Gr 9 social sciences study guide geography

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SOCIAL SCIENCES STUDY GUIDE: GEOGRAPHY Grade 9

A member of the FUTURELEARN group

Sosiale Wetenskappe Handleiding: Geografie

1809-A-SOS-SG02

Í2)È-A-SOS-SG02MÎ

Graad 9

Aangepas vir KABV

Study Guide G09 ~ Social Sciences: Geography

CONTENTS INTRODUCTION ................................................................................................................. 3 UNIT 1: MAP SKILLS.......................................................................................................... 5 Lesson 1: Orientation .................................................................................................. 7 ACTIVITY 1 ........................................................................................................... 7 ACTIVITY 2 ........................................................................................................... 8 ACTIVITY 3 ........................................................................................................... 9 Lesson 2: Scale, distance and bearing ........................................................................ 9 ACTIVITY 4 ......................................................................................................... 12 Lesson 3: Find places on maps ................................................................................. 13 ACTIVITY 5 ......................................................................................................... 15 Lesson 4: Photographs of the earth .......................................................................... 16 ACTIVITY 6 ......................................................................................................... 20 Lesson 5: Altitude on maps ....................................................................................... 21 ACTIVITY 7 ......................................................................................................... 22 Lesson 6: The landscape .......................................................................................... 23 ACTIVITY 8 ......................................................................................................... 25 Lesson 7: Cross sections .......................................................................................... 25 ACTIVITY 9 ......................................................................................................... 28 Lesson 8: How to draw and read graphs ................................................................... 30 ACTIVITY 10 ....................................................................................................... 32 Lesson 9: In the field ................................................................................................. 33 UNIT 2: DEVELOPMENT ISSUES .................................................................................... 35 Lesson 10: Development ........................................................................................... 36 ACTIVITY 11 ....................................................................................................... 37 Lesson 11: Ways of measuring development ............................................................ 37 ACTIVITY 12 ....................................................................................................... 41 Lesson 12: Factors affecting development ................................................................ 46 ACTIVITY 13 ....................................................................................................... 47 Lesson 13: Factors affecting development (continued) ............................................. 48 ACTIVITY 14 ....................................................................................................... 54 Lesson 14: Opportunities for development ................................................................ 55 UNIT 3: SURFACE FORCES THAT SHAPE THE EARTH ............................................... 61 Lesson 15: Structure of the earth .............................................................................. 62 ACTIVITY 15 ....................................................................................................... 64 Lesson 16: Types of rock .......................................................................................... 64 ACTIVITY 16 ....................................................................................................... 68 Lesson 17: Endogenic forces (internal forces) .......................................................... 69 ACTIVITY 17 ....................................................................................................... 72 Lesson 18: Landforms resulting from endogenic (internal) forces ............................. 72 ACTIVITY 18 ....................................................................................................... 78

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Study Guide G09 ~ Social Sciences: Geography

Lesson 19: Landforms caused by exogenic (external) forces.................................... 79 ACTIVITY 19 ....................................................................................................... 81 Lesson 20: Erosion .................................................................................................... 82 ACTIVITY 20 ....................................................................................................... 83 Lesson 21: The development of landforms ............................................................... 84 ACTIVITY 21 ....................................................................................................... 86 Lesson 22: Groundwater ........................................................................................... 87 ACTIVITY 22 ....................................................................................................... 89 Lesson 23: Karst Topography ................................................................................... 91 ACTIVITY 23 ....................................................................................................... 92 Lesson 24: Wind erosion and deposition ................................................................... 93 Task 3 ................................................................................................................. 93 ACTIVITY 24 ....................................................................................................... 95 Lesson 25: Marine erosion ........................................................................................ 96 ACTIVITY 25 ....................................................................................................... 97 Lesson 26: Landforms characteristic of marine erosion ............................................ 97 ACTIVITY 26 ....................................................................................................... 98 Lesson 27: Coastline patterns ................................................................................... 99 ACTIVITY 27 ..................................................................................................... 100 Lesson 28: Glaciations ............................................................................................ 100 ACTIVITY 28 ..................................................................................................... 101 Lesson 29: Alpine glaciers (valley glaciers) ............................................................. 102 ACTIVITY 29 ..................................................................................................... 103 UNIT 4: RESOURCE USE AND SUSTAINABILITY ....................................................... 104 Lesson 30: Types of natural resources ................................................................... 105 ACTIVITY 30 ..................................................................................................... 106 Lesson 31: How resources are being used ............................................................. 106 ACTIVITY 31 ..................................................................................................... 107 Lesson 32: Consequences of unwise resource use ................................................ 108 ACTIVITY 32 ..................................................................................................... 111 Lesson 33: Sustainable use of resources ................................................................ 111 ACTIVITY 33 ..................................................................................................... 113 Lesson 34: Working towards sustainability .............................................................. 114 ACTIVITY 34 ..................................................................................................... 117 Lesson 35: Food resources ..................................................................................... 118 ACTIVITY 35 ..................................................................................................... 121 Lesson 36: The roles of science and technology in food production ....................... 122 ACTIVITY 36 ..................................................................................................... 124 Lesson 37: Sustainable farming – appropriate technologies and farming techniques ............................................................................................ 125 ACTIVITY 37 ..................................................................................................... 126

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Study Guide G09 ~ Social Sciences: Geography

INTRODUCTION What is Geography?

Geography is the study of the human and physical environment. Geography is an integrated discipline that examines both physical and human processes over space and time. Geography helps us to understand our complex world. It offers us a bridge between the human and physical sciences.

There are many branches of Geography. Physical Geography examines natural processes and features, including the atmosphere, landforms and ecosystems. Human Geography is concerned with the activities and impact of people on the earth.

The concept that unifies Geography is space. All geographical phenomena have a spatial dimension. They also operate in a continuously changing environment.

Geography therefore includes the study of: • spatial patterns and trends: the location of people and places in the world • similarity and difference: how environments and lifestyles compare and the reasons for similarities and differences • movement: how and why people, goods, water, land and air move and change Source: http://www.education.gov.za/LinkClick.aspx?fileticket=RGnHZvQyYtI%3d&tabid=672&mid=1885

The Geography course for Grade 9 is designed in accordance with the South African National Curriculum Statement (NCS) in terms of CAPS (Curriculum and Assessment Policy Statement) for Geography in the SENIOR PHASE. (Grades 7 to 9). The NCS contains new learning material which promises to be very challenging and relevant to our day-to-day life.

Social Sciences is divided into Geography and History – each with its own study guide and facilitator’s guide.

The following topics will be covered this year: • Map skills • Development issues • Surface forces that shape the earth • Resource use and sustainability

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Learning programme (syllabus) and broad overview of the year plan UNIT/TERM 1: Map skills • Orientation • Scale, distance and bearing • Finding places on maps • Photographs of the earth • Altitude on maps • The landscape • Cross sections • How to draw and read graphs • A practical approach UNIT/TERM 2: Development issues • Defining development • Measuring development • The Human Development Index • Factors affecting development • Opportunities for development • Alternative development • Sustainable development UNIT/TERM 3: Surface forces that shape the earth • Structure of the earth • Rock types • Endogenic forces and landforms • Exogenic forces and landforms • Erosion • Development of landforms • Groundwater and Karst topography • Wind and deposition • Marine erosion and resulting landforms • Coastline patterns • Glaciations/Alpine glaciers UNIT/TERM 4: Resource use and sustainability • Renewable and non-renewable resources • How resources are being used • Consequences of unwise resource use • Sustainable resource use • Working towards sustainability • Food resources • Science and technology in food production • Sustainable farming

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UNIT 1: MAP SKILLS Proposed time frame for unit 1 In our first unit, we deal with map skills, an exciting unit with a large amount of expanded, enriching content. You should revise last year’s mapwork properly. However, the first two lessons will assist you in getting up to standard without much effort.

LEARNING AIMS By the end of this unit you should be able to do the following: 1.

Explain: Why and how aerial photographs are taken The attributes of contour lines How to draw cross sections using the contour lines on a map 2.

Distinguish between: True bearing and magnetic bearing Contour lines and contour intervals 3.

Describe/discuss: How human and physical environments are continuously interacting with each other 4.

Define: Terminology used in mapwork 5.

List or label on a diagram: The types of aerial photographs 6.

Name/identify: Direction using the 16 compass points The symbols on maps South Africa’s provinces, capital cities, neighbouring states, important harbours and oceans.

Ways of indicating altitude on maps Landforms and slope types Various types of graphs 7.

Apply: Your knowledge of mapwork in order to successfully use and identify items on maps Your mapwork knowledge to convert scale to actual distances on a topographical map and orthophoto map respectively Your knowledge of how topographical maps are subdivided, and use this information to calculate exact positions on a map Your knowledge to measure true bearing using a protractor Your knowledge of aerial photographs to interpret the earth’s surface Your knowledge of graphs to extract information from them

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Special requirements for mapwork In the mapwork section you will learn the basic skills required to read maps. To do this you will make use of the South African 1:50 000 topographical map series and aerial photographs. For this purpose, a topographical map of Volksrust (2729BD) and an orthophoto map of Volksrust (2729 BD 13) have been included along with your study material as an addendum.

To study mapwork effectively, a number of special instruments are required: o An accurate ruler is needed to measure distances. o A protractor is essential to measure bearings and angles. o A compass and divider are useful for calculating distances. o A simple calculator will help with calculations. o To get the most out of aerial photography a small magnifying glass will bring out detail that may help you to identify images and map features. Learners are allowed to use a magnifying glass in tests and examinations. o A set square is optional, but a sharp pencil and a soft eraser are vital. o An atlas covering Southern Africa in detail is essential.

Preparation of a topographical- and orthophoto map Sometimes a topographical- and orthophoto map is not prepared for the use for map work purposes. Below are some tips to prepare the different maps.

•

Firstly, prepare your topographical map as follows: o Cover your topographical map with a grid (blocks) of 1’ x 1’ according to the divisions on the edge of the map (these divisions are known as MINUTES, and they are indicated by the ’ sign). Neatly and accurately, draw lines from top to bottom and from left to right across the map, in pencil. o Mark the blocks at the top and bottom from left to right 1, 2, 3 …, and the blocks on the left- and right-hand sides from top to bottom A, B, C … o The lines you have drawn on the map represent lines of latitude (horizontal) and lines of longitude (vertical). o With the aid of these lines you are able to read and give co-ordinates.

(Co-ordinates will be discussed in a following lesson.) o Each degree of latitude or longitude is subdivided into 60 minutes (60’) and each minute into 60 seconds (60”).

• Draw a grid on the orthophoto map (aerial photograph) as well. Start at the top lefthand side corner and cover the whole photo area with blocks of 5 cm x 5 cm. Mark the columns at the top and bottom 1, 2, 3 … and the rows on the right- and left-hand sides from the top a, b, c …

Note: Use CAPITAL LETTERS on the topographical map and small letters on the orthophoto map.

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LESSON 1: ORIENTATION Maps are one of the most common ways we use to understand our world. We use maps to indicate the shapes and sizes of places as well as distance and direction. Maps show, amongst others, rivers, mountains and vegetation (natural features), and political divisions, population distribution, routes, etc. (human features), to mention only a few.

To continue your mapwork study in Grade 9, it is necessary to refresh some basic knowledge, skills and techniques gained previously.

Terminology A sound knowledge of terminology is important – it is the language of any subject. Learn the definitions by heart so that you can recall them in tests and examinations.

Do the following activity on your own.

ACTIVITY 1 Match a description in column B with a term/concept in column A. COLUMN A COLUMN B A. Direction to the magnetic north pole as indicated by the (a) A map compass needle. (b) Map scale

B.

The exact position of a point or feature.

(c) True north

C.

The indication of direction, e.g. east.

(d) Magnetic north

D.

The ratio between the distance on the map and the distance on the land.

(e) Direction

E.

The direction to the geographic north pole, as indicated by the lines of longitude.

(f) Bearing

F.

The earth represented on a flat surface according to scale, showing natural and man-made features.

(g) Location

G. The indication of direction in degrees, e.g. 90°.

(7 x 2) = [14]

Map of South Africa Knowledge of the map of South Africa is applicable right until you’ve completed your final Grade 12 examinations. It is vital that you are up to date on your South Africa map knowledge, and are aware of the positions of important places.

Apart from that, it is always convenient to have a basic knowledge about the geography of your country, especially when reading newspapers, taking part in conversations, and planning business opportunities, amongst others. © Impaq

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Make use of an atlas to do the following activity.

ACTIVITY 2 Make a copy (enlarged if possible) of the outline map of South Africa and fill in the following information at their correct positions: 1.

2.

3.

4.

5.

The names of South Africa’s provinces.

The name of each province’s capital city.

Indicate the Tropic of Capricorn and its degrees of latitude.

Write in the names of South Africa’s neighbouring states.

Write in the names of the following major harbour cities: Saldanha Bay, Port Elizabeth, East London, Durban, and Richards Bay. (Which major harbour city has been omitted?)

6. The names of the two adjacent oceans.

7. Cape Agulhas.

8. Circle the two neighbouring countries that are inland.

(9) (9) (2) (6) 5 + 1 = (6) (2) (1) (4) [39]

(The position of the provincial capital cities are indicated by dots as per this map, and labelled correctly)

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ACTIVITY 3 • •

You must consult an atlas to answer the following questions.

You must be able to use the table of contents (in front) and the index (at the back) of the atlas.

1.

Name the seven continents of the earth.

(7)

2.

Which ocean will you cross over when flying from: (a) London to New York? (b) Johannesburg to Perth? (c) Tokyo to San Francisco? (d) Adelaide (Australia) to the South Pole?

(4)

If you stand exactly on the South Pole, you can only look in one direction. (a) Which direction? (b) On which continent is the South Pole located?

(4)

Find the position of the Magnetic North Pole. Near which major country is it located?

(2)

Name the water mass between: (a) Africa and Europe. (b) Egypt and Saudi-Arabia. (c) Great Britain and Norway. (d) Mexico and Cuba.

(4)

Which line of longitude (degrees of longitude) is represented by: (a) Greenwich? (b) The International Date Line?

(4)

3.

4.

5.

6.

7.

On which continent is Timbuktu?

(2) [27]

LESSON 2: SCALE, DISTANCE AND BEARING

How to make mapwork easy When it comes to mapwork, many learners groan that mapwork is mathematics. In general, many learners struggle with mapwork.

All in all there are not many calculations, but it is important to master the few there are.

Without the skills of measurement and calculation one cannot appreciate the full value of map skills. All these techniques require very simple mathematical skills and with continuous practice, it is possible to master them.

Good advice: o Memorise the steps of the calculations and techniques (there are not that many). o Revise these techniques regularly or as frequently as possible by doing new exercises and not just redoing the old ones.

Map scale and distance In the flattening process of the spherical (rounded) earth some important cartographic aspects become distorted. One of them is map scale, due to the “stretching” of the earth’s surface in the direction of the poles. © Impaq

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Thus, the process of measuring distances on maps is not very accurate, especially on maps covering large areas. However, on maps representing small areas, e.g. topographical maps (such as the one of Volksrust), the rounded Earth’s surface has little effect on scale distortion, so that the calculation of real distances is more accurate.

Types of map scale • Word scale 1 cm represents 5 km

• Ratio scale or Representative fraction e.g. 1:500 000

• Linear scale (graphic scale) 0 1,5 km

(1 cm represents 500 000 cm; divide the denominator by 100 000 to get km)

The scale of topographical maps vs. scale of orthophoto maps Topographical map 1:50 000

Orthophoto map 1:10 000

cm

cm

cm

Map Land

Remember There are 100 000 cm in 1 km, and 1 000 m in 1 km.

cm

Map Land

So 1 cm on a topographical map is literally equal to 50 000 cm on the land it represents.

If there are 100 000 cm in a km, then it makes sense that 1 cm is equal to HALF a km.

Thus 1 cm represents 0,5 km.

In the same way, 1 cm on an orthophoto map represents 10 000 cm on the land it depicts.

If there are 100 000 cm in a km, 10 000 cm represents one tenth of a km i.e.

0,1 of a km. Thus 1 cm represents 0,1 km.

The sixteen major compass points (cardinal points) 0° NORTH North-north-east 22½° North-east 45°

East-north-east 67½° 270° WEST

EAST 90°

FIGURE 2.1

180° SOUTH

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Bearing Bearing refers to the indication of direction, measured in degrees. Figure 2.1 also shows the corresponding bearing for each major point of the compass.

Method to determine true bearing • Join the given points on the map with a fine line.

• Draw a true north line from the point of measurement. This line is accurately parallel to the edge of the map or the lines of longitude.

• Place a protractor with 0° on true north.

• Read (always) clockwise from the true north line.

• True bearing is the degrees measured. Always measure true bearing in full degrees.

The diagrams below show how to use the protractor, from X to Y (top) and from Y to X (bottom).

A.

B.

True north

True north

E.g. 95°

X

X Y

Y 180° + 95°

Figure 2.2: Bearing from X to Y (A) and from Y to X (B).

Always use the protractor clockwise. In the case from Y to X (illustration B), the bearing will be 180° PLUS the additional measurement.

What is magnetic bearing?

The positions of true and magnetic north do not correspond, as you will see at the bottom of the topographical map of Volksrust.

TN MN

Mean magnetic declination 20°37’ west of true north (February 2010). Mean annual change 3' westward.

Magnetic declination is the angle with which the magnetic north deviates from true north.

This angle changes continuously. (According to the example above, does this angle become larger or smaller with time?).

When using a protractor and magnetic north to measure the bearing, the angle (bearing) will be larger than the angle (bearing) when using true north. Therefore, we distinguish between true bearing (on the map) and magnetic bearing (in the field with a compass).

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ACTIVITY 4 1. Calculate the word scale of the: 1.1 Topographical map 1.2 Orthophoto map

(2) (2)

2. Give your answers to question 1.1 and 1.2 in metres.

Name your new answers question 2.1 and 2.2 respectively.

3. On the topographical map of Volksrust, calculate the straight line distance in kilometres from the railway station (F3) to the: 3.1 train station (block D4) 3.2 police station (block F3) 3.3 Wind pump (block A7) 3.4 purification plant (block D2)

2 x 2 = (4) Remember

(4) (4) (4) (4)

Your calculation of distance must show the following steps: Map distance … cm Word scale x … km Real distance … km

4. Complete the following compass by redrawing it in your answer booklet and filling in the missing information. Be sure to include the prime directions as well as their relevant bearing.

(14 x 1) = (14) 5. On the topographical map of Volksrust, give the direction from the 5.1 ∆235 (E8) to ∆86 (A9).

5.2 ∆235 (E8) to the police station (D4).

5.3 church (F3) to the dam wall (H2).

6. On the topographical map of Volksrust, measure the bearing from the: 6.1 railway station (A1) to the monument (I4).

6.2 railway station (A1) to the Mahawane dam wall (B5).

6.3 hospital (C4) to the excavations (D2).

(2) (2) (2)

(2) (2) (2) Remember When drawing lines on the map, do it lightly with a sharp pencil.

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Note: Compare your answer to question 5.1 with that of question 6.1. A direction of westnorthwest corresponds with a bearing of 292.5°. If the measured bearing differs slightly (±2°), you may use the point of the compass nearest to it. Otherwise your answer has to read “between south-southeast and south”, as in the case of questions 5.2 and 6.2.

LESSON 3: FIND PLACES ON MAPS To use maps to our best advantage, we have to understand certain basic characteristics of maps and mapping, and we should be able to use these skills as second nature.

Just as it is with the language we speak, we have to learn the alphabet, what it looks like and how it sounds.

Similarly, we need to learn the alphabet of mapping: • the way of representing features, and • how to find them.

Once we have mastered these skills we will be able to understand all phenomena occurring on the earth’s surface.

Map symbols You have already come across a few map symbols in the previous two lessons, such as a railway station, a monument, a post office and so on.

In map reading we make use of symbols to indicate particular features on the map.

These symbols are called conventional symbols and should be studied in order to understand the map. The standard map that is used in South Africa is called the 1:50 000 topographical map and most of the conventional symbols are indicated in the map key or reference.

It is important to be completely familiar with all the symbols in order to read and interpret the map well.

Find places quickly We can find a place quickly by using a grid reference. Numbers identify the columns and are found on the top and/or bottom of the page. The rows are identified by letters and are found on the left-hand and/or right-hand sides of the map. Any block can be identified quickly by using a letter and a number, e.g. D4. Go to row D and then move to column 4.

Where these two (row and column) meets is block D4.

Co-ordinates Co-ordinates refer to the intersecting point of a line of latitude and a line of longitude.

Remember: The equator divides the globe in northern and southern hemispheres.

Therefore lines of latitude are called “north” and “south”.

The Greenwich meridian divides the globe in eastern and western hemispheres. Therefore lines of longitude are called “east” and “west”.

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Figure 3.1: World map with lines of longitude and latitude.

The most popular method of indicating the co-ordinates on a topographical map is by using degrees (°), minutes (’) and seconds (”). There are 60 minutes in one degree, and 60 seconds in one minute. (Just the same as on your watch when you tell the time). You are already familiar with the subdivision of minutes on the edges of the map. Figure 3.2 shows you how to estimate the seconds if a place is located within the block.

180 00’

01’

02’

03’

30” 04’ 15” 45”05’

06’

35” Figure 3.2

In order to calculate seconds you first divide the minute block in half (30”) and then in quarters (15” and 45”). Then you calculate the seconds in relation to these major divisions, e.g. a position just greater than half will be 35”.

2. Longitude from left to right 1. Latitude from top downward

Always determine the latitude from top downward and the longitude from left to right, in this order.

TIP: Remember that the ‘A’ in latitude comes before the ‘O’ on longitude, so latitude is always read before longitude.

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Example: On the diagram below, the co-ordinates of X and Y will be as follows: X: 20°00’00” South; 25°16’00” East.

Y: 20°00’30” South; 25°15’30” East.

25°15’ 20°00’

16’ X

17’

18’

Y A 01’ B C 02’ Figure 3.3

A small variation of between 1” and 6”, will be accepted in tests and examinations, unless indicated otherwise.

ACTIVITY 5 1. Refer to your topographical map of Volksrust. Draw and colour the following conventional symbols: (a) A dam with perennial water in a non-perennial river. (b) Excvation. (c) Marshes (wetlands). (d) Secondary road. (e) A bench mark next to an arterial road.

5 x 2 = (10) 2. Refer to figure 3.1. Give the co-ordinates of: (a) A (b) B (c) C

(2) (2) (2)

3. Refer to figure 3.3. Give the co-ordinates of: 3.1 A 3.2 B 3.3 C

3 x 4 = (12)

Refer to your topographical map of Volksrust.

4. Name the features at the following co-ordinates: 4.1 27°22’55” South; 29°53’30” East 4.2 27°25’30” South; 29°59’20” East 5. Give the co-ordinates of the following features: 5.1 Majuba Monument (block J1) 5.2 Reservoir (block A8)

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(2) (2) (4) (4) [40]

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LESSON 4: PHOTOGRAPHS OF THE EARTH Aerial photographs complement maps. Aerial photographs show the exact detail of the landscape and therefore are invaluable in the interpretation of the landscape.

Where a map may show an urban area as grey shading, an aerial photograph will show the shapes and sizes of the buildings and even the vegetation like trees. With the aid of aerial photographs one can study any area in the world without visiting that specific area.

An aerial photograph is much easier and faster to produce than a map and there-fore it is a useful geographical tool. Aerial photographs are in fact used to draw contour lines and to construct maps.

Different types of aerial photographs Aerial photographs can be divided into three categories: vertical and oblique photographs and satellite images (see figure 4.1).

In the introductory paragraphs above we have already referred to some important advantages of aerial photographs. (They complement topographical maps, show exact detail, useful for interpreting landscape, are fast to reproduce and are used in the creation of topographical map construction).

Some disadvantages about aerial photographs o The unusual angle of photography (from above) makes the identification of certain features difficult. o The scale is distorted because some points on the photograph are closer to the camera than others. o Detail could be blocked out by shadows.

Advantages of satellite images o Satellite images are used to map the world very accurately. o It is a source to get detailed information about weather conditions and contributes to more accurate weather forecasts. o Geologists are able to identify rock types and even minerals. o Agricultural planners can see what type of crops are growing in a specific area, in which stage of growth the plants are and even if there are any plagues present. o Satellites play an important role as “spies” during times of war.

VERTICAL AERIAL PHOTOGRAPH 3 km

OBLIQUE AERIAL PHOTOGRAPH

Camera

SATELLITE IMAGE 300 km

Optical axis of lens Earth

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- Camera points directly downward.

- Optical axis of lens forms an angle of 90° with the earth’s surface.

Unit

- Camera is tilted.

- If little deviation from vertical – low oblique photograph, horizon not visible.

- High oblique if horizon is visible.

1

- Images are recorded by orbiting satellites at different distances into space.

Figure 4.1: Different photographic perspectives. The first two images are of the Tswaing Meteorite Crater, about 45 km north of Pretoria.

The official source of aerial photographs in South Africa is the Chief Directorate: Survey and Mapping, Mowbray, Cape Town.

The flight plan The flight plan is the way in which an area is photographed from above by a speciallyequipped aeroplane.

The area or task of taking aerial photographs is divided into a number of flight strips, usually flown east to west. Each flight strip consists of individual photographs, which overlap each other by 60% to ensure that no part is left out, and to make stereoscopic vision possible. Flight strips themselves overlap by 30%. Normally aerial photography is done between 10:00 and 14:00 when shadows are the shortest. Determining during which month aerial photography is to be undertaken, is an important consideration. Photographs taken during rainy weather, where cloud cover is present, would not be of much use. As clouds hamper the view from above, an area is best photographed during the dry season.

All this information (time, date, area and more) is printed on the edge of each photograph.

See the illustration of a flight plan in figure 4.2.

Figure 4.2: Illustration of a flight plan. © Impaq

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Figure 4.3: An example of a vertical aerial photograph, showing part of the Hartbeespoort Dam and the Magaliesberg Mountain Range. (Source: Chief Directorate: Surveying and Mapping, Mowbray).

Stereoscopic vision By means of a stereoscope (figure 4.4) we are able to see the photo images threedimensionally. It is possible when two consecutive vertical aerial photographs, which overlap by 60%, are placed under a stereoscope in such a way that the same objects on different photographs are merged to become single, three-dimensional objects.

Figure 4.4: Illustration of how stereoscope vision is used to create a 3D image.

Orthophoto maps An orthophoto map (such as the one of the Volksrust area) is a series of computerrectified vertical aerial photographs, in which photographic distortions have been removed. o Instead of showing objects from one point (the camera), orthophoto maps are modified to show all objects on the surface as from directly above. o Some man-made features are annotated on these types of photos. o Contour lines are drawn in with intervals of 5 metres. o The scale is 1:10 000; i.e. five times larger than the 1:50 000 topographical map, so that images are quite large and easy to identify. (More about larger and smaller scales in Grade 10).

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You have received a standard size orthophoto map of Volksrust. The area covered by the orthophoto map appears in blocks C, D en E/2, 3 en 4 (that’s nine blocks in all) on the topographical map of Volksrust.

Find these blocks on your topographical map and highlight the edge to make cross referencing easier. If you look at the corners of your orthophoto map, you will see that its size is 3’ x 3’ (27°21’ – 27° 23’ South and 29°51’ – 29°53’ East). This is how you can work out that nine blocks are shown: 3 minutes times 3 minutes is 9 minutes (i.e. 3’ x 3’ = 9’).

Identify images on aerial photographs Because of the unfamiliar angle of photography (observation from right above) it is often quite difficult to identify features on vertical aerial photographs. Objects are also very small on these types of photographs. However, on orthophoto maps with their larger scale it is easier to see what’s going on.

Some hints when reading aerial photographs: o Using comparison: Compare features on the aerial photograph with those found at the corresponding position on the topographical map, utilising the map symbols at your disposal. o Association: You could identify objects in relation to other familiar features near those objects, for example: - Buildings surrounded by cultivated lands would most likely be the farm house with its outbuildings.

- The Central Business District (CBD) or a large shopping complex in the suburbs can be identified by large buildings where main roads intersect in a town or city.

- Cultivated lands can be associated with typical farming activities in various parts of our country. (In the southern and south-western parts of our country the crop would in all probability be either wheat or vineyards). o Size: A block of flats would naturally display larger than a house would; an area full of large buildings near the centre of a town would most likely be the CBD. You are welcome to use a magnifying glass when you are busy with aerial photographs.

They are permitted both in tests and examinations.

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ACTIVITY 6 1.1

In terms of aerial photography and the flight plan chosen, name the: (a) general time that photography is usually undertaken (b) normal direction in which the photographic process takes place (c) the percentage of overlapping when taking aerial photographs

(1) (1) (2)

1.2

The season during which aerial photography is undertaken, is an important aspect.

Why? 3 x 2 = (6)

1.3

What is the main difference between a vertical aerial photograph and an orthophoto map, in terms of the way they are produced?

2 x 2 = (4)

1.4

What do the topographical map and the orthophoto map have in common?

2 x 2 = (4)

1.5

What makes an orthophoto map different from “just another aerial photograph”?

2 x 2 = (4)

Study the orthophoto map 2729 BD 13 Volksrust together with the topographical map of 2729BD Volksrust.

1.6 Why does the title of the orthophoto map refer to “Volksrust”? Hint: Search the corresponding area on the topographical map.

(2) 1.7

What is the scale of the orthophoto map?

(1)

1.8

What type of scale is this (question 1.7)?

(1)

1.9

Rewrite the scale so that: (a) 1 cm represents ________ kilometres. (b) 1 cm represents ________ metres.

(2) (2)

1.10

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On the orthophoto map, identify: (a) the main transport mode in block c1. (b) two types of roads in block a3. (c) two outstanding natural features in block c3.

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(1) (2) (2) [35]

Study Guide G09 ~ Social Sciences: Geography

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LESSON 5: ALTITUDE ON MAPS When paging through the physical maps in an atlas, you will see the different colours representing the landscape’s altitude or height above sea level (ASL). For example, the green represents an area between sea level and 200 metres above sea level, yellow 200 to 500 metres, brown 500 to 1 000 metres and so on. That is the norm on small-scale maps, i.e. maps that cover large areas, such as world maps.

On large-scale maps (maps covering small areas) such as topographical maps, cartographers use a variety of methods to indicate altitude.

Ways of indicating altitude

•

Contour line:

• •

Trigonometrical Station: 252.6 Spot height: . 231

•

Bench Mark:

220

(brown lines on a topographical map) (see figure 5.1 for the picture)

292 (next to a road or railway line)

[All numbers above refer to height above sea level in metres]

Terminology Contour line: Lines on a map that connect points with the same height above sea level.

Contour interval: The constant height difference between successive contour lines.

(It means that the vertical spaces between contour lines are the same on a specific map).

Trigonometrical station (beacon) on top of a hill

Side view of an island where contour lines are shown

Steep slopes where contour lines are closely spaced Map as seen from above

Figure 5.1: Side and top view of contoured hill © Impaq

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Study Guide G09 ~ Social Sciences: Geography

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What characteristics do contour lines display?

The definition itself is a characteristic of contour lines. Other characteristics are: • The contour interval on a map is constant.

• Contour lines are closely spaced on steep slopes and spaced further away from each other on gentle slopes.

• They do not end blind, but are joined to themselves or end at the edge of the map.

• Contour lines do not intersect themselves but may touch at a cliff.

ACTIVITY 7 1.

List all the ways in which altitude are indicated in blocks F10/G10 on the topographical map of Volksrust. Also give the respective heights.

(4)

2.

In which direction does altitude decrease in this area?

(1)

3.

What is the contour interval on the: 3.1 Topographical map?

3.2 Orthophoto map?

(1) (1)

4.

What is the height above sea level which is represented by the following contour lines: 4.1 Excavations to the north-east side of Vukuzakhe (block C5)?

(2) 4.2 Going around the dams in the northern direction (block D10)?

(2) 4.3 Touching the dam wall in (block D9)?

(2) 4.4 Going around the bottom of the mouth of the waterfall (block G6)?

(2)

5.

Estimate the height above sea level at the following points: 5.1 About the middle of the main runway (block D2).

5.2 The dam in (block H8).

5.3 The hospital (block D3).

5.4 The recreational ground (Rec.) in (block G3).

5.5 The middle of the cultivated land (block i10).

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(1) (1) (1) (1) (1) [20]

Study Guide G09 ~ Social Sciences: Geography

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LESSON 6: THE LANDSCAPE By studying the spacing and shape of contour lines one is able to identify steep and gentle slopes and the various landforms such as valleys and spurs and many others.

The shape of contour lines is either: • Straight, • Circular or • V-shaped.

These three major properties of contour lines enable us to identify all the landforms that make up the landscape.

On 1:50 000 maps the contour lines are shown as brown lines. The height is also shown in brown on some of the lines. The ways the numbers are written show the upside and the downside of the slope (figure 6.1).

Higher contour 1020

Lower contour Figure 6.1: Upside and downside of a slope.

Slopes Slopes can be classified as steep or gentle or as concave, convex or terraced (figure 6.2).

Side views of different slope forms and the spacing of the contour lines

Concave

Convex

Terraced

Figure 6.2

• • •

Concave: The contour lines become further spaced downward.

Convex: The contour lines become closer spaced downward.

Terraced: The contour lines show a grouping in pairs.

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Landforms ▪Steep slope (A) ▪ Mesa ▪ Saddle ▪Valley ▪Gentle slope (B) ▪ Spur Figure 6.3

Guidelines to identify some of the landforms •

Circular-shaped contour lines represent a hill. If the highest circular line has a large circumference, it is called a mesa. A butte is narrower with a smaller circumference and a pointed butte shows the crest as a very small circle or nearly a dot.

•

Contour lines are closely spaced at steep slopes and further apart at gentle slopes.

•

V-shaped contours indicate a valley if they point to the higher ground, and a spur if they point to the lower ground. If the contour lines of a valley are very closely spaced, it represents a gorge.

• •

At a vertical cliff, the contour lines touch.

A saddle or a pass is a lower lying area between two hillcrests.

•

A watershed follows the highest part of a mountain ridge and divides stream flow in opposite directions. (On figure 6.3 for instance, it will be the east-west line through the trigonometrical station and the spot height).

Figure 6.4: A mountainous scene in a semi-arid region. Look at the typical terraced slopes of a canyon-like landscape. (Source: Unknown).

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ACTIVITY 8 Refer to the topographical map of Volksrust.

1. Which major landforms can you observe in block H6?

(4) 2. How does the slope of the landscape differ between the eastern and western parts of block H6?

2 x 2 = (4) 3. Give the highest and lowest points above sea level in block H6.

(2) 4. What is the main direction of flow of the rivers?

(1) 5. Is the pattern of stream flow perennial or non-perennial?

(1) 6. Comment on human activities taking place in this block (H6).

(3) Study figure 6.3 and the “guidelines to identify some landforms” carefully.

7. Draw individual simplified contour maps (± 7 cm x 7 cm) to show the following landforms: (a) Valley (b) Spur (c) Mesa (d) Saddle (e) Waterfall 5 x 3 = (15) [30]

LESSON 7: CROSS SECTIONS Cross sections are side views of the landscape and are a useful technique in mapwork.

They can be used for many purposes, for example o to gain a better visual image of the relief (shape) of the land, and o to check for visibility between two points.

Accurate cross sections A profile is drawn accurately according to the map scale (horizontal scale) and a given vertical scale.

Step-by-step guide: how to draw an accurate cross section 1.

Join the given points on the map with a line.

2.

On a piece of paper mark off all the points where the contour lines cross this line. Be as accurate as possible.

3.

Determine the height of these contour lines.

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4. Draw a graph – vertical & horizontal axis (graph paper is usually supplied).

5. Fill in the vertical scale as per instruction (e.g. 1 cm represents 20 m/40 m).

6. Transfer the position of the contour lines from the piece of paper to the horizontal axis, the first one at the vertical axis. The first and last points may lie between contour lines and the heights should be estimated.

7. Transfer the contour heights to their proper heights on the graph.

8. Join these heights, free hand, taking into account that crests of hills and valley floors show curves and are not straight lines between contour heights.

Example: From the contour map (figure 7.1), draw an accurate cross section from the Trig. Station to Z. The vertical scale is as follows: 1 cm represents 40 m.

Figure 7.1

A cross section from the Trig. Station to Z

It is VERY important to practice drawing cross sections over and over.

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Study Guide G09 ~ Social Sciences: Geography

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TIP: Read step 1, DO step 1; read step 2, DO step 2, etc.

(Make a few copies of the grid below for future use).

For practice, draw another cross section, from X to Z1.

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