The document discusses map reading and interpretation. It covers relief representation using contour lines on maps, drainage patterns, and human-made features. Students will learn about contour lines, how they represent 3D relief on 2D maps, and how to draw contour lines and cross sections. Contour lines connect points of equal elevation and come in three types: index lines with elevation numbers every fifth line, intermediate lines between the index lines, and supplementary dashed lines for half-interval changes in elevation.
3. Learning outcomes
• At the end of this unit, students will be able to:
Review the definition and properties of contour
lines
Realize how contour lines are used to represent
relief features on maps and types of contour
• Acquire the skills of drawing contour lines,
cross sections.
4. Introduction
Map
What is map?
• A map is a drawing or graphical representation of the
land, as viewed from the air from a great height. This
perspective is called the "aerial view" or "map view." As
land bound creatures who usually walk across the land
rather than fly above it, the map view is not the natural
perspective for humans; rather, we have more of a "side
view" of the land surface.
8. Relief representation on contour map
• Relief
The term relief refers to the way that the earth’s
surface arranged.
The relief feature of the earth is 3D. These are:
length
Breadth
And height
9. Cont’d
• These three dimensional features are
represented on two dimensional ,maps.
• Traditionally reliefs of earth surface showed
by:
Hachuring
Hill shading
Layer tinting
Form lines
10. Current
• These days they are replaced by contour lines.
• Contour lines
• Contour lines are also known as isohypes.
• They are imaginary lines which are drawn on
maps connecting places having the same
height above or below sea level.
11. Contour lines
• The term contour line is most commonly used
in cartography. However, the term isobath for
underwater depths on bathymetric maps and
isohypse for elevations are also used.
• The process of drawing contours on a map is
called isopletion.
13. Types of contour
• Three are three types of contour lines shown
on standard topographic maps. These are:
I. Index : starting at a zero elevation or mean
sea level, every fifth contour line is a heavier
line.
Each index contour line is numbered at some
points. This number is the elevation of that line.
14. Cont’d
II. Intermediate : the contour line falling
between the index contour lines are called
intermediate contour lines.
These lines are finer and do not have elevation
given.
There are four intermediate contour lines
between index contour lines.
15. Cont’d
III. Supplementary: these contour lines resemble
dashes.
They show changes elevation of at least one half
the contour interval.