1. Mapping Earth’s surface
Field Maps
Mapping Earth’s surface

2. Field
A region in which there is a measurable quantity of some property at every point

3. examples Temperature Pressure Elevation Pollution Salinity gravity
Anything you can measure

4. isolines
Lines used to connect points of equal value in a field

6. Definitions Isotherm- lines which connect points of equal temperature
Isobar- lines connecting points of equal air pressure
Contour lines- lines connecting points of equal elevation

7. Zero foot contour line

8. 10 foot contour line

9. 20 foot contour line

10. 30 foot contour line

12. Interval
Change in value between isolines

13. Sometimes every line is not labeled
You have to figure out the interval

14. What is the value of A____ B_____ C_____ D____

15. Gradient Change in field value divided by distance
The formula is on the reference tables
Change in field value / distance

16. Gradient is greatest when the isolines are close together

17. On a contour map – close contour lines( high gradient) mean a steep slope widely spaced lines mean it is flatter

18. Contour lines bend upstream when they cross a river or a valley

19. Hachure marks
Comb like marks indicate a depression