Contours and Representation of Relief GeoSkills

Contours and Representation of Relief
Relief is the difference in elevation between the points of a high and low elevation over the land surface.
The relief features of a land surface are shown on a map by means of various techniques including contour lines.
Contours represent the elevation of places above a datum level, at regular intervals.
Different relief or topographical features such as lowlands, highlands, valleys, plains, and so on are shown on a map using contour lines.
Contours show the shape and direction of the slope of the earth’s surface of a particular region.
Representation of Relief
The following steps may be followed to draw cross-sections of the relief features from the given contours:
1. Draw a straight line cutting across the contours on the map and mark it as AB.
2. Mark the position and value of every contour that cuts the line AB.
3. Draw another line parallel to the AB line. Mark it A’B’. This is going to be the baseline for the cross-section.
4. Choose a suitable vertical scale, e.g. ½ cm =100 meters, to draw horizontal lines parallel to each other, along the A’B’.
The number of such lines should be equal to or more than the total contour lines.
Mark the appropriate values corresponding to the contour values along the horizontal line of the cross-section.
The numbering may be started with the lowest value represented by the contours.
5. Draw vertical lines perpendicular to the A’B’.
6. Smoothly join all the points marked on different lines at the cross-section base.
Shade the area ….
This is the cross-section of the given contour
Now the slope of the area represented in the cross-section can easily be identified (measured)