Area and grid references
FIGURE3 Working out a six-ýgure grid reference
A 1-kilometre-square grid is overprinted on a topographic map. These grid lines are numbered with two-digit numbers in the map’s margins. Lines that run up and down the map (north–south) are called ‘eastings’. The numbers increase as you move to the east. Lines that run horizontally across the map (east–west) are called ‘northings’. The numbers increase as you move north. In a grid reference, the eastings are given ýrst, and then the northings. Four-ýgure grid references tell you the grid square in which to ýnd a feature. The letters AR are placed in front of a four-ýgure reference to show the area reference. For example, AR8513 contains the town of Kymbalee (see FIGURE3 ). Six-ýgure grid references pinpoint an exact point in the grid square. The third and sixth ýgures represent one-tenth of the distance between the two grid numbers. These divisions are not written on the map,
012345 67 89 0 14
9
8
7
6
5
4
3
2
1
13
0
85
86
so they must be estimated. The letters GR are used in front of a six-ýgure grid reference. No spaces are used between the digits in four- or six-ýgure references; for example, Kymbalee’s grid reference is GR854132. 8.6.3 Letmedo it Complete the following activity to practise this skill. 8.6 SkillBuilder activity Answer these questions using the FIGURE1 aerial photograph and FIGURE2 topographic map extract of Mount Gambier. Use the checklist provided to make sure you complete all aspects of the task. 1. Examine FIGURE1 . From which direction was this photograph of the crater lakes taken? 2. Examine FIGURE2 . Look at the contour lines to the south of Blue Lake. Is the land þat or steep? How can you tell? 3. Sketch the special symbols used in the legend showing that the crater lakes:
a. form a depression b. have steep sides. 4. Give the main features found in the following area references.
a. AR8010 b. AR8013 5. Give area references for the following features. a. Valley Lake b. The trotting track 6. Find the following features.
a. GR858087 b. GR816077 c. GR807128 d. GR812123
Jacaranda Humanities Alive 7 Victorian Curriculum Third Edition
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