S-130 Map and Compass 3 — Questions and Answers
Question 1: When using a compass to travel a straight-line bearing in heavy smoke, what technique helps maintain direction?
- Follow the slope downhill
- Leapfrog — sight on a distant object along the bearing before moving (Correct answer)
- Walk parallel to the contour lines
- Use the sun as a reference
Correct answer: Leapfrog — sight on a distant object along the bearing before moving
Leapfrogging involves sighting an object along the desired bearing, moving to it, then re-sighting to stay on course without constant compass checks.
Question 2: What map color is typically used on USGS topographic maps to indicate water features such as streams, lakes, and swamps?
- Green
- Blue (Correct answer)
- Brown
- Black
Correct answer: Blue
Blue is the standard USGS color for water features including rivers, lakes, and wetlands on topographic maps.
Question 3: A back bearing (back azimuth) is calculated by doing what to the forward bearing?
- Adding 90°
- Adding or subtracting 180° (Correct answer)
- Dividing by 2
- Multiplying by the declination factor
Correct answer: Adding or subtracting 180°
A back azimuth is found by adding 180° if the bearing is less than 180°, or subtracting 180° if it is greater than 180°.
Question 4: On a topographic map, V-shaped contour lines pointing uphill generally indicate what terrain feature?
- A ridge
- A cliff
- A drainage or valley (Correct answer)
- A saddle
Correct answer: A drainage or valley
V-shaped contours with the point of the V pointing uphill indicate a drainage, canyon, or valley — important for predicting fire spread.
Question 5: What is the purpose of the declination diagram found on many USGS topographic maps?
- It shows the map's publication date
- It illustrates the angle between true north, magnetic north, and grid north (Correct answer)
- It indicates the map's scale
- It shows the boundaries of the mapped area
Correct answer: It illustrates the angle between true north, magnetic north, and grid north
The declination diagram visually shows the angular relationship between true north, magnetic north, and grid north to help users correct compass readings.
Question 6: Which map scale provides the MOST detail for navigating within a wildland fire area?
- 1:250,000
- 1:100,000
- 1:24,000 (Correct answer)
- 1:500,000
Correct answer: 1:24,000
A 1:24,000 scale map (7.5-minute USGS quad) provides the greatest detail, showing features at roughly 1 inch = 2,000 feet.
Question 7: When a firefighter reports their location using a township and range description, what system are they using?
- Universal Transverse Mercator (UTM)
- Public Land Survey System (PLSS) (Correct answer)
- Latitude/longitude decimal degrees
- Military Grid Reference System (MGRS)
Correct answer: Public Land Survey System (PLSS)
The Public Land Survey System (PLSS) divides land into townships (6-mile squares) and ranges, widely used in western U.S. wildland fire operations.
S-130 Map and Compass 3
When using a compass to travel a straight-line bearing in heavy smoke, what technique helps maintain direction?