Stereographic projections

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Stereographic projections
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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) -

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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

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A NS plane
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.and its pole
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Orientation of a line
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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
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Exercises today

• 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

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Read

• Text 691-720 - stereonets
• 34-35 The San Manuel fault