1. Reading and Interpreting Topographic Maps
Peaks and Valleys
Reading and Interpreting Topographic Maps

2. Peaks and Valleys

3. ~ Key Terms ~
Elevation
Topographic Map
Contour Line
Contour Interval

4. Elevation
A term that describes the height of a point on Earth’s surface above (or below) sea level.
This point is 6300 feet (1920 meters) above sea level.

5. Topographic Map
A map that show the elevation of the land, such as hills and valleys, using contour lines.

6. Contour Lines
Contour lines are lines connecting points of equal elevation. Every point along the line lies at the same elevation above sea level. Imagine walking around a hill in such a way that you never go up or down the hill, but stay at the same level. The trace of your path would be a contour line of that elevation.

7. Contour Interval
The vertical distance between one contour line and the next. On any map, the contour interval must be constant, and must be shown in the map’s legend. On this map, the contour interval is 20 feet, because each line represents a 20 foot increase in elevation.

8. Rules for Successful Contouring Rule #1
Every point along a contour line represents the same elevation.
This entire line represents 1200 feet above sea level.
1200
1150
1250

9. Rules for Successful Contouring Rule #2
Contour lines NEVER split or divide!
Can’t happen!
1150
1200
1150
1250

10. Rules for Successful Contouring Rule #3
This is fine!
Contour lines cannot just stop. They must either form a closed loop, or run off the edge of your map.
What’s the elevation here???
1100
1200
1150
1250 ? ?

11. Rules for Successful Contouring Rule #4
Contour lines NEVER, EVER cross
What’s going on?? Is this area above or below 1200 feet?
1100
1200
1150
1250 ?

12. Tip 1: What does contour line spacing indicate?
The closer together the contour lines are, the steeper the hill is. The more spread apart they are, the gentler the slope.
Traveling along the red line would be much steeper than traveling along the green line.

13. Tip 2: Which way is the stream flowing?
When contour lines cross a stream or river, they form v-shaped kinks in the lines that always point upstream.
Also remember - Water always flows DOWNHILL!
Blue Creek flow towards the East.

14. Tip 3: Finding the hill tops
Hill tops are easy to find. Just look for the concentric closed contour lines that form the top of a hill. Notice the contour lines that form the two peaks below.

15. Tip 4: What do those funny hachure marks mean?
Some features, such as the Grand Canyon, lakes, mines, or sinkholes actually are holes in the ground. The hachured contours indicate a depression. Don’t confuse it with a hilltop!
800
700
600

16. Weathering and Erosion
Weathering is the breakdown and alteration of rocks and minerals at or near the Earth's surface

17. Types of Weathering
Physical or mechanical weathering
Ice wedging - water expands when it freezes and breaks apart rocks

18. Types of Weathering Physical or mechanical weathering
Thermal expansion - repeated daily heating and cooling of rock; heat causes expansion; cooling causes contraction.

19. Types of Weathering
Chemical weathering - Rock reacts with water, gases and solutions (may be acidic); will add or remove elements from minerals.

20. Erosion
Erosion is the wearing away of land or soil by the action of wind, water, or ice.

21. Types of Erosion
Water Erosion – Water is the most important erosion agent and erodes most commonly as running water in streams. Water collecting on the surface of the soil collects as it moves towards tiny rivulets and streams and creates sheet erosion

22. SIMPLY PUT WEATHERING: BREAKS IT DOWN EROSION: CARRIES IT AWAY
DEPOSITION: SETS IT DOWN

23. TOPO QUIZ Now its time to test your topography map reading skills
TOPO QUIZ Now its time to test your topography map reading skills. Good Luck!!

24. What landform do you think this map depicts?
If you traveled from point A to point B, would you be going uphill or downhill?
What landform do you think this map depicts?
a. Valley
b. Mountain
c. Plain
700
750 A
800 X
825 B

25. Correct!

26. Sorry
Actually, you would be going uphill. Look at the elevations on the contour lines you will be crossing.

27. Sorry
Please try again.

28. In which direction does Maple Creek flow?
Northeast
Southwest
Can’t tell from information given
What is the contour interval of this map? 50
100
400
800
600
700
500
Maple Creek

29. 5. What is the approximate elevation at the top of this hill?b c
6. Which hike would be steeper, from A to B or from C to D? C D
1200 B
1150 A
1100

30. 7. What is the contour interval of this map? a. 20 feet b. -20 feet
c. 60 feet
8. What type of landform is depicted here?
a. a mountain
b. a depression
c. a valley 60 40 20

31. Link to Topozone
The USGS publishes topographic maps of the entire country. This website allows you to view any of these topographic maps.
Go to this site and use the map search to try to locate your city, town, school, or maybe even your own house. When you find a familiar area, examine the contours to see how well you recognize your own topographic features!