MAP READING AND
INTERPRETATION
Introduction
In the preceding lectures, you learnt about the extent to which your land can be developed to raise the standard of living of your society.
Introduction
In the preceding lectures, you learnt about the extent to which your land can be developed to raise the standard of living of your society.
Furthermore, you have been exposed to methods of measuring, recording
and interpreting phenomena as geographers. In this last lecture, you will be
further enlightened about topographical map interpretation
What is
topography?
The word
topography is derived from a Greek word Greek, from topographein to
describe a place, from topos place + graphein to write.
It is a term used
to describe all physical features of a given area.
Topographic maps
are small-scale drawings of part of the earth’s surface to show location,
landscape and cultural features.
It is important to
represent parts of the landscape in order to facilitate easy representation and
interpretation of features.
Learning objectives
At the
end of this lecture, you will be able to:
i.
Explain the common types of maps in relation to
their characteristics;
ii.
Calculate areas from maps using a variety of
methods;
iii.
Calculate the bearing of a place through use of
magnetic compass;
iv.
Relate features on the map to those found on
actual piece of land i.e. use of large-scale maps;
v.
Discuss the advantages and disadvantages of
topographical maps compared to photographs;
vi.
Draw a relief section and calculate gradient
and vertical exaggeration.
Maps
What is a map?
A map is a portion or part of the features of the earth’s surface drawn
to scale on a plane surface such as paper, card, plastic, cloth or some other
material (Dura, 1990:1).
The information given on a map sheet includes:
a)
the title of the map,
b)
the scale of the map,
c)
the indication of the North direction,
d)
the key or legend,
e)
the boundaries and,
f)
The latitudes and longitudes or grid lines.
Types of maps
There are a number of maps. However, most of the maps are grouped into two main
types –
a) Topographic maps and
b) Statistical or distribution maps (covered in lecture eleven).
Here,
our focus is on topographic maps.
Topographic Maps
a)
These are small-scale
maps, which Show both natural and man-made features.
b)
To make these maps aeroplanes
(aircraft) are used to take pictures for an area for the first survey.
c)
Later, only certain
points on land need to be measured and surveyed are considered.
d)
When all the necessary
data has been compiled it is then used to print and produce maps.
The relationship between the
earth’s surface and maps
I.
The actual surface of
the land is rarely smooth.
II.
Nevertheless, this is
represented on a flat surface.
III.
The map represent
surface relief features on flat paper but
IV.
The mapmaker cannot show
all these details since many maps are selective.
V.
More often a mapmaker
summarises information about the landscapes represented.
Reflecting from this situation,
Maps are not true, detailed copies of portions of the earth’s surface
(McMaster, 1978:5).
a.
Any topographical map is
much smaller in size than the actual tract of country it represents.
b.
In order to be more
realistic the mapmaker must reduce all the distances and areas on the ground in
the same proportions.
c.
This constant
relationship of lengths on the ground to the shorter areas on the map is the
scale of the map.
Statistical or Distribution maps
i.
The statistical or
distribution maps are the type of maps which have been made with the help of
exact statistics.
ii.
These maps show such
things as distribution of rainfall, temperature, pressure, vegetation, crops,
minerals and many other things.
iii.
The commonly used
Statistical or Distribution maps are the Atlas maps.
iv.
Atlas maps are maps
drawn on small scales.
v.
They show whole
countries, continents or even the world on a single sheet of paper or page.
