- Tell a globe, a plan and a map apart and classify maps by scale and content
- Recognise the three forms of scale and convert between them
- Use scale to calculate distances, a map’s scale and areas
- Recognise the ways information is shown on maps
Elvin wants to go hiking near Guba with his friends. How can you see a whole forest, its rivers and villages on one small sheet of paper? People have used maps for this for thousands of years. To read a map correctly, you need to know its language — the scale and the map symbols.
Globe, plan and map
- A globe is a small 3D model of the Earth. It shows shapes and distances without distortion, but its scale is very small and it is hard to carry on a trip.
- A plan of an area is a very detailed drawing of a small place, such as a school, a park or a village.
- A geographic map is a reduced, simplified picture of the Earth's surface or part of it on a flat sheet, drawn with map symbols.
| Feature | Plan of an area | Geographic map | Globe |
|---|---|---|---|
| Scale | very large (usually 1 : 5000 or larger) | large, medium or small | very small |
| Area shown | a small area | any area, even the whole Earth | the whole Earth |
| Grid of meridians and parallels | none | yes | yes |
| The Earth’s curvature | ignored | handled by a projection, with distortions | kept exactly, no distortion |
| Direction of north | shown by a north arrow | along the meridians | along the meridians |
What is scale?
A number that shows how many times distances on the map are smaller than the real distances on the ground.
| Form of scale | Example | Meaning |
|---|---|---|
| Numerical | 1 : 100 000 | 1 cm on the map equals 100,000 cm on the ground |
| Named (verbal) | 1 cm = 1 km | The same scale explained in words: how many km per 1 cm |
| Linear (bar) | 0 — 1 — 2 — 3 km | A line divided into equal parts; handy for measuring with dividers |
On a map with a scale of 1 : 250,000 the distance between two villages is 4 cm. What is the real distance?
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Real distance = 4 cm × 2.5 km = 10 km.
Check: 4 × 250,000 = 1,000,000 cm = 10,000 m = 10 km.
The smaller the second number, the larger the scale and the more detailed the map. A city plan uses a large scale such as 1 : 10,000, while a world map uses a small scale such as 1 : 50,000,000.
Calculations with scale
DİM tasks use scale in three kinds of calculation: finding a real distance from a distance on the map, finding the map’s scale from a known real length, and finding a real area from an area on the map. All of them rest on one idea: the scale tells you how many times every length on the map has been reduced.
- Mthe scale denominator (the second number in 1 : M)
- Lthe real distance on the ground, in cm
- lthe distance on the map, in cm
Convert the real distance to centimetres and divide by the length on the map. The other way round: L = l · M and l = L ÷ M.
1) A 960 km railway is drawn on a map as a 12 cm line. Find the numerical and the named scale of the map.
2) The Kura River is 1515 km long. On a map it is 30.3 cm long. What is the scale of the map?
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Numerical scale 1 : 8,000,000; named scale: 1 cm = 80 km.
2) 1515 km = 151,500,000 cm; M = 151,500,000 ÷ 30.3 = 5,000,000.
Scale 1 : 5,000,000 (1 cm = 50 km).
Shortcut: first divide the kilometres by the centimetres (1515 ÷ 30.3 = 50 km per cm), then add five zeros.
1) A map’s linear scale is divided into 1 cm parts marked 0, 50, 100 and 150 km. What real distance does 7.5 cm on this map show?
2) On a 1 : 2,000,000 map two towns are 6 cm apart. How far apart will they be on a 1 : 3,000,000 map?
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2) 1 : 2,000,000 → 1 cm = 20 km; the real distance is 6 × 20 = 120 km.
1 : 3,000,000 → 1 cm = 30 km; 120 ÷ 30 = 4 cm.
The smaller the scale, the shorter the same distance looks on the map.
The length of curved lines such as rivers, roads and coastlines is measured on a map with a thread or with dividers: open the dividers 0.5–1 cm, “walk” them along the line, multiply the number of steps by the step length and convert with the scale. Such a measurement is approximate: small bends are not shown on a small-scale map, so the same river comes out longer on a large-scale map.
- S(ground)real area on the ground, km²
- S(map)area on the map, cm²
- kkilometres per 1 cm in the named scale
Lengths grow k times, areas k² times: on a map where 1 cm = 2 km, 1 cm² = 4 km².
1) On a 1 : 200,000 map a lake covers 3 cm². Find the real area of the lake.
2) How many cm² will a 36 km² forest cover on a 1 : 300,000 map?
3) If a map’s scale is made 3 times larger, how do distances and areas on the map change?
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S = 3 × 4 = 12 km².
2) 1 : 300,000 → 1 cm = 3 km, 1 cm² = 9 km².
36 ÷ 9 = 4 cm².
3) Distances become 3 times longer, while areas become 3² = 9 times larger.
Types of maps
Maps are grouped by several features: by scale, by content, by the area covered and by purpose. By content, general maps (physical, topographic) show all the main elements of an area: relief, water, settlements and roads; thematic maps are devoted to one topic: climate, soil, population, political or economic maps. By area covered there are world, hemisphere, continent and ocean, country and regional maps; by purpose, school, scientific-reference, tourist and navigation maps.
A large-scale general map that shows an area’s relief (with contour lines), water, settlements, roads and vegetation in detail. It is used in building, farming, the military and tourism.
| Group | Scale | Examples |
|---|---|---|
| Large-scale | 1 : 10 000 – 1 : 200 000 | topographic maps (1 : 25,000, 1 : 50,000, 1 : 100,000) |
| Medium-scale | 1 : 200 000 – 1 : 1 000 000 | province and regional maps |
| Small-scale | smaller than 1 : 1,000,000 | country, continent and world maps |
There are three main ways of working with a map, or methods of cartographic research: visual analysis (looking at the map and comparing where objects are, their shapes and how they spread), cartometric analysis (measuring and calculating distances, areas, heights and angles, like the scale problems in this lesson) and graphic analysis (drawing profiles, graphs and diagrams from the map).
Map symbols and ways of showing information
- Map symbols are explained in the map's legend (key): there are point symbols (a city, a mine), line symbols (a river, a road, a border) and area symbols (a forest, a swamp).
- On a physical map green shows lowlands, yellow and brown show uplands and mountains, and blue shows water: the darker the blue, the deeper the water.
- On most maps the top is north, the bottom is south, the right is east and the left is west. Meridians run north–south and parallels run west–east.
| Method | What it shows | Example |
|---|---|---|
| Point symbols (icons) | objects at particular points | cities, mineral deposits, power stations |
| Line symbols | objects that run along a line | rivers, roads, borders, pipelines |
| Isolines | lines joining points of equal value | contours (height), isobaths (depth), isotherms, isobars, isohyets (precipitation) |
| Qualitative background | areas that differ in kind, each in its own colour | countries on a political map, soil types |
| Area (range) method | the area where something occurs | ranges of plants and animals |
| Dot method | each dot stands for a set amount | 1 dot = 10,000 people (where people live) |
| Flow lines | the direction and path of movement | ocean currents, winds, freight flows, migration |
| Diagram map (cartodiagram) | diagrams drawn inside each area (absolute values) | output of each district as bar or pie charts |
| Choropleth map (cartogram) | areas shaded by the intensity of an indicator (relative values) | population density, share of forest |
Match each method with the information it shows.
1. Isolines
2. Flow lines
3. Choropleth map (cartogram)
a) mean July temperature
b) ocean currents
c) population density by district
d) depth of the sea
e) routes of migrating birds
A) 1 – a, b; 2 – d, e; 3 – c
B) 1 – c, d; 2 – b; 3 – a, e
C) 1 – a; 2 – b, e; 3 – c, d
D) 1 – a, d; 2 – b, e; 3 – c
E) 1 – d, e; 2 – a, b; 3 – c
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2) Currents and bird routes show the direction of movement: flow lines (b, e).
3) Density by district is a relative value shown in colour: a choropleth map (c).
Correct answer: D) 1 – a, d; 2 – b, e; 3 – c.
Key points
- A map is a reduced picture of the Earth's surface on a flat sheet, drawn with symbols.
- Scale has three forms: numerical (1 : 100,000), named (1 cm = 1 km) and linear.
- 1 km = 100,000 cm: remove five zeros from the second number to get kilometres per centimetre.
- The scale is found with M = L ÷ l; areas change with the square of the scale: if 1 cm = k km, then 1 cm² = k² km².
- By scale, maps are large-scale (up to 1 : 200,000), medium-scale (up to 1 : 1,000,000) and small-scale; the smaller the second number, the more detailed the map.
- Ways of showing information: point symbols, line symbols, isolines, qualitative background, areas, dots, flow lines, diagram maps and choropleth maps.
Check yourself
12 questions. Every correct answer earns XP.