8. Area To calculate the area of a rectangular region:
1. Count the number of full grid squares across the top of the map. 2. Count the number of full grid squares up the side of the map. 3. Multiply the two figures. That is the area in square kilometres. In Fig. 20, the area of the whole map is 4 x 4 grid squares = 16 km2
. 37 38 39 00 99
98 V 97 37 38 Fig. 20 OS map of Dungarvan 9. Cross sections A B
A cross section is a side view of the landscape. It also shows whether one place can be seen from another (inter- visible) or if there is a mountain in between. To draw a cross section, you will need graph paper, a sharp pencil and a strip of paper. 1. Place the edge of the strip of paper along the line of the section to be drawn (A–B).
2. Mark the beginning and end of the section. If contours are tightly spaced, mark every 50 m.
Fig. 21 Cross section 222
3. Mark all the contours on the edge of the paper, noting the heights of each point.
39 97
To calculate the area of an irregularly-shaped region:
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(e.g. forest park, a lake, mountain range): 1. Count and place a tick in each complete grid square within the region.
2. Any square more than half covered by the region you are looking at is counted as one full square.
99
3. Add the two together. That is the approximate area in square kilometres.
The area of map covered by land on the Ventry map is 8 km2
. 98 MAP SKILLS EXERCISE
What area of the map in Fig. 20 is covered by the sea?