1. and Construction of Topographic Maps
Interpretation
and Construction of Topographic Maps

2. Goals of the Topographic Map Interpretation Lab
Understand how surface features are expressed on
the earth’s surface
Observe a 2-dimensional map and “convert” it to a
3-dimentional relief map
Locate geographical positions using the PLSS system
(a legal description)
Students will understand the nature of contour lines
and how contour lines can determine:
surface features
river gradients
map relief and elevation
Develop skills that enable the student to construct
topographic maps and topographic profiles
1st
Lab
2nd
Lab

3. Topographic Map Lab Types of maps
Planimetric Maps – a typical road map with cities
Topographic Maps – a planimetric map as well as a 3-d representation of the
“lay of the land” converts a D to a 3-D map
Shows streets, roadways
“sometimes not very accurate”
elevations
Shows accurate scaling, elevation
and geographic locations.

4. One cannot live without
What can one do with a Topographic Map
Calculate river gradients
Hiking- how rigorous is the trail
Hunting – where would game hang out?
Navigate your way
Interpret various geological features
One cannot live without
topographic maps !!!

5. Interpreting SCALE on a topographic map
Representative Fraction Scale (RF scale)
Graphic Bar Scale (graphical representation)
Verbal Scale (what does the map say?)
Model (Map size)
Actual Size
1:18 scale
1:1 scale 50
100
150
200
feet
Graphically shows
distance
“What is the map telling you???”

6. 1 map inch = 24,000 real earth inches
Representative Fraction Scale (RF scale)
the “ratio scale” or “unitless scale”
1 : 24,000 or 1/24,000 – can apply any units
(:) or (/) means equal (=)
How does this scale work? (let’s use inches and the
scale of 1:24,000
1 map inch = 24,000 real earth inches OR
1 map inch = 2000 feet
1” = 2000 feet
Which scale shows more map detail?
1:24,000 1:5,000 1:1000 1:525,000

7. Graphic Bar Scale: graphical representation of distance4
Kilometers 1 2 3
Comparing a map distance (from point A to B) to the
Bar scale (at the bottom of map)
What about a meandering river???
STRING

8. The Verbal Scale:
The map “tells” you what the scale is
(just listen?)
Usually located at the bottom of the map
ALL verbal scales should match the
RF scale and bar scale
Example:
1 inch equals 2000 feet

9. X Map Orientation – Where does your compass point ????
Magnetic Declination:
True North (Santa Claus) vs. Magnetic North
Magnetic Declination (MD)
North (Santa Claus)
Map points
to TN X
Bakeo
Compass needle
points to MN
EARTH TN MN MD
Map Symbol
The angle between TN and MN is
the magnetic declination

10. NEWS
North
MAP
East
West
South

11. 20 Townships North/South Ranges East/West NW 1/4 Sections SW 1/4
R3W
T2N
R2W
T2N
R1W
T2N
R1E
T2N
R2E
T2N
Ranges
East/West
T1N
R1E
T1N
R3W
T1N
R2W
T1N
R1W
T1N
R2E
T1N
Base Line
T2N, R2E
T1S
R2W
T1S
R3W
T1S
R1W
T1S
R1E
T1S
R2E
T1S 6 5 4 3 2 1 7 8 9 10 11 12 18 17 16 15 14 13 19 20 21 22 23 24
R3W
R2W
R1W
R1E
R2E
Principal Meridian
6 miles
1 mile 30 29 28 27 26 25
NW ¼ of
NE1/4
NE 1/4 of 31 32 33 34 35 36
NW 1/4
6 miles
SW 1/4 of
NE 1/4
SE ¼ of
NE 1/4 X
1 mile
Sections 20
SW 1/4
SE 1/4
T2N,R2E,Sec 20,1/4NE,1/4SW

13. Creating a Topographic map with Contour Lines
Contour line – a line that connects points of equal elevation 40
equal points of elevation
5 important rules of contour lines
Contours line do not cross or divide
2. Contour lines will eventually close – they don’t stop
3. Steep slopes – contour lines are close together
Gentle slopes – contour lines are widely spaced
4. Depressions shown with hachures pointing downward
5. Contour lines intersecting streams will always “V”
in the upwards direction (streams flow through the open
“V”)

14. Contour lines never cross or divide
200
100
Contour lines eventually close – Don’t stop
500

15. Steep Gentle Close together contour lines = STEEP SLOPES
Separated contour lines = GENTLE SLOPES
Steep
Gentle

16. Depressions are shown with hachures pointing inward
Rivers always flow in the direction of the
open “V” of a contour line
NORTH
WEST

17. How many contour lines can fit in a determined Space???
The Contour Interval
How many contour lines can fit in a determined
Space???
The Index contour line – the “dark numbered” elevation line
The contour interval – the amount of contour lines
in-between the index contour lines
200
300
Contour Interval = 20
CI = 20
500
Contour Interval = 100
CI = 100
100

18. Rise = highest elevation – lowest elevation
Calculating the gradient
how steep is the slope??
Higher slope # = steeper
Rise
Run
Rise = highest elevation – lowest elevation
Run = the length (distance)
Rise and Run MUST be in the same units
preferably “feet”

19. Making a Topographic Profile
represents a “cross-section” or side view of
topography
uses a horizontal and vertical scale
gives the map reader a “picture” of the “lay of
the land”.
How do you make a Topographic profile ?

20. Lay a strip of paper over the topographic area
“Mark off” contour lines that intersect the paper
strip – recording their elevations
Intersecting contour lines

21. Remove strip of paper and place it on graph
paper – plot elevation points (on strip) to
match vertical scale elevation points
potting points on the graph paper
Strip of paper

22. Outline the topography by “connecting” the
dots --- Use your artistic ability to construct
a “smooth” picture

23. B E D C F A