1. What are the Rules That All Contour Line Must Follow?
Today’s Objective:
What are the Rules That All Contour Line Must Follow?
What is Topography? (write this definition in your notes)
the arrangement of the natural and artificial physical features of an area

2. Rules for Contour Lines
A contour line represents a single equal elevation. (all points on the same contour line have the same elevation) 5 5 10 10 10 10 15 15

3. What is the contour interval of this map?
2. The elevation represented by a contour line is always a simple multiple (5, 10, 50, 100)
0 m
100 m
200 m
300 m
400 m
What is the contour interval of this map?

4. 3. Where one closed contour line surrounds another, the elevation increases. (representing a hill or mountain)
Lowest
elevation
0 m
400 m
Highest
elevation

5. 4. Closed depressions are shown by hachured contour lines
4. Closed depressions are shown by hachured contour lines. The hachures point into the depression. (Hachures = short dashes)

6. 5. A hachured contour line, lying between two different contour lines, is the same elevation as the lower contour line.
Count up
Count down
Contour
Elevation
Repeats

7. 6. Closely spaced contour lines indicate a relatively steep slope.
Gradient
Steep
Gradient

8. 7. Widely spaced contour lines indicate a relatively gentle slope.
Gradient
Gentle
Gradient

9. 8. Contour lines do not cross other contour lines
8. Contour lines do not cross other contour lines. They also never split or divide. A vertical cliff – contour lines will touch (not cross)
Cliff

10. These lines are off the map
9. Every contour line eventually closes against itself. However, the map area may not be large enough to show this closure. Therefore, the contours will end at the edge of the map.
These lines are off the map

11. 10. Where a contour line crosses a stream or valley, the contour bends to form a “V” that points upstream or up the valley.

12. Calculate the gradient of the cliff (show work)
Do Now:
Calculate the gradient of the cliff (show work)