Why do we use Stereonets?
The use of stereographic projection or stereonets is the bread and butter of structural analysis. They are used to work out many tricky three dimensional relationships; they are used to plot and represent all kinds of geometric data that you collect in the field; they are used in the analysis of that data.
What do Stereonets tell you?
Stereonets are a graphical tool representing the hemisphere of a globe, used for presentation, analysis and interpretation of three-dimensional directional data such as planes and lines. A plane will cut the sphere forming a line (great circle) on the sphere’s surface, whereas a line will generate a point.
What is a small circle on a stereonet?
The longitudes are planes that intersect in a common line (the N–S line), and thus appear as great circles in the stereonet. The projections of the latitudes, which are not planes but cones coaxial with the N–S line, are usually referred to as small circles (also their projections onto the stereonet).
What is a stereonet and how is it used?
What is a Stereonet? A stereonet is a tool used by geologists to analyze and interpret orientation data, such as planes and lines. The stereonet is a representation of the lower half of a sphere; however, because the stereonet is in 2D and a sphere is 3D all the 3D data needs to be projected into the 2D plane.
How do you find the trend and plunge of a stereonet?
The trend and plunge of this line can be read directly off the stereonet. Rotate the tracing paper until the intersection of the two planes lies on the east-west diameter of the stereonet. Measure the plunge of the line of intersection and add an arrow pointing in the direction of plunge.
How do you draw a Stereonet on tracing paper?
Lay the tracing paper over the stereonet and push the drawing pin through it so that the paper freely rotates round the net Draw the outline of the stereonet on to the tracing paper. Mark on north, south, east, west or 000°, 090°, 180°, 270° (figure 5).
What is an equal-area stereonet?
Stereographic Projection Equal-area stereonets are used in structural geology because they present no statistical bias when large numbers of data are plotted. On the equal-area net area is preserved so, for example, each 2 degrees polygon on the net has the same area.