1. Interpreting a Topographic Map
Today’s Objective:
Interpreting a Topographic Map
Do Now:
When would knowing your altitude be important?

2. ** Important Vocabulary **
Isoline -
A term used to describe lines that connect points of equal value on a map.
Types of Isolines -
Isotherms -
equal temperatures
Contour Lines -
equal elevations
Isobars –
equal pressures

3. Index Contour Line
Heavy lines spaced at a predetermined labeled elevations on a topographic map.
Index Contour

4. - The Distance between contour lines (what it is counting by).
Contour Interval
- The Distance between contour lines (what it is counting by).
What is the contour interval of this map?
100
Benchmark – tells the real elevation at that point

5. Estimating Elevation 15 m 23 m
Label the contour lines based on the map interval
Find the contour line before and after the point you are trying to determine
Your answer should be a point in between those lines
Contour Interval = 10 m 10
. a 20 30
. b
. c
Give a possible elevation for
point “a”
15 m
Give a possible elevation for
point “b”
23 m

6. Give the HIGHEST possible elevation for
What is the highest possible elevation?
The highest possible point on a contour map will always be one unit less than the next possible contour line.
Give the HIGHEST possible elevation for
point “c”
Contour Interval = 10 m 10
. a 20 30
. b
. c
39 m

7. Give the LOWEST possible elevation for
What about the LOWEST possible point?
The lowest possible point on a contour map will always be one unit more than the lower contour line.
Give the LOWEST possible elevation for
point “c”
Contour Interval = 10 m 10
. a 20 30
. b
. c
31 m

8. Where would it be easier to hike?
Why?
B has a gentle slope, or gradient.

9. Gradient Refers to the steepness of the land (slope)
Closer contour lines = steep slopes.
Further contour lines = gradual slopes.
Which side of the hill is the steepest?
WHY?
Steep
Gentle

10. Contour lines will either
Run off the map or
Close on themselves to create circles

11. Contour lines will NEVER cross.
If contour lines touch they represent a very steep gradient, otherwise called a cliff.

12. Closed contours with hachure marks represent depressions (holes).
Hachure Contours

13. The contour line with the marks, or hachures , has the same elevation as the line before it.
50 Meters

14. River and Streams
When a river or stream crosses a contour line, the contour line bends and points upstream.
upstream
downstream
Upstream is where the river starts, higher elevation.
Downstream is where the river ends, lower elevation.

15. 10 m Northwest 30 m 100 m 70 m 40 m What is the contour interval?
What compass direction is Eagle Mt. located?
What is the elevation at the edge of Wolf Pond?
What is the elevation of point B?
10 m
Northwest
30 m
Point C? Point E?
100 m
70 m
40 m

16. V points upstream (in this case East).
Place an “X” on the map where the steepest location would be.
What direction is the Creek flowing? Explain how your know.
upstream x
V points upstream (in this case East).
So the downstream (direction of creek flow) is West.

17. What is the contour interval of this map?20

18. If given the contour interval, can you label the lines?15 10 5