Learning to use a topographic map

1. Basic cartography activities IES Concepción Arenal

2. What is a map? A map shows a scaled representation of any real-world location or object on a two-dimensional surface. A map must show the scale to which it was made. Scale is the relationship between distance on the map and distance on the ground. A map scale is usually given as a fraction or a ratio, for example 1:25,000. This means that one unit of measurement on the map represents 25, 000 units of the same units on the ground. Classification of maps according to scale: Small-scale maps Small-scale maps cover a large area and have fewer details than large-scale maps. (The larger the denominator is, the smaller the scale). Small-scale maps are used to depict large areas. Large-scale maps Large-scale maps cover a small area in great detail. Scales between 1:5,000 and 1:20,000 are used in street maps. Scales between 1:20,000 and 1:50,000 are used in maps depicting small regions.

3. What is a topographic map ? A topographic map represents the three-dimensional configuration of the land by using contour lines and symbols. It shows the location and shape of mountains, valleys, plains, streams, wooded areas, roads, buildings, and many other features. A contour line joins points of equal elevation above a given level. In Spain, the reference level is the sea level in Alicante. The difference in elevation between two consecutive contour lines is called contour interval . Contour lines are usually drawn at 10 metre intervals on a 1:25,000 scale map. Every fifth contour line is printed as a bold line and labelled with heights. The contour line bounding an elevation may become indefinitely small and ultimately reduce itself to a point, which is a summit. STUDYING THE NATIONAL TOPOGRAPHIC MAP

5. A topographic map also shows the steepness of the land. The closer the contour lines are the steeper the land is. A description of some of the symbols used on topographic maps : Where a contour line crosses a stream, a river or a valley , the contour lines are bent sharply, forming a “V”. The point of the “V” points uphill or upstream. Ridges are shown by contour lines that bend downhill. A mountain pass is usually depicted with a “bridge like” symbol. A map legend is a key to all the symbols used on a map.

6. Contour lines (or isohypses) are isolines showing equal elevation

7. Escala 1:25.000 Contour lines (or isohypses) are isolines showing equal elevation. To determine differences in elevation between two points, the contour interval, or distance in altitude between two adjacent contour lines, must be known, and this is given at the bottom of the map

8. The rule of O's : closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area. Spacing of contours : close contours indicate a steep slope; distant contours a shallow slope. Two or more contour lines merging indicates a cliff.

9. stream The rule of V's : sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of erosion .

10. Ridges are shown by contour lines that bend downhill. A mountain pass is usually depicted with a “bridge like” symbol. Ridget Mountain pass

12. Activity 2: Use an arrow to match each drawing on the left with its topographic representation.

13. Draw the symbols used on maps and identify them on the topographic map. Activity 3:

14. Use the drawings and pictures to practise what you have studied and answer the following questions. Which image shows the steepest slope? Which one shows a valley? Which one shows a hill? Which one shows a beach? Pay attention to the distance between the contour lines in the four images and say which one represents the highest elevation and which one represents the lowest elevation. Activity 4:

15. Activity 4: Fig. 1 Fig. 3 Fig. 2 Fig. 4

16. http://www.ign.es/iberpix/visoriberpix/visorign.html Identify the symbols in the map legend of the topographic map and draw them on your copy using the right colours. For example a road, river, lighthouse...etc. Activity 4: