Lab: Contour Mapping
Name_______________________________
Purpose: To be able to understand the basics of topographic map reading and uses.
Introduction
Elevation is the vertical height that we feel as we climb a
mountain, descend into a deep canyon or the “ups and
downs” the sidewalk does while walking home from school.
Topographic maps are maps that help explain the elevation
of geological features (often called topography) such as
mountains, valleys, etc. that cannot be drawn on a flat,
two-dimensional map. Topographic maps are used in many
professions and occupational fields; construction, geology, military, city planning, environmental scientists
are just a few. These maps use lines called contours to show the change in elevation. Reading a contour
map follows a few simple rules that apply to all types of maps.
In order to successfully read a topographic map, you need to visualize the landscape as represented by the
map. This is not difficult once the basic concepts are understood.
Each contour line on a topographic map represents the ground’s
elevation, or vertical distance above a reference point such as sea level.
A contour line is level with the earth's surface; all points along any
one contour line are the same elevation.
The difference in elevation between two contour lines is called the
contour interval. This is typically given in the map legend. It
represents the vertical distance you would need to climb or descend
from one contour elevation to the next.
The distance between contour lines, on the other hand, is determined
by the steepness of the landscape and can vary greatly on a map. On
flat ground, two 20-foot contour lines can be far apart. On a steep cliff two 20-foot contours might be
directly above and below each other. In each case the elevation between the contour lines would still be
twenty feet.
One of the easiest landscapes to visualize on a topographic map is an isolated hill. If this hill is almost
circular, the map will show it as a group of contour lines that are circles, called enclosed contour lines
(Figure E-1). If two people start in opposite directions on the same contour line, beginning at point A,
they will eventually meet face to face. If these same two people start out in opposite directions on
different contours 20 feet apart, points A and B, when they pass each other their vertical distance would
remain 20 feet.
Lab: Contour Mapping
Name_______________________________
1. Study the topographic map in Fig. 1 and complete the rules of contour maps. For each rule, the section
of the map illustrating the rule has been lettered.
Fig. 1: A topographic contour map.
Lab: Contour Mapping
Name_______________________________
1. USING THE WRITING & TOPOGRAPHIC MAP PROVIDED, ANSWER THE QUESTIONS
(Circle or fill in the blank)
a. Contours show the ____________________________________________.
b. The difference of elevation between two contour lines is called a _______________________________.
c. On a topographic map, the top of a mountain looks like a ______________. Mark it with an “X”.
d. On the map, if the dotted line was blue it would represent a (river / road).
e. Downstream means (up / down) the mountain.
f. Contours point or make a V shape in the (upstream / downstream) direction [ A ].
g. Closely grouped contours indicate (steep / gradual) slopes [ B ].
h. Widely spaced contours indicate (steep / gradual) slopes [ C ].
i. Hiking over the top of a hill, you will cross the (same / different) contours on the opposite side of the hill [D]
j. Depressions are enclosed by
on the (uphill / downhill) side of the contour [ E ].
k. Contours (can / cannot) touch or cross.
l. Contours (can / cannot) split.
m. Closed contour lines indicate a
or a
[ F ].
n.
ELEVATION – Measurement of height, were “zero” (0) is sea-level. This is also known as local
relief. (example: 3500 km on map means 3500 km ABOVE sea-level)
RELIEF – Measurement of hieght, were the ending point is subtracted from the beginning point.
(example: You want to climb a mountian. The map shows the bottom (base) of the
mountian at an elevation of 1000 km and the top (peak) of the mountian at 3200 km.
The total relief of the mountian is 2200km [3200km – 1000km = 2200km]).
m. The map has a contour interval of
n. The elevation at point A is
o.
Is the slope at point B steep or gentle?
p. Is the slope at point C steep or gentle?
q. The maximum elevation on the map is
r. The minimum elevation on the map is
s. This map has a total relief of
t. The local relief at point C is
Lab: Contour Mapping
Name_______________________________
Fig. 2: The results of a topographic survey.
2. Plotted on the map in Fig. 2 are the results of a topographic survey. Each point is a position where the elevation
has been determined. The points are labeled with their height in meters. Dashed lines represent streams or rivers
(note: contour lines do not cross rivers or streams). Use these data points to construct a topographic map of the area.
a. Determine the maximum and minimum elevations in the map area. Enter your results below.
Minimum:
Maximum:
b. Using a contour interval of 10 m, determine the contour lines necessary to accommodate the maximum and
minimum elevations (rounding off the numbers makes this easier). Enter your results below (note that there
may not be contour lines to fill all the blanks).
c. Start drawing your contours in the southwest corner of the map. Use the rules of contours to draw your contour
lines correctly. Make your map as realistic as possible. After drawing two contour lines completely across your
map, have Mr. Cottrell check your work before you proceed further.
Blue Lake
Elevation: 600
Figure 2