1. STRUCTURAL GEOLOGY LAB. STEREOGRAPHIC PROJECTION Dr. Masdouq Al-Taj

2. STEREOGRAPHIC PROJECTION
Stereographic Projection is a method of representing and interpreting orientational data (such as the dip of bedding plane or joint trace).

4. What can stereographic projection be used for?
Representing inclined beds.
Representing joint traces and fractures.
Solving apparent dip and true dip problems.
Determining Pole to plane.
Determine the attitude Rake (Pitch) on planes.
Determine the attitude Intersection of two planes
- Determine the attitude of Fold axis

6. Equal area net, ( Schimdt net) and stereonet

9. Overlay sheet
* A sheet of tracing paper is placed over the stereo net.
* Mark the Primitive circle, the north, the east, the south, and the west.

10. We use the 2D paper image to represent the 3D

12. 1. Plotting a Plane
-Mark off the strike of the plane on the circumference of the stereonet

13. * Rotate the overlay so that the strike line is north-south.
* Count in the dip angle along the equator from the East or West ( here, from E).

14. * Trace the appropriate great circle.
* It may happen that the great circle you need to plot does not coincide with a plotted great circle, in that case interpolate between the two nearest plotted circles.

15. * Return the overlay to its starting position.

16. 2. Plotting a line
Line:
plunge 30
trend 270

17. 2. Plotting a line
* Count off the trend around the circumference of the stereonet and mark it.

18. * Rotate the overlay so the trend lies along (E-W line for example).

19. * Count in along the E-W line and plot the point at the appropriate plunge.

20. * Rotate the overlay to its starting position.

21. Determine the attitude from two apparent dips

22. On a vertical face striking 285º (F1), the apparent dip of bedding (S) pitches 23º W. on a second vertical face (F2) striking due north the apparent dip of S pitches 16º S. What is the strike and dip of S.?

23. Determine attitude from strike and one apparent dip

24. 3. Pole to Plane

26. 3.1 How to determine rake (pitch)

27. Plot the following plane and the line lying within it
Plot the following plane and the line lying within it. Work out the trend and plunge of the line.
a-plane strike 30º, dip 45º W, line pitches 30º N.

28. 4. Angles between lines on a plane
Plane 0/50 E
Rake 62 N or
Line1:
P50
Line2:
Rake 80 S or
T110
P 50

29. 5. Determine the angle between
two planes

30. A vein (V) striking 342º and dipping 16º SW intersects a fault (F) striking 70º and dipping 45º S. What is the trend and plunge of the line of intersection of F and V?

31. 6. Determine the attitude of intersection between
two planes