1 : 5,000 1cm to 100m

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1 4.1.1 Scales and Converting Scales In Hong Kong maps, there are 2 types of scales: 1. 1:5000 (Black and white with no color) 2. 1:20000 (With color) If there is no unit in a representative fraction scale, then the unit of the two numbers MUST be the same. (I.e. 1:5000 = 1cm:5000cm, 1:20000=1cm:20000cm) Usually in a contour map, the height of the contour lines are shown in metres (m). Therefore, to convert back into metre, you should: Measured Length of the Map (In cm) X Scale Denominator 100 = Actual Length in Reality (In m) (E.g. The measured length from the map is 3cm and the scale is 1: By using the convertion length formula: 3.5 x = 700m) More Scales of Maps 1 : 5,000 1cm to 100m Representative Fraction (R.F.) Unit is the same 1 1:5000 = :x = x Linear Scale Measure the length of the scale and convert it into word scale Each interval of scale may not be exactly 1cm Word Scale Unit may not be the same but directly shown Larger-scale Map Smaller coverage (zoom out), larger ratio value (i.e. 1:5000) Smaller-scale Map Larger coverage (zoom in), smaller ratio value (i.e. 1:20000) It is a comparative concept (Both maps exist to compare to have larger/smaller scale)

2 4.1.2 Contour Map and it s Features What is a contour map? Contour map is a map that shows contour lines and height of geographical features Elements in a Contour Map Contour Lines A line joining places of the same height Vertical Difference Difference between in height between two adjacent contour lines (Height) Fathom Line A line joining places with the same depth below sea level One fathom is m (Around 1.83m) Looking at horizontal distance: Use ruler to measure the length on the map in cm Use the convertion formula shown in to express the actual length in reality

3 4.1.3 Calculation of Gradient and Exaggerations Methods for calculating gradient: tan θ (Where θ is an angle) Rise Run V ertical Distance (VD/HD) Horizontal Distance Expression of Gradient (Presentation): 1:X = 1 X 1:X (In ratio form) Getting Vertical Distance and Horizontal Distance from a map: Vertical Distance (Rise) = Height Height of Higher Point - Height of Lower Point Horizontal Distance (Run) = Length Distance between two points Vertical Distance: Height of B - Height of A = = 100m Horizontal Distance: Measurement on the map using ruler: 4.2cm In metre (Using convertion formula): 4.2 x = 210m Scale: 1:5000 Gradient: Vertical / Horizontal =100/210 =1 : 2.1

4 4.1.4 Drawing Cross Section of a Contour Map Steps for drawing a cross section of a contour map 1. Write the title a. e.g. Cross Section along/of XY 2. Label of X-axis a. X on the left (origin) and Y on the right 3. Label of Y-axis a. Unit (Height - m) b. Determine the vertical scale (Sometimes, the question will provide the vertical scale) i. If the scale is 1:5000, then in your graph, your vertical scale should be 1cm: = 50m (1cm = 50m in your vertical y-axis) ii. If the scale is 1:20000, then in your graph, your vertical scale should be 1cm: = 200m (1cm = 200m in your vertical y-axis) c. Each interval marking (E.g. 100m, 200m, 300m, 400m..) d. The last marking should be the highest/second highest level of the contour 4. Draw the hill shape correspondingly according to the map a. Mark the corresponding contour points on the graph paper b. Mark points with the corresponding height on Y-axis c. Connect the marked points by using a curve d. Erase on unnecessary items Reminders: In the highest contour, if it does not show the highest point height, then you should draw above the height of that contour but do not exceed the height of the next contour Points must be connected with each other If the question requires to draw distance AB, then your showing must be from A (left) to B (right) Use ruler and a pencil for drawing cross section graphs

Example Demonstration Scale 1:5000 Draw the cross section of AB (Given vertical scale is 1:5000) (4 marks) According to the above steps: 1. Title: Cross Section of AB 2. Label of X-axis (A and B) 3.

5 Example Demonstration Scale 1:5000 Draw the cross section of AB (Given vertical scale is 1:5000) (4 marks) According to the above steps: 1. Title: Cross Section of AB 2. Label of X-axis (A and B) 3. Label of Y-axis a. Unit (Height - m) b. Vertical Scale = 1:5000 = 1 cm to 50m c. Each interval marking (0m, 50m, 100m, 150m, 200m, 250m, 300m, 350m, 400m) 4. Draw the hill shape Title (0.5 mark) Vertical Scale (1 mark) Unit (Height (m)) (0.5 mark) Vertical Scale (1cm to 50m) (0.5 mark) Horizontal Scale (0.5 mark) Distance of AB =4cm Correct label of AB Shape of the figure (2 marks) Marking the correct height of the points Connection of the points Total: 4 marks / 4 marks

4.1.5 Vertical Exaggeration Vertical Exaggeration The number of times that the scale of a cross section is greater than that of the horizontal scale It shows the ratio of the height of the cross

6 4.1.5 Vertical Exaggeration Vertical Exaggeration The number of times that the scale of a cross section is greater than that of the horizontal scale It shows the ratio of the height of the cross section to actual height of the relief feature Formula: V ertical Scale Horizontal Scale Vertical Scale Vertical Scale on the cross section Length of each interval on the cross section (I.e. 1:5000) Horizontal Scale The Scale provided from the map Directly copy from the map (I.e. 1:20000) If the vertical scale is 1:5000 and horizontal scale is 1:20000, what is the vertical 1:5000 1:20000 = = 1 exaggeration? = 4 Therefore, the vertical exaggeration is 4. (No need unit) Intervisibility Whether two places can be mutually seen Convex slope is usually has no intervisibility but concave slope usually has intervisibility Determining Method: Draw a straight line between the two points and see whether they are visible to each other P and Q are visible to each other Q and R are visible to each other P and R are NOT visible to each other R and S are NOT visible to each other

7 4.1.7 Concave and Convex Slope Concave Slope Convex Slope Upper section is comparatively steeper than the lower section Contour lines at upper section are closely packed Lower section is comparatively steeper than the upper section Contour lines at lower section are closely packed A slope that curves inwards A slope that bulges outwards

4.1.8 Conventional Signs and it s Features Conventional Height of a mountain (1:5000) Trigonometric Station With a number beside representing the height of that place

8 4.1.8 Conventional Signs and it s Features Conventional Height of a mountain (1:5000) Trigonometric Station With a number beside representing the height of that place (Trigonometric station) Locate at the peak of the mountain Spot Height Show the highest point of a place With a number beside representing the height Application of Conventional Height

overlapped Ridge Narrow and long part formed at the highest part

9 4.1.9 More about Geographical Features Cliff Vertical Slope A wall-like slope that develop sharply downwards Contour lines are overlapped Ridge Narrow and long part formed at the highest part of a mountain range Saddle Concave part between two mountain peaks

10 Spur The part that bulges outwards Found between valleys Shape like the inverted letter V Valley Narrow low-lying area between spurs In V-shape Can be found with valley together Valley Spur Higher Contour Lines Lower Contour Lines V-shaped Dry Rocky Little Vegetation U-shaped Wet

Exercises for Map Reading (Data-based Question) (Scale = 1:20000) (Note: C is a point pointing the trigonometric station 751m on the map) (a) Draw the cross section of AB with a vertical scale of 1cm

11 Exercises for Map Reading (Data-based Question) (Scale = 1:20000) (Note: C is a point pointing the trigonometric station 751m on the map) (a) Draw the cross section of AB with a vertical scale of 1cm to 100m on a graph paper. (4 marks) (b) Referring to (a), find the vertical exaggeration of AB. (2 marks) (c) Find the gradient of BC. (2 marks) (d) What is the geographical feature shown in D? Explain with one characteristic of feature D. (2 marks) (e) What is the geographical feature shown in E? (1 mark) (f) Is feature F and concave slope or convex slope? Explain with reasons. (2 marks) (g) What conventional sign was shown in G? (1 mark) (h) What is the difference between conventional feature C and conventional feature H? Provide one example of difference. (2 marks)

Shoe Box Activity Constructing a Topographic Map

Shoe Box Activity Constructing a Topographic Map Background Information All maps are models of some feature of the real world. The kind of map oen used by scientists is called a contour or topographic