Sterionet projection of 3-D structural data

• Stereonet basics

• plotting lines and planes

• Some example problem and solutions

Lower hemisphere of a sphere projected onto a flat

surface• a type of ‘3-dimensional protractor’

• allows analysis of structural data in 3-dimensions

• plot data on tracing paper overlaid on net

Elements of a Stereonet

Great Circles - large circular arcs running north-south

• equivalent to lines of longitude on globe

Small Circles - circular arcs running from east to west

• equivalent to lines of latitude on globe

Elements of a Stereonet

Primitive - the perimeter of the stereonet

• divided into 360 degrees at 2 ° increments

• perimeter indicates compass directions

Two types of stereonets used geology:

1. Schmidt net

2. Wulff net

Plot the planeStrike 30º, and Dip 60º