1. Topography Review DO NOW List three rules for drawing isolines.
On a topographic map, how can you tell which way a stream is flowing?
How do contour lines indicate a steep slope?
Write the formula for gradient

2. Rules for drawing isolines
Line must start and end at the edge of the map.
If the line cannot go to the edge of the map, make a circle.
Lines cannot cross or touch.
Connect every point, written or implied.
“Count by” the contour interval
If the line crosses a stream,
make a “v” over the stream.
This should point upstream,
or uphill 23 23 23 23

3. Draw contour lines at an interval of 2 meters23 27 21 25 19

4. Profiles

5. 1.Place scrap paper across the map
2. Every time an isoline crosses the scrap paper, make a mark and write the elevation of the isoline
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6. 3. Your scrap becomes the bottom of a graph
4. Label the y axis, and plot each point as if you were making a graph
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No flat tops or flat bottoms!

7. Other contour principles
Hatchure lines: depression
The first line you see has the same value as the one before it.
As you go toward the center, count down
by the contour interval 50 50 40 30 20

8. Lines closest together
On a contour map?
On a weather map?

9. Gradient Gradient = slope = how steep Gradient = change in elevation
distance
Do Now: Point A is 200 ft & point B is 300 feet. A and B are 2 miles apart. Find gradient
Gradient = ft
2 mi
Gradient = 100 ft
2 mi
Gradient= 50 ft/mi

10. Highest possible elevation
“one less than the next contour line would be”
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“Add the contour interval minus one”