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.
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.
How is a plane plotted on a stereonet?
A stereonet should be visualized as the bottom half of a sphere. Planes intersect the sphere as great circles and lines intersect the sphere as points. Its helpful when starting out with stereonets to visualize the plane or line as it cuts through a 3-dimensional bowl (props may be helpful). the north pole of the net.
What is the difference between true dip and apparent dip?
Note: When a vertical cross-section is perpendicular to the strike of the beds, the inclination seen in the cross section is called the true dip. The apparent steepness in the direction of travel is the apparent dip in that direction (the cross-section direction). The hill is of course the geologic bedding plane.
What is lineation theory?
Lineation theory is a blend of explanations and speculations. The lineation perspective focuses on media violence while seeking to integrate thinking about the media industries, the content they produce, the effects of violent content on audience members and society, and the processes that lead to those effects.
What are the types of lineation?
There are several types of lineations, intersection lineations, crenulation lineations, mineral lineations and stretching lineations being the most common. Lineation field measurements are recorded as map lines with a plunge angle and azimuth.
What is a stereonet used for in geology?
A stereonet allows the stereographical projection of three-dimensional information onto a two-dimensional plane (usually as a piece of paper or computer image) and is used as a tool applied to a range of geological problems including the removal of structural tilt.
What is a stereonet projection?
Stereonets involve the projection of lines or planes onto a sphere; two alternative projections are commonly used, the upper and lower hemisphere respectively, with use depending on the discipline of interpretation. See example to the left. Projections are usually completed on pre-formatted nets.
What is a Stereonet on a graph?
A stereonet is the plane of projection of the lower half of this sphere – it is a lower hemisphere graph. Imagine a plane cutting through the centre of a lower hemisphere (figure 1a). The stereonet forms the surface of this lower hemisphere.
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.
