# Chapter 3 Topographic Maps

## Presentation on theme: "Chapter 3 Topographic Maps"— Presentation transcript:

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.