1. Topographic maps

2. Rules for contours The coastline is the 0th contour.
Positions on either side of a contour must have different values (one above and one below the contour).
Contours cannot cross one another.
Adjacent contours can be:
the same value
one contour interval different (higher or lower)
If adjacent contours have the same value the ground between them is either:
going up and then back down (a hill) or
going down a little and then back up (a depression).
Examine the surrounding contours to clarify which is the case.

3. Rules of contours The closer the contours, the steeper the slope.
A closed contour with tick marks indicates an enclosed depression. The tick marks are drawn on the “down” side (i.e., they point into the depression).
Not all depressions will have tick marks. Other features, such as a lake within the contour (depression) or adjacent hills, will clarify the situation.

4. Rules of contours
As you move perpendicularly away from a stream you must be going uphill
In a valley, the contours have a “v” shape with the point of the “v” pointing upstream.
On a profile, if you start and finish at the same elevation you must cross each contour an even number of times (“what goes up must come down”).
The last contour you pass on the way up (or down) is the first one you pass on the way down (or up, respectively)

5. 90
Reading contours
110
120
The contours “v” upstream (rule 10)
130
140
130 m
100 m < B < 110 m

6. Reading contours 35 X 30 25 … and here I am below X m …this must be…
But here I am above X m …
… and going down here …
“A” must clearly be higher than 35 … 35 X
And here I must be above 35 m. 30
So if I’m going up here…
… but it must also be lower than 40, or there would be another contour.
Here I must be below 35 m.
And “B” must be below 35 m but above 30 (or there would be a 30 m contour 25
35 m < A < 40 m
30 m < B < 35 m

7. Drawing Contours
30 m
20 m
10 m
0 m

8. Page 2 map The spot heights are in metres
Draw contours at 10 m intervals
Label the contours
The 180 m contour is drawn for you

9. Learning objects
Throughout the lab you can/will use various Flash™ animation files on aspects of topographic files.
They are not embedded in this PowerPoint file.
You should download them to you own computer for use at any time (including tests!)
They are on Socrates at:

10. Topographic map features
The LO shows you the Wolfville sheet – a typical 1: sheet
After opening the LO, mouse over any of the blued areas to show the features of the map in more detail.
Wolfville sheet LO

11. Scale
Scale is represented as a ratio and shows the relationship between a distance on the map and the distance on the ground.
1:20 indicates that one unit on the map is the equivalent to 20 units on the ground
1:50,000 is the scale of the map you’ll be looking at today
The bigger the second number the smaller the ratio (fraction) = small scale.
Scale LO

12. “North” On a standard map there are three north directions
Magnetic north (the direction to the magnetic north pole)
True north (the direction to the north geographic pole)
Grid north. On Canadian topo maps there is a reference grid that is not the same as the other north directions.

13. Declination True north = rotational pole.
Magnetic north pole is not the same as rotational pole. Currently the magnetic pole is in the Canadian Arctic. And it’s moving!
For most places on the globe there is a difference in direction between magnetic north and true north called the “magnetic declination”.

15. Declination
Declination in Eastern Canada is westward, in Western Canada it is eastward.
Shown on side of the map with a date and a rate of change (because mag. north pole “wanders”).
Allows you to calculate the declination at any given date.

16. Declination at Wolfville
Declination for Wolfville sheet in …
… 2011

17. Latitude and Longitude
Latitude = angular distance north (or south) of the equator.
Longitude = angular distance east or west of the “prime” meridian (Greenwich, England).
Halifax (Citadel), is approximately:
44° 38’ N and 63° 35’ W.

19. Latitude and Longitude
angular distance / linear distance is constant
1° latitude at equator = 1° latitude near poles (=111 km)
Longitude
angular distance / linear distance is NOT constant
1° longitude at equator is ca. 111 km.
1° longitude at Wolfville is ca. 81 km.
1° longitude at the north pole = 0 km

20. UTM grid
UTM grid designed so that the coordinates are the same linear distance in both directions (E-W and N-S).
UTM grids are the pale blue lines across the map.
UTM coordinates are in meters.

21. Determining UTM coordinates
Use the Learning Objects.
Easting LO
Northing LO

22. Drawing a cross section
Another Learning Object
Drawing a cross section LO

23. Using Google Earth™
Must download the Google Earth app. (Can’t use Google Earth view in Google Maps)
Most exercises involve dropping a pin and editing the coordinates of that pin, viewing its location, then changing the coordinate system being used by Google Earth (UTM to Lats and Longs or v.v.) and checking the information of the pin.

24. Legibility!!!!!!! Use a pencil! Use an eraser if you make a mistake!
These are NEW(ish) maps. Do NOT write on them!
Write in full sentences where it’s called for!

25. Questions?