Transcript Slide 1

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