show some information. Maps are more useful than globes because they allow us to study specific parts of the Earth, such as continents, countries, states, cities, or villages. They give more detailed information than globes and are easier to carry around.

 

Maps can be physical, political, or thematic. Physical or relief maps show physical features like mountains, plains, plateaus, water bodies, etc. Political maps show different countries and states, cities, towns, and villages along with their political boundaries. Thematic maps are based on specific themes.  They provide specific information like road or railway networks, soil, distribution of forests, industries, rainfall, etc. They are named according to the information they provide, for example, rainfall maps, road maps, mineral distribution maps, etc.

 

A collection of maps in a book form is called an atlas. Earlier, maps were drawn by hand on clay tablets, metal plates, animal skins, cloth pieces, etc. Nowadays, they are drawn with computer-aided machines, which are very accurate and precise.

 

The main drawback of maps is that they do not represent accurate shapes and sizes of continents and oceans. For example, on the world map, the Polar regions of the Earth get stretched much beyond their actual size.

 

To understand this better, take a rubber ball and trace some patterns on it. Cut the rubber ball in half and place the halves side by side. Try and flatten them out. You will find that the drawings will seem distorted.

 

Cartography The science of making maps is called cartography. The first maps were made on paper by hand and therefore varied in quality. They were also limited in distribution. Nowadays we have digital maps, i.e., maps made in digital format which can be accessed through a computer. Besides software for making maps, cartographers can now take help of satellite images of the Earth to produce accurate and updated maps of the Earth.

 

 

2.4 HOW TO READ MAPS

Maps are by far the most important tools for studying the Earth. But one must know how to read them in order to use them effectively. The language of maps comprises the following elements which help us to read them:

 

 

TITLE

The title of a map tells us what it is about. It tells us whether the map is a physical map of India, a road map of Chandigarh, a map about annual rainfall in

 

SCALE

Maps represent large areas of the Earth on a small space. They reduce the entire world or a portion of it to fit into a paper in such a way that they represent the correct distance between places. A particular distance on a map represents a particular distance on the ground. This relation is called the scale of the map.

 

The scale is always given on a map. There are different ways to represent the scale:-

1.   By a Statement: The scale is described in words. For example, a map may state '10 cm on the map represents 500 m'. This means 10 cm on the map = 500 m on the ground.

 

By Representative Fraction (RF): The scale is given as a fraction For example, 1cm:10,00,000 km or 1cm/10,00,000 km. This means that 1 cm on map represents 10,00,000 km on ground.

 

By Linear Scale: The scale is shown as a straight line with uniform divisions, These divisions are used to measure the distance between two points on a map, length of a road, length of a river, etc. This is done with the help of a string. To measure a length or distance, a string is put on the required spots on the map and they are marked on the string with a pen. The string is then put on the linear scale and the distance or length between the two markings is measured.

 

Every map has its own scale. The scale of a map depends upon the purpose for which map is being made. Depending on the scale, maps can be categorized into two types - large scale maps and small scale maps.

 

A large scale map represents a small area in great detail. For example, a road map of a city. A large distance on the map represents a small distance on the ground. That means, a distance of 10 cm on the map may represent only 1000 metres on the ground.

A small scale map represents a large area with fewer details. For example, a world map. A small distance on the map represents a very large distance on the ground. So, 10 cm on the map may represent an actual distance of 1000 km.

DIRECTION

There are four cardinal points or main directions namely, north (N), south (S), east (E), and west (W). Between them lie the four intermediate directions namely, northeast (NE), northwest (NW), southeast (SE), and southwest (SW).

On the top right corner of any map, you will find an arrow marked 'N'. This arrow represents the north direction and is known as the north line. This can help you find other directions. The south is opposite to the north direction, the east is to the right, and the west is to the left. We can find out the main directions with the help of an instrument called compass. A compass has a magnetic needle which always points in the north- south direction.

 

 

KEY

Maps have a key or index at the bottom left-hand corner. This tells us what the various symbols on the map represent. As it is not possible to show the actual shape and size of features on the map, they are represented through symbols. Symbols comprise letters, shades, colours, pictures, or lines. The use of symbols makes the reading and drawing of a map easier and quicker. Certain symbols are universally accepted, i.e., all maps use these symbols. Such symbols are known as conventional symbols. Like symbols, there is international agreement regarding use of colours. Colours are used to represent major landforms. Green is used for plains, yellow for deserts, brown for highlands, and blue for oceans and seas.

 

2.5 SKETCH AND PLAN

Sketch- A sketch is a rough map drawn without a scale. It does not give accurate information. It only conveys a rough idea of the place Directions and distances are shown in sketches but no scale is used. Therefore, such maps do not give us much idea about the distance between places or their location. Sketches are often drawn to tell the routes or locations of particular places in a given locality.

 

Plan -A plan is s a large scale map of a small area. It is often drawn to show the layout of a building room, shopping complex, class room, etc. It gives all the minor details of the area and is very accurate) It is often used by architects who design houses and buildings.