Curriculum Shule Direct Tanzania Secondary School Form 1 Geography

Geography

MAP WORK
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Geography is the study of places and the relationship between people and their environment. Geographers explore both the physical properties of the Earth's surface and the human societies spread across it.In the context of dynamic and changing world, it is very crucial to study Geography so as to be able to achieve sustainable human development.

MAP WORK

Introduction
In this topic, you will learn about the concept of map work, components of a map, quantitative information on maps, and uses of maps. Also you will learn the difference between signs and symbols as well as measuring distance on the map with its conversion to the actual distance. Finally you will learn about directions and bearing of objects on maps. The chapter ends with summary, revision questions and references.
Objectives
By the end of this topic you should be able to define a map, list all the components of a map, define a scale, identify different ways used in representing scale, distinguish signs from symbols, measure the distance on the map and convert it to the actual ground distance by using scale, identify location of positions, find direction and bearing of objects on maps and in the environment, and describe different uses of maps.
The concept of a map
Definition of a map.
A map is a representation of an area of the Earth’s surface on a flat surface such as paper, wood, board, card, plastic, cloth or some other material.
The information given in a map is shown by conventional signs and symbols which are interpreted by the use of the key. A map shows important natural and man-made features. Some maps show distributions like rainfall, temperature, air pressure and population. On a map, lines of longitude and latitude are marked to show the position of different areas
Types of maps
There are different types of maps, which are generally classified according to the features they represent. Most of these maps are grouped into two major types namely
  1. Topographic maps
  2. Statistical or distribution maps
Topographic maps
These are maps that are used to show selected physical and human features of a given area. These maps show;
a.Location
The geographic location in a map may be shown using;
  1. compass bearing
  2. grid reference
  3. latitudes and longitudes
  4. political and administrative boundaries
  5. use of place names
b. Landscape
Some of the landscape features shown on a topographic map are mountains, hills, plains, lakes, rivers and shape of coastlines. Relief maps show the distribution of relief features such as hills, mountains, valleys and depressions
c. Man-made or artificial features
Some of the man-made or artificial features are roads, railways, cities, towns, dams and other structures built by man
Uses of topographic maps
  1. Topographic maps are useful for describing features of the Earth’s surface
  2. It is used to show the direction. People use maps to reach their destination
  3. Town planners use maps to plan the best use of land
  4. Road builders use maps to design new roads
  5. Farmers use maps to plan the best use of their farmlands
  6. It provides information on the nature and distribution of geographical phenomena e.g. settlement, population distribution, etc
Statistical or distribution maps
These maps show geographical phenomena as distribution of rainfall, temperature, pressure, vegetation, crops, minerals and many other phenomena. The commonly used statistical or distribution maps are Atlas maps. Atlas maps are usually drawn to scale. They represent a large area of the ground on a small space of paper. Maps of this nature are used to show various geographical aspects
  1. Population maps show the distribution of people and settlements e.g. towns and cities
  2. Vegetation maps show the distribution of vegetation, e.g. forests, bushes and grasslands
  3. Political maps show political administrative divisions e.g. countries, regions provinces and districts
  4. Climatic maps show information on elements of climate such as rainfall, temperature and winds
  5. Economic maps show the distribution of various human activities, for example farming, tourism, transport and mining
  6. Travel maps show the location of places and distribution of hotels, camping sites, historical sites and other interesting places
Characteristics of atlas maps
  1. Drawn with the use of scale
  2. Show countries, continents or even the world on a single sheet of paper or page
  3. Shows generalized information. Detailed information is not provided in such maps
  4. Atlas maps show the distribution of many features such as crops, minerals, roads, railways, towns, relief, vegetation and many others
  5. Atlas maps are simple and easy to read and interpret. They are easy to draw or to reproduce
Uses of statistical and distribution maps
  1. They are useful for describing the distribution of many features found on the Earth’s surface or showing certain selected features such as physical, political, historical or economic features
  2. They are useful for showing generalized information on large or small areas
The following are examples of the uses of statistical or distribution maps
  1. Physical maps show the arrangement or distribution of mountains, hills, highlands, lowlands, rivers etc
  2. Political maps show areas with their political and administrative boundaries
  3. Climatic maps show the distribution of temperatures, rainfall, pressure, winds, climatic regions, etc.
  4. Historical maps show the distribution of historical places e.g. historical sites
  5. Economic maps show the distribution of main crops, animals, industries, roads, mines, etc.
Components of a map
List all the components of a map
These are basic qualities that any map should have
  1. title, which tells what the map is about
  2. key which is used to interpret the signs and symbols found on a map
  3. margin which bounds the map
  4. an indication of the north direction
  5. scale for showing the relationship between the distance on the map and that on the ground
These components are presented in detail in the following section;
Title
The title shows the topic or subject matter of the map. It gives the name or caption of the area which the map represents or the features represented on that map. The name of the map enables the user to read and interpret the map easily
Key
A key is a list of symbols and signs with their meanings as used in the map. It appears in a box at one of the right bottom of the map. When these symbols and signs are given in the key, it becomes easier to interpret a map and get accurate information from it
North direction
This is a sign which shows the north direction. The sign gives an indication of the direction towards the north. It is from this direction that other cardinal points and positional locations of different areas on a map can be identified.
Margin
This is a frame which encloses the area covered by the map. The margin is useful in guiding and limits the map users
Scale
The scale of the map indicates the ratio between the map and ground distances. It enables the map readers to make an accurate estimation of distances on the map as they would be measured on the actual ground.
Map scales
A map scale is a ratio between the distance on the map and the actual distance on the Earth’s surface, Scale =distance on a map/distance on earths surface
Maps drawn to scale show the exact proportionality between the distance on the ground and that on the map.
Map scales are very important because they enable the map readers to calculate actual distances and areas on the ground based on the scales shown on maps. It is not possible to estimate the actual distance between two points on a map or a particular area on a map without the use of the scale. Though every map should have the scale, sketch maps are usually not drawn to scale. Sketch maps are rough sketches drawn on a flat surface to represent a particular area on the ground
Identify different ways used in representing scale.
Types of scales
Map scales are classified on two based on: (a) the way they are expressed; and (b) their size
Classification of scales based on the way they are expressed
Based on this category, map scales may be expressed in any of the following ways
  1. As a statement
  2. As a representative fraction
  3. As a linear scale
1. Statement scale
This is the map scale stated in words or it is a verbal scale. The scale may be stated as one centimeter represents ten kilometers or 1 centimeter to 10 kilometers or 1 cm to 10 km. It should be noted that in all statement scales map distances are stated in centimeters and ground distances in kilometers.
Characteristics of statement scales
  1. Expressed in word or verbal statements
  2. The scales bear specific units of measurement. Usually, the units representing map distances are smaller than the actual ground distances, e.g. 1 cm represents 5 kilometers
  3. The word ‘represent’ or ‘equivalent’ to is used when expressing statement scales. The distance on the map is taken as a representative of the distance on the ground
2. Representative fraction (RF) or Ratio scale
A representative fraction indicates ratio between the numbers of units on the map to the number of units on the ground. This is a type of scale which expresses the map distance as a fraction of the actual distance on the ground, for example, 1:10000 or 1/10000. This means that one unit on the map represents 10000 units on the ground
Characteristics of RF scales
  1. The scales are either expressed as a ratio or fraction and do not bear any units. The units may be deduced from the linear or statement scale shown on the map
  2. The top number (numerator) stands for the map distance and is always reduced to 1
  3. The bottom number (denominator) stands for the ground distance and is usually of more value than the numerator.
It is important to note that when assigning units of measurement to RF or ratio scales, both the numerator and the denominator should bear the same units, e.g. 1 cm: 100 cm. usually the units used in most scales are given in centimeters
Example, Given a map with an RF or ratio scale of 1/10000 or 1:100000, if a river on this particular map measures 5 cm; calculate the actual distance represented by the river in that map
Solution
Since 1 cm on a map represents 100000 cm on the ground, then 5 cm will represent 5×100,000 cm = 500,000 cm. Since 1 km = 100,000 cm. then, the actual ground distance is 500,000/100,000 = 5km , Thus, as RF it reads, 5 cm on a map represents 5 km on actual ground distance
3. Linear or graph or line scale
A linear scale or line scale or graph scale is a line showing the distance on the map that represents a given distance on the ground. It is expressed as a short or long line subdivided into smaller, equal units. The linear scale is commonly placed at the bottom of the map. There are two categories of linear scales: the short-line scale and the long-line scale.
A short line scale consists of a single, short line that represents the actual ground distance. To get the unit of measurement on the map, one has to measure the length of the line in centimeters.
<em>Fig .6.1 Short - line scale</em>
<em>Fig .6.1 Short - line scale</em>
A long line-scale consists of a long line that is sub-divided into several equal parts with two sections namely the primary section and the secondary section. Figure 6.2 shows sections of linear scale.
<em>Fig 6.2 Linear scale</em>
<em>Fig 6.2 Linear scale</em>
Characteristics of linear scales
  1. Scales are expressed graphically in the form of a line
  2. It shows the specific units of measurement
  3. It gives a direct measure of the distance on the ground represented by the corresponding distance on a map
  4. The scale has the advantage of remaining the same even after the map is reduced or enlarged
Classification of scales based on the sizes
Based on sizes, the scales are classified into three categories
  1. Small scales
  2. Medium scales
  3. Large scales
1. Small scale
A map drawn using a small scale is called a small-scale map. A small-scale map has the following characteristics;
  1. It represents a large area of the Earth’s surface on a piece of paper
  2. The features on a small scale map appear crowded and closer to each other than they really are. As a result, they are not seen clearly
  3. The map shows fewer details as it covers a large area on a piece of paper e.g. an atlas map of the world, Africa or Tanzania. It only gives a general picture of the area represented.
Examples of small scales are;
  1. 1:10,000,000 or 1 cm: 100 km
  2. 1:1,000,000 or 1 cm: 10 km
2. Medium scale
This is a scale ranging between a small scale and a large scale. Examples of medium scales are;
  1. 1:500,000 or 1 cm: 5 km
  2. 1:250,000 or 1 cm: 2.5 km
3. Large scale
A map drawn using a large scale is called a large-scale map. A large-scale map has the following characteristics;
  1. The map shows many details or features of a small area on a piece of paper, e.g. a map is drawn to represent a small area such as a town, a certain location or village etc. Therefore, more features can be represented on a large scale map
  2. The map appears large in size though it represents a small part of the Earth’s surface
  3. The features on the map are large in size, so they can be seen quite clearly
Examples of large scales are;
  1. 1:50,000 or 1cm: .0.5km
  2. 1:25,000 or 1cm: .0.25km
Selection of scales
Selection of a scale to use depends on the size of the area and the amount of details to be shown on a particular map. The smaller the scale, the larger the area of the land to be represented and the fewer details can be shown and vice versa. For example, a map of Tanzania will show few details than a small town map e.g. Morogoro
Conversion of scales
On most printed maps, the scale is given in more than one way. However, it is easy to convert a scale given in one way into another form.
(a). Conversion of statement scale into representative fraction (RF) scale
Example, One centimeter on map represents five kilometers. Convert this into RF scale
Solution, This means that 1 km =100000 cm Hence 5 km ×100000= 500000 cm, Therefore, RF= 1/500,000 or 1:500,000
(b) Conversion of RF scale into statement scale
Given a representative fraction (RF) scale of 1:500,000; convert this scale into a statement scale
Solution, If 100,000 cm = one kilometer Then, 500,000=half kilometer, Therefore, the statement scale for the given RF scale is one centimeter on map represents a half kilometer on actual ground
(c) Conversion of RF scale into linear scale
Consider an RF scale of 1:500000. Construct a linear scale to represent this scale
Solution, Consider an RF scale of 1:500000. Construct a linear scale to represent this scale;
Conversion of a linear scale into a statement scale Convert the linear scale below into a statement scale
Answer, One centimeter represents one kilometer
Distinguish signs from symbols.
Symbols and signs
The natural and artificial landscape features are represented on maps by means of symbols and signs. Symbols and signs are the alphabet or language of maps. As symbols and signs are important in giving information on a map they should have the following qualities. They should be;
  1. Easy to read
  2. Easy to understand
  3. Easy to interpret
  4. Correctly and clearly shown and presented on any map.
Symbols usually look like the features they represent (Figure 6.3 (a)) while signs do not look like the features they represent (Figure 6.3 (b)). Also, most of the symbols used in a map are pictorial while most signs are not
Symbols and signs are commonly shown at the key or reference or legend of the map. With the aid of a key, reference or legend we can read and interpret a map. Symbols that are used in maps usually look like the natural and artificial features they represent. Signs usually do not look like the features they represent. Also, most of the symbols are pictorial while most signs are not
The symbols and signs used on maps are used to improve the appearance and readability of the map. Various symbols are used to depict features such as buildings, mines, forests, water bodies, farmlands, etc
Features on maps can be represented using the colour of the actual feature. For example, vegetation is represented by green colour and water may be represented by blue colour. Likewise, features such as bridges, railways or airports are represented by small diagrams of bridges, railways or aeroplanes
<em>Fig 6.3 Features and their signs</em>
<em>Fig 6.3 Features and their signs</em>
Quantitative information on maps
Distance on the map and converted to the actual ground by using scale.
One of the many tasks that a map reader might encounter when reading maps is to take measurements. Measurements on maps involve;
  1. measurement of distances
  2. calculation of areas on maps
The conversion of map distances and areas into actual ground distances and areas requires the application of scales. A distance is a length between two specified points on a map.
Measurement of distances on maps
Distances on maps can either be straight or curved (bent). A straight or regular distance is one that has no bends or curves while a curved (or irregular) distance is the one with bends or curves. Figure 6.4 shows straight distance while figure 6.5 shows curved distance.
<em> Fig 6.4 Straight distance</em>
<em> Fig 6.4 Straight distance</em>
<em>Fig. 6.5 Curved distance</em>
<em>Fig. 6.5 Curved distance</em>
Tools for measuring distances
There are three main tools that can be used in measuring distances on maps. These are;
  1. a long, thin string or thread
  2. a piece of paper
  3. a pair of dividers.
Measurement of distance using a thread or string
A long, thin string such as sewing thread can be used to measure a stretch of many curves or bends. This is the commonest method used by geography students to estimate distances on maps. This method is also used to measure straight distances
Procedures
  • Identify the distance to be measured on the map (e.g. a river, road, railway line, etc.) and mark its two ends with a sharp pencil. Mark one end as A and another end as B
  • Figure 6.6 shows an example of a curved distance identified for measurement
<em>Fig. 6.6 Distance to be measured</em>
<em>Fig. 6.6 Distance to be measured</em>
  • Starting from one end of the string, trace the route (river, road, etc.) with a string to another end as shown in the figure 6.7 below
<em>Fig 6.7 Measuring the distance with a string</em>
<em>Fig 6.7 Measuring the distance with a string</em>
  • Mark the string with ink at point B
  • Using a ruler or linear scale, measure the length of the string between point A and B and estimate the actual distance on the ground using the scale of the map provided
Example, If the length of the section of the string between A and B is 20 cm and the scale of the map is one centimeter to one kilometer, then the length of the route on the ground is 20 km.
Measurement of distances using a piece of paper
A piece of paper can also be used to measure straight and irregular (curved, bent) distances
(a) Measuring straight distances
Procedures
  • Locate the distance to be measured on the map and mark its two ends as A and B using a sharp pencil
  • Take a piece of paper, fold it to form a straight edge and lay the edge along the line AB and mark the exact length of the line on the edge of the paper as shown in figure 6.8 below.
<em>Fig 6.8 A paperfolded to make a straight edge</em>
<em>Fig 6.8 A paperfolded to make a straight edge</em>
  • Transfer the paper to a linear scale (or ruler) as indicated in the figure below so that the left-hand mark (A) is on 0 (zero) as shown in figure 6.9
<em>Fig 6.9 A paper transferred to linear scale</em>
<em>Fig 6.9 A paper transferred to linear scale</em>
  • Use the provided scale to estimate the actual ground distance.
(b). Measuring irregular (curved) distances
Procedures..
  • Identify the length to be measured on the map. Use a sharp pencil to mark both ends A and B
  • Divide the route into sections which are more or less straight as shown in the figure 6.10 below
  • Lay the straight edge of the paper on the first straight section of the route. Mark with your pencil where the route bends (point 1)
<em>Fig. 6.11 Measuring the first section</em>
<em>Fig. 6.11 Measuring the first section</em>
  • Move the paper so that the edge now lies along the second section of the route. Make sure that the mark you made is still on the point where the route bends. Now make another mark with your pencil at the bend (point 2)
Fig 6.12 measuring the second section
Fig 6.12 measuring the second section
  • Continue moving the paper and marking the other distances between the points on the route
  • Remove the marked paper, and using a ruler, measure from where you started to the last mark on the paper. If this distance is 20 cm and the scale is 1 cm to 1 km, then the distance of the route between A and B is 20 km.
Measuring distances using a pair of dividers
(a). Measuring straight distances
Procedures of Measuring straight distances
  • Locate the distance to be measured on the map and mark its two ends using a pencil
  • Use a pair of dividers to measure the distance between the two points on the map
  • If the distance is longer than the length of the dividers even when fully stretched measure the distance in sections and then sum up the lengths of all sections to get the total length
  • Place the divider on the linear scale and read the distance. Then use the scale to convert the obtained map distance into the actual ground distance
(b) Measuring irregular (curved or bent) distances
In many occasions, a map reader may be required to measure the distance of a river, road or railway line which is not straight. There are two methods that can be used to measure curved distances on maps
  1. Division method
  2. Stepping method
(a) Division method
Procedures of Division method
  1. Divide the river, road, railway, etc. into many, short straight distances
  2. Open your dividers and measure all distances as shown in figure 6.13 below
  3. Add up the map lengths of all sections along the route
  4. Use the linear scale to get the actual ground length from the sum obtained in (iii) above. The length of the route is equal to the sum of all sections, divisions or short distances
Fig 6.13 division method
Fig 6.13 division method
Add up all the measurements, AB = 1 km; BC = 1 km; CD = 1 km; DE = 2 km; EF = 0.5 km; FG = 2 km; GH = 0.5km, HI= 1 km; IJ = 2 km = Total length = 10 km.
(b) Stepping method
Procedures of Stepping method
  • Open and set the pair of dividers to a known distance by using the linear scale e.g. quarter or half a kilometer as shown in figure 6.14 below
<em>Fig 6.14 Stepping method</em>
<em>Fig 6.14 Stepping method</em>
  • Follow the river, road or line by stepping along it using the set dividers
  • Add up the number of steps and multiply by quarter or half a kilometer (depending on the set length)
For example, suppose the number of steps when the divider is opened to a quarter kilometer wide is 20 and when it is a half kilometer is 10. Then, the length of the route is; 10 x ½ = 5 or 20 x ¼ =5kilometres.Note that if the distance of the last step is less than the set distance of the dividers, then Measure it separately and estimate its distance on the linear scale. Add up this distance to the total distance from the steps to get the full distance of the route (river, road or line)
Calculate areas of regular and irregular figures
The areas are to be calculated on maps can either be regular or irregular
Calculating areas of regular shapes
Features with regular shapes on maps are usually rectangular, triangular, square or circular. Finding the areas of such features is simple. Mathematical formulae are used to calculate their areas;
  1. Triangles = L x W, where L = length and W = width
  2. Squares =L2, where L = length of the side of a square
  3. Triangles = ½bh, where b = length of the base and h = length of the height. 4. Circle = πr2 or πD2/4, where r = radius, D = diameter and π = 3.14 or 22/7
Calculating areas of irregular shapes
<em>Fig. 6.15An irregular shape</em>
<em>Fig. 6.15An irregular shape</em>
There are three methods used to calculate areas of irregular shapes;
  1. division method
  2. tracing method
  3. grid square method
(a). Division method
n this method, the area to be measured is divided into rectangles or squares and triangles or into several strips of the same length and width. Then, the area of each resulting figure is calculated using mathematical formula and summed up to get the total area
1. Division of the area into rectangles, squares or triangles
  1. Divide the whole area into rectangles, squares or triangles
  2. Calculate the areas of the rectangles, squares and triangles using mathematical formulae
  3. Sum up individual areas to get the total area
Remember that the area should be in the same units as the map scale
Example The area in figure 6.16 is divided into three figures A, B and C. The area of the three resulting figures is calculated as follows
Rectangle A; area =L×W=10×5=50km2
Triangle B, Area = ½ bh = ½ x 6 x 4 = 12 km2
Triangle C, Area = ½ bh = ½ x 4 x 3 = 6 km2
Total area = A + B+ C= 50+12+6= 68 km2
2. Division of the area into strips
The stripping method involves dividing the area into strips and then calculating the area of each strip separately. The total area is obtained by summing up the areas of all rectangular strips
<em>Fig 6.17 Division of the area into strips</em>
<em>Fig 6.17 Division of the area into strips</em>
Procedures,
  1. Divide the area into uniform rectangular strips
  2. Calculate the area of each rectangular strip separately. Remember that the areas of the strips should be in the same units as the scale of the map
  3. Add up the area of each strip to get the total area. Area = sum of the areas of all individual strips, =1+2+3+4+5
(b) Tracing method
  1. Trace off the outline (boundary) of the figure to be measured onto a tracing paper (graph paper) or ordinary tracing paper and transfer the outline onto a squared paper.
  2. Tick and count all complete squares and sum up their areas. Remember that each full square measures 1 cm x 1 cm.
  3. Mark all incomplete squares with crosses
  4. Count all incomplete squares and divide the sum by 2 to get the number of complete squares
  5. Add up the squares in (iii) and (iv) to get the total number of squares covering the area of the figure to be estimated
  6. Using the scale provided, find the area of one square in order to obtain the actual area that would be covered on the ground. Note that the area that you calculate is the approximate area
<em>Fig 6.18 Counting the number of squares</em>
<em>Fig 6.18 Counting the number of squares</em>
According to the figure above, the number of complete squares is 28. The number of incomplete squares is 25. To get the complete squares, we divide 25 by 2, i.e., 25 ÷ 2 =12.5
Hence the total number of complete squares = 28 +12.5 = 40.5. This is the same as 40.5 cm2
Assume that the scale of the map is 1:50,000. Then, the area of 1cm by 1cm on the ground is 0.5 x 0.5 km = 0.25 km2
Therefore, the total actual ground area of the irregular shape is calculated thus: Area = 40.5 x 0.25 =10.125 km2
Remember that if you don’t have the tracing paper you can draw the squares straight on the map using the following procedures;
  1. Mark by a pencil the margin of area to be measured
  2. Using the grid reference lines as your guidelines, draw the squares with faint pencil lines across the area. If there is no grid lines make sure you draw right-angled squares across the figure
  3. Mark your full squares and half squares and follow the above tracing method procedures for calculating the area
Fig 6.19 summing up the square, number of full squares=100 number of half squares =48 total area =124 square km
Fig 6.19 summing up the square, number of full squares=100 number of half squares =48 total area =124 square km
(c) The grid square method
If the map provided has grid lines, the grid square method can be used to calculate the area on the map. The grid squares formed by the lines are used in this case. For example, in a topographical map of scale 1: 50,000 the distance between two successive grid lines is 2 cm. This length is equivalent to 1 km on the ground. Therefore, every grid square on a 1: 50,000 maps represent 1 km2 on the ground. Consider the diagram below.
<em>Fig 6.20 The grid square method</em>
<em>Fig 6.20 The grid square method</em>
Number of full grid squares = 18 Number of half grid squares = 19 Total area = 27.5 sq. km
The procedures for calculating the area of a feature on a map with grid squares are similar to those used in the tracing method discussed previous section in this chapter.
Identify location of positions.
Location of positions on maps
In map reading, position is a place where an object is situated on the Earth’s surface. The geographic position of a place may be shown by using;
  1. Place names
  2. Compass bearing
  3. Latitude and longitude
  4. Grid reference
  5. Political and administrative boundaries
1. Use of place names
Names of places on maps may be used to locate the position of an area or place. Names of places e.g. Morogoro, Tarime, Mbeya, etc are clearly marked and shown on maps.
2. Compass bearing
Many years ago it was discovered that a magnetized piece of iron or needle if hung or allowed to swing freely, it will always point to the same direction. This direction is called the North. It is from the North direction that we measure other directions, that is, East, West and South.
A compass is an instrument used to measure directions from the North. It consists of a free swinging, magnetized needle which points to the north and south magnetic poles.
<em>Fig. 6.21A compass</em>
<em>Fig. 6.21A compass</em>
The compass can be used to show directions in the following ways
(a) North direction
The North direction may be shown by using;
  • Geographic or True North
  • Magnetic North
  • Grid North
(1). Geographic or True North is the direction towards the North Pole from any place on the Earth’s surface. It is always indicated by the north arrow. When reading directions on maps we usually use the True North
ii.Magnetic North is the direction to which the compass needle points. The magnetic North is some distance from the True North and also varies from year to year in relation to the True North
iii. The Grid North is the direction towards the north in those maps drawn to grid system
Fig 6.22 magnetic declination as at january 1970, annual change 1<sup>0 </sup>
Fig 6.22 magnetic declination as at january 1970, annual change 1<sup>0 </sup>
(b). Compass directions
There are four major directions, bearings or cardinal points on maps with respect to a fixed point, be it true North or magnetic North. They are marked by 90o
Fig. 6.23 four copmass direction
Fig. 6.23 four copmass direction
The four cardinal points can further be sub-divided into eight points of 45o
eight compass directions
eight compass directions
fig 6.25 sixteen compass directions
fig 6.25 sixteen compass directions
(c) Bearings of a compass
Compass bearing shows the direction of a point with respect to another point measured clockwise from 0o to 360o. Bearing is expressed in degrees which are further subdivided into minutes and seconds.
<em>fig </em>6.26 bearings of compass
<em>fig </em>6.26 bearings of compass
Directions and bearings of objects on maps and in the environment
How to find the bearing of a place
The bearing of a place on a map can be found when the North is given. The North is usually an arrow sign pointing to the north
Example Find the bearing of point B from point A
Procedures of
  1. Join points B and A with a straight line
  2. At point A, draw a line parallel to the north-south line
  3. Using a protractor, measure the angle B from the north towards line BA as shown in figure 6.27 below
Fig 6.27 measuring B angle
Fig 6.27 measuring B angle
(d) Direction of a place
The direction of a place or point is its direction with respect to another point measured by using the points of the compass e.g. North, South, East and West
example Find the direction of point B from point A
Procedures,.
  1. Join points A and B with a straight line
  2. At point A, draw a line parallel to the north-south line or compass direction sign that is given on a map
  3. Draw a horizontal line at point A to get the East and West of the four points of the compass
  4. Find the direction of point B from A to the nearest point of the compass. The four, eight or sixteen points of a compass can be used
Fig 6.28 direction of point B from A
Fig 6.28 direction of point B from A
Wheni finding direction of a compass always use the true north which is given on the map
3. Latitudes and Longitudes
  1. Latitude is angular distance north and south of the equator
  2. Longitude is angular distance east and west of a fixed line known as the Greenwich Meridian. The line is zero longitudes and is known as the Prime Meridian
Latitudes and longitudes are measured in degrees which are further subdivided into minutes and seconds. Latitudes and longitudes are commonly used to locate positions of places in atlas maps
Locating the approximate position of a place on a map using latitude and longitude lines
Procedures;
  1. First, read the degrees of the latitude.
  2. Then read the degrees of the longitude
  3. Write the position of the place in degrees of latitude north or south and degrees of longitude east or west.
Example.
The approximate geographic positions of the following cities are as shown below; Dar es Salaam: 6o 48‘S, 39o12‘E Nairobi : 1o15‘S, 36o48‘E Havana : 23o0‘N, 83o32‘W, Large stretches of land on atlas maps can also be located by using lines of latitudes and longitudes.
Procedures
  1. First, read the degrees of the lines of latitudes bounding the area to be located
  2. Then read the lines of longitude bounding the area to be located
  3. Finally, write the position of the area in degrees of latitudes N or S and degrees of longitude E or W
Example
Tanzania lies between 1oS to 10o30‘S and 30oE to 40oE
Fig 6.29 Geographical location of Tanzania
Fig 6.29 Geographical location of Tanzania
4. Grid reference
A grid system is a pattern of horizontal and vertical lines forming squares of uniform sizes drawn on a map. Grid system is numbered East and North and is referred in terms of Easting and Northing
Fig 6.30. the grid system
Fig 6.30. the grid system
Grid lines are not lines of latitude and longitude but are drawn to a definite distance apart, which varies according to the scale of the map and unit of measurement used in a map. The reading in a grid system is referred to as grid reference and is given in a six-figure number.
Using grid reference
  1. The full grid reference is given in a six-figure number
  2. Easting – the eastward direction or reading are always given first
  3. Northing – the northward direction or reading follows after the Easting
Example; Eastings =351, nothings 421, full grid reference = 351421
(d) When a place or point falls on the main gridlines or bisected by the grid line, add 0 to each reading
Example; A place is bisected by: Easting =35 Northing = 40, The grid reference of a point will be 350400
e). When a place or point falls in the middle of a grid square, the grid square is subdivided into ten equal squares or tenths. The grid reading or direction is given to the nearest tenths. Consider the point, A, in the figure below)
Example; See point B in the figure below. The point lies between the following grid references easting = 35, northing = 42
Procedures.;
  1. Divide the grid square into tenth to locate the point or place. For example, point A in the figure below lies at Easting = 5 tenths Northing = 5 tenths
  2. Read the easting adding the 5 tenth digit = 565
  3. Read the nothing adding the 5 tenth digit =225
  4. Full grid reference of the point is 565225
Fig 6.31 the grid reference of point
Fig 6.31 the grid reference of point
5. Political and administrative boundaries
The location of a place may be shown by the administrative boundaries that separate that place from other places on a map. Most atlas maps have boundaries or frontiers which separate different areas. For example, on a map of Tanzania, the location of regions and districts are shown by using political boundaries.
Uses of maps
describe the uses of maps
Map orientation
The orientation of a map is the relationship between the direction on the map and the corresponding compass direction in reality. The word ―orient is derived from the Latin ‘oriens’ meaning East. In the past, many maps were drawn with the East at the top. Today, most maps are drawn with the North at the top of the map. However, several kinds of maps are often not oriented with the North at the top.
Uses of maps.
Maps are important tools for a geographer. They are the crucial means of reading and communicating information about the location and spatial characteristics of the natural world
Maps are not only important to geographers. They are used throughout the world by scientists, scholars, governments and the general public to meet environmental, economic, political and social needs. The following are some of the uses of maps
  1. Maps are important tools for geographers. They help geographers understand, in a visual way, important things about the surface of the earth. For example, maps help the geographers locate important features such as volcanoes; hilly and mountainous areas; dense forests; etc
  2. Maps are used to record and store information about the environment, the location of natural resources, capital assets and people. This is because the features change while map information does not change. As such, maps store information for future reference
  3. Maps allow us to convey information and findings that are difficult to express verbally. Thus, the maps make the studying and understanding of geography easier since they have pictorial characteristics
  4. A map shows the relationship between and among features, for example, a map clearly indicates the location of places, rivers, a network of roads, vegetation, etc
  5. Maps enable us to study the distribution of geographical phenomena such as water bodies, valleys, mountains, vegetation and other features
  6. Maps, especially those drawn to grid systems, give the location or position of a place or feature
  7. Maps can be used for estimating travel costs between two or more places. This may be done by estimating the distance to be covered (by using map scales) and then multiplying the distance by the cost per kilometer or mileage to obtain the total travelling costs
  8. Climate maps provide crucial information about the climates of different parts of the world and how these climates influence daily human activities.
Chapter summary
A map is a representation of an area of the Earth’s surface on a flat surface such as paper, wood, board, card, plastic, cloth or some other material
The two broad types of maps are topographic maps and statistical or distribution maps, Topographic maps are used to show location, landscape and cultural features
The components of a map include a key, scale, title, north direction, and margin
A map scale is a ratio between the distance on the map and the true distance on the Earth’s surface
Map scales are classified based on the way they are expressed; and their size
Based on the way maps are expressed, maps are classified as a statement, a representative fraction or a linear scale
Based on the size, maps are classified as large-, medium- and small-scale maps
Selection of the scale to use depends on the size of the area and the amount of details to be shown on a particular map
Symbols and signs should be easy to read, understand, interpret, and shown clearly and correctly represented on a map
The symbols and signs used on maps are used to improve the appearance and readability of the map
Measurements on maps involve (a) measurement of distances; and (b) calculation of areas on maps
Tools for measuring distances on maps include (i) a long, thin string or thread; (ii) a piece of paper; and (iii) a pair of dividers
There are three methods that are used to calculate areas of irregular shapes; (a) Division method; (b) tracing method; and (c) grid square method
The geographic position of a place may be shown by using
  1. Place names
  2. Compass bearing
  3. Latitude and longitude
  4. Grid reference
  5. Political and administrative boundaries
The north direction may be shown by using: (a) Geographic or True North; (b) Magnetic North; or (c) Grid North
Maps are the crucial means of reading and communicating information about the location and spatial characteristics of the world.
Revision questions
Question Time 6
1.(i) Select a set that indicate essentials of a map
  1. title, key, margin, scale and grid lines
  2. key, scale, north direction, margin and colour
  3. title, key, scale, margin and north direction
  4. key, scale, margin, title and bearing
ii.The direction to which a compass needle points is called
  1. True North
  2. Magnetic North
  3. Compass direction
  4. North Pole
iii.Which is the largest scale among the following?
  1. 1:25,000
  2. 1: 50,000
  3. 1: 20,000
  4. 1:10,000
iv.The grid reference of station X is 261582. Identify figures that represent the Easting and Northing
  1. 582 are Easting and 261 are Northing
  2. 582 are Northing and 261 are Easting
  3. 651 are Northing and 582 are Easting
  4. 261 are latitudes and 582 are longitudes
v.What helps a map reader to interpret different features on the map?
  1. Scale
  2. Orientation
  3. Key
  4. Map reading knowledge
vi. If the ground distance between two points is 13 km, what will be the map distance if the scale is 1 cm to 0.5 km?
  1. 13 cm
  2. 26 km
  3. 6.5 cm
  4. 26 cm
viii. All of these ways may be used to show the location of a place on a map. Which is the odd one out?
  1. Latitude and longitude lines
  2. Grid references
  3. Scales
  4. Place names
ix. The list below contains landscape features that may be shown on a topographic map. Which one is not one of the landscape features?
  1. Hills
  2. Valleys
  3. Lakes
  4. Forests
x.Distribution maps may show all of the following except
  1. Rainfall
  2. Vegetation
  3. Climate
  4. Escarpments
xi. To which of the following groups of people are topographic maps not helpful?
  1. Road builders
  2. Surveyors
  3. Travellers
  4. None of the above
xiii. Which of the following features is not necessarily shown on a climatic map?
  1. Winds
  2. Pressure
  3. Rainfall
  4. Weather station
xiv Which of the following is not a characteristic of Atlas maps?
  1. They show the distribution of many features
  2. Atlas maps are drawn to scale
  3. They show particular information of interest to map makers only
  4. The maps are easy to read and interpret
xv. Consider a map with a scale of 1:100000. If a river on this particular map measures 5 cm, what is the actual ground length of the river in kilometers?
  1. 1000km
  2. 1 km
  3. 5 km
  4. 5000 km
2.Against each of the following statements, write TRUE if the statement is correct or FALSE if the statement is wrong
  1. All maps are drawn to scale
  2. On a topographic map, lines of longitude and latitude are marked to show altitudes of different areas on a map
  3. Every map shows important natural features only
  4. One of the various means of locating the position of a place on a map is by use of place names
  5. Some cultural features or artificial features on a map include roads, railways, cities, towns and forests
  6. Vegetation maps show the distribution of vegetation, e.g. forests, bushes, grasslands and thickets
  7. Historical maps show the arrangement or distribution of mountains, hills, highlands, lowlands and rivers
  8. A title is a list of symbols and signs with their meanings as used in the map
  9. A scale is a ratio between the distance on the map and the true distance on the Earth’s surface
  10. True North is the same as Magnetic North
3. Fill in the blanks in each of the following questions
  1. ____maps show selected physical and human features of a given area
  2. ____of the map shows the topic or subject matter of the map
  3. A frame which encloses the area covered by the map is called . (iv) is a type of scale expressed in words or verbally
  4. A river with a length of 5 cm on a map whose scale is 1:500000 will cover a distance of km on land
  5. ____shows the direction of a point with respect to another point measured clockwise from 0o to 360o
  6. The angular distance north or south of the equator which can also be used to show the location of a place on a map is called____
  7. The Greek word, oriens, means____
  8. In a grid reference which reads 361559, the numbers which represent easting are___
4. Explain the importance of each of the following essentials of a map
  1. Title
  2. Key
  3. Margin
  4. Scale
  5. North direction
5.brify
  1. List two major types of maps
  2. Mention any 3 uses of topographic maps
  3. Mention five ways in which the geographic location in a map may be shown
6. Explain the procedures for calculating the area of an irregular figure on a map by the division method which involves division of the figure into strips
7. Explain the following terms
  1. True North
  2. Magnetic North
  3. Grid North
8. Differentiate between symbols and signs
9. Mention any five cultural features that can be shown on a map
10. Enumerate any 3 properties of linear scales
11. State the properties of each of the following types of maps:
  1. Small scale map
  2. Large scale map
12. Explain in sequential the procedures for finding the bearing of point B from point A on a map
13. Outline any five uses of maps
14. Explain how the grid square method can be used to find the area of a given region on a map
references
  1. Chege, J. and Kibuuka, P. (2009). Map Reading and Photograph Interpretation. Oxford University Press. Nairobi
  2. Durra, S.E. (1989). Map Reading for Secondary Level. Tanzania Publishing House (TPH). Dar es Salaam
  3. Kamili, Z. (2016). Practical Geography Alive. Kamili Books and General Supplies. Dar es Salaam
  4. MacMaster,D.N.(1995).MapReading forEastAfrica.CambridgeUniversityPress.London
  5. Mzezele, S. and Kibuuka, P. (2015). Geography In Focus Form One. Oxford University Press Ltd. Da es Salaam
  6. Prichard, J.P. (1994). Practical Geography for Africa. Longhorn Publishers. London.
  7. Tanzania Instituteof Education(1986). GeographyforSecondarySchools, BookOne.NPC–(KIUTA).DaresSalaam.
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