1. Earth Science Presentation
Topographic Maps
Earth Science Presentation

2. Topography Topography
The shape of a surface, including its relief and the relative position of features.

3. Topography
Relief – refers to the difference in the highest and lowest elevations on the map.
An area with ‘low’ relief would be relatively flat,
An area with ‘high’ relief would be more rugged
HIGH RELIEF
LOW RELIEF

4. Topographic Maps Topographic Map
– a map that uses contour lines to show the changes of elevation at Earth’s surface;
- shows natural features such as lakes and streams
- shows cultural features such as cities, schools, dams, etc.

11. Topographic Maps Contour Lines
A line on a map that connects points of equal elevation.
Elevation refers to height above or below sea level.
Contour line
500
Index contour
400
Contour Interval = 20 feet

12. Topographic Maps Contour Interval – C.I.
The difference in elevation between two side-by-side contour lines.
1250 – 1200 = 50
50 feet every 5 lines
50/5 = 10 feet per line
Contour Interval = 10 ft.
1250
1200

13. Topographic Maps Index Contour
Every 5th line is darker than the others.
Indicates the elevation.
Helps determine the C.I.
1250
1200

14. Which slope is steepest?
Reading Contour Lines
1250
1200
1300
1250
1200
Which slope is steepest?

15. The closer the contours are to each other, the steeper the terrain.
Reading Contour Lines
1250
1300
1250
1200
1200
The closer the contours are to each other, the steeper the terrain.

16. Rules for Topo maps: 1. Contour lines close around hills and basins or depressions.
MAP VIEW
CROSS SECTION

17. Rules for Topo maps: 1. Contour lines close around hills and basins or depressions.
Hachures – short lines at right angles to the contour lines that indicate depressions.
Elevations of hachured contour lines are equal to the adjacent non-hachured line.
Usually indicate sink holes, quarries, or other areas of subsidence.
1220
1230
1230
1220
1210
1200

18. Rules for Topo Maps: 2. Contour lines never cross.
If they did it would mean a spot would have two elevations.

19. Rules for Topo Maps: 3. Contours form V’s that point upstream when crossing creeks.

20. Contour lines V upstream and water flows downstream.

22. Maps
Map Legend
Explanation of meaning of symbols used on a map.