What are the Rules That All Contour Line Must Follow? Today’s Objective: What are the Rules That All Contour Line Must Follow? Do Now: Calculate the gradient of the cliff (show work)

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

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?

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

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)

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

6. Closely spaced contour lines indicate a relatively steep slope 6. Closely spaced contour lines indicate a relatively steep slope. and widely spaced contour lines indicate a relatively gentle slope. Steep Gradient Steep Gradient

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

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

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

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