1. Topographic Maps

2. Topographic Maps

3. A topographic map of part of Ithaca

4. Topographic Maps Maps of an elevation field
Show elevation by contour lines
Also show other natural and
man-made features by using
symbols

5. HOW TO READ TOPOGRAPHIC MAPS

6. 1. Contour lines – lines the connect points of equal elevation

7. Steep slope Gentle slope Contour Lines close together –
Contour Lines far apart –
Steep slope
Gentle slope

8. 2. Contour Interval  The contour interval on this map is 20?
What do you think is a contour interval?

9. Contour Interval
Change in elevation in between two consecutive contour lines
Usually listed in key or legend

10. If you are at sea level, your elevation is 0.
The contour line for the coastline is 0.

11. 3. Index Contour Line
The Index Contour lines on the map below are the 700 and 800 lines
Why do you think they are darker?

12. Index Contour Lines Every 4th or 5th line that is thicker or bolder
Line is labeled with the elevation
Helps to read the map

13. Index contour lines are placed every 50 units on this map

14.  What is the spacing of Index Contours on this map?
 What is the contour interval?

15. 4. Hills
How is a hill depicted on a topographic map?

16. Hills Closed contours in a circle or elliptical (oval) shape
“Bulls eye”

17. 5. Depressions
The opposite of a hill is a depression which is a low point in the ground. They are represented by hachure lines.
Describe what a hachure line looks like.
Feathered line or a line with hash marks

18. 5. Hachured Lines
Does the elevation go up or down when you see the hachured lines?
The first depression line is going to the ________ elevation as the closest contour line
down
same

19. 6. Benchmark - EXACT Elevation
Indicated by a BM or X on a topographic map

20. What is the exact elevation of the benchmark on this map?
2919 feet

21. Can a stream flow northward?
7. Streams always flow Downhill – from higher elevation to lower elevation
Can a stream flow northward?
Yes

22. What direction is this stream flowing?
South

23. Contour lines point in the opposite direction the stream is flowing!
Describe what the contour lines look like when they are crossing a stream?
Contour lines point in the opposite direction the stream is flowing!

24. Streams always flow in the opposite direction the V or U is pointing.

25. 8. Maximum Elevation of a Hill
Steps to follow:
1. Count up the contour lines using the contour interval.
2. Pretend that there is one more contour line at the top of the hill (imaginary line).
3. Subtract 1

26. How is the highest possible elevation?
Highest contour line = 40
Pretend one more so that would be 50
Subtract 1
50 – 1 =
Maximum elevation of hill is 49

27. 9. Minimum Elevation of a Depression
Steps to follow:
1. Count down the contour lines using the contour interval.
2. Pretend that there is one more contour line at the bottom of the depression (imaginary line).
3. add 1

28. Map Scales
The relationship between distance as measured on a map and the actual distance on Earth’s surface

29. Types of Map Scales Verbal Scale – 1 inch = 20 miles Bar Scale
One Mile

30. Types of Map Scales c. Ratio Scale -
One of any unit on this map represents 24,000 of the same unit on Earth’ s surface. Ex, one inch would equal 24,000 inches on the Earth

31. Maps often give you more than one way to measure distance
Represents one mile on the map
Represents parts of one mile, ex: one tenth of a mile
One kilometer