1. Intervals Depressions Gradients Rivers
Contour Maps
Intervals
Depressions
Gradients
Rivers

2. Intervals 20 meters 10 meters
Interval- the difference in value between any two adjacent isolines

3. Notice the “different” lines – Called Hachure lines
Depressions and Hills
Hills
Depressions
Notice the “different” lines – Called Hachure lines

4. Isolines that are close together show a greater gradient
Use the formula to solve for gradient
To calculate the gradient between points Y and Z, determine their values then use a scrap piece of paper to determine the distance between the points
Isolines that are close together show a greater gradient
520 ft
490 ft
Gradient = 6 ft/mi
Distance = 5 miles

5. Rivers Rivers always flow downhill.
Contour lines will always bend upstream.
The river flows in the opposite direction that the contours point.

6. Profiles Step 1: Get a scrap piece of paper10 20 20 10 10 20 30 40 40 30 20
Step 1: Get a scrap piece of paper
Step 2: Line it up under the line X-Y
Step 3: Draw “tick marks” for each instance that a contour crosses the line X-Y
Step 4: Label each “tick” with its appropriate value

7. Step 5: Align your scrap paper with the profile as shown above.10 20 30 40
Step 5: Align your scrap paper with the profile as shown above.
Step 6: Place a dot on the graph for each of your “ticks” at the indicated elevation.
Step 7: Connect the dots with a smooth curving line.