Todays Objective Interpreting a Topographic Map Do Now

Today’s Objective: Interpreting a Topographic Map Do Now: When would knowing your altitude be important?

** Important Vocabulary ** Isoline A term used to describe lines that connect points of equal value on a map. Types of Isolines Contour Lines equal elevations Isotherms equal temperatures Isobars – equal pressures

Index Contour Line Heavy lines spaced at a predetermined labeled elevations on a topographic map. Index Contour

Contour Interval - The Distance between contour lines (what it is counting by). What is the contour interval of this map? 100 Benchmark – tells the real elevation at that point

Estimating Elevation • • • Label the contour lines based on the map interval Find the contour line before and after the point you are trying to determine Your answer should be a point in between those lines 10 . b . c 20 30 Give a possible elevation for point “a” 15 m Give a possible elevation for. a point “b” 23 m Contour Interval = 10 m

What is the highest possible elevation? The highest possible point on a contour map will always be one unit less than the next possible contour line. Give the HIGHEST possible elevation for point “c” 10 . b . c 20 39 m 30 . a Contour Interval = 10 m

What about the LOWEST possible point? The lowest possible point on a contour map will always be one unit more than the lower contour line. Give the LOWEST possible elevation for point “c” 10 . b . c 20 31 m 30 . a Contour Interval = 10 m

Where would it be easier to hike? B. A. Why? B has a gentle slope, or gradient.

Gradient • Refers to the steepness of the land (slope) Closer contour lines = steep slopes. Gentle Which side of the hill is the Steep steepest? WHY? Further contour lines = gradual slopes.

Contour lines will either • Run off the map or • Close on themselves to create circles

Contour lines will NEVER cross. If contour lines touch they represent a very steep gradient, otherwise called a cliff.

Closed contours with hachure marks represent depressions (holes). Hachure Contours

The contour line with the marks, or hachures , has the same elevation as the line before it. Same Elevation 50 Meters

River and Streams When a river or stream crosses a contour line, the contour line bends and points upstream. • Upstream is where the river starts, higher elevation. upstream • Downstream is where the river ends, lower elevation. downstream

1. What is the contour interval? 10 m 2. What compass direction is Eagle Mt. located? Northwest 3. What is the elevation at the edge of Wolf Pond? 30 m 4. What is the elevation of point B? Point C? 100 m 70 m Point E? 40 m

5. Place an “X” on the map where the steepest location would be. 6. What direction is the Creek flowing? Explain how your know. m a e r pst u x V points upstream (in this case East). So the downstream (direction of creek flow) is West.

What is the contour interval of this map? 20

If given the contour interval, can you label the lines? 15 10 5 0