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4. The representation of the Earth

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Did you know?

In the 16th century, the cartographer Gerardus Mercator put an image of the mythological Titan Atlas on the cover of his books of maps. Atlas was condemned to hold the heavens on his shoulders. This is where the name of this type of book comes from.

Cartography is the science of studying and making maps.

The most difficult thing about making maps is how to represent the Earth's sphere on a flat surface. Map projections make this possible.

4.1. Map projections

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A projection is the result of projecting a 3D image onto a flat surface.

There are many types of map projections, but the main three are: cylindrical, conical and planar.

⁷ concentric

⁸ mapped

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4.2. Maps

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A map is the true representation of the whole or part of an area on a flat surface.

Since the ancient past, people have used maps to represent the world. Often, these primitive maps represented what people knew about the world at the time, more than the geographic reality. Until Columbus discovered America in 1492, maps only represented the continents of the Old World: Europe, Africa and Asia.

Nowadays there are many types of maps.

Topographic maps represent in detail the relief, cities, towns or villages, roads and railways and other features of an area.
Thematic maps show specific aspects of an area. For example, they can be political (with borders or administrative divisions), show infrastructures (with motorways or railway lines), show relief, climate or population.

Weblink 5: Maps home page

Video 5: Reading a map

4.3. Street maps and plans

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Street maps represent smaller areas than other maps, such as cities or towns. Plans show us how the inside of buildings are organised.

Street maps are used to show the location of monuments, museums, public buildings and bus or metro lines.

Plans show us the interior organisation of buildings or facilities such as hospitals, museums and schools.

4.4. The scale of maps and plans

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Maps and plans represent large areas on small surfaces, so we need to know the relation between real size and the size shown on the map.

Scale is the between the size of the area represented on the map and the real size of the area. It can be expressed numerically and graphically.

Numeric scale is expressed using a fraction in which the numerator is the unit of size on the map and the denominator shows the number of equivalent units in real size. A scale of 1:25 000, means that one unit, for example 1 cm, represents 25 000 centimetres in real size.
Graphic scale indicates the distances on a map using a straight line divided into equal parts, like a ruler.

Depending on the ratio between the size on the map and the real size of the area, we use three kinds of scale: small, medium and large.

Large scale maps show a lot of detail because they represent small areas and their denominator is also small. They have a scale of up to 1:50 000 and are used to represent towns, cities, provinces or sections of rivers.
Small scale maps show few details because they represent large areas and their denominator is very large. They are used to represent the world, continents, large regions of the Earth or medium to large countries.

SCALE	RATIO	PLACES REPRESENTED
Large	from 1:10 000 to 1:100 000	cities, towns, provinces
Medium	from 1:100 000 to 1:500 000	not very large regions and countries
Small	from 1:500 000 to 1:50 000 000	large countries, continents, world maps

Weblink 6: Understanding scales

Activity 18
Responde a las siguientes preguntas: (500 palabras máximo cada pregunta)

Activity 19
Listen to the questions and choose the correct answer.

Activity 20
Responde a las siguientes preguntas: (500 palabras máximo cada pregunta)

Activity 21
Responde a las siguientes preguntas: (500 palabras máximo cada pregunta)

Activity 22
Classify these maps as small, medium or large scale.

Activity 23
Fill in the blank spaces with the correct answer.

Activity 24
Fill in the blank spaces with the correct answer.

Activity 25
Responde a las siguientes preguntas: (500 palabras máximo cada pregunta)

Activity 26
Responde a las siguientes preguntas: (500 palabras máximo cada pregunta)

	Meridians	Parallels
Cylindrical
Conical
Planar or flat

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4. The representation of the Earth

4.1. Map projections

4.2. Maps

4.3. Street maps and plans

4.4. The scale of maps and plans

Activity 18

Activity 19

Activity 20

What is a cartographer?

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Activity 22

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Activity 26