1. Map Reading and Interpretation
Contour Lines

2. Contour Lines

3. Contour lines are always the same distance apart on a map.
25 feet on this. Not all topographic maps have been converted
Contour Interval
Is the height difference between any two adjacent contour lines on a map
Constant across a map

4. Reading Contour Lines Elevation of Point A: 25 feet
Elevation of Point B: feet approximately

5. Activity: Contour Lines
On the map provided, determine the elevation of the following points:
Marie Plateau
Mount Adams
Mount Gould
Mount DesBarres
Mount Marie

6. Contours Contour Profile / Cross section
Allows the map reader to take a flat, two dimensional map and develop an idea of what the land looks like
Questions: Is it steep? Is it flat?

7. Contour Profiles / Cross Section

8. To create a profile …
Step 1: Mark the contour lines on a small sheet of paper; place
the contour height at each marked point (A / B)
Step 2: On the side, record a contour value above the highest contour identified (B) and below the lowest contour identified (A).
Note: Your map: intervals are 50 feet apart
Step 3: On loose leaf, make a scale (Think y-axis). Print the highest value at the top. Number down until you reach your lowest value (This number does not have to be zero)

9. To create a profile (cont’d)…
Step 4: Place the small sheet of paper along the lowest line
Step 5: Align the lettered point with the axis line (see below)
Step 6: Using the scale (lower line) as a guide, place a dot at the correct height
Step 7: Join the dots
Result: The map view is converted
To a profile view

10. Purpose of Contour Profile
Intervisibility:
Profiles allow you to tell whether one point can be seen from another.
Question: Profile A to B
Is Point B on your map visible from Point A?
Can you see the top of the mountain from both points?

11. On-line Practice