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

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

Draw contour lines at an interval of 2 meters 23 27 21 25 19

Profiles

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 100 200 300 200 400 200 400 100 200 400 200 100 300 300 300 500 100 300 100 100

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 500 400 300 200 100 100 200 300 400 500 No flat tops or flat bottoms!

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

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

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 = 300-200 ft 2 mi Gradient = 100 ft 2 mi Gradient= 50 ft/mi

Highest possible elevation “one less than the next contour line would be” 100 400 399 200 300 “Add the contour interval minus one”