1. Intro to Maps
Since most of you got your lab books today, I’ll give this little introduction
Normally you are expected to study the lab before coming to class

2. Points of the Compass

3. Degrees, Minutes, Seconds
There are 360o degrees around a circle
Each degree can be divided into 60’ minutes
Each minute can be divided into 60” seconds

4. X

5. Global Positioning
We can use lines parallel to the equator and lines between the poles to position objects on the surface
30oN Lat 60oW Long

6. Latitude 90 degrees North Latitude 0 degrees Latitude (Equator)
90 degrees South Latitude

8. 0 degrees Longitude
at Greenwich, England

10. 40o0’0”N 74o0’0”W X

11. Topo Maps Types of contours

12. Every point on a contour line represents the exact same elevation
500
Use the scale to measure distance
UNITS MUST MATCH
Contour Interval,
Scale, Series, Sectors
Every point on a contour line represents the exact same elevation
Contour lines can never cross one another. Exception:
Moving from one contour line to another always indicates a change in elevation.
On a hill with a consistent slope, there are always four intermediate contours for every index contour.
The closer contour lines are to one another, the steeper the slope

13. Contour Rules
The rule of V's: sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of erosion.
The rule of O's: closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area. If a loop instead represents a depression, some maps note this by short lines radiating from the inside of the loop, called "hachures".
Spacing of contours: (repeat) close contours indicate a steep slope; distant contours a shallow slope.

15. Making a Topo Map
Suppose you measured elevations and positions with your GPS
Use the Latitudes and Longitudes you measured and lay out the elevations
Pick an elevation you will draw

16. Making a Topo Map Pick an elevation you will draw
Find a place with two nearby elevations, one larger, one smaller

17. Making a Topo Map Pick an elevation you will draw
Find a place with two nearby elevations, one larger, one smaller
Place a X where the elevation would lie

18. Making a Topo Map Pick an elevation you will draw
Find a place with two nearby elevations, one larger, one smaller
Place a X where the elevation would lie
Repeat and connect the X’s

19. Drawing a Cross-Section (Elevation Profile)
Hold a sheet of paper along line
Mark contours
Write elevation next to each

20. Make a vertical scale (usually exaggerated)
Make a dot at each contour at its elevation

21. Connect the dots for your elevation profile
Later we will use these to make geologic cross sections
Topo Maps, Air Photo Pairs, GPS, etc

22. Township and Range System
Washington and Oregon Initial Point
Initial Point
Meridian vertical
Baseline horizontal
Township 36 mi2
Range distance E or W refer. principal meridian, ea. 6 miles
Section 1 mi2
Section numbers wind back and forth,
edges always have same matching number