Stereographic projections Flashcards
What is another name is stereographic projections?
Stereonets
What are stereonets?
the simplest and most effective tools to record, plot, and analyse 3-D data on 2-D systems
What do stereonets allow for?
Record and easily view thousands of data in one small plot
What planar geological features can be plotted on stereonets?
Bedding planes
Fault planes
Axial planes of folds
Veins
Joints
Cleavage/foliation
What linear geological features can be plotted on stereonets?
Fault plane striations (e.g., slickenlines)
Fold axes
Hinge lines
Paleocurrent directions
how are linear structures measured?
Plunge (angle of line horizontal)- 2 digits
Plunge azimuth (measured down)- 3 digits
How are planar structures measured?
Strike (angle of horizontal line on the plane to north; 3 digits)
Dip (angle of plane from horizontal; 2 digits)
Dip direction (direction of maximum inclination of the plane)
What would the stereonet be like on a sphere split at its equator?
stereonet would be the projection of lower hemisphere onto equator plane (projector plane)
What is the Zenith?
The view point for the projection of a stereonet
How is the projection plane divided?
Grid
Small circles = latitude
Large circles = longitude
How are strike and azimuths read of a stereonet?
outer circle like on a compass
What is the spacing like between longitude and latitude?
2*
What is the primitive on a stereonet?
The outer edge of the sphere
How are dips and plunges read off a stereonet?
read along lines connecting primitive to centre
How will 2 planes interect?
Always along a line
