Name: _____________________________________ Period:_______
UNIT 2-Topic 2
Topographic Maps
VOCABULARY
1. Field
2. Isolines
3. Gradient
4. Contour Lines
5. Topographic Maps
6. Contour Interval
7. Index Contours
8. Benchmark
9. Depression Contour Lines
10. Map Scale
Focus Questions:
1. How do we interpret contour maps?
2. How do we calculate gradient? What does gradient tell
us?
3. How do we construct a topographic profile?
A. Contour Maps:
FOCUS: How do we interpret contour map
Field: ____________________________________________________________
Examples: _________________________________________________________
Isolines: ___________________________________________________________
Examples: _________________________________________________________
Lines are drawn between points of the
same value. Sometimes lines must be
drawn between two points, one of lesser
value and one of greater value, but
where there is no point equal to the
value of the isolines.
In those cases, your best judgment must
be your guide as to where to position the
lines.
Contour Lines: _____________________________________________________
Topographic (Contour) Map: __________________________________________
__________________________________________________________________
Contour Interval: ___________________________________________________
Rules Of Drawing Contour Lines:
 Contour lines never cross!!
 When contour lines cross a stream, they bend: _______________________
 When there is a series of smaller and smaller contour line circles, it means
that elevation is: _______________________________________________
________________________________________________________________
 Most maps have Index Contours, which are: _________________________
________________________________________________________________
 Often maps show benchmarks, which are: ___________________________
________________________________________________________________
 Depression contour lines are marked with: ___________________________
When going uphill on a map, the first depression contour line has the same
value as the last regular contour line. Each smaller and smaller depression
contour line has a value of one contour interval less than the previous line.
Map Scale: Most maps will have a distance conversion scale displayed.
Using this scale, you can convert distances on the map into actual distances on the
ground. NOTE: Don’t confuse this with vertical distance that is shown using
contour lines.
Distance between two points on a map can be determined by marking the
two points on a piece of scrap paper and then laying that scrap paper along the map
scale.
B. Gradient:
FOCUS: How do we calculate gradient? What does gradient tell us?
Gradient: __________________________________________________________
Change in field value
Formula: gradient = ----------------------------Change of Distance
Example: A stream flows between two locations. One location is 100 meters
above sea level. The second location is 50 meters above sea level. The length of
the stream between the two points is 25 kilometers. What is the stream’s gradient?
__________________________________________________________________
-Now lets put everything you have learned all together.
On the next page, follow all the directions and answer all the questions.
C. Drawing Topographic Profiles:
FOCUS: How do we construct a topographic profile? ______________________
__________________________________________________________________
__________________________________________________________________
Topographic Profile: ________________________________________________
Drawing a Topographic Profile:
1. Lay a piece of scrap paper along BOTTOM of the profile line.
3. At the point where the profile line intersects a contour line, put a mark on the
scrap paper and mark its elevation. (You may cross the same elevation more than
once.)
4. Move your scrap paper to the graph. Line up one point with the left side of the
graph and mark each elevation above each mark on the scrap paper.
5. Connect the points with a smooth line.
NOTE:
At the top of a hill or bottom of a valley, you will have to pass
beyond the last elevation mark before reversing direction. Almost no hill top
or valley bottom will be completely flat and be exactly on a contour elevation.
Practice: Draw a topographic profile of the map below.
Making a Topographic Profile I
30
40
A
110
100
100
90
80
70
60
50
40
30
20
10
0
50
60
70
80
90
100
B
Making A Topographic Profile II
40
30
50
60
A
110
100
100
90
80
70
60
50
40
30
20
10
0
70
50
60 70
80
B
Making A Topographic Profile III
10
20
30
A
B
20
60
30
40
110
100
100
90
80
70
60
50
40
30
20
10
0
50