Presentation on theme: "Chapter 3 Topographic Maps Topography Means: “Shape of the land”"— 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 – 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! A B Scale (km) 1km Elevation Change (rise)= Distance (run)=
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.