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
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 Gentle River Direction
Gradient = Average rate of slope Determined by change in elevation divided by distance. Rise over Run! Elevation Change (rise)= Distance (run)= B A Scale (km) 1km
A line that shows the changes in elevation Topographic Profiling A line that shows the changes in elevation across a section of a topographic map.
Contouring: Elevation points have been determined using ground surveying techniques or GPS but contour lines need to be drawn in.