Stereographic projections

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# Stereographic projections - PowerPoint PPT Presentation

## Stereographic projections

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##### Presentation Transcript

1. Stereographic projections

2. Need to project planes and lines • Orthographic projections (will use in lab a little, less widely applied) • Stereographic projection ( a form of spherical projections) - great deal of use in structural geology) -

3. Imagine planes or lines being projected onto a hemisphere • Lower hemisphere projection (always look from above) - convention • Can use azimuth (200 degrees) or geographic (S20W) with stereonets

4. A NS plane

5. ….and its pole

6. Orientation of a line

7. Can use to :1plot data and 2 calculate geometries For example: if you have two lines in a plane, one can easily determine the orientation of the plane

8. Exercisestoday • Plotting a plane • Plotting a line • Plotting a plane and a line contained in the plane • Finding apparent dips • Finding true strike and dip from apparent dips • Finding the plunge and trend of 2 intersecting planes • Determining the dihedral angle between planes

9. Read: • Text 691-720 - stereonets • 34-35 The San Manuel fault