Red Card Land Navigation & Topographic Map Reading — Questions and Answers
Question 1: On a topographic map, contour lines that are spaced very close together indicate:
- Gentle, gradual terrain with a slow rate of elevation change
- Steep terrain with a rapid rate of elevation change (Correct answer)
- A valley or drainage running perpendicular to the lines
- An area of flat terrain at high elevation
Correct answer: Steep terrain with a rapid rate of elevation change
Closely spaced contour lines represent steep terrain because each line marks the same elevation interval — when those intervals are packed tightly together, the ground rises or falls sharply over a short horizontal distance.
Question 2: The contour interval on a topographic map is 40 feet. If you count 5 contour lines between your position and a ridgeline, the elevation difference is:
- 40 feet
- 120 feet
- 160 feet
- 200 feet (Correct answer)
Correct answer: 200 feet
The elevation difference equals the number of contour lines multiplied by the contour interval: 5 × 40 = 200 feet. Each line represents one full interval.
Question 3: When using a baseplate compass on a topographic map, 'declination' refers to:
- The compass bearing from your position to a known landmark
- The angle between true north (map north) and magnetic north (Correct answer)
- The rate at which the compass needle deviates in mountainous terrain
- The difference in elevation between two map features
Correct answer: The angle between true north (map north) and magnetic north
Magnetic declination is the angular difference between true (geographic) north shown on a map and the magnetic north that a compass needle points to. Failing to account for declination leads to significant navigation errors over long distances.
Question 4: A 'saddle' on a topographic map is best described as:
- A high, flat-topped ridge with gentle slopes on all sides
- A low point or depression between two higher summits on a ridge (Correct answer)
- A drainage channel that runs from a ridgeline down to a valley floor
- A cliff face represented by closely spaced hachure marks
Correct answer: A low point or depression between two higher summits on a ridge
A saddle (also called a col or notch) is the low point connecting two peaks along a ridge. On a topo map it appears as two sets of concentric contour lines facing each other with a narrowing between them. Saddles are important terrain features for route planning and escape route identification.
Question 5: In wildland firefighting, understanding aspect (the direction a slope faces) is important primarily because:
- South- and west-facing slopes typically receive more solar radiation, producing drier, more flammable fuels (Correct answer)
- North-facing slopes are always steeper and present greater physical hazards to crew members
- Aspect determines which compass bearing a crew must follow when constructing fireline
- East-facing slopes generate stronger upslope winds that accelerate fire spread regardless of fuel conditions
Correct answer: South- and west-facing slopes typically receive more solar radiation, producing drier, more flammable fuels
South- and west-facing slopes in the Northern Hemisphere receive more direct solar radiation throughout the day, leading to lower fuel moisture, warmer temperatures, and faster drying. This makes fuels on those aspects significantly more flammable and fire spread faster compared to shaded north- or east-facing slopes.
Question 6: When determining your location on a topographic map using the technique of 'triangulation,' you need at minimum:
- One identifiable landmark and the map's contour interval
- Two identifiable landmarks and two compass bearings (Correct answer)
- Three identifiable landmarks and three compass bearings
- Your GPS coordinates and one identifiable landmark
Correct answer: Two identifiable landmarks and two compass bearings
Triangulation (also called resection) requires at least two known landmarks. You shoot a compass bearing to each, plot the back-bearings on the map, and your position is where those two lines intersect. Three landmarks improve accuracy but two is the minimum needed to fix a position.
Red Card Land Navigation & Topographic Map Reading
On a topographic map, contour lines that are spaced very close together indicate: