1. Topographic Maps
Thursday, April 20, 2017

2. What is a topographic map?
A map that shows elevation changes for a specific region.

3. PURPOSE OF A TOPO MAP
A MAP PROVIDES INFORMATION ON THE EXSISTENCE OF, THE LOCATION OF, AND THE DISTANCES BETWEEN GROUND FEATURES.
SUCH AS
POPULATED PLACES
ROUTES OF TRAVEL
VARIATIONS IN TERRAIN
HEIGHTS OF NATURAL FEATURES
THE EXTENTOF VEGETATION COVER.

4. Contour Lines
Contour lines indicate elevation. They are the main part of any topographic map.

5. Regular Contour Lines
Regular contour lines are normally the thin brown lines which dominate a topo map.

6. Index Contour Lines
                                 
Are thicker and are labeled with an elevation.

7. Read Between the Lines!
The closer the lines are, the steeper the slope. The further, the more gentle

8.                                                                                      
Gradient

9. Contour
Each of these kids stands upon a different contour line. Yes, it’s imaginary.

10. Get the Idea?
With a regular map, we can get the outline of the island, but have no idea as to elevation change (topography).

11. All Elevation Below 10 Feet Under Water
Notice how the island has shrank a bit.

12. All Below 20’ Under!

13. All Below 30’ Under!

14. That’s The Idea!

15. Can You Guess The Elevation?

16. Contour Interval
Amount of elevation change between each contour line.

17. What is the Contour Interval?

18. Streams

19. Closer Look: Streams

20. Plateaus (Summits)

21. Note: Index, Depression

22. Note: Pond/Lake

23. Various Roads/Highways

24. HILL: AN AREA OF HIGH GROUND. FROM A HILLTOP, THE GROUND SLOPE DOWN IN
ALL DIRECTIONS.
Contour lines forming concentric circles.

25. VALLEY: A STRETCHED-OUT GROOVE IN THE LAND, USUALLY FORMED BY
STREAMS OR RIVERS.
Contour lines form U lines tend to parallel stream before crossing.
Contour line crossing streams ALWAYS point up stream.
Usually plenty of room to maneuver

26. RIDGE: A SLOPING LINE OF HIGH GROUND.
Contour lines forming a U or V; always point to high ground.

27. SADDLE: A DIP OR LOW POINT BETWEEN TWO AREAS OF HIGHER GROUND.
Between 2 hilltops or a break in the level crest of a ridge.
Saddle usually appear as an hourglass

28. DEPRESSION: A LOW PO INT IN THE GROUND
OR SINKHOLE. THEY ARE REPRESENTED BY CLOSE
CONTOUR LINES THAT HAVE TICK MARKS POINTING
TOWARD LOW GROUND.
In a depression there is higher ground on ALL sides

29. DRAW: A LESS DEVELOPED STEAM COURSE THAN A VALLEY.
THERE IS ESSENTIALLY NO LEVEL GROUND AND, THEREFORE,
LITTLE OR NO MANEUVER ROOM WITHIN ITS CONFINES. )
Contour lines are V Shaped with the points of the V POINTING UPHILL and UPSTREAM

30. SPUR: A SHORT, CONTINUOUS SLOPING LINE OF
HIGHER GROUND, NORMALLY JUTTING OUT FROM
THE SIDE OF A RIDGE.
FM 21-26: PAGE (FIGURE 10-23)
ususally formed by parrallel streams cutting down the side of a ridge
Contour lines shaped like U or Vs point AWAY From HIGH GROUND

31. CLIFF: A VERTICAL OR NEAR VERTICAL FEATURE; IT IS AN ABRUPT
CHANGE OF THE LAND. THE SLOPE IS SO STEEP THAT THE
CONTOUR LINES CONVERGE INTO ONE CONTOUR LINE OR THE LAST
CONTOUR LINE HAS TICK MARKS POINTING TO LOW GROUND.

33. CUT: A MAN-MADE FEATURE RESULTIING FROM CUTTING
THROUGH RAISED GROUND, USUALLY TO FROM A LEVEL BED
FOR A ROAD OR RAILROAD TRACK.
FILL: A MAN-MADE FEATURE RESULTING FROM FILLING A LOW
AREA, USUALLY TO FORM A LEVEL BED FOR A ROAD OR RAIL-
ROAD TRACK.