Geography 101 Lab 16 Introduction to Topographic Maps – Practice Questions

You should be able to draw contour lines from spot elevations.

1. Draw contour lines at a twenty-foot interval from the spot elevations in Figure 1 starting with a low of 1080 feet. The blue lines are rivers.

Figure 1

You should be able to use a representative fraction to calculate distances separating points on a map.

Conversion factors: 12 inches = 1 foot 5280 feet = 1 mile

2. The distance from point A to point B on the Hamburg, WI map in Figure 2 is 3.7 inches. How many miles separate these two points on the earth’s surface? Method 1: 

3.7

124,0001

112

15280

3.7 24,00012 5280

88,80063,360

1.4

Method 2: 

Rewrite map scale so the units on the right side of the scale are miles, not inches. 

1 map in = 24,000 earth inches; convert earth inches to feet: 24,000/12 = 2000 

1 map in = 2000 ft; convert feet to miles: 2000/5280 = 0.38 

1 map in = 0.28 miles 

3.7

10.381

1.4

Method 3: do the math one step at a time. 

1. Calculate earth inches by multiplying 3.7 times the map scale: 

  3.7 map inches × 24,000 = 88,800 earth inches 

2. Convert inches to feet: 

  88,800/12 = 7400 feet 

3. Convert feet to miles: 

  7400/5280 = 1.4 mi 

3. The distance from point A to point B on the Palmerton, PA map in Figure 3 is 3.9 inches. How many miles separate these two points on the earth’s surface?

3.9

124,0001

112

15280

3.9 24,00012 5280

93,60063,360

1.5

4. The distance across the bottom of the Lehigh River valley on the Palmerton, PA map in Figure 3 is 0.25 inches. How many feet is it across the valley bottom on the earth’s surface?

0.25

124,0001

112

0.25 24,00012

600012

500

5. The distance separating points A and B on the Allentown, PA-NJ map in Figure 4 is 1 inch. How many miles separate these two points on the earth’s surface? Note: it makes no difference that the elevations on the Allentown map are in meters.  The representative fraction can 

be used with any unit of measurement. 

Method 1: 

1

1100,0001

112

15280

1 100,00012 5280

100,00063,360

1.6

Method 2: 

Rewrite map scale so the units on the right side of the scale are miles, not inches. 

1 map in = 100,000 earth inches; convert earth inches to feet: 100,000/12 = 8333.3 

1 map in = 8333.3 ft; convert feet to miles: 8333.3/5280 = 1.58 

1 map in = 1.6 miles 

1

11.61

1.6

Method 3: do the math one step at a time. 

1. Calculate earth inches by multiplying 1 times the map scale: 

  1 map inches × 100,000 = 100,000 earth inches 

2. Convert inches to feet: 

  100,000/12 = 8333.3 feet 

3. Convert feet to miles: 

  8333.3/5280 = 1.6 mi 

You should be able to calculate elevation gradients from topographic maps.

6. Points x and y on the Hamburg, WI map in Figure 2 are 0.5 inches apart. What is the gradient between these two points in feet/mile? 1. Calculate the change in elevation between points x and y: 1340 ft – 1250 ft = 90 ft 

2. Calculate the distance separating points x and y in miles. 

0.5

124,0001

112

15280

0.5 24,00012 5280

12,00063,360

0.2

3. Calculate the gradient: ∆ 90

0.2450 /  

7. Points x and y on the Palmerton, PA map in Figure 3 are 0.8 inches apart. What is the gradient between these two points in feet/mile? 1. Calculate the change in elevation between points x and y: 1200 ft – 400 ft = 800 ft 

2. Calculate the distance separating points x and y in miles. 

0.8

124,0001

112

15280

0.8 24,00012 5280

19,20063,360

0.3

3. Calculate the gradient: ∆ 800

0.32667 /  

You should be able to interpret contour lines correctly, including determining their elevation using the contour interval, assessing gradient based on contour line spacing, and identifying hills, valleys, and other landforms based on contour line patterns.

8. Compare the contour line spacing at the two locations for which you calculated gradients in questions 6 and 7. The contour lines are much closer together on the Palmerton map and the Palmerton map has a much steeper gradient.  

The closer the contour lines the steeper the gradient. 

9. If there were no elevation labels associated with the contour lines on the Hamburg, WI map in Figure 2, could you still determine that points A and C sit on hilltops? Explain. Yes.  The contour lines surrounding the letters are closed.  Closed contour lines indicate high spots. 

10. How does the gradient on the ridge between points C and D on the Palmerton, PA map in Figure 3 change on the ridge top compared to the sides of the ridge? Explain. The gradient on the sides  is quite steep while the top of the ridge  is relatively flat.  The contour  lines are very close 

together on the sides of the ridge, but at the top, the contour lines are farther apart. 

11. Based on the shape of the contour lines on the Hamburg, WI map in Figure 2, in what direction is Einert Creek flowing? Explain. Einert Creek  is flowing from east/northeast to west/southwest.  The 1250 ft contour  line forms a V when  it crosses 

Einert Creek and the V points to the east/northeast.  The V points upstream. 

12. Although no stream appears at the location of the line marked m–n on the Hamburg, WI map in Figure 2, a stream could be located here. How can you tell this is a possible location for a stream? The contour lines that cross line m–n bend uphill (form V’s pointing uphill), which is what contour lines do when they 

cross rivers. 

13. What’s the best estimate of the elevation of point z on the Hamburg, WI map in Figure 2? 1245 feet.  The contour interval = 10 feet.  Since z is in between the 1250 index contour and the 1240 intermediate 

contour, add half the contour interval to 1240. 

14. If you walked along the line labeled s–t on the Hamburg, WI map in Figure 2, what type of landform would you be walking across? You would be walking up over a ridge and down the other side.  The contour elevations increase and then decrease. 

15. Line C–D on the Allentown, PA-NJ map in Figure 4 crosses a ridge (as does line A–B). If the word “Ridge” didn’t appear on the Allentown map, could you still determine that a ridge exists here? Explain. Yes.  There is a string of closed contour lines and closed contour lines indicate high spots. 

16. A series of ridges exist on the Allentown PA-NJ map in Figure 4 that run approximately parallel to each other and stretch the length of the map. Draw a line along the top of each of these ridges. How many ridges appear on this map?

17. The maps in Figures 2 and 3 have the same scale but their contour intervals are different. Why? The total relief on the two maps is very different.   

The total relief of the Hamburg, WI is approximately 1375 (elevation of point A) – 1235 (elevation of Big Rib River where 

it flows off the south edge of the map) = 140 feet.   

The  total  relief of  the Palmerton, PA map  is approximately 1440  feet  (intermediate  contour  left of point A) – 380 

(elevation of intermediate contour line adjacent to Lehigh River) = 1060 feet. 

If the Palmerton map had a 10‐foot contour interval, you wouldn’t be able to distinguish the lines from one another.  

Plus, the lines would obscure other information on the map.  If the Hamburg map had a 20‐foot contour interval, you 

wouldn’t be able to see any details regarding the relief. 

You should be able to draw a topographic profile with a given vertical exaggeration.

18. Draw a profile of the topography along lines A–B and A–C on the topographic map of Hamburg, WI shown in Figure 1. Use all the contour lines (index and intermediate) to draw these profiles. Draw the profiles with a 20X vertical exaggeration. Add all the necessary labeling to the profile so a reader can understand exactly what you did. You can draw the profiles side-by-side with a little bit overlap between the right side of the A–B profile and the left side of the A–C profile. See profile below map. 

19. Draw a profile of the topography along lines A–B and C–D on the topographic map of Palmerton, PA shown in Figure 2. Use just the index contour lines to draw these profiles. Draw the profiles with a 10X vertical exaggeration. Add all the necessary labeling to the profile so a reader can understand exactly what you did. You can draw the two profiles with a little bit of overlap between the right edge of one profile and the left edge of the second profile. See profile below map. 

20. What is the approximate local relief for the Big Rib River valley according to the profile you drew from the Hamburg, WI map? What is the approximate local relief for the Lehigh River valley according to the profile you drew from the Palmerton, PA map? Big Rib River: approximately 100 feet. 

Lehigh River: approximately 1000 feet 

21. If you want to compare the river valley in Wisconsin to the one in Pennsylvania, is it OK to use the two profiles you drew for questions 17 and 18? Explain. No, it is not OK because the profiles do not have the same vertical exaggeration.  Only compare profiles with the same 

vertical exaggeration.  If you didn’t look at the elevations on the y‐axis, you might think the Lehigh River valley was only 

slightly deeper than the Big Rib River valley when in fact it is 10‐times deeper. 

You should be able to describe the color coding used for categorizing topographic map symbols.

22. What do the following colors generally represent on topographic maps? Areas shaded green – forested areas Areas shaded red – urban areas Brown lines – contour lines Thick brown lines – index contours; have elevation labels Thin brown lines – intermediate contours; follow contour interval Dotted brown lines – supplemental contours; drawn at half the contour interval Areas shaded blue – water bodies (e.g. lakes) Solid blue lines – perennial rivers (flow all‐year round)

Blue lines drawn as a dash and three dots – intermittent streams (flow only part of the year) Red lines – survey lines or roads Black lines – political boundaries or roads Features drawn in purple – updated information

You should be able to differentiate small-scale maps from large-scale maps and describe how the scale of a map affects the representation of the landscape.

23. Compare and contrast the characteristics of the Palmerton, PA map (Figure 3) and the Allentown, PA-NJ map (Figure 4) with regard to the following:

Palmerton, PA Allentown, PA-NJ

Representative Fraction 1:24,000  1:100,000

Amount of detail shown Lots of details;  Little detail; no road names;  

   road names shown  small roads not shown

Amount of land area covered Small area  Large area

Contour interval in feet 20 feet  20 m: 20 × 3.281 = 65.62 feet

Total relief in feet ≈1060 feet  500m (lookout) – 120m (Lehigh River  

     valley) = 380m; 380 × 3.281 = 1247 feet

Size of ridge Lehigh Large; ridge occupies Small; just one of several ridges  

River cuts through most of map shown on map

Length of line (inches) C-D about 3.7 inches A-B about 1 inch

24. Based on your answers to question 22, which map has a smaller scale? The Allentown map has a smaller scale. 

25. Line A–B on the Allentown, PA-NJ map (Figure 4) crosses the same ridge as line C–D on the Palmerton, PA map (Figure 3). Why is line A–B on the Allentown map shorter than line C–D on the Palmerton map? Because the Allentown map has a smaller scale.  Features are smaller on small scale maps than on larger scale maps. 

26. Why does the Palmerton map (Figure 3) have a larger contour interval than the Allentown map (Figure 4)? The difference in local relief is not sufficient to warrant a change in the contour interval.  The key reason is the change 

in the map scale.  Since the Allentown map covers a much larger area, there isn’t enough space to draw contour lines 

at a 20‐foot interval. 

Figure 2

x y

z

m

n

s

t

Figure 3

x y

Figure 4