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Chapter 3 Topographic Maps
Topography Means:
“Shape of the land”
Contour Lines• Indicate areas of equal elevation• Will never cross or divide
Hill top
– Circles within circles
Specific points are called Benchmarks
Contour interval• Distance between contour lines
500’
Contour Interval Contour Interval = 500’
Indicating all contour lines make it look cluttered – Index Contour Lines
• To get C.I. : Take the Change in Elevation between two contour index lines and divide that by the number of lines between them. C.I. = 250’
You Try!!!
• Map A– C.I. =
• Map B– C.I. =
Benchmark: Exact elevation Marker
Close lines = steep slope
What do you think it looks like from the side?
?
Closed depressions on the land are shown by contour lines with “hachure lines” that point down slope.(indicate holes or craters)
6. A contour line forms a “V” shape
pointing upstream when crossing
a river or stream. Downhill!!!
“V” Shaped
Contour Lines
Steep vs GentleRiver Direction
Gradient = Average rate of slopeDetermined by change in elevation divided by
distance. Rise over Run!
A
B
Scale (km)1km
Elevation Change (rise)=
Distance (run)=
Topographic ProfilingA line that shows the changes in elevation
across a section of a topographic map.
Contouring:
Elevation points have beendetermined using groundsurveying techniques orGPS but contour lines needto be drawn in.
